Patent Publication Number: US-2022230644-A1

Title: Methods and devices for generation and processing of modified bitstreams

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 62/887,111, filed Aug. 15, 2019 and European Patent Application No. 19191919.0, filed Aug. 15, 2019, each of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNOLOGY 
     The present disclosure relates generally to a method and source device for generating a modified bitstream, and more specifically to generating a modified bitstream by embedding payload of additional media data into a bitstream including coded media data. The present disclosure also relates to a method and sink device for processing said modified bitstream. 
     While some embodiments will be described herein with particular reference to that disclosure, it will be appreciated that the present disclosure is not limited to such a field of use and is applicable in broader contexts. 
     BACKGROUND 
     Any discussion of the background art throughout the disclosure should in no way be considered as an admission that such art is widely known or forms part of common general knowledge in the field. 
     Recent efforts have been made to establish AAC-family based codecs as part of the Bluetooth (BT) Ecosystem. In this context, the Bluetooth SIG may define use-cases which require to pass-through bitstreams received on, for example, a mobile device (BT source) to connected speaker systems (BT sink). As the data-format used from the service throughout the BT endpoint may be coded audio, there is no easy way of conveying earcons and/or system sounds from the mobile device to the BT speaker. Such earcons may include ringtones, mail notification sounds, key-press sounds and so on. 
     In currently deployed systems, the audio received from a service is usually decoded in the device into the uncompressed domain (PCM), where it can be modified and/or mixed. If a pass-through mode of operation is enabled, there may be no easy possibility on the BT-source device in order to enable and/or mix system sounds into the experience which is transported from BT source to BT sink. 
     One possibility to overcome this limitation by still enabling pass-through, would be to open an additional link between both devices. However, this setup has the drawback that it needs an additional link and encoder-decoder pair of a Bluetooth-codec in order to work. This comes with unwanted additional system complexity and burdens both the BT source and sink device with additional computational complexity, which may cost battery as well. 
     Accordingly, there is an existing need for simultaneous generating and processing of earcons and/or system sounds in parallel to the media content via bitstreams, in particular via MPEG-D USAC-based bitstreams. 
     SUMMARY 
     In accordance with a first aspect of the present disclosure there is provided a method for generating a modified bitstream by a source device. The source device may comprise a receiver, and an embedder. The method may include the step of a) receiving, by the receiver, a bitstream including coded media data. The method may further include the step of b) generating, by the embedder, payload of additional media data and embedding the payload in the bitstream, for obtaining, as an output from the embedder, a modified bitstream including the coded media data and the payload of the additional media data. And the method may include the step of c) outputting the modified bitstream to a sink device. 
     Configured as proposed, the method allows to insert system sounds or Earcons into a bitstream that includes coded media data and that is passed through by a source device (e.g., a Bluetooth source device, such as a mobile phone) for a sink device (e.g., a Bluetooth sink device, such as a Bluetooth loudspeaker). This enables to pass system sounds/Earcons to the sink device without having to establish an additional connection between the source device and the since device, and without having to decode and re-encode the coded media data. Moreover, the method enables simultaneous processing of the system sounds/Earcons and the coded media data. 
     In some embodiments, the additional media data may be played back by the sink device. 
     In some embodiments, the additional media data may be played back by the source device. 
     In some embodiments, the coded media data in the received bitstream may be passed through the source device to the sink device via the modified bitstream. 
     In some embodiments, step b) may further include generating information on the additional media data and embedding the information in the bitstream. 
     In some embodiments, the generated information may include one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data. 
     In some embodiments, step b) may further include generating information relating to a relative gain between the coded media data and the additional media data and embedding the information relating to the relative gain in the bitstream. 
     In some embodiments, the modified bitstream may be an MPEG-D USAC-based bitstream. Accordingly, system sounds/Earcons can be transmitted to the sink device as part of the coded bitstream when the source device is in pass-through mode for media data that is coded in MPEG-4 audio format, without need to decode and re-encode the media data. 
     In some embodiments, the generated payload may be embedded in the bitstream by transporting the payload in the (modified) bitstream via a USAC-type bitstream extension mechanism. 
     In some embodiments, the generated information and/or the generated information relating to the relative gain may be embedded in the modified bitstream by transporting the generated information and/or the generated information relating to the relative gain in the (modified) bitstream via the USAC-type bitstream extension mechanism. 
     In some embodiments, the USAC-type bitstream extension mechanism may be a new USAC-type bitstream extension element including a unique identifier. 
     In some embodiments, in step c) the modified bitstream may be output to the sink device via a Bluetooth connection. 
     In some embodiments, the additional media data may be compressed media data or uncompressed media data. 
     In some embodiments, the uncompressed media data may be PCM data generated at the source device. 
     In some embodiments, the generation of the PCM data may be based on a user input. 
     In some embodiments, the PCM data may include one or more of earcon-data and system sounds data. 
     In some embodiments, the compressed data may be in SBC format or in an aptX-based format. 
     In accordance with a second aspect of the present disclosure there is provided a method for processing a modified bitstream by a sink device. The sink device may comprise a receiver, a bitstream parser The method may include the step of a) receiving, by a receiver, a modified bitstream including coded media data and payload of additional media data. The method may further include the step of b) parsing, by a bitstream parser, the modified bitstream into the coded media data and the payload of additional media data. The method may further include the step of c) core decoding, by a core decoder, the coded media data to obtain core decoded media data. The method may further include the step of d) mixing, by a mixer, the core decoded media data and the additional media data to obtain an output signal. And the method may include the step of e) outputting the output signal. 
     In some embodiments, the modified bitstream may further include information on the additional media data, and the method may further include, after step a) and before step b), a step of processing the modified bitstream may be based on the information. 
     In some embodiments, the information may include one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data. 
     In some embodiments, the modified bitstream may further include information relating to a relative gain between the coded media data and the additional media data, and mixing in step d) the core decoded media data and the additional media data may be based on the information relating to the relative gain. 
     In some embodiments, the method may further include the step of processing, by a processing unit, the additional media data prior to mixing the core decoded media data and the additional media data. 
     In some embodiments, processing the additional media data may include one or more of resampling, delay adaption and loudness processing. 
     In some embodiments, the additional media data may be compressed media data and the method may further include the step of decoding, by a decoder, the compressed media data to obtain decoded additional media data, and in step d) the decoded additional media data may be mixed with the core decoded media data. 
     In some embodiments, the compressed media data may be in SBC format or in an aptX-based format. 
     In some embodiments, the additional media data may be uncompressed media data, and in step d) the uncompressed additional media data may be mixed with the core decoded media data. 
     In some embodiments, the modified bitstream may be an MPEG-D USAC-based bitstream. 
     In some embodiments, the modified bitstream may include a USAC-type bitstream extension mechanism, and parsing in step b) may further be based on identifying the USAC-type bitstream extension mechanism in the modified bitstream. 
     In some embodiments, the USAC-type bitstream extension mechanism may be a new USAC-type bitstream extension element including a unique identifier. 
     In accordance with a third aspect of the present disclosure there is provided a source device for generating a modified bitstream. The device may include a) a receiver configured to receive a bitstream including coded media data. The device may further include b) an embedder configured to generate payload of additional media data and to embed the generated payload in the bitstream to obtain a modified bitstream including the coded media data and the payload of the additional media data. And the device may include c) a control unit configured to output the modified bitstream to a sink device. 
     In some embodiments, the embedder may further be configured to generate information on the additional media data and to embed the information in the bitstream. 
     In some embodiments, the embedder may further be configured to generate information relating to a relative gain between the coded media data and the additional media data and to embed the information relating to the relative gain in the bitstream. 
     In some embodiments, the modified bitstream may be an MPEG-D USAC-based bitstream. 
     In some embodiments, the additional media data may be compressed media data or uncompressed media data. 
     In some embodiments, the uncompressed media data may be PCM data generated at the source device. 
     In some embodiments, the generation of the PCM data may be based on a user input. 
     In some embodiments, the PCM data may include one or more of earcon-data and system sounds data. 
     In some embodiments, the compressed media data may be in SBC format or in an aptX-based format. 
     In accordance with a fourth aspect of the present disclosure there is provided a sink device for processing a modified bitstream. The device may include a) a receiver configured to receive a modified bitstream including coded media data and payload of additional media data. The device may further include b) a bitstream parser configured to parse the modified bitstream into the coded media data and the payload of the additional media data. The device may further include c) a core decoder configured to core decode the coded media data to obtain core decoded media data. The device may further include d) a mixer configured to mix the core decoded media data and the additional media data to obtain an output signal. And the device may include e) a control unit configured to output the output signal. 
     In some embodiments, the device may further include a processing unit configured to process the additional media data prior to mixing the core decoded media data and the additional media data. 
     In some embodiments, the additional media data may be uncompressed media data, and the mixer may be configured to mix the core decoded media data and the uncompressed additional media data. 
     In some embodiments, the additional media data may be compressed media data and the device may further include a decoder to decode the compressed media data to obtain decoded additional media data, and the mixer may be configured to mix the core decoded media data and the decoded additional media data. 
     In some embodiments, the modified bitstream may further include information on the additional media data, and the sink device may be configured to process the modified bitstream based on the information. 
     In some embodiments, the modified bitstream may further include information relating to a relative gain between the coded media data and the additional media data, and the mixer may further be configured to mix the core decoded media data and the additional media data based on the information relating to the relative gain. 
     In some embodiments, the core decoder may be an MPEG-D USAC-based decoder. 
     In accordance with a fifth aspect of the present disclosure there is provided a system of a source device for generating a modified bitstream, wherein the source device includes one or more processors configured to perform a method for generating a modified bitstream on said source device and a sink device for processing a modified bitstream, wherein the sink device includes one or more processors configured to perform a method for processing a modified bitstream on said sink device. 
     In accordance with a sixth aspect of the present disclosure there is provided a computer program product comprising a computer-readable storage medium with instructions adapted to cause the device to carry out a method for generating a modified bitstream on a source device when executed by a device having processing capability. 
     In accordance with a seventh aspect of the present disclosure there is provided a computer program product comprising a computer-readable storage medium with instructions adapted to cause the device to carry out a method for processing a modified bitstream on a sink device when executed by a device having processing capability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  illustrates a flow diagram of an example of a method for generating a modified bitstream on a source device. 
         FIG. 2  illustrates a flow diagram of a further example of a method for generating a modified bitstream on a source device. 
         FIG. 3  illustrates a flow diagram of an example of a method for processing a modified bitstream on a sink device. 
         FIG. 4  illustrates a flow diagram of a further example of a method for processing a modified bitstream on a sink device. 
         FIG. 5  illustrates a flow diagram of yet a further example of a method for processing a modified bitstream on a sink device. 
         FIG. 6  illustrates a flow diagram of yet a further example of a method for processing a modified bitstream on a sink device. 
         FIG. 7  illustrates an example of a source device for generating a modified bitstream. 
         FIG. 8  illustrates a further example of a source device for generating a modified bitstream. 
         FIG. 9  illustrates an example of a sink device for processing a modified bitstream. 
         FIG. 10  illustrates a further example of a sink device for processing a modified bitstream. 
         FIG. 11  illustrates yet a further example of a sink device for processing a modified bitstream. 
         FIG. 12  illustrates yet a further example of a sink device for processing a modified bitstream. 
         FIG. 13  illustrates an example of a device having one or more processors. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Generation and Processing of MPEG-D USAC-Based Modified Bitstreams 
     In the following, methods and devices will be described for generation and processing of modified MPEG-D USAC-based bitstreams. Within this document, MPEG-D USAC-based bitstreams may refer to bitstreams compatible with the standard set out in ISO/IEC23003-3 MPEG audio technologies-Part 3: Unified speech and audio coding (hereinafter “MPEG-D USAC”), and all future editions, versions and amendments therein. Hereinafter references to MPEG-D USAC-based bitstreams shall mean bitstreams that are compatible with one or more requirements described in the MPEG-D USAC standard. By the described methods and devices, additional media data, being uncompressed or compressed media data, may be transported and processed together with coded media data delivering media content. This may enable to transmit and process earcon and/or system sounds data without the additional burden of system- and computational complexity in both, source and sink device. 
     Additionally, it may be possible to control all settings (e.g. level of system sounds, DRC etc.) on both the source device and the sink device using a same mechanism and bitstream variables. This means, a relative gain (or mixing gain) used by an embedder of the source device may be exactly the same as a control parameter used by a mixer of the sink device. 
     Generating a Modified Bitstream on a Source Device 
     Referring to the example of  FIG. 1 , an example of a method for generating a modified bitstream on a source device is illustrated. In step S 100  a bitstream including coded media data (to be core decoded by a sink device as detailed below) may be received by a receiver of the source device. The bitstream including the coded media data may be received, for example, from one or more media server. The coded media data may include coded speech and audio data. The coded speech and audio data may be compliant with the MPEG-D USAC standard as given above. The bitstream may, for example, deliver audio content to be played back by a sink device connected to the source device. The source device is not limited. For example, the source device may be a mobile device, including one or more of a mobile phone, a smart watch, a laptop and a tablet pc including convertibles. 
     Referring again to the example of  FIG. 1 , in step S 101 , payload of additional media data (i.e. other than and in addition to the coded media data, e.g. additional audio data) may be generated and embedded in the bitstream by an embedder. 
     The additional media data generated in step S 101  is to be mixed with the media data by (at a side of) the sink device. Advantageously, this enables mixing of the additional media data with the media data at the sink device side. 
     The coded media data and the additional media data are different (e.g. type of) media data. For example, as explained below, the coded media data and the additional media data may have different format. The coded media data and the additional media data include different type of media content. The coded media data may include main audio content, e.g., music, audio, etc. The additional media data may include secondary audio content, e.g., earcons, system sounds, key press sounds, e-mail notification sounds, etc. The main audio content and the secondary audio content may be played back by the sink device. Alternatively or additionally, the main audio content and the secondary audio content may be played back by the source device. 
     In an embodiment, the coded media data may be played back by the source device, the sink device or both the source device and the sink device. 
     In an embodiment, the additional media data may be played back by the source device, the sink device or both the source device and the sink device. 
     In an embodiment, the additional media data may be compressed media data (to be decoded by a sink device as detailed below to obtain decoded additional media data) or uncompressed media data. While the uncompressed media data is not limited, in an embodiment, the uncompressed media data may be PCM data generated at the source device. While the generation of PCM data is also not limited, in an embodiment, the generation of the PCM data may be based on a user input. The user input may be, for example, a key-press. Alternatively, or additionally, the generation of the PCM data may be facilitated at the source device independent of a user input, e.g. based on an email notification. In an embodiment, the PCM data may include one or more of earcon-data and system sounds data. Also, while the format of the compressed media data is not limited, the format may belong to the Bluetooth ecosystem. In an embodiment, the compressed media data may be in SBC format or in an aptX-based format. 
     Referring again to the example of  FIG. 1 , in step S 102 , as an output from the embedder, a modified bitstream including the coded media data and the payload of additional media data may be obtained. In step S 103  the modified bitstream may then be output to a sink device. 
     The coded media data in the received bitstream is passed through the source device to the sink device via the modified bitstream. The coded media data as received from the source device is embedded in the modified bitstream and outputted to the sink device. 
     Advantageously, generating (at the source device) and outputting the modified bitstream to the sink device streamlines mixing of the media data with the additional media data at the side of the sink device. A single bitstream is used by the source device to embed and transport the media data and the additional media data to the sink device, thereby a single channel/connection can be used between the source and the sink device. Furthermore, no additional decoders and/or encoders are present in the source device to, e.g., decode and re-encode the coded media data. No additional mixers are used in the source device to, e.g., mix decoded coded media data with the additional media data. 
     In an embodiment, the modified bitstream may be output to the sink device via a Bluetooth connection. In other words, the source device may be connected to a sink device via a Bluetooth connection. For example, earphones connected to a mobile phone via Bluetooth. 
     In general, the proposed technique and implementations and examples thereof described throughout this disclosure involve generating and outputting a modified bitstream to the sink device facilitates transmission of the payload of additional media data (e.g., system sounds/Earcons) to the sink device, e.g, when the source device is in a pass-through mode of operation. In other words, the payload of additional media data may be generated and embedded into the received bitstream including the coded media data to generate the modified bitstream without, for example, decoding and re-encoding the coded media data. Likewise, the additional media data can be passed to the sink device without need to establish an additional connection between the source device and the since device. As a further advantage, the proposed technique enables simultaneous processing of the additional media data and the coded media data. 
     Referring now to the example of  FIG. 2 , a further example of a method for generating a modified bitstream on a source device is illustrated. The example of  FIG. 2  differs from the example of  FIG. 1  detailed above in that in step S 101  further information on the additional media data may be generated (e.g. as part of metadata) and embedded in the bitstream (as indicated by the dashed line). In an embodiment, the generated information may include one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data. The generated information may be utilized by the sink device to process the received modified bitstream as detailed below. The information on the configuration of the additional media data may, for example, include information on a sampling rate which may enable to decide at the side of the sink device as to whether the additional media data may need to be resampled prior to mixing. Alternatively, or additionally, the information on the configuration of the additional media data may further include, for example, information on a channel mode which may enable to decide at the side of the sink device if the additional media data may need to be downmixed/upmixed prior to mixing. The information on a default loudness value may include, for example, a measured loudness as according to one of the methods specified in ITU-R BS.1770-4. The measured loudness may enable to decide at the side of the sink device at which level the additional media data may be mixed with the core decoded media data. Further, the information on the type of the additional media data may indicate at the side of the sink device as to whether the additional media data may need to be decoded, for example, as to whether the additional media data may be uncompressed or compressed media data. 
     Alternatively, or additionally, step S 101  may further include generating information relating to a relative gain between the coded media data and the additional media data (e.g. also as part of metadata) and embedding the information relating to the relative gain in the bitstream (as indicated by the dashed line). The relative gain between the coded media data and the additional media data may be used by the sink device to generate an output signal based on the received modified bitstream as detailed below. In this, source device and sink device may use the same relative gain value. For example, if the source device is a mobile phone, optimal system sound mixing settings may be automatically determined based on an estimated loudness ratio of the system sounds and coded media data content. For example, the relative gain value may include a mixing gain value and/or an attenuation gain value which may be used by the mixer of the sink device. By including this information into the bitstream, it can be ensured that the additional media data can be mixed with the coded media data, after decoding, in an appropriate manner, and cases in which the additional media data is rendered at an inappropriate sound level compared to the coded media data can be avoided. In general, by including the information on the additional media data into the bitstream, the source device is given control over the processing (e.g., including rendering) of the additional media data at the sink device. This ensures appropriate rendering of the additional media data at the sink device. 
     While the format of the modified bitstream is not limited, in an embodiment, the modified bitstream may be an MPEG-D USAC-based bitstream (i.e. an MPEG-D USAC standard compliant bitstream). Referring to the example of  FIG. 1 , in an embodiment, the generated payload may be transported in the modified bitstream via a USAC-type bitstream extension mechanism. Referring to the example of  FIG. 2 , in an embodiment, the generated information and/or the generated information relating to the relative gain may be transported in the modified bitstream via the USAC-type bitstream extension mechanism. 
     As an example, the following syntax may be used in order to embed the generated payload of the additional media data, the generated information on the additional media data and/or the generated information relating to the relative gain into the modified MPEG-D USAC-based bitstream. 
     Syntax of System_Sound_Info( ) 
     Top level syntactic element to convey the generated payload of the additional media data, the generated information (information on the additional media data) and/or the generated information relating to the relative gain. 
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                 system_sound_info( ) { 
               
               
                   
                  // Configuration 
               
            
           
           
               
               
               
               
            
               
                   
                  system_sound_config_present; 
                 1 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                  if(system_sound_config_present) { 
               
               
                   
                   static_config = system_sound_config( ) 
               
               
                   
                  } 
               
               
                   
                  // Payload 
               
            
           
           
               
               
               
               
            
               
                   
                  system_sound_payload_present; 
                 1 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                  if(system_sound_payload_present) { 
               
               
                   
                   system_sound_payload(config) 
               
               
                   
                  } 
               
               
                   
                 } 
               
               
                   
                   
               
            
           
         
       
     
     Semantics of System_Sound_Info( ) 
       
     
       
         
           
               
               
             
               
                   
               
               
                 Element 
                 Description 
               
               
                   
               
             
            
               
                 system_sound_config_present 
                 If set, system_sound_config is 
               
               
                   
                 present in the stream 
               
               
                 system_sound_payload_present 
                 If set, system_sound_payload is 
               
               
                   
                 present in the stream 
               
               
                   
               
            
           
         
       
     
     Syntax of System_Sound_Config( ) 
       
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                 system_sound_config( ) { 
               
            
           
           
               
               
               
               
            
               
                   
                  num_sys_sounds; 
                 8 
                 uimsbf 
               
            
           
           
               
               
            
               
                   
                  for(s = 0; s &lt;= num_sys_sounds; ++s) { 
               
            
           
           
               
               
               
               
            
               
                   
                   sys_sound_id[s]; 
                 8 
                 bslbf 
               
               
                   
                   sys_sound_type[s]; 
                 4 
                 bslbf 
               
               
                   
                   reserved; 
                 1 
                 bslbf 
               
               
                   
                   sys_sound_panning[s]; 
                 8 
                 uimsbf 
               
               
                   
                   sys_sound_gain_present; 
                 1 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                   if(sys_sound_gain_present) { 
               
            
           
           
               
               
               
               
            
               
                   
                    sys_sound_gain[s] 
                 8 
                 uimsbf 
               
            
           
           
               
               
            
               
                   
                   } 
               
            
           
           
               
               
               
               
            
               
                   
                   sys_sound_loudness_present; 
                 1 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                   if(sys_sound_loudness_present) { 
               
            
           
           
               
               
               
               
            
               
                   
                    sys_sound_loudness[s]; 
                 8 
                 uimsbf 
               
            
           
           
               
               
            
               
                   
                   } 
               
            
           
           
               
               
               
               
            
               
                   
                   sys_sound_attenuation_gain_present; 
                 1 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                   if(sys_sound_attenuation_gain_present) { 
               
            
           
           
               
               
               
               
            
               
                   
                    sys_sound_attenuation_gain[s]; 
                 8 
                 uimsbf 
               
            
           
           
               
               
            
               
                   
                   } 
               
               
                   
                   switch(sys_sound_type[s]) { 
               
               
                   
                   case SYS_PCM: 
               
               
                   
                    pcm_data_config( ); 
               
               
                   
                    break; 
               
               
                   
                   case SYS_SBC: 
               
               
                   
                    sbc_data_config( ); // Placeholder: Not defined here 
               
               
                   
                    break; 
               
               
                   
                   case SYS_APTX: 
               
               
                   
                    aptx_data_config( ); // Placeholder: Not defined here 
               
               
                   
                    break; 
               
               
                   
                   default: 
               
               
                   
                    // Not supported 
               
               
                   
                    break; 
               
               
                   
                   } 
               
               
                   
                  } 
               
               
                   
                 } 
               
               
                   
                   
               
            
           
         
       
     
     Semantics of System_Sound_Config( ) 
       
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Semantics of system_sound_config( ) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Element 
                 Description 
               
               
                   
               
               
                 num_sys_sound 
                 The number of system sounds embedded in the 
               
               
                   
                 stream minus 1 
               
               
                 sys_sound_id 
                 Unique identifier for each system sound in the stream 
               
               
                 sys_sound_type 
                 System sound encoding type according to: 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 sys_sound_type 
                   
                 Encoding 
               
               
                   
                   
               
               
                   
                 0 
                 SYS_PCM 
                 PCM 
               
               
                   
                 1 
                 SYS_SBC 
                 SBC 
               
               
                   
                 2 
                 SYS_APTX 
                 AptX 
               
               
                   
                 3 . . . 15 
                   
                 reserved 
               
            
           
           
               
               
            
               
                 sys_sound_panning 
                 Panning of the system sound: 
               
               
                   
                 (sys_sound_panning * 360)/(2 8  − 1), 0° 
               
               
                   
                 front center, positive values to the left 
               
               
                 sys_sound_gain_present 
                 If set, a gain value is available for the 
               
               
                   
                 corresponding system sound ID 
               
               
                 sys_sound_gain 
                 Absolute gain value for system sound audio 
               
               
                   
                 signal (default: 0 dB) 
               
               
                 sys_sound_loudness_present 
                 If set, a loudness value is available for 
               
               
                   
                 the corresponding system sound ID 
               
               
                 sys_sound_loudness 
                 Loudness value for the system sound audio signal 
               
               
                 sys_sound_attenuation_gain_present 
                 If set, an attenuation gain value is available 
               
               
                   
                 for the corresponding system sound ID 
               
               
                 sys_sound_attenuation_gain 
                 Attenuation gain (“ducking”) to be applied 
               
               
                   
                 on the main audio program, default 0 dB 
               
               
                   
               
            
           
         
       
     
     Syntax of System_Sound_Payload( ) 
       
     
       
         
           
               
             
               
                   
               
             
            
               
                 system_sound_payload(config) { 
               
               
                  // config of type system_sound_config 
               
               
                  for(s = 0; s &lt;= config.num_sys_sounds; ++s) { 
               
            
           
           
               
               
               
            
               
                   if(!sys_sound_active) { 
                 1 
                 bslbf 
               
            
           
           
               
            
               
                    continue; 
               
               
                   } 
               
               
                   switch(config.sys_sound_type[s]) { 
               
               
                   case SYS_PCM: 
               
               
                    pcm_data_payload( ); 
               
               
                    break; 
               
               
                   case SYS_SBC: 
               
               
                    sbc_data_payload( ); // Placeholder: Not defined here 
               
               
                    break; 
               
               
                   case SYS_APTX: 
               
               
                    aptx_data_payload( ); // Placeholder: Not defined here 
               
               
                    break; 
               
               
                   default: 
               
               
                    break; 
               
               
                   } 
               
               
                  } 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     Semantics of System_Sound_Payload( ) 
       
     
       
         
           
               
               
             
               
                   
               
               
                 Element 
                 Description 
               
               
                   
               
             
            
               
                 sys_sound_active 
                 System sound is active and shall be decoded 
               
               
                   
               
            
           
         
       
     
     Syntax of Pcm_Data_Config( ) 
       
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                 pcm_data_config( ) { 
               
            
           
           
               
               
               
               
            
               
                   
                  pcm_num_channels; 
                  8 
                 uimsbf 
               
               
                   
                  pcm_endianness; 
                  1 
                 bslbf 
               
               
                   
                  pcm_align_audio; 
                  1 
                 bslbf 
               
               
                   
                  reserved; 
                  1 
                 bslbf 
               
               
                   
                  pcm_sample_rate_index; 
                  5 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                  if(0x1f == pcm_sample_rate_index) { 
               
            
           
           
               
               
               
               
            
               
                   
                   pcm_sample_rate; 
                 24 
                 uimsbf 
               
            
           
           
               
               
            
               
                   
                  } 
               
            
           
           
               
               
               
               
            
               
                   
                  pcm_frame_size_index; 
                  3 
                 bslbf 
               
               
                   
                  reserved; 
                  1 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                  if(0x06 == pcm_frame_size_index) { 
               
            
           
           
               
               
               
               
            
               
                   
                   pcm_frame_size; 
                 16 
                 uimsbf 
               
            
           
           
               
               
            
               
                   
                  } 
               
            
           
           
               
               
               
               
            
               
                   
                  pcm_data_format_index; 
                  4 
                 bslbf 
               
            
           
           
               
               
            
               
                   
                 } 
               
               
                   
                   
               
            
           
         
       
     
     Semantics of Pcm_Data_Config( ) 
       
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Semantics of pcm_data config( ) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Element 
                 Description 
               
               
                   
               
               
                 pcm_num_channels 
                 Number of PCM channels 
               
               
                 pcm_endianness 
                 0: big endian, 1: little endian 
               
               
                 pcm_align_audio 
                 If set, PCM data should be delay aligned 
               
               
                   
                 with the main audio program before 
               
               
                   
                 mixing, controls delay adaption. 
               
               
                 pcm_sample_rate_index 
                 Sampling rate index as defined in ISO/ 
               
               
                   
                 IEC14496-3 and ISO/IEC 23003-3, resp. 
               
               
                 pcm_sample_rate 
                 PCM sampling rate 
               
               
                 pcm_frame_size_index 
                 Index into frame size table below: 
               
            
           
           
               
               
               
            
               
                   
                 pcm_frame_size_index 
                 Number of samples per frame 
               
               
                   
                 0x00 
                 outputFrameLength as defined in 
               
               
                   
                   
                 ISO/IEC 23003-3 
               
               
                   
                 0x01 
                 768 
               
               
                   
                 0x02 
                 960 
               
               
                   
                 0x03 
                 1024 
               
               
                   
                 0x04 
                 2048 
               
               
                   
                 0x05 
                 4096 
               
               
                   
                 0x06 
                 Frame size signaled in 
               
               
                   
                   
                 pcm_data_config 
               
               
                   
                 0x07 
                 reserved 
               
            
           
           
               
               
            
               
                 pcm_frame_size 
                 Frame size in samples per channel 
               
               
                 pcm_data_format_index 
                 Index into format table below 
               
               
                   
                 (i: integer, f: floating point) 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Index 
                 Encoding 
                 Bits per Sample (bps) 
               
               
                   
                   
               
               
                   
                 0 
                 LPCM_16i 
                 16 
               
               
                   
                 1 
                 LPCM_24i 
                 24 
               
               
                   
                 2 
                 LPCM_32i 
                 32 
               
               
                   
                 3 
                 LPCM_32f 
                 32 
               
               
                   
                 4 
                 LPCM_64f 
                 64 
               
               
                   
                 5 
                 mu-law 
                 8 
               
               
                   
                 6 
                 A-law 
                 8 
               
               
                   
                 7 . . . 15 
                 reserved 
               
               
                   
                   
               
            
           
         
       
     
     Syntax of Pcm_Data_Payload( ) 
       
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                 pcm_data_payload( ) { 
               
            
           
           
               
               
               
            
               
                   
                  for(i = 0; i &lt; pcm_frame_size; ++i) { 
                  (NOTE 1) 
               
            
           
           
               
               
            
               
                   
                   for(ch = 0; ch &lt; pcm_num_channels) { 
               
            
           
           
               
               
               
            
               
                   
                    pcm_sample; 
                 bps bslbf (NOTE 2) 
               
            
           
           
               
               
            
               
                   
                   } 
               
               
                   
                  } 
               
               
                   
                 } 
               
               
                   
                   
               
               
                   
                 (NOTE 1): 
               
               
                   
                 ‘pcm_frame_size’ is either derived from ‘pcm_frame_size_index’ or set directly in ‘pcm_data_config’ 
               
               
                   
                 (NOTE 2): 
               
               
                   
                 Bits per sample (bps) can be derived from ‘pcm_data_format_index’ 
               
            
           
         
       
     
     Semantics of Pcm_Data_Payload( ) 
       
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Semantics of pcm_data_payload( ) 
               
            
           
           
               
               
               
            
               
                   
                 Element 
                 Description 
               
               
                   
                   
               
               
                   
                 pcm_sample 
                 PCM sample, either IEEE 754 (floating point) or 
               
               
                   
                   
                 two&#39;s complement 
               
               
                   
                   
               
            
           
         
       
     
     In an embodiment, the USAC-type bitstream extension mechanism may be a new USAC-type bitstream extension element including a unique identifier. In USAC-type bitstreams, system sound info may be transported by means of a USAC-type extension element as defined in ISO/IEC 23003-3. A new usacExtElementType may be named ID_EXT_ELE_SYS_SOUND_INFO. 
     To transport only the configuration part, the syntax in Table 17, “Syntax of UsacExtElementConfig( )” may be amended as follows: 
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Syntax 
                 No. of bits 
                 Mnemonic 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 UsacExtElementConfig( ) 
               
               
                 { 
               
               
                   ... 
               
               
                  case ID_EXT_ELE_SYS_SOUND_INFO: 
               
               
                   system_sound_info( ) 
               
               
                   ... 
               
               
                  } 
               
               
                  ... 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     In this case system_sound_info( ) may only carry configuration data, i.e. the field system_sound_config_present may be set to 1 and the field system_sound_payload_present may be set to 0. 
     Generated PCM data payload may be transmitted on a frame-by-frame basis according to Table 25, “Syntax of UsacExtElement( )” of ISO/IEC 23003-3. 
     In an embodiment, the generated payload of additional media data may be embedded in an array extension element of the USAC-type bitstream. The structure system_sound_info as defined above may be embedded into the array “usacExtElementSegmentData” of Table 25 and may contain either generated information (information on the additional media data, e.g. configuration) or generated payload, or both. 
     The array extension element (e.g. array element “usacExtElementSegmentData”) of the USAC-type bitstream usually contains coded media data and/or metadata. In an embodiment of the invention, the array extension element carries (contains) generated payload of additional media data which is uncoded/raw data (e.g. uncompressed additional media data such as PCM data). Therefore, in this embodiment of the invention, an existing array element of the USAC-type bitstream which usually carries coded audio data and/or metadata is instead used for carrying uncoded/raw media data. 
     Using the above techniques, the additional media data and the information on the additional media data can be readily embedded into an existing MPEG-D USAC-based bitstream that is passed-through by the source device. 
     Processing a Modified Bitstream on a Sink Device 
     Referring now the example of  FIG. 3 , an example of a method for processing a modified bitstream on a sink device is illustrated. In step S 200 , a modified bitstream including coded media data (e.g. as received by the source device) and payload of additional media data may be received by a receiver of a sink device. 
     In step S 201 , the received modified bitstream may be parsed, by a bitstream parser, into the coded media data and the payload of additional media data. While the format of the modified bitstream is not limited, the modified bitstream may be an MPEG-D USAC-based bitstream (i.e. an MPEG-D USAC standard compliant bitstream). Referring to the example of  FIG. 4 , in an embodiment, the modified bitstream may include a USAC-type bitstream extension mechanism, and parsing in step S 201  may further be based on identifying the USAC-type bitstream extension mechanism in the modified bitstream. In an embodiment, the USAC-type bitstream extension mechanism may be a new USAC-type bitstream extension element including a unique identifier. 
     Referring to the example of  FIG. 3 or 4 , in step S 202 , the coded media data may be core decoded by a core decoder. 
     In step S 203 , the core decoded media data may be mixed with the additional media data, by a mixer, to obtain an output signal. 
     In step  204 , the obtained output signal may then be output by a control unit. 
     Referring now to the example of  FIG. 5 , a further example of a method for processing a modified bitstream on a sink device is illustrated. In the example of  FIG. 5 , in an embodiment, the modified bitstream may further include information on the additional media data, and processing the modified bitstream by the sink device may be based on the information. In an embodiment, the information may include one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data. 
     In the example of  FIG. 5 , the method may further include the step S 202   a  of processing, by a processing unit, the additional media data prior to mixing the core decoded media data and the additional media data. In step S 203 , the core decoded media data are then mixed with the processed additional media data. In an embodiment, processing the additional media data may include one or more of resampling, delay adaption and loudness processing. The processing of the additional media data may be guided by (based on) the generated information included in the modified bitstream and provided in step S 201  by the bitstream parser (as indicated by the dashed line). For example, resampling may be guided by information on a sampling rate of the additional media data which may be included in the information on the configuration of the additional media data. Alternatively, or additionally, processing the additional media data may include downmixing/upmixing the additional media data which may be guided by information on a channel mode which may be included in the information on the configuration of the additional media data. Loudness processing may be guided, for example, by information on a default loudness value which may include a measured loudness as according to one of the methods specified in ITU-R BS.1770-4. 
     Alternatively, or additionally, in an embodiment, the modified bitstream may further include information relating to a relative gain between the coded media data and the additional media data, and mixing in step S 203  the core decoded media data and the additional media data, which may have optionally been processed prior to mixing to obtain processed additional media data (as indicated by the dotted lines), may be based on the information relating to the relative gain. In this, the sink device may use the relative gain value generated at the source device. In other words, both, source device and sink device may use the same relative gain value. The relative gain value may also further be modified via a user input in the mixing step S 203 . The relative gain value may include a mixing gain and/or an attenuation gain value. 
     The information relating to the relative gain may be provided in step S 201  by the bitstream parser as indicated by the dashed line. The information on the additional media data and alternatively, or additionally, the information relating to the relative gain value may be embedded in the modified bitstream in the system_sound_config top level syntax element as described above. 
     In an embodiment, the additional media data may be compressed media data or uncompressed media data. 
     Referring now to the example of  FIG. 6 , in an embodiment, the additional media data may be compressed media data and the method may further include the step S 205  of decoding, by a decoder, the compressed media data to obtain decoded additional media data, and in step S 203  the decoded additional media data may be mixed with the core decoded media data. If the method includes further a step of processing the additional media data, S 202   a , in case of compressed media data, the decoded additional media data may optionally be subjected to processing in step S 202   a , as detailed above and indicated by the dotted lines, prior to mixing with the core decoded media data. While the format of the compressed media data is not limited, the format may belong to the Bluetooth ecosystem. In an embodiment, the compressed media data may be in SBC format or in an aptX-based format. Also in case of compressed media data, processing in step S 202   a  may be guided by (based on) generated information on the additional media data included in the modified bitstream and provided in step S 201  as indicated by the dashed line. 
     Alternatively, or additionally, mixing in step S 203  the core decoded media data and the decoded additional media data, which may have optionally been processed prior to mixing, may also be based on information relating to a relative gain as detailed above. The information relating to the relative gain may also be provided in step S 201  as indicated by the dashed line. 
     Alternatively, in an embodiment, the additional media data may be uncompressed media data, and in step S 203  the uncompressed additional media data may be mixed with the core decoded media data in accordance with the example illustrated in  FIG. 3  or  FIG. 4 . In accordance with the example of  FIG. 5 , the uncompressed media data may also optionally be subjected to processing in step S 202   a , as detailed above, prior to mixing with the core decoded media data. In an embodiment, the uncompressed media data may be PCM data generated at the source device. In an embodiment, the PCM data may include one or more of earcon-data and system sounds data. 
     Source Device 
     Referring now to the example of  FIG. 7 , an example of a source device for generating a modified bitstream is illustrated. The source device  100  may include a receiver  102  configured to receive a bitstream including coded media data  101 . The bitstream may be received, for example, from one or more media server. The bitstream may, for example, deliver audio content to be played back by a sink device connected to the source device  100 . The source device  100  is not limited. For example, the source device  100  may be a mobile device including one or more of a mobile phone, a smart watch, a laptop and a tablet pc including convertibles. 
     In an embodiment, the coded media data may be played back by the source device, the sink device or both the source device and the sink device. In an embodiment, the additional media data may be played back by the source device, the sink device or both the source device and the sink device. The source device  100  may further include an embedder  104  configured to generate payload of additional media data  103  and to embed the generated payload in the bitstream to obtain a modified bitstream including the coded media data  101  and the payload of additional media data  103 . In this, a modified bitstream may also be generated even if the source device is operated in pass-through mode. The source device  100  may be configured to pass through the coded media data to the sink device via the modified bitstream. The coded media data as received from the source device is embedded in the modified bitstream and outputted to the sink device. 
     Advantageously, generating (at the source device) and outputting the modified bitstream to the sink device streamlines mixing of the media data with the additional media data at the side of the sink device. A single bitstream is used by the source device to embed and transport the media data and the additional media data to the sink device, thereby a single channel/connection can be used between the source and the sink device. Furthermore, no additional decoders and/or encoders are present in the source device to, e.g., decode and re-encode the coded media data. No additional mixers are used in the source device to, e.g., mix decoded coded media data with the additional media data. 
     While the format of the modified bitstream is not limited, in an embodiment, the modified bitstream may be an MPEG-D USAC-based bitstream (i.e. an MPEG-D USAC standard compliant bitstream). In an embodiment, the embedder  104  may be configured to transport the generated payload via a USAC-type bitstream extension mechanism in the modified bitstream as detailed above. 
     In an embodiment, the additional media data  103  may be compressed media data or uncompressed media data. While the uncompressed media data is not limited, in an embodiment, the uncompressed media data may be PCM data generated at the source device  100 . While the generation of PCM data is not limited, in an embodiment, the generation of the PCM data may be based on a user input. The user input may be, for example, a key-press. The source device  100  may then include a user interface which may be, for example, a touch display. Alternatively, or additionally the source device  100  may further include at least a keyboard. However, the generation of the PCM data may also be facilitated at the source device  100  independent of a user input, e.g. based on an email notification. In an embodiment, the PCM data may include one or more of earcon-data and system sounds data. The PCM data may be stored in the source device  100 . 
     While the compressed media data is not limited, the format of the compressed media data may belong to the Bluetooth ecosystem. In an embodiment, the compressed media data may be in SBC format or in an aptX-based format. The compressed media data may be generated at the source device  100 . The compressed media data may be stored in the source device  100 . Alternatively, or additionally, the compressed media data may be received via the receiver  102 . 
     Referring now to the example of  FIG. 8 , in an embodiment, the embedder  104  may further be configured to generate information  106  on the additional media data  103  and to embed the generated information  106  in the bitstream (as indicated by the dashed line). Alternatively, or additionally, in an embodiment, the embedder  104  may further be configured to generate information  106  relating to a relative gain between the coded media data  101  and the additional media data  103  and to embed the information  106  relating to the relative gain in the bitstream (as also indicated by the dashed line). In an embodiment, the embedder  104  may further be configured to transport the generated information  106  and/or the generated information  106  relating to the relative gain via the USAC-type bitstream extension mechanism in the modified bitstream as detailed above. 
     The source device  100  may further include a control unit  105  configured to output the modified bitstream to a sink device. 
     Sink Device 
     Referring now to the example of  FIG. 9 , an example of a sink device for processing a modified bitstream is illustrated. The sink device  200  may include a receiver  201  configured to receive a modified bitstream including coded media data and payload of additional media data. The sink device  200  is not limited. The sink device  200  may be a peripheral device to the source device, for example, earphones. The sink device  200  and the source device may be connected via Bluetooth. The sink device  200  may be configured to play back audio content included in the modified bitstream. For example, the sink device  200  may be configured to play back the coded media data or the additional media data or both the coded media data and the additional media data. 
     The sink device  200  may further include a bitstream parser  202  configured to parse the modified bitstream into the coded media data and the payload of the additional media data. While the format of the modified bitstream is not limited, the modified bitstream may be an MPEG-D USAC-based bitstream (i.e. an MPEG-D USAC standard compliant bitstream). As already detailed above, in an embodiment, the bitstream parser  202  may be configured to parse the bitstream based on identifying a USAC-type bitstream extension mechanism in the modified bitstream. 
     The sink device  200  may further include a core decoder  203  configured to core decode the coded media data to obtain core decoded media data. In an embodiment, the core decoder  203  may be an MPEG-D USAC-based decoder (compliant with the MPEG-D USAC standard as detailed above). 
     The sink device  200  may further include a mixer  204  configured to mix the core decoded media data and the additional media data to obtain an output signal. In an embodiment, the additional media data may be compressed media data or uncompressed media data. In an embodiment, the additional media data may be uncompressed media data, and the mixer  204  may be configured to mix the core decoded media data and the uncompressed additional media data. 
     Referring now to the example of  FIG. 10 , the modified bitstream may further include information on the additional media data, and the sink device  200  may be configured to process the modified bitstream based on the information. In an embodiment, the sink device  200  may further include a processing unit  206  configured to process the additional media data prior to mixing the core decoded media data and the additional media data in the mixer  204 . In an embodiment, processing the additional media data by the processing unit  206  may include one or more of resampling, delay adaption and loudness processing. Processing the additional media data by the processing unit  206  may be guided by (based on) the information on the additional media data as detailed above. The information on the additional media data may be provided by the bitstream parser  202  to the processing unit  206  as indicated by the dashed line. In case of the additional media data being uncompressed media data, the uncompressed media data may be directly processed after the modified bitstream has been parsed in the bitstream parser  202  and prior to entering the mixer  204 . 
     Alternatively, or additionally, in an embodiment, the modified bitstream may further include information relating to a relative gain between the coded media data and the additional media data, and the mixer  204  may further be configured to mix the core decoded media data and the additional media data, which may optionally have been processed prior to mixing (as indicated by the dotted lines), based on the information relating to the relative gain as described above. The information relating to the relative gain may be provided to the mixer  204  by the bitstream parser  202  as indicated by the dashed line. 
     In an embodiment, the additional media data may be compressed media data. Referring now to the example of  FIG. 11 , the sink device  200  may further include a decoder  207  configured to decode the compressed media data to obtain decoded additional media data, and the mixer  204  may be configured to mix the core decoded media data and the decoded additional media data. Alternatively or additionally, the modified bitstream may further include information relating to a relative gain between the coded media data and the additional media data, and the mixer  204  may further be configured to mix the core decoded media data and the decoded additional media data based on the information relating to the relative gain as described above. The information relating to the relative gain may be provided to the mixer  204  by the bitstream parser  202  as indicated by the dashed line. 
     Referring further to the example of  FIG. 12 , the decoded additional media data may further optionally be processed by the processing unit  206  prior to mixing with the core decoded media data in the mixer  204  (as indicated by the dotted lines). Processing the decoded additional media data by the processing unit  206  may be guided by (based on) information on the additional media data which may be included in the modified bitstream as detailed above. The information on the additional media data may be provided by the bitstream parser  202  to the processing unit  206  as indicated by the dashed line. 
     Referring to the examples of  FIGS. 9 to 12 , the sink device  200  may further include a control unit  205  configured to output the output signal. For example, the output signal may be output via earphones to a user of the sink device  200 . 
     The above described methods may be implemented individually on the above described devices. The above described devices capable of performing the above described methods may also form a respective system. Devices  300 , as referred to herein, may include one or more processors  301 ,  302  as illustrated by way of example in  FIG. 13 . Alternatively, or additionally, the above described methods may also be implemented as a computer program product comprising a computer-readable storage medium with instructions adapted to cause the device  300  to carry out said methods when executed on a device  300  having processing capability  301 ,  302 . 
     Interpretation 
     Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the disclosure discussions utilizing terms such as “processing,” “computing,” “calculating,” “determining”, analyzing” or the like, refer to the action and/or processes of a computer or computing system, or similar electronic computing devices, that manipulate and/or transform data represented as physical, such as electronic, quantities into other data similarly represented as physical quantities. 
     In a similar manner, the term “processor” may refer to any device or portion of a device that processes electronic data, e.g., from registers and/or memory to transform that electronic data into other electronic data that, e.g., may be stored in registers and/or memory. A “computer” or a “computing machine” or a “computing platform” may include one or more processors. 
     The methodologies described herein are, in one example embodiment, performable by one or more processors that accept computer-readable (also called machine-readable) code containing a set of instructions that when executed by one or more of the processors carry out at least one of the methods described herein. Any processor capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken are included. Thus, one example is a typical processing system that includes one or more processors. Each processor may include one or more of a CPU, a graphics processing unit, and a programmable DSP unit. The processing system further may include a memory subsystem including main RAM and/or a static RAM, and/or ROM. A bus subsystem may be included for communicating between the components. The processing system further may be a distributed processing system with processors coupled by a network. If the processing system requires a display, such a display may be included, e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT) display. If manual data entry is required, the processing system also includes an input device such as one or more of an alphanumeric input unit such as a keyboard, a pointing control device such as a mouse, and so forth. The processing system may also encompass a storage system such as a disk drive unit. The processing system in some configurations may include a sound output device, and a network interface device. The memory subsystem thus includes a computer-readable carrier medium that carries computer-readable code (e.g., software) including a set of instructions to cause performing, when executed by one or more processors, one or more of the methods described herein. Note that when the method includes several elements, e.g., several steps, no ordering of such elements is implied, unless specifically stated. The software may reside in the hard disk, or may also reside, completely or at least partially, within the RAM and/or within the processor during execution thereof by the computer system. Thus, the memory and the processor also constitute computer-readable carrier medium carrying computer-readable code. Furthermore, a computer-readable carrier medium may form, or be included in a computer program product. 
     In alternative example embodiments, the one or more processors operate as a standalone device or may be connected, e.g., networked to other processor(s), in a networked deployment, the one or more processors may operate in the capacity of a server or a user machine in server-user network environment, or as a peer machine in a peer-to-peer or distributed network environment. The one or more processors may form a personal computer (PC), a tablet PC, a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. 
     Note that the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. 
     Thus, one example embodiment of each of the methods described herein is in the form of a computer-readable carrier medium carrying a set of instructions, e.g., a computer program that is for execution on one or more processors, e.g., one or more processors that are part of web server arrangement. Thus, as will be appreciated by those skilled in the art, example embodiments of the present disclosure may be embodied as a method, an apparatus such as a special purpose apparatus, an apparatus such as a data processing system, or a computer-readable carrier medium, e.g., a computer program product. The computer-readable carrier medium carries computer readable code including a set of instructions that when executed on one or more processors cause the processor or processors to implement a method. Accordingly, aspects of the present disclosure may take the form of a method, an entirely hardware example embodiment, an entirely software example embodiment or an example embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of carrier medium (e.g., a computer program product on a computer-readable storage medium) carrying computer-readable program code embodied in the medium. 
     The software may further be transmitted or received over a network via a network interface device. While the carrier medium is in an example embodiment a single medium, the term “carrier medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “carrier medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by one or more of the processors and that cause the one or more processors to perform any one or more of the methodologies of the present disclosure. A carrier medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical, magnetic disks, and magneto-optical disks. Volatile media includes dynamic memory, such as main memory. Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise a bus subsystem. Transmission media may also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications. For example, the term “carrier medium” shall accordingly be taken to include, but not be limited to, solid-state memories, a computer product embodied in optical and magnetic media; a medium bearing a propagated signal detectable by at least one processor or one or more processors and representing a set of instructions that, when executed, implement a method; and a transmission medium in a network bearing a propagated signal detectable by at least one processor of the one or more processors and representing the set of instructions. 
     It will be understood that the steps of methods discussed are performed in one example embodiment by an appropriate processor (or processors) of a processing (e.g., computer) system executing instructions (computer-readable code) stored in storage. It will also be understood that the disclosure is not limited to any particular implementation or programming technique and that the disclosure may be implemented using any appropriate techniques for implementing the functionality described herein. The disclosure is not limited to any particular programming language or operating system. 
     Reference throughout this disclosure to “one example embodiment”, “some example embodiments” or “an example embodiment” means that a particular feature, structure or characteristic described in connection with the example embodiment is included in at least one example embodiment of the present disclosure. Thus, appearances of the phrases “in one example embodiment”, “in some example embodiments” or “in an example embodiment” in various places throughout this disclosure are not necessarily all referring to the same example embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more example embodiments. 
     As used herein, unless otherwise specified the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common object, merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner. 
     In the claims below and the description herein, any one of the terms comprising, comprised of or which comprises is an open term that means including at least the elements/features that follow, but not excluding others. Thus, the term comprising, when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression a device comprising A and B should not be limited to devices consisting only of elements A and B. Any one of the terms including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising. 
     It should be appreciated that in the above description of example embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single example embodiment, Fig., or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed example embodiment. Thus, the claims following the Description are hereby expressly incorporated into this Description, with each claim standing on its own as a separate example embodiment of this disclosure. 
     Furthermore, while some example embodiments described herein include some but not other features included in other example embodiments, combinations of features of different example embodiments are meant to be within the scope of the disclosure, and form different example embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed example embodiments can be used in any combination. 
     In the description provided herein, numerous specific details are set forth. However, it is understood that example embodiments of the disclosure may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. 
     Thus, while there has been described what are believed to be the best modes of the disclosure, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the disclosure, and it is intended to claim all such changes and modifications as fall within the scope of the disclosure. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present disclosure. 
     Enumerated example embodiments (EEEs) of the present disclosure are listed below. 
     A-EEE 1. A method for generating a modified bitstream on a source device, wherein the method includes the steps of:
         a) receiving, by a receiver, a bitstream including coded media data;   b) generating, by an embedder, payload of additional media data and embedding the payload in the bitstream for   obtaining, as an output from the embedder, a modified bitstream including the coded media data and the payload of the additional media data; and   c) outputting the modified bitstream to a sink device.
 
A-EEE 2. Method according to A-EEE 1, wherein step b) further includes generating information on the additional media data and embedding the information in the bitstream.
 
A-EEE 3. Method according to A-EEE 2, wherein the generated information includes one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data.
 
A-EEE 4. Method according to any of A-EEEs 1 to 3, wherein step b) further includes generating information relating to a relative gain between the coded media data and the additional media data and embedding the information relating to the relative gain in the bitstream.
 
A-EEE 5. Method according to any of A-EEEs 1 to 4, wherein the modified bitstream is an MPEG-D USAC-based bitstream.
 
A-EEE 6. Method according to A-EEE 5, wherein the generated payload is embedded in the bitstream by transporting the payload in the bitstream via a USAC-type bitstream extension mechanism.
 
A-EEE 7. Method according to A-EEE 5 or 6, wherein the generated information and/or the generated information relating to the relative gain are embedded in the bitstream by transporting the generated information and/or the generated information relating to the relative gain in the bitstream via the USAC-type bitstream extension mechanism.
 
A-EEE 8. Method according to any of A-EEEs 6 or 7, wherein the USAC-type bitstream extension mechanism is a new USAC-type bitstream extension element including a unique identifier.
 
A-EEE 9. Method according to any of A-EEEs 1 to 8, wherein in step c) the modified bitstream is output to the sink device via a Bluetooth connection.
 
A-EEE 10. Method according to any of A-EEEs 1 to 9, wherein the additional media data are compressed media data or uncompressed media data.
 
A-EEE 11. Method according to A-EEE 10, wherein the uncompressed media data are PCM data generated at the source device.
 
A-EEE 12. Method according to A-EEE 11, wherein the generation of the PCM data is based on a user input.
 
A-EEE 13. Method according to A-EEE 11 or 12, wherein the PCM data include one or more of earcon-data and system sounds data.
 
A-EEE 14. Method according to A-EEE 10, wherein the compressed data are in SBC format or in an aptX-based format.
 
A-EEE 15. A method for processing a modified bitstream on a sink device, wherein the method includes the steps of:
   a) receiving, by a receiver, a modified bitstream including coded media data and payload of additional media data;   b) parsing, by a bitstream parser, the modified bitstream into the coded media data and the payload of additional media data;   c) core decoding, by a core decoder, the coded media data to obtain core decoded media data;   d) mixing, by a mixer, the core decoded media data and the additional media data to obtain an output signal; and   e) outputting the output signal.
 
A-EEE 16. Method according to A-EEE 15, wherein the modified bitstream further includes information on the additional media data, and wherein the method further includes, after step a) and before step b), a step of processing the modified bitstream based on the information.
 
A-EEE 17. Method according to A-EEE 16, wherein the information includes one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data.
 
A-EEE 18. Method according to any of A-EEEs 15 to 17, wherein the modified bitstream further includes information relating to a relative gain between the coded media data and the additional media data, and wherein mixing in step d) the core decoded media data and the additional media data is based on the information relating to the relative gain.
 
A-EEE 19. Method according to any of A-EEEs 15 to 18, wherein the method further includes the step of processing, by a processing unit, the additional media data prior to mixing the core decoded media data and the additional media data.
 
A-EEE 20. Method according to A-EEE 19, wherein processing the additional media data includes one or more of resampling, delay adaption and loudness processing.
 
A-EEE 21. Method according to any of A-EEEs 15 to 20, wherein the additional media data are compressed media data and the method further includes the step of decoding, by a decoder, the compressed media data to obtain decoded additional media data, and wherein in step d) the decoded additional media data are mixed with the core decoded media data.
 
A-EEE 22. Method according to A-EEE 21, wherein the compressed media data are in SBC format or in an aptX-based format.
 
A-EEE 23. Method according to any of A-EEEs 15 to 20, wherein the additional media data are uncompressed media data, and wherein in step d) the uncompressed additional media data are mixed with the core decoded media data.
 
A-EEE 24. Method according to any of A-EEEs 15 to 23, wherein the modified bitstream is an MPEG-D USAC-based bitstream.
 
A-EEE 25. Method according to A-EEE 24, wherein the modified bitstream includes a USAC-type bitstream extension mechanism, and wherein parsing in step b) is further based on identifying the USAC-type bitstream extension mechanism in the modified bitstream.
 
A-EEE 26. Method according to A-EEE 25, wherein the USAC-type bitstream extension mechanism is a new USAC-type bitstream extension element including a unique identifier.
 
A-EEE 27. Source device for generating a modified bitstream, wherein the device includes:
   a) a receiver configured to receive a bitstream including coded media data;   b) an embedder configured to generate payload of additional media data and to embed the generated payload in the bitstream to obtain a modified bitstream including the coded media data and the payload of the additional media data; and   c) a control unit configured to output the modified bitstream to a sink device.
 
A-EEE 28. Device according to A-EEE 27, wherein the embedder is further configured to generate information on the additional media data and to embed the information in the bitstream.
 
A-EEE 29. Device according to A-EEE 27 or 28, wherein the embedder is further configured to generate information relating to a relative gain between the coded media data and the additional media data and to embed the information relating to the relative gain in the bitstream.
 
A-EEE 30. Device according to any of A-EEEs 27 to 29, wherein the modified bitstream is an MPEG-D USAC-based bitstream.
 
A-EEE 31. Device according to any of A-EEEs 27 to 30, wherein the additional media data are compressed media data or uncompressed media data.
 
A-EEE 32. Device according to A-EEE 31, wherein the uncompressed media data are PCM data generated at the source device.
 
A-EEE 33. Device according to A-EEE 32, wherein the generation of the PCM data is based on a user input.
 
A-EEE 34. Device according to A-EEE 32 or 33, wherein the PCM data include one or more of earcon-data and system sounds data.
 
A-EEE 35. Device according to A-EEE 31, wherein the compressed media data are in SBC format or in an aptX-based format.
 
A-EEE 36. Sink device for processing a modified bitstream, wherein the device includes:
   a) a receiver configured to receive a modified bitstream including coded media data and payload of additional media data;   b) a bitstream parser configured to parse the modified bitstream into the coded media data and the payload of the additional media data;   c) a core decoder configured to core decode the coded media data to obtain core decoded media data;   d) a mixer configured to mix the core decoded media data and the additional media data to obtain an output signal; and   e) a control unit configured to output the output signal.
 
A-EEE 37. Device according to A-EEE 36, wherein the device further includes a processing unit configured to process the additional media data prior to mixing the core decoded media data and the additional media data.
 
A-EEE 38. Device according to A-EEE 36 or 37, wherein the additional media data are uncompressed media data, and wherein the mixer is configured to mix the core decoded media data and the uncompressed additional media data.
 
A-EEE 39. Device according to A-EEE 36 or 37, wherein the additional media data are compressed media data and the device further includes a decoder to decode the compressed media data to obtain decoded additional media data, and wherein the mixer is configured to mix the core decoded media data and the decoded additional media data.
 
A-EEE 40. Device according to any of A-EEEs 36 to 39, wherein the modified bitstream further includes information on the additional media data, and wherein the sink device is configured to process the modified bitstream based on the information.
 
A-EEE 41. Device according to any of A-EEEs 36 to 40, wherein the modified bitstream further includes information relating to a relative gain between the coded media data and the additional media data, and wherein the mixer is further configured to mix the core decoded media data and the additional media data based on the information relating to the relative gain.
 
A-EEE 42. Device according to any of A-EEEs 36 to 41, wherein the core decoder is an MPEG-D USAC-based decoder.
 
A-EEE 43. System of a source device for generating a modified bitstream, wherein the source device includes one or more processors configured to perform the method according to A-EEEs 1 to 14 and a sink device for processing a modified bitstream, wherein the sink device includes one or more processors configured to perform the method according to A-EEEs 15 to 26.
 
A-EEE 44. A computer program product comprising a computer-readable storage medium with instructions adapted to cause the device to carry out the method according to any one of A-EEEs 1 to 14 when executed by a device having processing capability.
 
A-EEE 45. A computer program product comprising a computer-readable storage medium with instructions adapted to cause the device to carry out the method according to any one of A-EEEs 15 to 26 when executed by a device having processing capability.
 
B-EEE 1. A method for generating a modified bitstream on a source device, wherein the method includes the steps of:
   a) receiving, by a receiver, a bitstream including coded media data;   b) generating, by an embedder, payload of additional media data and embedding the payload in the bitstream for   obtaining, as an output from the embedder, a modified bitstream including the coded media data and the payload of the additional media data; and   c) outputting the modified bitstream to a sink device.
 
B-EEE 2. Method according to B-EEE 1,
   wherein step b) further includes generating information on the additional media data and embedding the information in the bitstream; and optionally   wherein the generated information includes one or more of information on a configuration of the additional media data, information on a presence of the additional media data in the modified bitstream, information on a default loudness value, information on a value for delay alignment, information on delay adaption, information on panning and information on a type of the additional media data.
 
B-EEE 3. Method according to B-EEE 1, wherein step b) further includes generating information relating to a relative gain between the coded media data and the additional media data and embedding the information relating to the relative gain in the bitstream.
 
B-EEE 4. Method according to B-EEE 1,
   wherein the modified bitstream is an MPEG-D USAC-based bitstream; and   wherein the generated payload is embedded in the bitstream by transporting the payload in the bitstream via a USAC-type bitstream extension mechanism.
 
B-EEE 5. Method according to B-EEE 3,
   wherein the modified bitstream is an MPEG-D USAC-based bitstream; and   wherein the generated information and/or the generated information relating to the relative gain are embedded in the bitstream by transporting the generated information and/or the generated information relating to the relative gain in the bitstream via the USAC-type bitstream extension mechanism.
 
B-EEE 6. Method according to B-EEE 4, wherein the USAC-type bitstream extension mechanism is a new USAC-type bitstream extension element including a unique identifier.
 
B-EEE 7. Method according to B-EEE 1, wherein in step c) the modified bitstream is output to the sink device via a Bluetooth connection.
 
B-EEE 8. Method according to B-EEE 1, wherein the additional media data are PCM data generated at the source device.
 
B-EEE 9. Method according to B-EEE 8, wherein the PCM data include one or more of earcon-data and system sounds data.
 
B-EEE 10. Method according to B-EEE 1, wherein the additional media data are compressed data in SBC format or in an aptX-based format.
 
B-EEE 11. A method for processing a modified bitstream on a sink device, wherein the method includes the steps of:
   a) receiving, by a receiver, a modified bitstream including coded media data and payload of additional media data;   b) parsing, by a bitstream parser, the modified bitstream into the coded media data and the payload of additional media data;   c) core decoding, by a core decoder, the coded media data to obtain core decoded media data; d) mixing, by a mixer, the core decoded media data and the additional media data to obtain an output signal; and   e) outputting the output signal.
 
B-EEE 12. Method according to B-EEE 11, wherein the modified bitstream further includes information relating to a relative gain between the coded media data and the additional media data, and wherein mixing in step d) the core decoded media data and the additional media data is based on the information relating to the relative gain.
 
B-EEE 13. Method according to B-EEE 11,
   wherein the method further includes the step of processing, by a processing unit, the additional media data prior to mixing the core decoded media data and the additional media data; and optionally   wherein processing the additional media data includes one or more of resampling, delay adaption and loudness processing.
 
B-EEE 14. Method according to B-EEE 11,
   wherein the modified bitstream is an MPEG-D USAC-based bitstream; and   wherein the modified bitstream includes a USAC-type bitstream extension mechanism, and wherein parsing in step b) is further based on identifying the USAC-type bitstream extension mechanism in the modified bitstream.
 
B-EEE 15. Method according to B-EEE 11, wherein the USAC-type bitstream extension mechanism is a new USAC-type bitstream extension element including a unique identifier.
 
B-EEE 16. Source device for generating a modified bitstream, wherein the device includes:
   a) a receiver configured to receive a bitstream including coded media data;   b) an embedder configured to generate payload of additional media data and to embed the generated payload in the bitstream to obtain a modified bitstream including the coded media data and the payload of the additional media data; and   c) a control unit configured to output the modified bitstream to a sink device.
 
B-EEE 17. Sink device for processing a modified bitstream, wherein the device includes:
   a) a receiver configured to receive a modified bitstream including coded media data and payload of additional media data;   b) a bitstream parser configured to parse the modified bitstream into the coded media data and the payload of the additional media data;   c) a core decoder configured to core decode the coded media data to obtain core decoded media data;   d) a mixer configured to mix the core decoded media data and the additional media data to obtain an output signal; and   e) a control unit configured to output the output signal.
 
B-EEE 18. System of a source device for generating a modified bitstream, wherein the source device includes one or more processors configured to perform the method according to B-EEE 1 and a sink device for processing a modified bitstream, wherein the sink device includes one or more processors configured to perform the method according to B-EEE 11.
 
B-EEE 19. A computer program product comprising a computer-readable storage medium with instructions adapted to cause the device to carry out the method according to B-EEE 1 when executed by a device having processing capability.
 
B-EEE 20. A computer program product comprising a computer-readable storage medium with instructions adapted to cause the device to carry out the method according to B-EEE 11 when executed by a device having processing capability.