Abstract:
The present invention relates to the field of processing a video stream, and more particular to the field of post processing of a video stream using shaders. The processing of the video stream is divided between a video stream processing device and a client device.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to the field of processing a video stream, and more particular to the field of post processing of a video stream using shaders. 
         [0002]    BACKGROUND 
         [0003]    Today, many of the video processing systems follow a standard architecture that typically include a sever that receives a video stream, processes the video stream, and then transmits the processed video stream, via a network, to a remote client. 
         [0004]    It may be advantageous for computational reasons and for increasing performance to use processing power of both the server and the remote client. 
         [0005]    Some of the processing relate to processing made by a graphical processing unit (GPU). The GPU creates images intended for output to a display. The GPU may also be adapted to manipulate images in a video stream. In a server-client system, it may be advantageous to be able to use the GPU both on the server and on the client for performing graphical processing. 
         [0006]    US 2013/0016107 (CHNOW INC.) relates to a method for rendering graphics that can utilize both server-side rendering and client-side rendering. The main idea in this document is to decide if the rendering should be made on the server or on the client. If the rendering is made on the server, video data (i.e. pixel data) is sent from the server to the client and then displayed. If the rendering is made on the client, graphics data (i.e. vector data) is sent to the client and then rendered into video data using the GPU of the client. The choice is made based on the available processing power of the GPU in the client and in the server and based on the network bandwidth. 
         [0007]    The method of US 2013/0016107 may be advantageous in application where graphics data is processed and rendered into video data, e.g. computer games. Different approaches are needed in order to process video data both on the server and on the client, for example by applying shaders for special effects and video post processing. 
       SUMMARY 
       [0008]    In view of the above, an objective of the invention is to solve or at least reduce one or several of the drawbacks discussed above. Generally, the above objective is achieved by the attached independent patent claims. 
         [0009]    According to a first aspect, the present invention is realized by a method for processing a video stream in a system comprising a video stream processing device connected to a client device, comprising: setting one or more shaders to be applied to the video stream, applying, by a first processing, at the video stream processing device, at least one of the one or more shaders to at least a subset of the video stream, applying, by a second processing, at the client device, at least one of the one or more shaders to at least a subset of the video stream, wherein the at least one of the one or more shaders applied in the second processing is transmitted from the video stream processing device to the client device. 
         [0010]    Shaders are computer programs used in computer graphics. Shaders are for example used for special effects and video post processing. There are various sorts of shaders, for example Vertex shaders that may be used for perspective transforms, Pixel shaders that may be used for altering pixel colors and positions, and Compute shaders that may be used for video analytics computations. A shader requires a compatible graphical processing unit (GPU) to be executed. For example, all GPUs do not support Compute shaders. The GPU may support OpenGL which is a multi-platform application programming interface (API) for rendering 2D and 3D vector graphics. 
         [0011]    By the term “processing” should, in the context of present specification be understood the execution of shaders on the at least a subset of the video stream that the processing relate to. 
         [0012]    A client device may be a device, having a GPU, running a web application from a web server and displaying the processed video stream, for example a tablet computer or a Smartphone. A client device may also refer to a device which processes the video stream using its GPU and subsequently sends it to a display for viewing purposes. An example of such a device could be a PC with a connected display that would display the processed video stream in same way as a tablet computer or a Smartphone, but in this case on a display connected to the computer whereas a tablet computer or a Smartphone would use its embedded display for the same purposes. The client device may also be used in a Video Management System (VMS) for managing and viewing video from a monitoring system comprising one or more cameras. A VMS could be based on a variety of technologies e.g. including cloud based systems (e.g. through various cloud-based video hosting services), systems based on central servers (e.g. “Axis Camera Station” produced by Axis Communications AB) or server-less systems where software installed on the cameras of the system handle the video management (e.g. “Axis Camera Companion” produced by Axis Communications AB). The client device would in this case be connected to the VMS. 
         [0013]    By the term “subset of the video stream” should, in the context of the present specification be understood that not the entire video stream needs to be processed at the video stream processing device and/or the client device. The processing at the video stream processing device and the processing at the client device can relate to (different) parts of a frame (e.g. half the frame), or (different) subset of frames (e.g. every other frame in the video stream), or a mix of the two. According to other embodiments, the first and second processing both processes the entire video stream. 
         [0014]    The present invention is based upon the realization that by providing all shaders at the video stream processing device, and let the video stream processing device transmit shaders needed for the processing at the client device, an increased flexibility for the first and second processing is achieved. In other words, the execution of the shaders can be divided dynamically at runtime, based e.g. on the network topology, the capabilities and load of both the video stream processing device and the client device, and characteristics of the use case. Alternatively, the division of the execution can be static. 
         [0015]    According to some embodiments, the first processing is different from the second processing. This may advantageously divide the processing required for the execution of the one or more shaders on the video stream between the video stream processing device and the client device. 
         [0016]    According to some embodiments, the at least one shader applied in the first processing differs from the at least one shader applied in the second processing. For example, any vertex shader(s) can be executed on the video stream processing device and any pixel shader(s) can be executed on the client device. 
         [0017]    According to some embodiments, said at least a subset of the video stream to which the first processing relate differs from said at least a subset of the video stream to which the second processing relate. As mentioned above, the processing at the video stream processing device and the processing at the client device can relate to different parts of a frame (e.g. half the frame is processed in the video stream processing device and the remaining half is processed on the client device), or different subset of frames (e.g. every other frame in the video stream is processed on the video stream processing device and the remaining frames is processed on the client device). 
         [0018]    However, it should be noted that according to some embodiments, the first processing and the second processing are not different from each other, i.e. the same shaders are applied to the same parts of the video stream both on the video stream processing device and the client device. This may be advantageous when the first and second processing relate to incremental filtering. In this case, the execution of the shaders is still divided between the video stream processing device and the client device since the first part of the incremental filtering is executed on the video stream processing device and the second part of the incremental filtering is executed on the client device. 
         [0019]    According to some embodiments, the first processing and/or the second processing depends on at least one from the group of: a type of a graphics processing unit, GPU, of the client device, and a type of a graphics processing unit, GPU, of the video stream processing device. As mentioned above, different types of GPUs may support different types of shaders. For example, normally only the GPU in the client device supports Tessellation or Geometry shaders. Since a Vertex shader needs to be executed before a Tessellation and/or a Geometry shader, the division of the execution may be done such that the Vertex shader is executed on the video stream processing device and the Tessellation and Geometry shaders are executed on the client device. 
         [0020]    According to some embodiments, the first processing and/or the second processing changes over the duration of the video stream. This may further increase the flexibility of the inventive method since the division of the shader execution between the video stream processing device and the client device could be independently determined for each time period of the video stream and thus advantageously follow changes in the network topology, changes of load and other important properties of both the video stream processing device and the client device, and changed use cases (e.g. latency demands of the execution). 
         [0021]    For example, the first processing and/or the second processing may dynamically change over the duration of the video stream based on information pertaining to at least one from a group consisting of: bandwidth of the connection between the video stream processing device and the client device, battery level of the client device, battery level of the video stream processing device, processing power of the GPU of the client device, and processing power of the GPU of the video stream processing device. 
         [0022]    The client device may, as mentioned above, be a battery driven device such as a tablet computer. Since execution of shaders may drain the battery of the client device, it may be advantageous if the video stream processing device, in the case where the client device is running short of battery, runs a larger part of the required processing for executing the one or more shaders on the video stream. 
         [0023]    According to some embodiments, the video stream is transmitted as an encoded video stream from the video stream processing device to the client device where the video stream is decoded before the second processing. This is advantageous since the video stream will be encoded and transmitted to the client device no matter what processing that is applied at the video stream processing device. For example, the video stream may be semi processed when encoded and transmitted to the client device. Moreover, the present embodiment is advantageous in that the execution flow of the shaders can be easily set up and maintained, since the encoder in the video stream processing device (and a corresponding decoder on the client device) are constantly running. A further advantage may be that the basic system layout with an encoder in the video stream processing device and a decoder in the client device do not change according to this embodiment. Further, the network load may be relatively steady, no matter how execution of the one or more shaders is divided between the video stream processing device and the client device. 
         [0024]    According to some embodiments, the transmission of the video stream has a first priority level, and the transmission of the at least one of the one or more shaders applied in the second processing from the video stream processing device to the client device has a second priority level lower than the first priority level. Consequently, an order of performing the transmissions is based on their respective priority level. According to this embodiment, the transmission of the video stream is always prioritized over the transmission of the shaders to be applied in the client device. This may reduce the risk of sluttering when the video stream is displayed at a display connected to the client device or in the client device. According to this embodiment, the shaders in the second processing will not be applied to the frames of the video stream that has already been transmitted before the shaders of the second processing are transferred. 
         [0025]    According to some embodiments, the transmission of the video stream is performed via a first network connection, and wherein the transmission of the at least one of the one or more shaders applied in the second processing from the video stream processing device to the client device is performed via a second network connection different from the first network connection. For example, the video stream may be transmitted via a Real Time Streaming Protocol (RTSP) connection or Hypertext Transfer Protocol (HTTP) connection while the shaders may be transmitted via a socket or HTTP connection. 
         [0026]    According to some embodiments, the video stream processing device comprises a plurality of threads of execution, and wherein the transmission of the video stream is performed by executing a first thread, and wherein the transmission of the at least one of the one or more shaders applied in the second processing is performed by executing a second thread different from the first thread. This may further facilitate that the video stream is transmitted prioritized to the transmission of the shaders of the second processing. 
         [0027]    According to some embodiments, the method further comprises the steps of: receiving, at the video stream processing device, from the client device, a request for a video stream to be transmitted from the video stream processing device to the client device, and extracting, at the video stream processing device, information pertaining to the client device from the request, the information pertaining to the client device comprises at least information of a type of a GPU of the client device, wherein the first processing and/or the second processing depends on the extracted information. 
         [0028]    By extracting information needed for the division of shader execution already from the request of a video stream from the client device, determination of the first processing and the second processing may be performed early. 
         [0029]    According to some embodiments, the video stream processing may include a request for information pertaining to the client device in the response to the request for the video stream sent by the client device. The video stream processing device may for example request the information via JavaScript included in the response. When the client device receives this response, it may provide the requested information in a further communication sent to the video processing device. 
         [0030]    In a second aspect, the present invention provides a video stream processing device for processing a video stream, comprising: a memory for storing one or more shaders to be applied to the video stream, a shader handling unit for determining: a first processing relating to at least a subset of the video stream to which at least one of the one or more shaders is to be applied, and a second processing relating to at least a subset of the video stream to which at least one of the one or more shaders is to applied. The video stream processing device further comprises a graphical processing unit, GPU, for performing the first processing, and, a digital network module configured to transmit the at least one of the one or more shaders to be applied in the second processing, and data pertaining to the at least a subset of the video stream to which the second processing relate. 
         [0031]    The video processing device may advantageously be a part of a digital video camera, wherein the video stream is acquired by the digital video camera. This reduces the need of further electronic devices connected to the video camera and is e.g. advantageous for assembling reasons and for reducing the required space for mounting the video stream processing device and the camera. 
         [0032]    In a third aspect, the present invention provides a system for processing a video stream, comprising: a video stream processing device comprising: a memory for storing one or more shaders to be applied to the video stream, a shader handling unit for determining: a first processing relating to at least a subset of the video stream to which at least one of the one or more shaders is to be applied, and a second processing relating to at least a subset of the video stream to which at least one of the one or more shaders is to applied. The video processing device further comprises a graphical processing unit, GPU, for performing the first processing, an encoder configured to encode the video stream into a encoded video stream, and a digital network module configured to transmit, via a digital network, the at least one of the one or more shaders to be applied in the second processing, data pertaining to the at least a subset of the video stream to which the second processing relate, and the encoded video stream. The system further comprises a client device comprising: a digital network module configured to receive, via the digital network, the at least one of the one or more shaders to be applied in the second processing, data pertaining to the at least a subset of the video stream to which the second processing relate, and the encoded bitstream, a decoder configured to decode the encoded video stream into a video stream, and a GPU for performing the second processing using the received at least one of the one or more shaders and the received data pertaining to the at least a subset of the video stream to which the second processing relate. 
         [0033]    In a fourth aspect, the present invention provides a computer program product comprising a computer-readable storage medium with instructions adapted to carry out the method according to the first aspect when executed by a device having processing capability. 
         [0034]    The second, third and fourth aspect may generally have the same features and advantages as the first aspect. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein: 
           [0036]      FIG. 1  describes a flow chart of processing of a video stream using shaders, wherein the processing is divided between a video processing device and a client device, 
           [0037]      FIG. 2  shows by way of example messages and data sent between the video stream processing device and the client device in order to divide the processing of the video stream using shaders between the video stream processing device and the client device, 
           [0038]      FIG. 3 a    describes a scenario of processing of a video stream using shaders, 
           [0039]      FIGS. 3 b - c    show different ways of dividing the processing described in  FIG. 3 a    between the video stream processing device and the client device, 
           [0040]      FIG. 4 a    describes a scenario of processing of a video stream using shaders, 
           [0041]      FIG. 4 b - c    describe a dynamically changing division of the processing described in  FIG. 4 a    between the video stream processing device and the client device, and 
           [0042]      FIG. 5  describe a system comprising the video stream processing device and the client device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]      FIG. 1  describes by way of example a flow chart of processing of a video stream using shaders. The first step in the flow chart is the step of setting S 102  one or more shaders  105  to be applied to a video stream  102 . As described in  FIG. 1 , the video stream  102  may be acquired outside the video stream processing device and transmitted to the video stream processing device. According to some embodiments, the video stream processing device is a digital video camera. In this case the video stream  102  is acquired by the digital video camera and consequently not transmitted into the video stream processing device as described in  FIG. 1 . However, according to other embodiments, the video stream processing device is a device separate from the video camera acquiring the video stream  102 . In this case, the connection between the video stream processing device and the video camera may be a wired connection or a wireless connection. 
         [0044]    Moreover, the step of setting S 102  the shaders  105  is in  FIG. 1  made outside the video stream processing device, for example in a pre-processing step where the video stream  102  is analyzed and where the shaders  105  to be applied is determined based on the analysis. In other embodiments, the step of setting S 102  the shaders  105  is performed in the video stream processing device. According to yet another embodiment, the one or more shaders are fixed shaders that are always applied to the video stream and may consequently be hardcoded into the video stream processing device. 
         [0045]    The application of the one or more shaders  105  to the video stream  102  is divided into a first and a second processing step. The dividing into two processing steps will be described further below. The first processing will be performed by the video stream processing device, and the second processing will be performed by a client device which is connected to the video stream processing device. The connection between the video stream processing device and the client device may be a wired connection or a wireless connection. 
         [0046]    The next step in the flow chart described in  FIG. 1  is the step of applying S 104 , by the first processing, at the video stream processing device, at least one  107  of the one or more shaders  105  (that were set in S 102  previously) to at least a subset of the video stream  102 . This step is performed using a GPU of the video stream processing device as will be described more in detail below. 
         [0047]    Further, the shader(s)  108  needed for the second processing is transmitted S 106  from the video stream processing device to the client device. It should be noted that if the second processing comprises texture mapping using a texture, the texture may also be transmitted as part of the transmission S 106  of the shader(s)  108  needed for the second processing or as a separate transmission (not shown). 
         [0048]    As clearly seen in  FIG. 1 , the flow chart comprises two separate tracks. One track for the application of the one or more shaders  105  on the video stream  102 ,  102 ′ and any transmission of the one or more shaders  105  from the video stream processing device and the client device, and one track for encoding S 108  the video stream  102  at the video stream processing device, transmitting S 109  the encoded video stream  106  to the client device and decoding S 110  the encoded video stream  106  at the client device. In other words, the video stream is transmitted S 109  as an encoded video stream  106  from the video stream processing device to the client device where the video stream is decoded S 110  before the second processing S 112 . The second processing thus relates to application of the transmitted at least one  108  of the one or more shaders  105  to at least a subset of the video stream  102 ′. 
         [0049]    The video stream  102 ′ may later be displayed by a display  104 . In case all of the one or more shades have been applied to the full video stream, the video stream  102 ′ that is displayed by the display  104  is fully processed. However, since the two track design of the flow facilitate different priority levels for transmitting S 109  the encoded video and for transmitting S 106  the at least one  108  of the one or more shaders  105  to be applied in the second processing at the client device, it may be so that at least a part of the video stream  102 ′ displayed at the display  104  is only half processed or not processed at all. E.g. the first frames of the video stream  102 ′ may only be processed by a subset of the one or more shaders  105  that were set in S 102  previously, and/or the shaders that have been applied to the first frames of the video stream may only have been applied to a subset of the first frames of the video stream. In other words, the second processing will not have been applied to the frames of the video stream already displayed before the shader(s)  108  needed for the second processing have been transmitted S 106  to the client device. In real time applications, i.e. when the video is acquired, processed and displayed in real time, it may be advantageous to give the transmission S 109  of the video stream priority over the transmission S 106  of the shaders  108  for the second processing. 
         [0050]      FIG. 2  describes by way of example the transmissions that take place between the video stream processing device and the client device. The first transmission is a request for video sent S 202  from the client device and the video stream processing device, e.g. an http(s) request. When the request is received by the video stream processing device, the video stream processing device may immediately start to transmit video  202  to the client device. From the request for video, the video stream processing device may extract information regarding the client device such as if the client device has a GPU, the type of GPU, the operating system (OS) of the client device etc. This information may be used for deciding if the execution of the one or more shaders should be divided between the video stream processing device and the client device, and how the execution of the shaders in that case should be divided. 
         [0051]    However, if further information is required for making the division of the processing, that video stream processing device may, in its response message sent S 204  to the client device, request for more information regarding the client device. For example, the request for further information may be embedded in JavaScript code included in the http(s) response. 
         [0052]    If such further information was requested, the client device may provide the requested information in a message transmitted S 206  to the video stream processing device. 
         [0053]    No matter if further info was requested S 204  by the video stream processing device and later transmitted S 206  to the video stream processing device, or if the information provided in the request for video from the client device were considered to be sufficient, after the dividing of the processing of the shader(s) is done, the at least one of the one or more shaders to be applied in the second processing at the client device, and data pertaining to the at least a subset of the video stream to which the second processing relate are transmitted S 208  to the client device. 
         [0054]    According to some embodiments, the first processing and/or the second processing dynamically changes over the duration of the video stream  202 . This may be facilitated by that further information is transmitted S 212  from the client device to the video stream processing device. This further information may for example pertain to a battery level of the client device and/or a processing power of the GPU of the client device. This type of information may already been transmitted S 202  in the request for video or in the first message with further information transmitted S 206  from the client device, but since the information pertain to properties of the client device which may dynamically change over a time period, it may be advantageous to take updated information into account when dividing the processing of the shaders between the video stream processing device and the client device. The further information may be transmitted S 212  on the client device&#39;s own initiative or as a response to a transmission S 210  of a request for such further information from the video stream processing device. Moreover, the first processing and/or the second processing may dynamically change based on information available directly at the video stream processing device, for example bandwidth of the connection between the video stream processing device and the client device, processing power of the GPU of the video stream processing device and/or battery level of the video stream processing device. 
         [0055]    If the second processing is changed based on new information according to above, the at least one of the one or more shaders to be applied in the changed second processing at the client device, and data pertaining to the at least a subset of the video stream to which the changed second processing relate, are transmitted S 214  to the client device. 
         [0056]    According to some embodiments, if the second processing is changed based on the new information, but the same at least one of the one or more shaders is applied in the changed second processing compared to the original second processing, only data pertaining to the at least a subset of the video stream to which the changed second processing relate may be transmitted S 214  to the client device. The same applies if only the at least one of the one or more shaders is changed, in that case only the at least one of the one or more shaders to be applied in the changed second processing at the client device may be transmitted S 214  to the client device. 
         [0057]    Moreover, if the second processing is changed in that for example one of the shaders that was previously applied in the second processing is no longer part of the second processing, the video stream processing device may just send a command to the client device to stop applying the removed shader. 
         [0058]    It should be noted that the video stream processing may transmit video streams  202  to several client devices concurrently. In this case the division of the total processing between the first processing and the second processing may be done differently for different client devices depending on their capabilities and performance. Since the GPU of the video stream processing device may handle that several different shaders (e.g. vertex shaders, pixel shaders, compute shaders) are executed in parallel, it is possible to make such device specific divisions. Moreover it should be noted that different client devices may request different video streams (e.g. with different resolution, frame rate, and/or digitally zoomed in part of the field of view etc). 
         [0059]      FIG. 3 a    describes a scenario of processing of a video stream using shaders. In this scenario, three shaders S 1 , S 2 , S 3  are set to be applied to the video stream comprising three frames # 1 , # 2 , # 3 . In  FIG. 3 b   , the processing of the three frames is divided between the video stream processing device and the client device as follows. 
         [0060]    For both the first and the second processing, all of pixels in each of the frames # 1 , # 2 , # 3  are processed, which is represented by that the areas representing the frames # 1 , # 2 , # 3  in  FIG. 3 b    are fully dotted. However, the first processing comprises applying two of the shaders S 1 , S 2  to the frames # 1 , # 2 , # 3  while the second processing comprises applying the third shader S 3  to the frames # 1 , # 2 , # 3 . Consequently, the at least one shader S 1 , S 2  applied in the first processing differs from the at least one shader S 3  applied in the second processing. 
         [0061]    In  FIG. 3 c   , a different type of division of the processing of the shaders is made. According to this embodiment all of the three shaders, S 1 , S 2 , S 3  are applied in both of the first and the second processing. Instead the first and the second processing relate to different subsets of the frames # 1 , # 2 , # 3  of the video stream. In  FIG. 3 c   , the first processing relates to half of the pixels in each frame # 1 , # 2 , # 3 , while the second processing relates to the other half of the pixels of each frame # 1 , # 2 , # 3 . Consequently, the subset of the video stream to which the first processing relates differs from the subset of the video stream to which the second processing relates. Other ways of dividing the frames are equally possible, for example, every other frame can be processed on the video stream processing device while the processing on the client device takes care of the rest of the frames. Other possibilities comprise processing ⅔ of the pixels at the video stream processing device and the remaining ⅓ of the pixels at the client device or any other suitable way of dividing the pixels to be processed. 
         [0062]      FIG. 4 a    describes another scenario of processing of a video stream using shaders. In this scenario, three shaders S 1 , S 2 , S 3  are set to be applied to the video stream comprising six frames # 1 , # 2 , # 3 , # 4 , # 5 , # 6 . 
         [0063]      FIG. 4 b    describes the processing of the first three frames # 1 , # 2 , # 3 . For both the first and the second processing in  FIG. 4 b   , all of pixels in each of the frames # 1 , # 2 , # 3  are processed. However, the first processing comprises applying two of the shaders S 1 , S 2  to the frames # 1 , # 2 , # 3  while the second processing comprises applying the third shader S 3  to the frames # 1 , # 2 , # 3 . 
         [0064]    As described above, the first processing and/or the second processing may dynamically change over the duration of the video stream. This is described in  FIG. 4 c    which describe the processing of the last three frames # 4 , # 5 , # 6 . In  FIG. 4 c   , the first and the second processing have changed compared to the first and the second processing in  FIG. 4 b    in that the execution of the second shader S 2  have been moved and now is part of the second processing at the client device. 
         [0065]    When dividing the processing of the shaders between the video processing device and the client device, further considerations, other than the ones describe above, may be made. For example, in the case one of the one or more shaders generates a privacy mask on the video stream, it may be advantageous if the privacy mask is generated in its entirety in the first processing. This reduces the risk of displaying sensitive video data to a viewer since the privacy mask is already applied in the encoded video sent to the client device. 
         [0066]    Moreover, for shaders that requires low latency, and for shaders that relates to an interactive user interface at the client device or at a display connected to the client device, the execution of these shaders are advantageously performed at the client device. 
         [0067]    In the  FIGS. 3 b - c  and 4 b - c    the first processing is different from the second processing. However, as mentioned before, the first processing and the second processing may be identical, for example when the shader are performing incremental filtering of the video stream. 
         [0068]      FIG. 5  describes a system  500  for processing a video stream. The system  500  comprises a video stream processing device  502  connected to a client device  516 . 
         [0069]    The video stream processing device comprises a memory  504  for storing one or more shaders to be applied to the video stream. The memory  504  may include, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer. 
         [0070]    The video stream processing device  502  further comprises a shader handling unit  506  which may be used for determining a first processing relating to at least a subset of the video stream to which at least one of the one or more shaders is to be applied, and a second processing relating to at least a subset of the video stream to which at least one of the one or more shaders is to applied. The shader handling unit  506  may take into account information pertaining to the video stream processing device, the client device and/or the connection between the video stream processing device and the client device when determining the first processing and the second processing. The shader handling unit  506  may also take the content of video stream into account, i.e. by employing video analytics algorithms or being provided with video analytics data from another device. For example, if it is determined that the video stream comprises human faces that need to be covered, i.e. by a privacy mask, the shader handling unit may determine that the first processing should comprise a shader for applying such privacy masks to the video stream. According to some embodiments, the shader handling unit is provided away from the video stream processing device. According to this embodiment, the first and the second processing are provided to the video stream processing device instead of determined in the video stream processing device. 
         [0071]    The video stream processing device further comprises a GPU  508  for performing the first processing and an encoder  512  configured to encode the video stream into an encoded video stream  106 . The encoded video stream  106  is then transmitted by a digital network module  510 , via a digital network  514  to the client device  516 . The digital network module  510  will also transmit the at least one  108  of the one or more shaders to be applied in the second processing and data  524  pertaining to the at least a subset of the video stream to which the second processing relate. For example, in the embodiment shown in  FIG. 3 c   , the data  524  pertaining to the at least a subset of the video stream to which the second processing relate describes that the right half of each frame should be processed in the second processing. The shader handling unit  506  and the encoder  512  may be implemented in software and executed by one or more processors in the video stream processing device  502 . 
         [0072]    As described above, the transmission of the encoded video stream  106  may be prioritized over the transmission of the at least one  108  of the one or more shaders to be applied in the second processing and data  524  pertaining to the at least a subset of the video stream to which the second processing relate. This feature is in  FIG. 5  described by that the line that represents the transmission of the video stream  106  is thicker compared to the line that represents the transmission of the shader(s)  108  and the data  524 . This prioritization may be attained in a plurality of ways. For example, the transmission of the video stream  106  may be performed via a first network connection, and the transmission of shader(s)  108  and data  524  may be performed via a second network connection different from the first network connection. In this case, the connection for the transmission of the video stream  106  may have a higher bandwidth compared to the connection for transmission of the shader(s)  108  and the data  524 . According to other embodiments, the video stream processing device  502  comprises a plurality of threads of execution, and wherein the transmission of the video stream  106  is performed by executing a first thread, and wherein the transmission of the shader(s)  108  applied in the second processing, and the data  524 , is performed by executing a second thread different from the first thread. 
         [0073]    The encoded video stream  106 , the shader(s)  108  and the data  524  are received by a digital network module  522  in the client device. The digital network module  522  in the client device  516  is thus configured to receive, via the digital network  514 , the at least one  108  of the one or more shaders to be applied in the second processing, data  524  pertaining to the at least a subset of the video stream to which the second processing relate, and the encoded video stream  106 . The client device  516  further comprises a decoder  520  configured to decode the encoded video stream  106  into a video stream, and a GPU  518  for performing the second processing using the received at least one  108  of the one or more shaders and the received data  524  pertaining to the at least a subset of the video stream to which the second processing relate. Finally, the client device may be connected to a display  104  for displaying the processed video stream  526 .