Patent Description:
High Definition Multimedia Interface (HDMI) Licensing Administrator, Inc. (HDMI LA) specifies an Audio Return Channel (ARC) which allows audio signals to be transmitted in different directions. As transmission speed of signals reaches <NUM> Giga bits per second in the HDMI <NUM> specification, a length of HDMI cable is severely limited (e.g. <NUM>-<NUM> meters at most) under a condition of not introducing signal errors, which greatly limits locations of a projector (or TV) and an amplifier. Thus, there is a need for a novel multi-media signal processing method and associated multi-media device to solve the problem of limited cable length.

This in mind, the application aims at providing a method for processing a multi-media signal and an associated multi-media device, which can prevent locations of a projector (or TV) and an amplifier from being limited by the length of an HDMI cable in order to improve user experience.

This is achieved by a method for processing a multi-media signal according to claim <NUM> and a multi-media device according to claim <NUM>. The dependent claims pertain to corresponding further developments and improvements.

As will be seen more clearly from the detailed description following below, the claimed method comprises: receiving, by a High Definition Multimedia Interface of a multi-media device, a first audio signal within the multi-media signal from a display device through an Audio Return Channel (ARC) or an enhanced ARC, the first audio signal being of a first transmission format suitable to be transmitted by the High Definition Multimedia Interface; within the multi-media device, converting the first audio signal into a second audio signal applicable to a Universal Serial Bus, hereafter USB, interface, the second audio signal being of a second transmission format suitable to be transmitted by the USB interface and being different from the first transmission format; and outputting the second audio signal from the multi-media device to an audio device through the USB interface for playback; wherein the multi-media device obtains power from a power management circuit within the audio device through at least one cable connecting the USB interface to the audio device, and wherein the power management circuit also supplies power internally to the audio device.

In addition, the claimed multi-media device comprises a High Definition Multimedia Interface, a Universal Serial Bus, hereafter USB, interface and a system chip, wherein the system chip comprises a conversion circuit coupled between the High Definition Multimedia interface and the USB interface. In operations of the multi-media device, the High Definition Multimedia interface is configured to receive a first audio signal within a multi-media signal from a display device through an Audio Return Channel (ARC) or an enhanced ARC, the first audio signal being of a first transmission format suitable to be transmitted by the High Definition Multimedia Interface, and the USB interface is configured to output a second audio signal from the multi-media device to an audio device for playback, wherein the audio device comprises a power management circuit, configured to perform power management, wherein the multi-media device obtains power from the power management circuit through at least one cable connecting the USB interface to the audio device, wherein the power management circuit also supplies power internally to the audio device. In addition, the system chip may utilize the conversion circuit to convert the first audio signal into the second audio signal applicable to the USB interface, the second audio signal being of a second transmission format suitable to be transmitted by the USB interface and being different from the first transmission format.

The multi-media device of the present invention converts the first audio signal into the second audio signal, where a transmission length of the second audio signal is less likely to be limited by the length of HDMI cable. For example, the second transmission interface is implemented by a Universal Serial Bus (USB) interface in order to solve the related art problems of using HDMI cables. In addition, embodiments of the present invention will not greatly increase costs, so the present invention can solve the problem of the related art without introducing any side effect or in a way that is less likely to introduce side effects.

At least one embodiment of the present invention provides a multi-media device. The multi-media device may utilize a video decoding circuit therein to perform video decoding to generate video output signals, and transmit the aforementioned video output signals to at least one video output device (e.g. digital TV, projector) through at least one High Definition Multimedia Interface (HDMI) cable. General digital TV performance has undergone recent improvements. For example, smart TVs can execute some video application programs (e.g. YouTube, Google Play and Netflix) which support high level audio specifications (e.g. Dolby Digital and Digital Theater System (DTS)). The multi-media device can support signal processing during execution of these video application programs, in order to allow users to enjoy the experience of using audio output equipment coupled to the multi-media device (e.g. audio output of the audio output equipment).

<FIG> is a diagram illustrating a video system <NUM> according to an embodiment of the present invention. The video system <NUM> comprises a multi-media device <NUM>, a display device <NUM> and an audio device <NUM>, where examples of the display device <NUM> include, but are not limited to: a display device without the function of executing the video application programs (such as a projector or a conventional TV), and a display device with the function of executing the video application programs (such as a smart TV); and examples of the audio device <NUM> include, but are not limited to: an audio device integrating a speaker and an amplifier into a single device, and an audio system constituted by connecting a speaker and an amplifier. In some embodiments, the multi-media device <NUM> is implemented in small sized multi-media devices such as an Over The Top (OTT) box and a TV stick.

In this embodiment, the multi-media device <NUM> comprises a first transmission interface such as an HDMI interface <NUM>, a video decoding circuit <NUM>, a second transmission interface such as a Universal Serial Bus (USB) interface <NUM>, and a system chip such as a System on a Chip (SoC) <NUM>, where the SoC <NUM> comprises a conversion circuit <NUM> coupled between the HDMI interface <NUM> and the USB interface <NUM>. The HDMI interface <NUM> allows the multi-media device <NUM> to be coupled to the display device <NUM> through an HDMI cable, and the USB interface <NUM> allows the multi-media <NUM> to be coupled to the audio device <NUM> through at least one USB cable (e.g. a USB type-C cable). In some embodiments, in addition to the conversion circuit <NUM>, the SoC <NUM> may further comprises one or more processing circuits (not shown) for executing various types of video application programs (e.g. YouTube, Google Play, Netflix).

In this embodiment, the audio device <NUM> comprises an audio amplifier <NUM> and a speaker <NUM> (e.g. a passive speaker) coupled to the audio amplifier, where the audio amplifier <NUM> comprises an amplifier circuit <NUM>, a digital-to-analog converter (DAC) <NUM> coupled to the amplifier circuit <NUM>, and a power management circuit <NUM> respectively coupled to the amplifier circuit <NUM> and the DAC <NUM>. In this embodiment, the DAC <NUM> obtains a digital audio signal from the multi-media device <NUM> through the aforementioned at least one USB cable, and performs digital-to-analog conversion on the digital audio signal to output an analog audio signal; and then the amplifier circuit <NUM> amplifies the analog audio signal to drive the speaker <NUM> with the analog audio signal for playback. In this embodiment, the power management circuit <NUM> provides the amplifier circuit <NUM> and the DAC <NUM> with power, and also provides the multi-media device <NUM> (such as the HDMI interface <NUM>, the USB interface <NUM> and the SoC <NUM> therein) with power through the aforementioned at least one USB cable. Thus, the present invention provides a design of separated power sources, which makes the multi-media device <NUM> able to obtain power from the power management circuit <NUM> within the audio device <NUM> through at least one USB cable connecting the USB interface <NUM> to the audio device <NUM>, to thereby allow the multi-media device <NUM> to normally operate without any built-in power management circuit, and required hardware size can be reduced.

In this embodiment, both the multi-media device <NUM> and the display device <NUM> have a function of obtaining streaming data (e.g. streaming data comprising image data and audio data) from a data streaming source. For better comprehension, the following description takes a smart TV as an example of the display device <NUM>. When the display device <NUM> operates in an ordinary mode, the aforementioned streaming data is obtained from the data streaming source (e.g. a remote server or internet connected to the remote server) through the multi-media device <NUM> rather than through the display device <NUM>, where the SoC <NUM> utilizes the video decoding circuit <NUM> to perform video decoding. In addition, the multi-media device <NUM> utilizes the HDMI interface <NUM> to transmit the image data within the streaming data to the display device <NUM> for display and utilizes the USB interface <NUM> to transmit the audio data within the streaming data to the audio device <NUM> for playback. When the display device <NUM> operates in an internet mode, the aforementioned streaming data is obtained from the data streaming source (e.g. a remote server or internet connected to the remote server) through the display device <NUM> rather than through the multi-media device <NUM>, where the SoC <NUM> receives a first audio signal within a multi-media signal from the display device <NUM> through an Audio Return Channel (ARC) or an enhanced ARC (eARC) (e.g. the first audio signal carries the audio data within the streaming data obtained by the display device <NUM>), and then the SoC <NUM> utilizes the conversion circuit <NUM> therein to convert the first audio signal into a second audio signal applicable to the USB interface <NUM>, and outputs the second audio signal to the audio device <NUM> through the USB interface <NUM> for playback.

In some embodiments, the conversion circuit <NUM> comprises a decoder (not shown) to make the multi-media <NUM> able to process compressed audio data in addition to uncompressed audio data. For example, when the first audio signal (e.g. the audio data within the streaming data obtained by the display device <NUM> is audio data having Dolby Digital or Digital Theater System (DTS) format), the decoder within the conversion circuit <NUM> decodes (decompresses) the audio data first, and then converts the decoded data into a USB signal format for being outputted by the USB interface <NUM>; in another example, when the first audio signal is uncompressed audio data, the conversion circuit <NUM> skips the aforementioned decoding step and directly converts the uncompressed data into a USB signal format for being outputted by the USB interface <NUM>.

<FIG> is a diagram illustrating a video system <NUM> according to an embodiment of the present invention, where the USB interface <NUM> within the multi-media device <NUM> comprises a USB type-C interface. A difference between this embodiment and the embodiment shown in <FIG> is that the audio device <NUM> connected to the multi-media device <NUM> does not comprise the DAC <NUM>, and the audio device <NUM> is implemented by merely utilizing the power management circuit <NUM>, the amplifier circuit <NUM> (e.g. a class-D amplifier) and the speaker <NUM>. In comparison with the audio device <NUM>, an audio signal received by the audio device <NUM> is an analog audio signal rather than a digital signal. In this embodiment, the USB interface <NUM> determines whether the audio device <NUM> is an audio device without any DAC (e.g. a passive audio device) by detecting a set of input resistors (e.g. a set of resistors of configuration channel (CC) pins) of the audio device <NUM> (amplifier circuit), e.g. by detecting voltage levels corresponding to resistances of the set of resistors; wherein when the audio device <NUM> is an audio device without any DAC, the USB interface <NUM> operates in an audio adapter accessory mode, and outputs an analog audio signal to the audio device <NUM> for playback. For example, when the multi-media device <NUM> (such as the SoC <NUM> and the USB interface <NUM> therein) operates in the audio adapter accessory mode, the conversion circuit <NUM> utilizes a DAC therein (not shown) to convert the audio signal received from the display device <NUM> into an analog audio signal, and further transmit the analog audio signal to the audio device <NUM> through the USB interface <NUM> for playback.

In practice, based on the limitation of a length of HDMI cable, the multi-media device <NUM> is usually arranged at a position near the display device <NUM>. According to user experience, an audio device may need to be arranged at a position having a specific distance from the display device <NUM> (or the multi-media device <NUM>). In the related art, an audio signal from the display device <NUM> may be transmitted by optical fibers to overcome the limitation of the length of HDMI cable, but equipment for optical fiber transmission is usually expensive. In comparison with the related art, based on the USB interface <NUM> within the multi-media device <NUM> of the present invention, a plurality of cables can be connected in series to connect the USB interface <NUM> to the audio device (e.g. the audio device <NUM> shown in <FIG>) through at least one hub to increase a transmission distance of an audio signal (such as the aforementioned second audio signal) between the multi-media device <NUM> and the audio device (e.g. the audio device <NUM> shown in <FIG>). For example, when a single USB cable is not long enough to satisfy requirements of the video system established by a user, the user may utilize a hub to connect two USB cables (or utilize two or more hubs to connect three or more USB cables) to increase the transmission distance of the audio signal, but the present invention is not limited thereto.

<FIG> is a flowchart illustrating a method for processing a multi-media signal (e.g. the streaming data obtained by the display device <NUM> from a data streaming source in the aforementioned embodiment) according to an embodiment of the present invention. For better comprehension, please refer to <FIG> in conjunction with <FIG> and <FIG>.

In Step <NUM>, a first transmission interface such as the HDMI interface <NUM> of the multi-media device <NUM> receives a first audio signal within the multi-media signal from the display device <NUM>. More specifically, the HDNI interface <NUM> may utilize an ARC or an eARC to receive the first audio signal.

In Step <NUM>, the multi-media device <NUM> (more particularly, the conversion circuit <NUM> within the SoC <NUM>) converts the first audio signal into a second audio signal applicable to a second transmission interface such as the USB interface <NUM> of the multi-media device <NUM>.

In Step <NUM>, the multi-media device <NUM> may output the second audio signal to an audio device through the second transmission interface for playback. Note that, when the multi-media device <NUM> is coupled to the audio device <NUM> (as shown in <FIG>), the second audio signal comprises a digital audio signal; and when the multi-media device <NUM> is coupled to the audio device <NUM> (as shown in <FIG>), the multi-media <NUM> (e.g. the USB interface <NUM>) operates in an audio adapter accessory mode to make the second audio signal comprise an analog audio signal.

Claim 1:
A method for processing a multi-media signal, comprising:
Receiving, by a High Definition Multimedia Interface (<NUM>) of a multi-media device (<NUM>), a first audio signal within the multi-media signal from a display device (<NUM>) through an Audio Return Channel, ARC, or an enhanced ARC, the first audio signal being of a first transmission format suitable to be transmitted by the High Definition Multimedia Interface (<NUM>);
within the multi-media device (<NUM>), converting the first audio signal into a second audio signal applicable to a Universal Serial Bus, hereafter USB, interface (<NUM>), the second audio signal being of a second transmission format suitable to be transmitted by the USB interface and being different from the first transmission format; and
outputting the second audio signal from the multi-media device (<NUM>) to an audio device (<NUM>, <NUM>) through the USB interface (<NUM>) for playback;
wherein the multi-media device (<NUM>) obtains power from a power management circuit (<NUM>) within the audio device (<NUM>, <NUM>) through at least one cable connecting the USB interface (<NUM>) to the audio device (<NUM>, <NUM>), and wherein the power management circuit (<NUM>) also supplies power internally to the audio device (<NUM>, <NUM>).