Audio return channel transmitter of high-definition multimedia interface

Abstract

An audio return channel transmitter for a high-definition multimedia interface is disclosed. The audio return channel transmitter outputs an audio signal and includes: a digital-to-interface converter, a buffer circuit, a frame encoder, an audio return channel analog transmitter, and a clock tracking circuit. The digital-to-interface converter converts a first audio packet into a plurality of audio samples. The buffer circuit stores the audio samples according to a first clock and outputs the audio samples according to a second clock. The frame encoder encodes the audio samples to generate a second audio packet. The audio return channel analog transmitter generates the second clock and generates the audio signal based on the second clock and the second audio packet. The clock tracking circuit adjusts the second clock according to the first clock and the second clock.

Claims

1. An audio return channel transmitter for a high-definition multimedia interface, used to output an audio signal, comprising: a digital transmission interface converter (DIP) for converting a first audio packet into a plurality of audio samples; a buffer circuit coupled to the DIP, for storing the plurality of audio samples according to a first clock and outputting the plurality of audio samples according to a second clock; a frame encoder coupled to the buffer circuit for encoding the plurality of audio samples to generate a second audio packet; an audio return channel analog transmitter coupled to the buffer circuit and the frame encoder for generating the second clock and generating the audio signal based on the second clock and the second audio packet; and a clock tracking circuit coupled to the DIP and the audio return channel analog transmitter for adjusting the second clock according to the first clock and the second clock.

2. As in request item 1, the audio return channel transmitter, wherein, The audio return channel analog transmitter includes: a non-integer phase-locked loop used to generate the second clock based on a divisor.

3. As in request item 2, the audio return channel transmitter, wherein, The clock tracking circuit includes: a first counter for generating a first count value based on the first clock, wherein the first counter generates a first signal when the first count value is equal to a first numerical value; a second counter for generating a second count value based on the second clock, wherein the second counter generates a second signal when the second count value is equal to a second numerical value; a comparator circuit coupled to the first counter and the second counter for generating a control signal based on the first signal and the second signal; and a control circuit coupled to the comparator circuit for generating an adjustment signal based on the control signal; wherein the adjustment signal is the divisor or is used to adjust the divisor.

4. As in request item 3, the audio return channel transmitter, wherein, When the first signal is generated before the second signal, the control circuit increases the divisor.

5. As in request item 3, the audio return channel transmitter, wherein, When the first signal is generated later than the second signal, the control circuit reduces the divisor.

6. As in request item 3, the audio return channel transmitter, wherein, The first value is equal to the second value.

7. As in request item 3, the audio return channel transmitter, wherein, The audio return channel transmitter is an enhanced audio return channel transmitter and has N input channels and M output channels, where N and M are both positive integers, and the ratio of the second value to the first value is one of M / 2, M / N, and 4.

8. As in request item 1, the audio return channel transmitter, wherein, This buffer circuit is a asynchronous first-in-first-out buffer circuit.

9. As in request item 1, the audio return channel transmitter, wherein, The digital transmission interface converter is an S / PDIF (Sony / Philips Digital Interface Format) converter, the audio signal conforms to the IEC60958-1 specification, and the first clock is included in the first audio packet.

10. An audio return channel transmitter for a high-definition multimedia interface, used to output an audio signal, comprising: a digital transmission interface converter for converting a first audio packet into a plurality of audio samples; a buffer circuit coupled to the digital transmission interface converter for storing the plurality of audio samples according to a first clock and outputting the plurality of audio samples according to a second clock; a frame encoder coupled to the buffer circuit for encoding the audio samples to generate a second audio packet; an audio return channel analog transmitter coupled to the buffer circuit and the frame encoder for generating the second clock and generating the audio signal based on the second clock and the second audio packet; and a clock adjustment circuit coupled to the buffer circuit and the audio return channel analog transmitter for adjusting the second clock according to an increasing rate of the number of the plurality of audio samples in the buffer circuit.

Images