Method and device for packaging audio samples of a non-PCM encoded audio bitstream into a sequence of frames

Abstract

An audio bitstream is read from a digital video disc DVD for transfer, subsequent to parsing thereof, via an IEC 958 protocolled interface, for use in a multi-channel audio reproduction apparatus. For each respective audio channel MPEG audio samples are packaged recurrently in burst payloads, and these burst payloads are packaged as user data in IEC958 format frames. Pause bursts are used for signalling absence of audio for all associated channels with, each pause burst representing such audio absence during a perceptibly acceptable time interval only.

I claim: 
     
       1. A method of transferring a non-PCM encoded multichannel bitstream to digital audio reproduction apparatus via an interface which is adapted for transfer of PCM encoded bitstreams, the non-PCM encoded multichannel bitstream resulting from parsing a multichannel bitstream received from a digital video disc (DVD), comprising the steps of:
 (i) recurrently packaging audio samples of the non-PCM encoded multichannel bitstream in data burst payloads;   (ii) packing the data burst payloads as user data in successive frames having a predetermined format including pause bursts signifying the absence of audio in all channels, each pause burst having a duration in the range below 10 milliseconds; and   (iii) decoding and supplying the packaged data burst payloads of the respective channels to respective channel inputs of said audio reproduction apparatus.   
     
     
       2. A method as claimed in  claim 1 , wherein each pause burst has a repetition interval of 32 or a multiple of 32 of the periods of said audio samples. 
     
     
       3. A method as claimed in  claim 1 , wherein the presence of a pause burst is indicated by a burst header in the non-PCM encoded multichannel bitstream. 
     
     
       4. A method as claimed in  claim 1 , wherein each pause burst has a repetition period not over one-fifth that of any non-pause burst in the non-PCM encoded multichannel bitstream. 
     
     
       5. A method as claimed in  claim 1 , wherein the data bursts have a repetition period of 384 periods of the audio samples. 
     
     
       6. A method as claimed in  claim 1 , further comprising adding stuffing zeros to the data burst payloads in order to maintain a uniform size burst format, the bursts being multiplexed among the multiple channels in a recurrent manner, relevant data from other channels being superposed on stuffing zero positions in channels having stuffing zeros. 
     
     
       7. A coupling device for transferring a non-PCM encoded multichannel bitstream to digital audio reproduction apparatus via an interface which is adapted for transfer of PCM encoded bitstreams, the non-PCM encoded multichannel bitstream resulting from parsing a multichannel bitstream read from a digital video disc (DVD); comprising:
 means for recurrently packaging audio samples of the non-PCM encoded multichannel bitstream in data burst payloads;   means for packing the data burst payloads as user data in successive frames having a predetermined format including pause bursts signifying the absence of audio in all channels, each pause burst having a duration in the millisecond range below 10 milliseconds; and   means for decoding and supplying the packaged data burst payloads of the respective channels to respective channel inputs of said audio reproduction apparatus.   
     
     
       8. A method of transferring a non-PCM encoded multichannel bitstream to digital audio reproduction apparatus via an interface which is adapted for transfer of PCM encoded bitstreams, the non-PCM encoded multichannel bitstream resulting from parsing a multichannel bitstream read from a digital video disc (DVD), the parsed bitstream being received as a sequence of frames which accumulates, for each channel, a uniform number of data bits, comprising the steps of:
 storing each frame in an intermediate frame buffer;   detecting the presence of data pertaining to a particular output channel or the absence of such data as represented by one or more sequential pause bursts;   upon detecting the presence of said data in said detecting step, decoding and outputting decoded information for the particular channel; and   upon detecting one or more sequential pause bursts in the detecting step, controlling a soft mute block to conceal the absence of said data.   
     
     
       9. A coupling device for transferring a non-PCM encoded multichannel bitstream to digital audio reproduction apparatus via an interface which is adapted for transfer of PCM encoded bitstreams, the non-PCM encoded multichannel bitstream resulting from parsing a multichannel bitstream read from a digital video disc (DVD), comprising:
 means for receiving said parsed bitstream as a sequence of frames which each accommodate, for each channel, a uniform number of data bits;   an intermediate frame buffer for storing each frame;   detection means for detecting the presence of data pertaining to a particular output channel or the absence of such data as represented by one or more sequential pause bursts;   decoding means controlled by said detection means for decoding and outputting from a stored frame decoded information for said particular channel; and   means responsive to detection by said detection means of said one or more sequential pause bursts to control an audio soft mute block of said one or more sequential pause bursts to conceal the absence of data in said mute block.   
     
     
       10. A device for packaging audio samples of a non-PCM encoded multichannel audio bitstream into a sequence of IEC958 format frames, the device comprising:
 a processor configured to
 detect the presence or absence of audio data in an audio channel of a non-PCM encoded bitstream; 
 generate pause data-bursts in response to the absence of audio data in the audio channel, 
 recurrently package data words of the audio channel of the non-PCM encoded audio bitstream into payloads of audio data-bursts when audio data is present 
 recurrently package the audio data-bursts and the pause data-bursts in a sequence of IEC958 format frames; 
 output the sequence of IEC958 format frames including the inserted pause data-bursts. 
   
     
     
       11. The device of claim 10, wherein the processor is configured to generate the data-bursts with a burst preamble and a payload, a size of the payload depending on the type of the data-burst. 
     
     
       12. The device of claim 11, wherein the burst preamble consists of four 16-bit control words. 
     
     
       13. The device of claim 12, wherein information in a third control word of the four control words indicates the type of data-burst. 
     
     
       14. The device of claim 10, wherein the audio samples are MPEG audio samples, and the processor is configured to generate the pause data-bursts with a repetition time interval that is equal to at most one MPEG LFE sample recurrency time interval, the pause data-burst repetition time being 96 audio sample periods. 
     
     
       15. The device of claim 14, wherein the processor is configured to generate the pause data-bursts with a repetition time interval equal to an integer multiple of 32 audio sample periods. 
     
     
       16. The device of claim 10, wherein the processor is configured to indicate a presence of the pause data-bursts in a third control word in a header of the pause data-bursts and to insert a 16 bit gap-length parameter in a payload of a first pause data-burst of a series of pause data-bursts, and a 32-bit payload of each pause burst being stuffed with zeros except the 16-bit gap length parameter. 
     
     
       17. The device of claim 10, wherein the pause data-bursts have a repetition time that is at least five times shorter than a repetition time of any non-pause data-burst. 
     
     
       18. The device of claim 10, wherein the processor is configured to generate MPEG-1 layer data-bursts with a repetition time interval of 384 audio sample periods per channel. 
     
     
       19. The device of claim 10, wherein the processor is configured to generate MPEG-1 layer 2 or 3, or MPEG-2 without extension type data-bursts with a repetition time interval of 1152 audio sample periods per channel. 
     
     
       20. The device of claim 10, wherein the processor is configured to generate MPEG-2 with extension type data-bursts with a repetition time interval of 1152 audio sample periods per channel. 
     
     
       21. The device of claim 10, wherein the processor is configured to generate MPEG-2 layer 1 low sample rate type data-bursts with a repetition time interval of 384 audio sample periods per channel. 
     
     
       22. The device of claim 10, wherein the processor is configured to generate MPEG2 layer 2 or 3 low sample rate type data-bursts with a repetition time interval of 1152 audio sample periods per channel. 
     
     
       23. The device of claim 10, wherein the processor is configured to add stuffing zeroes after the date-bursts to fill a space between data-bursts, the minimum number of stuffing zeros being 32, the amount of stuffing depending on a predetermined recurrency period for the date-bursts that depends on the type of data-burst. 
     
     
       24. The device of claim 10, wherein the audio channel is one of a plurality of audio channels and the processor configured to recurrently multiplex the data-bursts among the plurality of channels. 
     
     
       25. A device for transferring a non-PCM encoded multichannel audio bitstream, the device comprising:
 a processor configured to
 recurrently package audio data words of the non-PCM encoded multichannel bitstream into burst payloads of audio data-bursts that have a predetermined format, 
 generate pause data-bursts indicating an absence of audio samples in the bitstream for a predetermined duration; and 
 output successive data-bursts including the audio data-bursts and the pause data-bursts. 
   
     
     
       26. A device for transmitting a non-PCM encoded multichannel bitstream of audio samples with soft mute blocks to conceal the effect of audio data discontinuities when the audio samples are played, the device comprising:
 a processor configured to:
 detect the presence of an audio data discontinuity in a particular audio channel in a bitstream; 
 determine the length of the audio data discontinuity; 
 generate one or more soft mute blocks depending on the length of the audio data discontinuity; 
 insert the soft mute blocks into the audio bitstream to conceal the audio discontinuity when the audio is played; 
 transmitting the audio bitstream containing the soft mute blocks to user audio equipment. 
   
     
     
       27. A device for receiving a non-PCM encoded multichannel bitstream of audio samples which have audio data discontinuities and for providing soft mute blocks to conceal the audio data discontinuities when the audio samples are played, the device comprising:
 a processor configured to:
 receive a non-PCM encoded multichannel bitstream of audio samples from user audio equipment; 
 detect the presence of an audio data discontinuity in a particular audio channel in a bitstream; 
 determine the length of the audio data discontinuity; 
 generate one or more soft mute blocks based on a length of the audio data discontinuity; 
 insert the soft mute blocks into the audio bitstream to conceal the audio discontinuity when the audio is played; 
 output the audio bitstream including the soft mute blocks. 
   
     
     
       28. A device for outputting audio samples of a non-PCM encoded multichannel audio bitstream which have audio data discontinuities, the device comprising:
 a processor configured to
 detect the presence or absence of audio data in an audio channel of a non-PCM encoded bitstream; 
 recurrently package data words of the audio channel of the non-PCM encoded audio bitstream into payloads of audio data-bursts when audio data is present and into pause data-bursts in response to the audio data discontinuities in the audio channel; 
 output the sequence of audio data-bursts and pause data-bursts. 
   
     
     
       29. A device for receiving a non-PCM encoded bitstream and outputting multichannel audio data for subsequent reproduction, the device comprising:
 a receiver configured to receive a non-PCM encoded bitstream for a plurality of audio channels as a sequence of data bits;   a decoder configured to detect a presence or absence of audio data in the sequence of data bits and configured to decode audio information and output decoded audio information depending on the detection of audio data and to conceal the absence of audio data depending on the detection of the absence of audio data.   
     
     
       30. The device of claim 29, wherein the absence of audio is detected by detecting presence of one or more pause frames. 
     
     
       31. The device of claim 29, wherein the decoder mutes the audio output based on the presence of one or more pause frames. 
     
     
       32. The device of claim 31, wherein the mute is a soft mute.