[FFmpeg-devel] [PATCH] support e-ac-3 in mpeg ps/ts

[Justin Ruggles]

M?ns Rullg?rd wrote:
> Justin Ruggles <justin.ruggles at gmail.com> writes:
> 
>> Hi,
>>
>> Here is a patch which adds basic support for E-AC-3 decoding/encoding in
>> MPEG PS and TS.  The only case I can't seem to differentiate is EVOB,
>> which uses the same descriptor type and start codes for AC-3 and E-AC-3.
>>  Since regular AC-3 is also valid E-AC-3, I'm setting them to E-AC-3.
>>
>> Index: libavformat/mpegts.c
>> ===================================================================
>> --- libavformat/mpegts.c	(revision 15138)
>> +++ libavformat/mpegts.c	(working copy)
>> @@ -554,9 +554,12 @@
>>              if (desc_tag < 0)
>>                  break;
>>              if (stream_type == STREAM_TYPE_PRIVATE_DATA) {
>> -                if((desc_tag == 0x6A) || (desc_tag == 0x7A)) {
>> +                if (desc_tag == 0x6A) {
>>                      /*assume DVB AC-3 Audio*/
>>                      stream_type = STREAM_TYPE_AUDIO_AC3;
>> +                } else if (desc_tag == 0x7A) {
>> +                    /* DVB E-AC-3 audio */
>> +                    stream_type = STREAM_TYPE_AUDIO_EAC3;
>>                  } else if(desc_tag == 0x7B) {
>>                      /* DVB DTS audio */
>>                      stream_type = STREAM_TYPE_AUDIO_DTS;
>> @@ -627,6 +630,7 @@
>>          case STREAM_TYPE_AUDIO_AAC:
>>          case STREAM_TYPE_AUDIO_AC3:
>>          case STREAM_TYPE_AUDIO_DTS:
>> +        case STREAM_TYPE_AUDIO_EAC3:
>>          case STREAM_TYPE_AUDIO_HDMV_DTS:
>>          case STREAM_TYPE_SUBTITLE_DVB:
>>              if((stream_type == STREAM_TYPE_AUDIO_HDMV_DTS && !has_hdmv_descr)
>> @@ -971,6 +975,10 @@
>>          codec_type = CODEC_TYPE_AUDIO;
>>          codec_id = CODEC_ID_AC3;
>>          break;
>> +    case STREAM_TYPE_AUDIO_EAC3:
>> +        codec_type = CODEC_TYPE_AUDIO;
>> +        codec_id = CODEC_ID_EAC3;
>> +        break;
>>      case STREAM_TYPE_AUDIO_DTS:
>>      case STREAM_TYPE_AUDIO_HDMV_DTS:
>>          codec_type = CODEC_TYPE_AUDIO;
>> Index: libavformat/mpegts.h
>> ===================================================================
>> --- libavformat/mpegts.h	(revision 15138)
>> +++ libavformat/mpegts.h	(working copy)
>> @@ -55,6 +55,7 @@
>>  #define STREAM_TYPE_VIDEO_DIRAC     0xd1
>>  
>>  #define STREAM_TYPE_AUDIO_AC3       0x81
>> +#define STREAM_TYPE_AUDIO_EAC3      0x84
>>  #define STREAM_TYPE_AUDIO_DTS       0x8a
>>  #define STREAM_TYPE_AUDIO_HDMV_DTS  0x82
>> Index: libavformat/mpegtsenc.c
>> ===================================================================
>> --- libavformat/mpegtsenc.c	(revision 15138)
>> +++ libavformat/mpegtsenc.c	(working copy)
>> @@ -233,6 +233,9 @@
>>          case CODEC_ID_AC3:
>>              stream_type = STREAM_TYPE_AUDIO_AC3;
>>              break;
>> +        case CODEC_ID_EAC3:
>> +            stream_type = STREAM_TYPE_AUDIO_EAC3;
>> +            break;
>>          default:
>>              stream_type = STREAM_TYPE_PRIVATE_DATA;
>>              break;
> 
> Where does the value 0x84 come from?  ATSC uses the same stream_type
> value (0x81) for AC-3 and E-AC-3, differentiating the two using a
> special descriptor.  DVB sets the stream_type to 6 (private data), and
> uses different descriptors to distinguish the two types.

That's my mistake... It's supposed to be 0x87 according to ATSC A/53,
not 0x84.

-Justin