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

[Måns Rullgård]

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.

-- 
M?ns Rullg?rd
mans at mansr.com