matroska: implement support for ALAC

Support Matroska native formatting.

On demuxing reconstruct the 36-bytes QuickTime atom that the ALAC
decoder expects by prepending the "atom size", "tag" and
"tag version" fields missing from the Matroska's CodecPrivate
element.

On muxing remove the initial 12 bytes

Sample files are available:
http://www.bunkus.org/videotools/mkvtoolnix/samples/alac/alac-in-matroska.mka
and the CoreAudio file it was created from with today's mkvmerge:
http://www.bunkus.org/videotools/mkvtoolnix/samples/alac/alac-in-matroska-source.caf

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
release/1.0
Moritz Bunkus 13 years ago committed by Luca Barbato
parent 870e75524a
commit 8071dca3d5
  1. 1
      libavformat/matroska.c
  2. 13
      libavformat/matroskadec.c
  3. 10
      libavformat/matroskaenc.c

@ -24,6 +24,7 @@
const CodecTags ff_mkv_codec_tags[]={
{"A_AAC" , AV_CODEC_ID_AAC},
{"A_AC3" , AV_CODEC_ID_AC3},
{"A_ALAC" , AV_CODEC_ID_ALAC},
{"A_DTS" , AV_CODEC_ID_DTS},
{"A_EAC3" , AV_CODEC_ID_EAC3},
{"A_FLAC" , AV_CODEC_ID_FLAC},

@ -1528,6 +1528,19 @@ static int matroska_read_header(AVFormatContext *s)
extradata_size = 5;
} else
extradata_size = 2;
} else if (codec_id == AV_CODEC_ID_ALAC && track->codec_priv.size) {
/* Only ALAC's magic cookie is stored in Matroska's track headers.
Create the "atom size", "tag", and "tag version" fields the
decoder expects manually. */
extradata_size = 12 + track->codec_priv.size;
extradata = av_mallocz(extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
if (extradata == NULL)
return AVERROR(ENOMEM);
AV_WB32(extradata, extradata_size);
memcpy(&extradata[4], "alac", 4);
AV_WB32(&extradata[8], 0);
memcpy(&extradata[12], track->codec_priv.data,
track->codec_priv.size);
} else if (codec_id == AV_CODEC_ID_TTA) {
extradata_size = 30;
extradata = av_mallocz(extradata_size);

@ -475,6 +475,16 @@ static int mkv_write_codecprivate(AVFormatContext *s, AVIOContext *pb, AVCodecCo
ret = ff_flac_write_header(dyn_cp, codec, 1);
else if (codec->codec_id == AV_CODEC_ID_H264)
ret = ff_isom_write_avcc(dyn_cp, codec->extradata, codec->extradata_size);
else if (codec->codec_id == AV_CODEC_ID_ALAC) {
if (codec->extradata_size < 36) {
av_log(s, AV_LOG_ERROR,
"Invalid extradata found, ALAC expects a 36-byte "
"QuickTime atom.");
ret = AVERROR_INVALIDDATA;
} else
avio_write(dyn_cp, codec->extradata + 12,
codec->extradata_size - 12);
}
else if (codec->extradata_size)
avio_write(dyn_cp, codec->extradata, codec->extradata_size);
} else if (codec->codec_type == AVMEDIA_TYPE_VIDEO) {

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