[Ffmpeg-devel] Re: [PATCH] mp4 codecs objecttype handling

[Baptiste COUDURIER]

Hi,

Michael Niedermayer wrote:
> Hi
> 
> On Sat, Feb 11, 2006 at 01:38:40AM +0100, Baptiste COUDURIER wrote:
>> Hi,
>>
>> This patch adds mp4 specific codec objecttype handling is esds atom.
> 
> [...]
> 
>>  
>> +/* http://gpac.sourceforge.net/tutorial/mediatypes.htm */
>> +static const CodecTag mp4_codec_tags[] = {
>> +    { CODEC_ID_MPEG4     , 0x01 }, /* MPEG4 Systems 1 */
>> +    { CODEC_ID_MPEG4     , 0x02 }, /* MPEG4 Systems 2 */
>> +    { CODEC_ID_MPEG4     , 0x20 }, /* MPEG4 */
>> +    { CODEC_ID_AAC       , 0x40 }, /* MPEG4 Audio */
>> +    { CODEC_ID_MPEG2VIDEO, 0x60 }, /* MPEG2 Simple */
>> +    { CODEC_ID_MPEG2VIDEO, 0x61 }, /* MPEG2 Main */
>> +    { CODEC_ID_MPEG2VIDEO, 0x62 }, /* MPEG2 SNR */
>> +    { CODEC_ID_MPEG2VIDEO, 0x63 }, /* MPEG2 Spatial */
>> +    { CODEC_ID_MPEG2VIDEO, 0x64 }, /* MPEG2 High */
>> +    { CODEC_ID_MPEG2VIDEO, 0x65 }, /* MPEG2 422 */
>> +    { CODEC_ID_AAC       , 0x66 }, /* MPEG2 AAC Main */
>> +    { CODEC_ID_AAC       , 0x67 }, /* MPEG2 AAC Low */
>> +    { CODEC_ID_AAC       , 0x68 }, /* MPEG2 AAC SSR */
>> +    { CODEC_ID_MP3       , 0x69 }, /* MP3 */
>> +    { CODEC_ID_MPEG1VIDEO, 0x6A }, /* MPEG1 Video */
>> +    { CODEC_ID_MP2       , 0x6B }, /* MPEG1 Audio */
>> +    { CODEC_ID_MJPEG     , 0x6C }, /* JPEG Video */
>> +};
> 
> duplicate of ff_mov_obj_type
> 

Thanks, I did not see this one. Added missing objecttypes.

> [...]
> 
>> @@ -650,12 +671,22 @@ static int mov_read_esds(MOVContext *c, 
>>  
>>      len = mov_mp4_read_descr(pb, &tag);
>>      if (tag == MP4DecConfigDescrTag) {
>> +        enum CodecID id;
>> +
>>          sc->esds.object_type_id = get_byte(pb);
>>          sc->esds.stream_type = get_byte(pb);
>>          sc->esds.buffer_size_db = get_be24(pb);
>>          sc->esds.max_bitrate = get_be32(pb);
>>          sc->esds.avg_bitrate = get_be32(pb);
>>  
>> +        id = codec_get_id(mp4_codec_tags, sc->esds.object_type_id);
>> +        if (id >= 0) {
>> +            AVCodec *codec;
>> +            codec = avcodec_find_decoder(id);
>> +            if (codec)
>> +                st->codec->codec_id = id;
>> +        }
> 
> wth is this supposed to do? why not:
> 
> if(st->codec->codec_id <= 0)
>     st->codec->codec_id= codec_get_id(mp4_codec_tags, sc->esds.object_type_id);
> 
> 

MOV 4CC is 'mp4v' and parser actually assigns codec_id to
CODEC_ID_MPEG4. And objecttype is MPEG2 for example :

http://www.coudurier.com/mpeg2_in_mp4.mp4

It is not 0. I just ensure that the codec exists before overriding.

Attached a fixed patch.

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
SMARTJOG S.A.                                    http://www.smartjog.com
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