[FFmpeg-devel] [PATCH] MOV muxer : Add SoundDescriptionV2 support

[Baptiste Coudurier]

On 11/28/09 1:21 AM, Jai Menon wrote:
> On Sat, Nov 28, 2009 at 12:03:47AM -0800, Baptiste Coudurier wrote:
>> Hi,
>>
>> On 11/27/09 11:41 PM, Jai Menon wrote:
>
> [...]
>
>>> sounddescv2.patch
>>>
>>>
>>> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
>>> index ac6378c..36b156e 100644
>>> --- a/libavformat/movenc.c
>>> +++ b/libavformat/movenc.c
>>> @@ -405,13 +405,21 @@ static int mov_write_glbl_tag(ByteIOContext *pb, MOVTrack *track)
>>>   static int mov_write_audio_tag(ByteIOContext *pb, MOVTrack *track)
>>>   {
>>>       int64_t pos = url_ftell(pb);
>>> -    int version = track->mode == MODE_MOV&&
>>> +    int version;
>>> +
>>> +    if (track->mode == MODE_MOV&&
>>>           (track->audio_vbr ||
>>>            track->enc->codec_id == CODEC_ID_PCM_S32LE ||
>>> -         track->enc->codec_id == CODEC_ID_PCM_S24LE);
>>> +         track->enc->codec_id == CODEC_ID_PCM_S24LE)) {
>>> +        if (track->timescale>   UINT16_MAX)
>>> +            version = 2;
>>
>> The stsd v2 must always be used when timescale>  UINT16_MAX
>> regardless of codec.
>
> Yes, I agree, but right now I just dont have the time required to make
> samples, remux and test against quicktime. Maybe someone who requires
> this for other codecs can add it later?

Well, by experience, half-baked solutions for specific codecs rot 
forever in the codebase, so I would prefer avoiding it.

>>> +        else version = 1;
>>> +    }
>>>
>>>       put_be32(pb, 0); /* size */
>>> -    put_le32(pb, track->tag); // store it byteswapped
>>> +    if (version == 2)
>>> +        put_le32(pb, AV_RL32("lpcm"));
>>
>> Technically all codecs can use stsd v2, I have an ALAC sample using
>> stsd v2 since sample rate is 192000. It was just for test :)
>
> Okay, modified the patch to make it work for ALAC>  96Khz and others.
>
>>> +    else put_le32(pb, track->tag); // store it byteswapped
>>>       put_be32(pb, 0); /* Reserved */
>>>       put_be16(pb, 0); /* Reserved */
>>>       put_be16(pb, 1); /* Data-reference index, XXX  == 1 */
>>> @@ -444,6 +452,15 @@ static int mov_write_audio_tag(ByteIOContext *pb, MOVTrack *track)
>>>           put_be32(pb, track->sampleSize / track->enc->channels); /* Bytes per packet */
>>>           put_be32(pb, track->sampleSize); /* Bytes per frame */
>>>           put_be32(pb, 2); /* Bytes per sample */
>>> +    } else if (version == 2) {
>>> +        put_be32(pb, 72);
>>
>> Please split it according to specs:
>>
>>     SInt16     always3;
>>     SInt16     always16;
>>     SInt16     alwaysMinus2;
>>     SInt16     always0;
>>     UInt32     always65536;
>>     UInt32     sizeOfStructOnly;
>
> Sorry, I didnt understand this part, 72 is the
> sizeof(SoundDescriptionV2), and the rest are subsequent values.
>

Specs says stsd structure fields must be set to specific values, which 
is not done currently.

[...]

-- 
Baptiste COUDURIER
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