[FFmpeg-devel] [PATCH] movenc: support non-standard DVD subtitles muxing.

[Baptiste Coudurier]

On 07/10/2012 09:04 PM, Philip Langdale wrote:
> On Mon,  9 Jul 2012 10:30:51 +0200
> Nicolas George <nicolas.george at normalesup.org> wrote:
> 
>> The format is imitated on what can be found in the file
>> unsupported-embedded-subs-2.mp4 from the MPlayer sample collection.
>> The subtitles in a file remuxed from that sample can now be decoded
>> by ffplay and vlc (2.0.2).
>>
>> Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
>> ---
>>  libavformat/movenc.c |    9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
>> index 89072d5..51bf97b 100644
>> --- a/libavformat/movenc.c
>> +++ b/libavformat/movenc.c
>> @@ -325,6 +325,8 @@ static int mov_write_esds_tag(AVIOContext *pb,
>> MOVTrack *track) // Basic // plus 1 bit to indicate upstream and 1
>> bit set to 1 (reserved) if(track->enc->codec_type ==
>> AVMEDIA_TYPE_AUDIO) avio_w8(pb, 0x15); // flags (= Audiostream)
>> +    else if(track->enc->codec_type == AVMEDIA_TYPE_SUBTITLE)
>> +        avio_w8(pb, 0xE1); // flags
>>      else
>>          avio_w8(pb, 0x11); // flags (= Visualstream)
>>  
>> @@ -997,11 +999,17 @@ static int mov_write_subtitle_tag(AVIOContext
>> *pb, MOVTrack *track) {
>>      int64_t pos = avio_tell(pb);
>>      avio_wb32(pb, 0);    /* size */
>> +    if (track->enc->codec_id == CODEC_ID_DVD_SUBTITLE)
>> +        ffio_wfourcc(pb, "mp4s");
>> +    else
>>      avio_wl32(pb, track->tag); // store it byteswapped
>>      avio_wb32(pb, 0);    /* Reserved */
>>      avio_wb16(pb, 0);    /* Reserved */
>>      avio_wb16(pb, 1);    /* Data-reference index */
>>  
>> +    if (track->enc->codec_id == CODEC_ID_DVD_SUBTITLE)
>> +        mov_write_esds_tag(pb, track);
>> +    else
>>      if (track->enc->extradata_size)
>>          avio_write(pb, track->enc->extradata,
>> track->enc->extradata_size); 
>> @@ -1388,6 +1396,7 @@ static int mov_write_hdlr_tag(AVIOContext *pb,
>> MOVTrack *track) descr = "SoundHandler";
>>          } else if (track->enc->codec_type == AVMEDIA_TYPE_SUBTITLE) {
>>              if (track->tag == MKTAG('t','x','3','g')) hdlr_type =
>> "sbtl";
>> +            else if (track->tag == 0xE0)              hdlr_type =
>> "subp"; else                                      hdlr_type = "text";
>>              descr = "SubtitleHandler";
>>          } else if (track->enc->codec_tag == MKTAG('t','m','c','d')) {
> 
> Looks reasonable to me, and matches what I've seen in other dvd subtitle
> samples.
> 

I believe this can be simplified by using already existing functions.
mp4_get_codec_tag and setting track->tag to "mp4s"
This is only valid in mp4 as well.

-- 
Baptiste COUDURIER
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