[FFmpeg-devel] [PATCH] close parser in av_find_stream_info is parsing is not needed

Baptiste Coudurier baptiste.coudurier
Tue May 18 15:51:05 CEST 2010

On 5/18/10 5:58 AM, Michael Niedermayer wrote:
> On Mon, May 17, 2010 at 01:17:42PM -0700, Baptiste Coudurier wrote:
>> Hey guys,
>> $subject.
>> The parser is opened here:
>>          //only for the split stuff
>>          if (!st->parser&&  !(ic->flags&  AVFMT_FLAG_NOPARSE)) {
>>              st->parser = av_parser_init(st->codec->codec_id);
>>              if(st->need_parsing == AVSTREAM_PARSE_HEADERS&&  st->parser){
>>                  st->parser->flags |= PARSER_FLAG_COMPLETE_FRAMES;
>>              }
>>          }
>> So either, it must be closed after, or it shouldn't be opened if parsing is
>> not needed. I'm not sure of the side effects.
> Parsers that have a AVCodecParser.split() must be opened and must stay open
> until they have extracted the global headers into extradata
> after that they could be closed if they arent needed for any other reasons
> There are several problems with this though, for example streams that start
> later (after av_find_stream_info()) might not have a parser enabled even if
> they need one for split().
> also if we close them before they have set extradata that similarly would
> be a problem

IMHO this is an ugly hack anyway, extradata should be extracted with a 
bitstream filter. This has proven to produce side effects.

Anyway, in ffmpeg.c:
                     int ticks= ist->st->parser ? 
ist->st->parser->repeat_pict+1 : ist->st->codec->ticks_per_frame;

This is no good for H264 in mkv, since parser is set but does not set 
repeat_pict. What do suggest ?
Using repeat_pict like this outside libavformat looks a bit weird to me 

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