[FFmpeg-devel] flv decoder question

Michael Niedermayer michaelni
Sun Jul 26 22:15:18 CEST 2009


On Sun, Jul 26, 2009 at 02:52:09PM -0400, Justin Ruggles wrote:
> Reimar D?ffinger wrote:
> > On Sat, Jul 25, 2009 at 06:43:02PM -0700, Baptiste Coudurier wrote:
> >> On 07/25/2009 05:41 PM, Justin Ruggles wrote:
> >>> Can someone who knows about the FLV decoder explain these lines in
> >>> flv_read_header()?
> >>>
> >>>      if((flags&  (FLV_HEADER_FLAG_HASVIDEO|FLV_HEADER_FLAG_HASAUDIO))
> >>>               != (FLV_HEADER_FLAG_HASVIDEO|FLV_HEADER_FLAG_HASAUDIO))
> >>>          s->ctx_flags |= AVFMTCTX_NOHEADER;
> >>>
> >>> I ask because it is causing av_find_stream_info() to read way more data
> >>> than necessary for audio-only FLV files containing Speex.
> >> The idea is to read packets to create streams if flags is wrongly set,  
> >> but the check will cause NOHEADER to be always be set audio only or  
> >> video only files.
> > 
> > I think this is intentional, since IIRC there are files with audio and video
> > where the header still indicates only one of them.
> 
> Ok, well I guess that's the price of supporting broken files...  I was
> just curious.

the stuff could maybe use a check based on strict_std_compliance so the
user could avoid the delay if he knows his files are standard compliant that
is have the flags set correctly

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Rewriting code that is poorly written but fully understood is good.
Rewriting code that one doesnt understand is a sign that one is less smart
then the original author, trying to rewrite it will not make it better.
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