[FFmpeg-devel] [PATCH] S/PDIF demuxer ( was:[PATCH]?Detect?DTS?in wav (issue70) + about ac3-in-wav)

Michael Niedermayer michaelni
Fri Aug 6 15:17:29 CEST 2010


On Wed, Aug 04, 2010 at 06:15:12PM +0300, Anssi Hannula wrote:
> Michael Niedermayer kirjoitti keskiviikko, 4. elokuuta 2010 15:53:04:
> > On Wed, Jul 28, 2010 at 05:12:21AM +0300, Anssi Hannula wrote:
> > > Michael Niedermayer kirjoitti tiistai, 27. hein?kuuta 2010 16:59:27:
> > > > On Tue, Jul 27, 2010 at 07:59:13AM +0300, Anssi Hannula wrote:
> > > > > +    if (sync_codes == consecutive_codes + 1 &&
> > > > > +        !memcmp(p->buf + 8, "WAVE", 4) && !memcmp(p->buf, "RIFF",
> > > > > 4)) +        /* all sync codes (except first one as it was only
> > > > > after WAV headers)
> > > > > +           were consecutive, but the buffer was too small;
> > > > > +           also, this looks like a WAV file, so we need to delay wav
> > > > > demuxer
> > > > > +           from grabbing this file until we get a big enough
> > > > > buffer to see if
> > > > > +           there are more consecutive codes (we want
> > > > > to be selected for
> > > > > +           (ac3-in-)spdif-in-wav as chained demuxers
> > > > > are not yet supported),
> > > > > +           therefore return the same score as
> > > > > wav demuxer to make it a tie */
> > > > > +        return AVPROBE_SCORE_MAX - 1;
> > > > 
> > > > or make the wav demuxer only return a low score for small probe sizes
> > > > above would for example behave oddly if the wav demuxer is disabled
> > > 
> > > How low?
> > 
> >  < AVPROBE_SCORE_MAX/4 so the code in utils.c doesnt stop early
> > 
> > > I mean, if we change it to AVPROBE_SCORE_MAX / 8 or so, every wav file
> > > would needlessy be probed 1MB, even while 2k would have been enough (if
> > > no spdif sync codes were in first 2k).
> > 
> > we can return a larger score once the amount of data available becomes
> > large enough like 100k ?
> 
> It would still mean that all normal wavs are probed 50-100k even if 2k would 
> be enough (as spdif-in-wav would've started in the beginning).

thats only s16le wavs iirc and 50-100k of raw 16bit audio doesnt seem much to
me


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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