[FFmpeg-devel] [PATCH] WebM mux/demux

[Michael Niedermayer]

On Wed, May 19, 2010 at 03:42:12PM -0400, Ronald S. Bultje wrote:
> Hi,
> 
> On Wed, May 19, 2010 at 3:38 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Wed, May 19, 2010 at 03:27:22PM -0400, Ronald S. Bultje wrote:
> >> On Wed, May 19, 2010 at 3:14 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> > On Wed, May 19, 2010 at 03:05:30PM -0400, David Conrad wrote:
> >> >> - ? ?/* The header must contain the document type 'matroska'. For now,
> >> >> + ? ?/* The header must contain a known document type. For now,
> >> >> ? ? ? * we don't parse the whole header but simply check for the
> >> >> ? ? ? * availability of that array of characters inside the header.
> >> >> ? ? ? * Not fully fool-proof, but good enough. */
> >> >> - ? ?for (n = 4+size; n <= 4+size+total-(sizeof(probe_data)-1); n++)
> >> >> - ? ? ? ?if (!memcmp(p->buf+n, probe_data, sizeof(probe_data)-1))
> >> >> - ? ? ? ? ? ?return AVPROBE_SCORE_MAX;
> >> >> + ? ?for (i = 0; i < FF_ARRAY_ELEMS(matroska_doctypes); i++)
> >> >> + ? ? ? ?for (n = 4+size; n <= 4+size+total-(strlen(matroska_doctypes[i])-1); n++)
> >> >> + ? ? ? ? ? ?if (!memcmp(p->buf+n, probe_data, strlen(matroska_doctypes[i])-1))
> >> >> + ? ? ? ? ? ? ? ?return AVPROBE_SCORE_MAX;
> >> >>
> >> >> ? ? ?return 0;
> >> >> ?}
> >> >
> >> > it would be more future proof if we didnt check this string at all (as long
> >> > as reliable detection is still possible of course)
> >>
> >> That would fail if someone creates an EMBL-based, but
> >> matroska-incompatible format (e.g. matroska2).
> >
> > such format would fail with svn, with my suggestion and with any of
> > the patches posted. So no real difference except that with my suggestion
> > it would be detected as matroska while the others might detect it as
> > ac3 or mp3 with low score
> 
> True, I was thinking though that you'd prefer to decrease false
> positives, not add to it... But either way is fine with me of course.

we could print a "warning unknown doctype blah blah this might fail"

and false positive it is only if we have a matroska2 demuxer implemented
completely seperately otherwise detecting it as matroska is more correct.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In a rich man's house there is no place to spit but his face.
-- Diogenes of Sinope
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20100519/33d62e1c/attachment.pgp>