[FFmpeg-devel] [PATCH] RealMedia muxer: support audio codecs other than AC-3
Mon May 3 18:39:48 CEST 2010
On Mon, May 03, 2010 at 03:47:12PM +0100, M?ns Rullg?rd wrote:
> "Ronald S. Bultje" <rsbultje at gmail.com> writes:
> >> i think stream copy of codecs which we dont support should work.
> >> for that though we must accept "unknown" codec tags without codec id
> There is no reason whatsoever to believe that codec_tag from an
> unknown codec/container will be at all meaningful in the target
> >> an actual example where someone wanted it and i fixed it was nellymoser
> >> in flv before we had nelly support
> And how did you fix that? FLV uses completely different codec
> identifiers, so blindly copying the AVI tag could not have worked.
i dont remember but it was about stream copy of nellymoser from flv->flv
> > I'm OK with doing it if codec_id is unset (CODEC_ID_NONE). In any
> > other case, codec_tag should be ignored (imo) and if codec_id is not
> > in our table, we should error out. This way, we force ourselves to add
> > the *correct* tag for each codec_id, rather than taking the AVI fourcc
> > and probably ending up creating files only mplayer can playback.
this breaks stream copy of old xvid and some mpeg4 variants like XVIX
iam thus not in favor of it
what you 2 can do if you like to improve the situation is to implement the
FIXME below from libavformat/utils.c
//check that tag + id is in the table
//if neither is in the table -> OK
//if tag is in the table with another id -> FAIL
//if id is in the table with another tag -> FAIL unless strict < ?
st->codec->codec_tag= av_codec_get_tag(s->oformat->codec_tag, st->codec->codec_id);
I understand you want to fail in a broader set of cases and iam not
even saying iam neccessarily against that but i think we first should
implement the cases we agree about. Once thats done we can discuss
the remaining cases
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> ... defining _GNU_SOURCE...
For the love of all that is holy, and some that is not, don't do that.
-- Luca & Mans
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