[FFmpeg-devel] [PATCH] Move packed B-frames message level to info.

[wm4]

On Mon, 9 Sep 2013 00:09:54 +0200
Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:

> On 08.09.2013, at 23:48, wm4 <nfxjfg at googlemail.com> wrote:
> > On Sun,  8 Sep 2013 19:49:55 +0200
> > Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:
> > 
> >> Since they generally decode fine, printing it as a warning
> >> might not really be appropriate.
> >> 
> >> Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> >> ---
> >> libavcodec/mpeg4videodec.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
> >> index c81a917..fa32aa6 100644
> >> --- a/libavcodec/mpeg4videodec.c
> >> +++ b/libavcodec/mpeg4videodec.c
> >> @@ -1912,7 +1912,7 @@ static int decode_user_data(MpegEncContext *s, GetBitContext *gb){
> >>         s->divx_build= build;
> >>         s->divx_packed= e==3 && last=='p';
> >>         if(s->divx_packed && !s->showed_packed_warning) {
> >> -            av_log(s->avctx, AV_LOG_WARNING, "Video uses a non-standard and "
> >> +            av_log(s->avctx, AV_LOG_INFO, "Video uses a non-standard and "
> >>                    "wasteful way to store B-frames ('packed B-frames'). "
> >>                    "Consider using a tool like VirtualDub or avidemux to fix it.\n");
> >>             s->showed_packed_warning=1;
> > 
> > +1
> > 
> > By the way, I've noticed that the redundant messages are actually
> > printed by the parser. libavformat recreates the parser after each
> > seek, and the parser uses parts of the decoder. Consequently, the
> > messages is printed again after each seek.
> > 
> > Maybe the parser should initialize s->showed_packed_warning to 1, so
> > that only the actual decoder prints the warning? (However, I'm not sure
> > if that matches with the ffmpeg policy about handling broken data.)
> 
> I don't know how to avoid it, but I think the parser isn't supposed to print these messages really.
> In fact, I don't really understand why the parser would/should even cause that code to be executed, it doesn't really seem right to me.

It reuses some of the parsing code, and the code printing the message
is part of it. You can also see AVCodecContexts spread throughout the
parsing code. (I'm not really sure how this parsing stuff is supposed
to work, but it doesn't seem unusual for it to involve decoders or
parts of them.)