[FFmpeg-devel] [PATCH] bring -qpfile option of x264 to ffmpeg

[Michael Niedermayer]

On Sat, Feb 28, 2009 at 06:56:15PM +0800, Ying Bian wrote:
> On Fri, Feb 27, 2009 at 11:25 PM, Michael Niedermayer <michaelni at gmx.at>wrote:
> 
> > On Fri, Feb 27, 2009 at 10:44:43PM +0800, Ying Bian wrote:
> > > Hi,
> > >
> > > This is a patch which brings the -qpfile option of x264 to ffmpeg.
> > > See the help message from "x264 --longhelp":
> > >       --qpfile <string>       Force frametypes and QPs for some or all
> > > frames
> > >                               Format of each line: framenumber frametype
> > QP
> > >                               QP of -1 lets x264 choose. Frametypes:
> > > I,i,P,B,b.
> > >
> > > I believe sometimes this is useful.
> > >
> > > - by
> >
> > > From 2a1f8d36b4895fc00c28bf014756700cf53edf04 Mon Sep 17 00:00:00 2001
> > > From: ybian <bianying at gmail.com>
> > > Date: Thu, 26 Feb 2009 02:14:28 +0800
> > > Subject: [PATCH] bring -qpfile option of x264 to ffmpeg
> > >
> > > ---
> > >  libavcodec/avcodec.h |    7 +++++++
> > >  libavcodec/libx264.c |   43 +++++++++++++++++++++++++++++++++++++++++++
> > >  libavcodec/options.c |    1 +
> > >  3 files changed, 51 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > > index f38ad2b..38d2dd0 100644
> > > --- a/libavcodec/avcodec.h
> > > +++ b/libavcodec/avcodec.h
> > > @@ -2315,6 +2315,13 @@ typedef struct AVCodecContext {
> > >       * - decoding: unused.
> > >       */
> > >      float rc_min_vbv_overflow_use;
> > > +
> > > +    /**
> > > +     * qpfile to force frametypes or QPs for some or all frames, only
> > used for libx264
> > > +     * - encoding: Set by user.
> > > +     * - decoding: unused.
> > > +     */
> > > +    char* qpfile;
> > >  } AVCodecContext;
> >
> > lavc does not access files out of design principles ... (its something
> > about
> > the media file not being a file, there being no disk or such ...)
> >
> > also setting QPs should be supported over the input AVFrames
> > its the user apps job (=ffmpeg.c) to read and parse qpfile and
> > set the fields of the structs.
> >
> > now i see and agree this would be code duplication between user apps,
> > and libav could provide helper functions to do such common tasks but that
> > has to be kept as optional part not as only and mandatory way to
> > perform something
> >
> > [...]
> > --
> > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> >
> > He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
> >
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> > _______________________________________________
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> >
> 
> Michael,
> 
> Thanks for comments.  As I am new to ffmpeg, can you confirm my following
> questions?
> 
> 1. I agree to put the option in the application level.  If I do, I would
> parse the qpfile (with a helper function)
>    against ost->frame_number at the beginning of ffmpeg.c/do_video_output,
> and then set the fields of
>    in_picture structure.  I assume the in_picture.pict_type should be set to
> frame_type from qpfile, but
>    how to set qp value to in_picture?

AVFrame.quality should work but it might not in which case that need fixing ...
and there is rc_override


> 
> 2. Where do you think is the best place to put the parse_qpfile helper
> function?

a new libavcodec/helper_api.c/h


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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