[FFmpeg-devel] [PATCH] libvpx: Disable frame dropping as rate control method
Michael Niedermayer
michaelni
Sun Jun 6 23:26:44 CEST 2010
On Mon, Jun 07, 2010 at 12:22:32AM +0300, Martin Storsj? wrote:
> On Sun, 6 Jun 2010, Michael Niedermayer wrote:
>
> > On Sun, Jun 06, 2010 at 11:31:26PM +0300, Martin Storsj? wrote:
> > > Hi,
> > >
> > > libvpx has the feature of dropping frames as a rate control method,
> > > enabled by default:
> > >
> > > * Temporal resampling allows the codec to "drop" frames as a strategy to
> > > * meet its target data rate. This can cause temporal discontinuities in
> > > * the encoded video, which may appear as stuttering during playback. This
> > > * trade-off is often acceptable, but for many applications is not. It can
> > > * be disabled in these cases.
> > >
> > > I'm not particularly fond of this feature, I'd much rather get a bitrate
> > > slightly too high compared to suddenly getting half the framerate. The
> > > attached patch disables this in the libvpx wrapper - is this ok as
> > > default, or should it be changeable through some AVCodecContext field?
> > >
> > > // Martin
> > > libvpxenc.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > > 2e549024a0953c946f20da0379b4f7e1cde99131 0001-libvpx-Disable-frame-dropping-as-rate-control-method.patch
> > > From 02cf305dde17a792c584d6b645a49bc9f2a240c6 Mon Sep 17 00:00:00 2001
> > > From: Martin Storsjo <martin at martin.st>
> > > Date: Sun, 6 Jun 2010 23:27:17 +0300
> > > Subject: [PATCH] libvpx: Disable frame dropping as rate control method
> > >
> > > ---
> > > libavcodec/libvpxenc.c | 1 +
> > > 1 files changed, 1 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/libavcodec/libvpxenc.c b/libavcodec/libvpxenc.c
> > > index fa393b8..bdbaaf5 100644
> > > --- a/libavcodec/libvpxenc.c
> > > +++ b/libavcodec/libvpxenc.c
> > > @@ -240,6 +240,7 @@ static av_cold int vp8_init(AVCodecContext *avctx)
> > > //convert [1,51] -> [0,63]
> > > enccfg.rc_min_quantizer = ((avctx->qmin * 5 + 1) >> 2) - 1;
> > > enccfg.rc_max_quantizer = ((avctx->qmax * 5 + 1) >> 2) - 1;
> > > + enccfg.rc_dropframe_thresh = 0;
> >
> > should be set based on AVCodecContext.frame_skip*
>
> Ok, so if e.g. avctx->frame_skip_threshold <= 0 (which is the default) we
> should set enccfg.rc_dropframe_thresh = 0, otherwise we keep the default
> rc_dropframe_thresh - or set a value based on the frame_skip_threshold
> value in some way?
whatever you like, maybe something in the direction of:
enccfg.rc_dropframe_thresh= avctx->frame_skip_threshold
> The value range of frame_skip_threshold doesn't seem to
> be documented in the header.
our documentation sucks like always
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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