[FFmpeg-devel] [PATCH 1/3] avcodec/nvenc: Fix b-frame parameter handling

Michael Niedermayer michaelni at gmx.at
Sun Jan 25 13:58:26 CET 2015


On Sun, Jan 25, 2015 at 10:28:22AM +0100, Timo Rothenpieler wrote:
> >> +    /* 0 is intra-only, 1 is I/P only, 2 is one B Frame, 3 two B frames, and so on. */
> >> +    ctx->encode_config.frameIntervalP = avctx->max_b_frames + 1;
> > 
> > how can the user choose between intra only and IP ?
> > 
> > i would have assumed that gop_size <= 1 would select intra only
> > 
> 
> max_b_frames goes from -1 to INT_MAX, so -1 would be intra-only, 0, the
> default, I/P only, 1 IBP, 2 IBBP, and so on.

In libavcodec, intra only is selected by setting gop_size to 0
which is what happens when -intra is passed on the commad line to
ffmpeg.
Also other applications using libavcodec will use the gop_size
and not contain code to change max_b_frames in the nvenc case
so i dont think using max_b_frames would work very well

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is dangerous to be right in matters on which the established authorities
are wrong. -- Voltaire
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