[FFmpeg-devel] [PATCH v4 2/2] libavcodec/libaomenc.c: Support lossless encoding

[Ryo Hirafuji]

I see, Thanks.
I'm looking forward to the answer.

(If you are OK, please CC to me. I also would like to know about lossless
mode in libaom, because I also use my software)

2020年4月15日(水) 10:00 James Zern <jzern-at-google.com at ffmpeg.org>:

> On Tue, Apr 7, 2020 at 5:14 PM Ryo Hirafuji <ryo.hirafuji at gmail.com>
> wrote:
> >
> > From: Ryo Hirafuji <psi at 7io.org>
> >
> > AV1 support lossless encoding.
> > In this patch, I added a command line flag to enable it.
> >
> > Fixes ticket #7600
> > ---
> >  libavcodec/libaomenc.c | 14 +++++++++++---
> >  1 file changed, 11 insertions(+), 3 deletions(-)
> >
> > [...]
> > @@ -574,7 +577,9 @@ static av_cold int aom_init(AVCodecContext *avctx,
> >      if (avctx->rc_min_rate == avctx->rc_max_rate &&
> >          avctx->rc_min_rate == avctx->bit_rate && avctx->bit_rate) {
> >          enccfg.rc_end_usage = AOM_CBR;
> > -    } else if (ctx->crf >= 0) {
> > +    } else if (ctx->crf == 0) {
> > +        enccfg.rc_end_usage = AOM_Q;
>
> I saw the earlier comments around using crf=0 as the trigger for this.
> libaom will behave differently with q vs cq mode. This also differs
> from the -lossless in libvpxenc where this feature originated; mostly
> we've been mapping options one to one with vpx/aomenc. Let me ask
> around about the preference for lossless usage in libaom.
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