[FFmpeg-user] VBR encoding for libsvtav1.

[Aditya Dandavate]

Thank you sir. 🙏

On Mon, 27 Nov, 2023, 1:43 pm Ferdi Scholten, <ferdi at sttc-nlp.nl> wrote:

> On Mon, 27 Nov, 2023, 7:32 am Aditya Dandavate,
> <adityadandavate04 at gmail.com>
> > wrote:
> >
> >> On Mon, 27 Nov, 2023, 4:16 am Ferdi Scholten,<ferdi at sttc-nlp.nl>
> wrote:
> >>
> >>> What is the quality rate control when encoding in VBR mode ?
> >>>> I get message :
> >>>>
> >>>> Svt[warn]: The input q value is ignored in vbr mode 20 when I set the
> >>> -crf
> >>>> to 20 when enabling the -svtav1-params rc=1.
> >>>> When I set -qp 20, the conversion fails.
> >>>>
> >>>> Which mode to set quality when encoding in VBR mode ?
> >>>>
> >>> vbr encoding does not support quality setting, you get the maximum
> >>> quality that fits the specified bitrate and it uses lower bitrates if
> >>> possible if the content does not require high bitrates.
> >>>
> >>>
> >>> If you want CRF with a cap on the bitrate you need to set mbr
> >>> (MaximumBitRate)
> >>>
> >>>       -crf 20 -svtav1-params mbr=5000k
> >>>
> >>> You do not need to specify rc=0, because that is default. You also do
> not
> >>> specify -b:v 5000k
> >>>
> >>>
> >>> Or if you want VBR
> >>>
> >>>       -svtav1-params rc=1 -b:v 5000k
> >>>
> >>> No quality settings like crf or qp as they require rc=0 you can however
> >>> set -qmin (default 1) and -qmax (default 63)
> >>>
> >>>
> >>> OR if you want CQP
> >>>
> >>>       -qp 20 -svtparams aq-mode=0 -b:v 5000k
> >>>
> >>> qp only works when aq-mode=0 (default aq-mode=2)
> >>>
> >>>
> >>> Hope that helps?
> >>
> > Also, a quick question about Constrained Quality Mode:
> >
> > In VP9, we trigger it by combination of '-crf' and 'b:v' and the value of
> > bitrate is must be non zero to trigger the mode.
> >
> > How to trigger it in libsvtav1 ?
> >
> by setting -qp AND aq-mode=0 AND bitrate
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
>