On Mon, 27 Nov, 2023, 7:32 am Aditya Dandavate,
<adityadandavat...@gmail.com>
wrote:
On Mon, 27 Nov, 2023, 4:16 am Ferdi Scholten,<fe...@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
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