[FFmpeg-devel] [PATCH v2 4/6] avcodec/libsvtav1: Fix CQP mode doesn't work as expection

[Jan Ekström]

On Sat, Sep 18, 2021 at 4:27 AM <lance.lmwang at gmail.com> wrote:
>
> From: Limin Wang <lance.lmwang at gmail.com>
>
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---

Commit message should probably be something along the lines of

"""
avcodec/libsvtav1: properly enforce CQP mode when set in wrapper

SVT-AV1 seems to have switched their default from CQP to CRF in February,
so enforce the controlling option accordingly.
"""

>  libavcodec/libsvtav1.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/libavcodec/libsvtav1.c b/libavcodec/libsvtav1.c
> index 0dc25ca..b029e01 100644
> --- a/libavcodec/libsvtav1.c
> +++ b/libavcodec/libsvtav1.c
> @@ -208,6 +208,8 @@ static int config_enc_params(EbSvtAv1EncConfiguration *param,
>      if (param->rate_control_mode) {
>          param->max_qp_allowed       = avctx->qmax;
>          param->min_qp_allowed       = avctx->qmin;
> +    } else {
> +        param->enable_tpl_la = 0; /* CQP need turn off enable_tp_la */

As the default changing in the underlying library has now shown us, I
think (for now) it's better to move this next to
param->rate_control_mode earlier in the function, and then do
something like:

param->enable_tpl_la = !!param->rate_control_mode;

(I would have utilized param->enable_tpl_la = param->rate_control_mode
== SVTAV1_RC_MODE_CQP;` but alas SVT-AV1 does not have such
enums/defines that make such things more readable).

This way the parameter is set correctly no matter if the default is
switched over at SVT-AV1. In the future the wrapper can be reworked so
that by default SVT-AV1's own rate control defaults are utilized, and
then if either bit rate or cqp or something like that is set, we can
start enforcing that.

Jan