[FFmpeg-devel] 回复： [PATCH] avcodec/videotoolboxenc: add low-latency encoding

[Rick Kern]

On Fri, May 19, 2023 at 1:56 AM 徐福隆 <839789740 at qq.com> wrote:

> Thank you for your review, and point out the details.
> Actually, I have also considered this issue.
> I see that some keys are used directly, some are used by compatibility.
>

The compat_keys are used for symbols that might not exist. For constants
available in the earliest version of VideoToolbox, compat_keys doesn't need
to be used.

Your patch looks good - I'll push it shortly.


> I will use compat_key instead, and submit a new patch.
>
>
> ------------------ 原始邮件 ------------------
> 发件人:
>                                                   ""zhilizhao(赵志立)""
>
> <quinkblack at foxmail.com>;
> 发送时间: 2023年5月19日(星期五) 中午11:34
> 收件人: "FFmpeg development discussions and patches"<
> ffmpeg-devel at ffmpeg.org>;
> 抄送: "徐福隆"<839789740 at qq.com>;
> 主题: Re: [FFmpeg-devel] [PATCH] avcodec/videotoolboxenc: add
> low-latency encoding
>
>
>
>
>
> > On May 19, 2023, at 11:17, xufuji456 <839789740 at qq.com> wrote:
> >
> > When using low-latency mode, it eliminates frame reordering
> > and follows a one-in-one-out encoding mode
> >
> > Signed-off-by: xufuji456 <839789740 at qq.com>
> > ---
> > libavcodec/videotoolboxenc.c | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/libavcodec/videotoolboxenc.c
> b/libavcodec/videotoolboxenc.c
> > index c6f22723d6..ae1ef32b2d 100644
> > --- a/libavcodec/videotoolboxenc.c
> > +++ b/libavcodec/videotoolboxenc.c
> > @@ -1441,6 +1441,17 @@ static int
> vtenc_create_encoder(AVCodecContext   *avctx,
> >         }
> >     }
> >
> > +    // low-latency mode: eliminate frame reordering,
> follow a one-in-one-out encoding mode
> > +    if ((avctx->flags &
> AV_CODEC_FLAG_LOW_DELAY) && avctx->codec_id == AV_CODEC_ID_H264)
> {
> > +        status =
> VTSessionSetProperty(vtctx->session,
> >
> +                                     
> kVTVideoEncoderSpecification_EnableLowLatencyRateControl,
> >
> +                                     
> kCFBooleanTrue);
>
> Please use compat_keys in case of
> kVTVideoEncoderSpecification_EnableLowLatencyRateControl
> isn’t available.
>
> > +
> > +        if (status) {
> > +           
> av_log(avctx, AV_LOG_ERROR, "Error setting low latency property: %d\n",
> status);
> > +        }
> > +    }
> > +
> >     status =
> VTCompressionSessionPrepareToEncodeFrames(vtctx->session);
> >     if (status) {
> >         av_log(avctx,
> AV_LOG_ERROR, "Error: cannot prepare encoder: %d\n", status);
> > --
> > 2.32.0 (Apple Git-132)
> >
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