[Libav-user] how to set crf for vp8 encoder in ffmpeg programmatically?

[Hendrik Leppkes]

On Mon, May 20, 2013 at 10:23 AM, YIRAN LI <mrfun.china at gmail.com> wrote:
> Hi guys,
>
> I've downloaded latest libvpx code and built it into ffmpeg, so that my
> application can use ffmpeg dlls.
>
> Vp8 encoding works correctly and my application can generate webm videos.
>
> But what I want to know is, how can I set crf when encoding?
>
> What I do in my application is just calling ffmpeg interface
> 1. AVStream* pVideoStream = av_new_stream(pFormatCtx, 0);
> 2. AVCodec* pVideoCodec = avcodec_find_encoder(AVCODE_ID_VP8)
> 3. AVCodecContext* pVideoCodecCtx = pVideoStream->codec;
>
>    pVideoCodexCtx->bit_rate =
>                            ->rc_min_rate=
>                            ->rc_max_rate=   (set all these bit rate control
> param)
>
>   I checked libvpxenc.c under libavcodec and seems when initing the encoder,
> it doesn't directly refer to any member
>  of AVCodecContext to set crf.
>
>  So could anyone tell me, how to set crf when open vp8 encoder
> programmatically?
>
>  Great thanks!
>

This should do it:
av_opt_set_int(pVideoCodexCtx, "crf", 10, AV_OPT_SEARCH_CHILDREN)