[FFmpeg-devel] [PATCH v2] avcodec/v4l2_m2m_enc: Check encoder pix_fmt matches pix_fmt on device

Andriy Gelman andriy.gelman at gmail.com
Wed Dec 4 18:57:21 EET 2019


On Sat, 23. Nov 06:18, Andriy Gelman wrote:
> On Tue, 12. Nov 22:46, Andriy Gelman wrote:
> > From: Andriy Gelman <andriy.gelman at gmail.com>
> > 
> > Fixes #8079
> > 
> > During initialization of a v4l2m2m device, the configured pix_fmt can be
> > different to the pix_fmt of the encoder (i.e. avctx->pix_fmt).
> > 
> > For example on the Odroid XU4:
> > ./ffmpeg -f lavfi -i yuvtestsrc -codec:v h264_v4l2m2m out.h264
> > 
> > will configure the v4l2 encoder to pix_fmt nv21, whereas the input
> > frames will be yuv444p.
> > 
> > This commit checks that the configured v4l2 pix_fmt on device is the
> > same as avctx->pix_fmt. If they are different the initialization fails
> > and an error is returned. Tested on RPI4 and Odroid XU4.
> > 
> > Signed-off-by: Andriy Gelman <andriy.gelman at gmail.com>
> > ---
> >  libavcodec/v4l2_m2m_enc.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
> > 
> > diff --git a/libavcodec/v4l2_m2m_enc.c b/libavcodec/v4l2_m2m_enc.c
> > index 474e6bef897..c0e82afe354 100644
> > --- a/libavcodec/v4l2_m2m_enc.c
> > +++ b/libavcodec/v4l2_m2m_enc.c
> > @@ -30,6 +30,7 @@
> >  #include "libavutil/opt.h"
> >  #include "v4l2_context.h"
> >  #include "v4l2_m2m.h"
> > +#include "v4l2_fmt.h"
> >  
> >  #define MPEG_CID(x) V4L2_CID_MPEG_VIDEO_##x
> >  #define MPEG_VIDEO(x) V4L2_MPEG_VIDEO_##x
> > @@ -288,6 +289,8 @@ static av_cold int v4l2_encode_init(AVCodecContext *avctx)
> >      V4L2Context *capture, *output;
> >      V4L2m2mContext *s;
> >      V4L2m2mPriv *priv = avctx->priv_data;
> > +    enum AVPixelFormat pix_fmt_output;
> > +    uint32_t v4l2_fmt_output;
> >      int ret;
> >  
> >      ret = ff_v4l2_m2m_create_context(priv, &s);
> > @@ -316,6 +319,18 @@ static av_cold int v4l2_encode_init(AVCodecContext *avctx)
> >      }
> >      s->avctx = avctx;
> >  
> > +    if (V4L2_TYPE_IS_MULTIPLANAR(output->type))
> > +        v4l2_fmt_output = output->format.fmt.pix_mp.pixelformat;
> > +    else
> > +        v4l2_fmt_output = output->format.fmt.pix.pixelformat;
> > +
> > +    pix_fmt_output = ff_v4l2_format_v4l2_to_avfmt(v4l2_fmt_output, AV_CODEC_ID_RAWVIDEO);
> > +    if (pix_fmt_output != avctx->pix_fmt) {
> > +        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt_output);
> > +        av_log(priv, AV_LOG_ERROR, "Encoder requires %s pixel format.\n", desc->name);
> > +        return AVERROR(EINVAL);
> > +    }
> > +
> >      return v4l2_prepare_encoder(s);
> >  }
> >  
> > -- 
> > 2.23.0
> > 
> 
> ping 
> 

The underlying issue is that supported .pix_fmts may vary for different v4l2m2m
devices. Ideally, if .pix_fmts could be set at runtime that would solve problem. 

I did see that libx264 sets .pix_fmts via .init_static_data function. But I
don't think we want to call this v4l2m2m initialization each time
avcodec_register() is called.

Perhaps figuring out supported .pix_fmts via configure, and then creating a
define symbol for the supported option? 

Anyone have suggestions? 

-- 
Andriy


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