Re: [FFmpeg-devel] [PATCH 1/2] avcodec/mpegvideo_enc: Reject input incompatible with chroma subsampling

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 1/2] avcodec/mpegvideo_enc: Reject input incompatible with chroma subsampling
Date: Mon, 8 Apr 2024 18:02:02 +0200
Message-ID: <20240408160202.GG6420@pb2> (raw)
In-Reply-To: <GV1P250MB07377C33946D1950C29130CE8F012@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM>

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On Mon, Apr 08, 2024 at 12:51:08AM +0200, Andreas Rheinhardt wrote:
> Andreas Rheinhardt:
> > Fixes ticket #10952.
> > 
> > Discovered by: Zeng Yunxiang
> > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> > ---
> > I am pretty sure that a lot of other encoders don't handle this well
> > either. Maybe we should handle this more generically in
> > ff_encode_preinit?
> > 
> >  libavcodec/mpegvideo_enc.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
> > index d1b1917824..a65ecc6839 100644
> > --- a/libavcodec/mpegvideo_enc.c
> > +++ b/libavcodec/mpegvideo_enc.c
> > @@ -314,6 +314,7 @@ av_cold int ff_mpv_encode_init(AVCodecContext *avctx)
> >      AVCPBProperties *cpb_props;
> >      int i, ret;
> >      int mb_array_size, mv_table_size;
> > +    int chroma_h_subsampling = 1, chroma_v_subsampling = 1;
> >  
> >      mpv_encode_defaults(s);
> >  
> > @@ -325,14 +326,25 @@ av_cold int ff_mpv_encode_init(AVCodecContext *avctx)
> >      case AV_PIX_FMT_YUVJ422P:
> >      case AV_PIX_FMT_YUV422P:
> >          s->chroma_format = CHROMA_422;
> > +        chroma_h_subsampling = 2;
> >          break;
> >      case AV_PIX_FMT_YUVJ420P:
> >      case AV_PIX_FMT_YUV420P:
> >      default:
> >          s->chroma_format = CHROMA_420;
> > +        chroma_h_subsampling = 2;
> > +        chroma_v_subsampling = 2;
> >          break;
> >      }
> >  
> > +    if (avctx->width &  (chroma_h_subsampling - 1) ||
> > +        avctx->height & (chroma_v_subsampling - 1)) {
> > +        av_log(avctx, AV_LOG_ERROR,
> > +               "Dimensions %dx%d incompatible with chroma subsampling.\n",
> > +               avctx->width, avctx->height);
> > +        return AVERROR(EINVAL);
> > +    }
> > +
> >      avctx->bits_per_raw_sample = av_clip(avctx->bits_per_raw_sample, 0, 8);
> >  
> >      s->bit_rate = avctx->bit_rate;
> 
> Will apply this patchset tomorrow unless there are objections.

this breaks
./ffmpeg -i 'samples.multimedia.cx/game-formats/sierra-vmd/lastdynasty/HG060808.VMD' -y test.avi

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The worst form of inequality is to try to make unequal things equal.
-- Aristotle

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