Re: [FFmpeg-devel] [PATCH v3 1/3] avcodec/mjpegdec: fix non-subsampled RGB JPEGs

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH v3 1/3] avcodec/mjpegdec: fix non-subsampled RGB JPEGs
Date: Wed, 19 Apr 2023 20:58:38 +0200
Message-ID: <20230419185838.GS275832@pb2> (raw)
In-Reply-To: <20230419181126.38662-2-leo.izen@gmail.com>

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On Wed, Apr 19, 2023 at 02:11:24PM -0400, Leo Izen wrote:
> The change introduced in b18a9c29713abc3a1b081de3f320ab53a47120c6
> created a regression for non-subsampled progressive RGB jpegs. This
> should fix that.
> ---
>  libavcodec/mjpegdec.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
> index 01537d4774..1e3ddb72fb 100644
> --- a/libavcodec/mjpegdec.c
> +++ b/libavcodec/mjpegdec.c
> @@ -1698,7 +1698,8 @@ int ff_mjpeg_decode_sos(MJpegDecodeContext *s, const uint8_t *mb_bitmask,
>          s->h_scount[i]  = s->h_count[index];
>          s->v_scount[i]  = s->v_count[index];
>  
> -        if(nb_components == 3 && s->nb_components == 3 && s->avctx->pix_fmt == AV_PIX_FMT_GBRP)
> +        if((nb_components == 3 || nb_components == 1) && s->nb_components == 3
> +                && s->avctx->pix_fmt == AV_PIX_FMT_GBRP && !s->progressive)
>              index = (index+2)%3;

Why is progressive/!progressive special cased in all the new RGB code ?

thx

[...]

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