Re: [FFmpeg-devel] [PATCH 2/5] avcodec/proresenc_kostya: use a compatible bitstream version

From: Stefano Sabatini <stefasab@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Cc: "Clément Bœsch" <u@pkh.me>
Subject: Re: [FFmpeg-devel] [PATCH 2/5] avcodec/proresenc_kostya: use a compatible bitstream version
Date: Mon, 8 Jan 2024 20:57:13 +0100
Message-ID: <ZZxTmXcI4hYB8CMi@mariano> (raw)
In-Reply-To: <20240107181647.3049578-2-u@pkh.me>

On date Sunday 2024-01-07 19:16:44 +0100, Clément Bœsch wrote:
> Quoting SMPTE RDD 36:2015:
>   A decoder shall abort if it encounters a bitstream with an unsupported
>   bitstream_version value. If 0, the value of the chroma_format syntax
>   element shall be 2 (4:2:2 sampling) and the value of the
>   alpha_channel_type element shall be 0 (no encoded alpha); if 1, any
>   permissible value may be used for those syntax elements.
> 
> So if we're not in 4:2:2 or if there is alpha, we are not allowed to use
> version 0.
> ---
>  libavcodec/proresenc_kostya.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/proresenc_kostya.c b/libavcodec/proresenc_kostya.c
> index 8d45e42d1a..de63127192 100644
> --- a/libavcodec/proresenc_kostya.c
> +++ b/libavcodec/proresenc_kostya.c
> @@ -1037,7 +1037,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
>      // frame header
>      tmp = buf;
>      buf += 2;                                   // frame header size will be stored here
> -    bytestream_put_be16  (&buf, 0);             // version 1
> +    bytestream_put_be16  (&buf, ctx->chroma_factor != CFACTOR_Y422 || ctx->alpha_bits ? 1 : 0);

LGTM, thanks.
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