[FFmpeg-devel] [PATCH v2] avcodec/mpeg12dec: report error when picture type is unknown and err_detect is EXPLODE

[Michael Niedermayer]

On Mon, Aug 02, 2021 at 08:50:05PM +0200, Marton Balint wrote:
> Also split error message to error and warning.
> 
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
>  libavcodec/mpeg12dec.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
> index 858dca660c..49d865853b 100644
> --- a/libavcodec/mpeg12dec.c
> +++ b/libavcodec/mpeg12dec.c
> @@ -1529,7 +1529,7 @@ static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)
>          load_matrix(s, s->chroma_inter_matrix, NULL, 0);
>  }
>  
> -static void mpeg_decode_picture_coding_extension(Mpeg1Context *s1)
> +static int mpeg_decode_picture_coding_extension(Mpeg1Context *s1)
>  {
>      MpegEncContext *s = &s1->mpeg_enc_ctx;
>  
> @@ -1539,8 +1539,10 @@ static void mpeg_decode_picture_coding_extension(Mpeg1Context *s1)
>      s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);
>      s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);
>      if (!s->pict_type && s1->mpeg_enc_ctx_allocated) {
> -        av_log(s->avctx, AV_LOG_ERROR,
> -               "Missing picture start code, guessing missing values\n");
> +        av_log(s->avctx, AV_LOG_ERROR, "Missing picture start code\n");
> +        if (s->avctx->err_recognition & AV_EF_EXPLODE)
> +            return AVERROR_INVALIDDATA;
> +        av_log(s->avctx, AV_LOG_WARNING, "Guessing pict_type from mpeg_f_code\n");

If we are nitpicking then this is not ideal
"Missing picture start code" is only an error when AV_EF_EXPLODE is set
because it only in that case results in wrong output, when AV_EF_EXPLODE
is not set the output from the decoder might be correct si it too should
be a warning in that case

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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