On Tue, 21 May 2024 01:17:32 +0000 Cosmin Stejerean via ffmpeg-devel
<ffmpeg-devel@ffmpeg.org> wrote:
> From: Cosmin Stejerean <cos...@cosmin.at>
>
> It looks like the el_bitdepth_minus8 value in the header can also encode
> ext_mapping_idc in the upper 8 bits.
>
> Samples having a non-zero ext_mapping_idc fail validation currently because
> the
> value returned is out of range. This bypasses this by currently ignoring the
> ext_mapping_idc and using only the lower 8 bits for el_bitdepth_minus8.
What is ext_mapping_idc? If it's signalled data that can't be
reconstructed, we need to store it somewhere into AVDOVIMetadata and
then re-synthesize it during encoding. Otherwise the RPU transcode will
be lossy.
>
> ---
> libavcodec/dovi_rpudec.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/dovi_rpudec.c b/libavcodec/dovi_rpudec.c
> index 7c7eda9d09..1b11ad3640 100644
> --- a/libavcodec/dovi_rpudec.c
> +++ b/libavcodec/dovi_rpudec.c
> @@ -411,7 +411,9 @@ int ff_dovi_rpu_parse(DOVIContext *s, const uint8_t *rpu,
> size_t rpu_size,
>
> if ((hdr->rpu_format & 0x700) == 0) {
> int bl_bit_depth_minus8 = get_ue_golomb_31(gb);
> - int el_bit_depth_minus8 = get_ue_golomb_31(gb);
> + // this can encode a two byte value, with higher byte being
> ext_mapping_idc
> + // use only the lower byte for el_bit_depth_minus8
> + uint8_t el_bit_depth_minus8 = get_ue_golomb_long(gb) & 0xFF;
> int vdr_bit_depth_minus8 = get_ue_golomb_31(gb);
> VALIDATE(bl_bit_depth_minus8, 0, 8);
> VALIDATE(el_bit_depth_minus8, 0, 8);
> --
> 2.42.1
>
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
