[FFmpeg-devel] [PATCH 6/6] lavc/h264_ps: always include the stop bit in [s|p]ps->data

[Andreas Rheinhardt]

rcombs:
> From: rcombs <rcombs at rcombs.me>
> 
> The VideoToolbox hwaccel needs the entire NAL (including the stop bit),
> but ff_h2645_packet_split may remove it. Detect this case by looking for
> bit counts divisible by 8 and insert a stop-bit-only 0x80 byte.
> 
> Signed-off-by: rcombs <rcombs at rcombs.me>
> ---
>  libavcodec/h264_ps.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/libavcodec/h264_ps.c b/libavcodec/h264_ps.c
> index 051f06692c..e16da68dec 100644
> --- a/libavcodec/h264_ps.c
> +++ b/libavcodec/h264_ps.c
> @@ -351,6 +351,10 @@ int ff_h264_decode_seq_parameter_set(GetBitContext *gb, AVCodecContext *avctx,
>      }
>      memcpy(sps->data, gb->buffer, sps->data_size);
>  
> +    // Re-add the removed stop bit (may be used by hwaccels).
> +    if (!(gb->size_in_bits & 7) && sps->data_size < sizeof(sps->data))
> +        sps->data[sps->data_size++] = 0x80;
> +
>      profile_idc           = get_bits(gb, 8);
>      constraint_set_flags |= get_bits1(gb) << 0;   // constraint_set0_flag
>      constraint_set_flags |= get_bits1(gb) << 1;   // constraint_set1_flag
> @@ -775,6 +779,10 @@ int ff_h264_decode_picture_parameter_set(GetBitContext *gb, AVCodecContext *avct
>      }
>      memcpy(pps->data, gb->buffer, pps->data_size);
>  
> +    // Re-add the removed stop bit (may be used by hwaccels).
> +    if (!(bit_length & 7) && pps->data_size < sizeof(pps->data))
> +        pps->data[pps->data_size++] = 0x80;
> +
>      pps->sps_id = get_ue_golomb_31(gb);
>      if ((unsigned)pps->sps_id >= MAX_SPS_COUNT ||
>          !ps->sps_list[pps->sps_id]) {

Modifying these functions affects more than just VideoToolbox. Are you
sure that the other users of this file are ok with this change?

- Andreas