Quoting Josh Allmann (2024-07-09 21:05:47)
> Encoders may emit a buffering period SEI without a corresponding
> SPS/PPS if the SPS/PPS is carried out-of-band, eg with avcc.
>
> During Annex B conversion, this may result in the SPS/PPS being
> inserted *after* the buffering period SEI but before the IDR NAL.
>
> Since the buffering period SEI references the SPS, the SPS/PPS
> needs to come first.
> ---
>
> Notes:
> v2: Updated FATE test refs
>
> libavcodec/bsf/h264_mp4toannexb.c | 13 +++++++++++++
> tests/ref/fate/h264-bsf-mp4toannexb | 2 +-
> tests/ref/fate/h264_mp4toannexb_ticket2991 | 18 +++++++++---------
> tests/ref/fate/segment-mp4-to-ts | 12 ++++++------
> 4 files changed, 29 insertions(+), 16 deletions(-)
>
> diff --git a/libavcodec/bsf/h264_mp4toannexb.c
> b/libavcodec/bsf/h264_mp4toannexb.c
> index 92af6a6881..6607f1e91a 100644
> --- a/libavcodec/bsf/h264_mp4toannexb.c
> +++ b/libavcodec/bsf/h264_mp4toannexb.c
> @@ -363,6 +363,19 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx,
> AVPacket *opkt)
> if (!new_idr && unit_type == H264_NAL_IDR_SLICE && (buf[1] &
> 0x80))
> new_idr = 1;
>
> + /* If this is a buffering period SEI without a corresponding
> sps/pps
> + * then prepend any existing sps/pps before the SEI */
> + if (unit_type == H264_NAL_SEI && buf[1] == 0 && !sps_seen &&
> !pps_seen) {
That 0 should be SEI_TYPE_BUFFERING_PERIOD, right?
> + if (s->sps_size) {
> + count_or_copy(&out, &out_size, s->sps, s->sps_size,
> PS_OUT_OF_BAND, j);
> + sps_seen = 1;
> + }
> + if (s->pps_size) {
> + count_or_copy(&out, &out_size, s->pps, s->pps_size,
> PS_OUT_OF_BAND, j);
> + pps_seen = 1;
> + }
Is there a reason to insert the PPS? IIUC only the SPS is needed.
--
Anton Khirnov
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