[FFmpeg-devel] [PATCH] avcodec/h264_mp4toannexb: Prepend SPS/PPS to buffering period SEI

[Josh Allmann <joshua.allmann@gmail.com>]

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.
---
 libavcodec/bsf/h264_mp4toannexb.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

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) {
+                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;
+                }
+            }
+
             /* prepend only to the first type 5 NAL unit of an IDR picture, if no sps/pps are already present */
             if (new_idr && unit_type == H264_NAL_IDR_SLICE && !sps_seen && !pps_seen) {
                 if (s->sps_size)
-- 
2.39.2

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