After changes like ef13faf, the h264_metadata bitstream filter stopped
working when using the fixed_frame_rate_flag option on an input stream
that doesn't contain VUI because the default inferred value of
low_hrd_delay_flag seems to be 1. ffmpeg used to raise a warning, but
proceeded anyway but now aborts after the other fixes since the output
is rightfully invalid.
I believe this change makes the bitstream filter conform to page 403
of the ITU spec: "When fixed_frame_rate_flag is equal to 1,
low_delay_hrd_flag shall be equal to 0. When low_delay_hrd_flag is not
present, its value shall be inferred to be equal to 1 −
fixed_frame_rate_flag."
Signed-off-by: Keshav Varma <kesha...@gmail.com>
---
libavcodec/h264_metadata_bsf.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c
index 9df99cbae3..59a7eba546 100644
--- a/libavcodec/h264_metadata_bsf.c
+++ b/libavcodec/h264_metadata_bsf.c
@@ -228,7 +228,13 @@ static int h264_metadata_update_sps(AVBSFContext *bsf,
sps->vui.timing_info_present_flag = 1;
need_vui = 1;
}
- SET_VUI_FIELD(fixed_frame_rate_flag);
+
+ // Set fixed frame rate flag and update low_delay_hrd_flag to match
+ if (ctx->fixed_frame_rate_flag >= 0) {
+ sps->vui.fixed_frame_rate_flag = ctx->fixed_frame_rate_flag;
+ sps->vui.low_delay_hrd_flag = 1 - sps->vui.fixed_frame_rate_flag;
+ }
+
if (ctx->zero_new_constraint_set_flags) {
sps->constraint_set4_flag = 0;
sps->constraint_set5_flag = 0;
--
2.31.1
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