On 2/15/2022 9:03 AM, Anton Khirnov wrote:
Quoting James Almer (2022-02-15 12:48:09)
On 2/15/2022 8:41 AM, Anton Khirnov wrote:
Quoting James Almer (2022-02-14 23:41:54)
A keyframe could be buffered in the bsf and not be output until more packets
had been fed to it.
Signed-off-by: James Almer <jamr...@gmail.com>
---
fftools/ffmpeg.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 6aa0986f02..48d9016b4c 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -2026,7 +2026,8 @@ static void do_streamcopy(InputStream *ist, OutputStream
*ost, const AVPacket *p
}
if ((!ost->frame_number && !(pkt->flags & AV_PKT_FLAG_KEY)) &&
- !ost->copy_initial_nonkeyframes)
+ !ost->copy_initial_nonkeyframes &&
+ !(ost->bsf_ctx && ost->bsf_ctx->filter->capabilities &
AV_BSF_CAP_DELAY))
return;
Wouldn't it be simpler to add an OutputStream field that tracks whether
we've seen a keyframe packet yet? No new API required.
Probably. It would also only trigger when a keyframe was seen instead of
unconditionally for all delay flagged bsfs.
I still think this new API is a good addition, either way. Only a
handful of bsfs buffer packets and require the caller to flush them
after sending NULL (av1_frame_merge, vp9_superframe, and setts after
this set) so library users could have all this time never signaled EOF
and never noticed anything wrong, much like it happened here.
The presence of this flag might help library users know they really need
to signal EOF.
I don't see where the advantage would be. The callers still need to have
the flushing code, so might as well always call it.
Then we probably need to enforce it in the doxy, or at least strongly
suggest it with a @note or @warning line to ensure you get complete output.
Right now it's optional, mentioned as "If you send a NULL packet, it
will trigger EOF", meaning not doing so is still a valid scenario, and
there's nothing letting the user know he's got packets stuck in the bsf
even after receive_packet() returned EAGAIN if they don't.
The disadvantage for us is more complixity and we have to maintain the
list of delay BSFs.
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