[FFmpeg-cvslog] fftools/ffmpeg_enc: unbreak -force_key_frames source_no_drop

[Anton Khirnov]

ffmpeg | branch: master | Anton Khirnov <anton at khirnov.net> | Sat Sep  9 14:11:56 2023 +0200| [735b082231a93f7193448ed5cb2a461b3df531e2] | committer: Anton Khirnov

fftools/ffmpeg_enc: unbreak -force_key_frames source_no_drop

Unlike the 'source' mode, which preserves source keyframe-marking as-is,
the 'source_no_drop' mode attempts to keep track of keyframes dropped by
framerate conversion and mark the next output frame as key in such
cases. However,
* c75be061487 broke this functionality entirely, and made it equivalent
  to 'source'
* even before it would only work when the frame immediately following
  the dropped keyframe is preserved and not dropped as well

Also, drop a redundant check for 'frame' in setting dropped_keyframe, as
it is redundant with the check on the above line.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=735b082231a93f7193448ed5cb2a461b3df531e2
---

 fftools/ffmpeg_enc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fftools/ffmpeg_enc.c b/fftools/ffmpeg_enc.c
index c42bfce905..2d86cee22d 100644
--- a/fftools/ffmpeg_enc.c
+++ b/fftools/ffmpeg_enc.c
@@ -1054,7 +1054,7 @@ finish:
     }
 
     ost->last_dropped = *nb_frames == *nb_frames_prev && frame;
-    ost->kf.dropped_keyframe = ost->last_dropped && frame && (frame->flags & AV_FRAME_FLAG_KEY);
+    ost->kf.dropped_keyframe |= ost->last_dropped && (frame->flags & AV_FRAME_FLAG_KEY);
 }
 
 static enum AVPictureType forced_kf_apply(void *logctx, KeyframeForceCtx *kf,
@@ -1097,8 +1097,9 @@ static enum AVPictureType forced_kf_apply(void *logctx, KeyframeForceCtx *kf,
                (in_picture->flags & AV_FRAME_FLAG_KEY) && !dup_idx) {
             goto force_keyframe;
     } else if (kf->type == KF_FORCE_SOURCE_NO_DROP && !dup_idx) {
+        int dropped_keyframe = kf->dropped_keyframe;
         kf->dropped_keyframe = 0;
-        if ((in_picture->flags & AV_FRAME_FLAG_KEY) || kf->dropped_keyframe)
+        if ((in_picture->flags & AV_FRAME_FLAG_KEY) || dropped_keyframe)
             goto force_keyframe;
     }