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fftools/ffmpeg: Add new variant source_no_drop to the force_key_frames option 

Suggested-By: ffmpeg@fb.com
This commit is contained in:
Keyun Tong 2021-06-20 21:42:29 +02:00 committed by Thilo Borgmann
parent b7e350af3e
commit b7266302a4
3 changed files with 14 additions and 0 deletions
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7
doc/ffmpeg.texi
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@ -1011,6 +1011,7 @@ Deprecated see -bsf
@item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
@item -force_key_frames[:@var{stream_specifier}] expr:@var{expr} (@emph{output,per-stream})
@item -force_key_frames[:@var{stream_specifier}] source (@emph{output,per-stream})
@item -force_key_frames[:@var{stream_specifier}] source_no_drop (@emph{output,per-stream})
@var{force_key_frames} can take arguments of the following form:
@ -1072,6 +1073,12 @@ starting from second 13:
If the argument is @code{source}, ffmpeg will force a key frame if
the current frame being encoded is marked as a key frame in its source.
@item source_no_drop
If the argument is @code{source_no_drop}, ffmpeg will force a key frame if
the current frame being encoded is marked as a key frame in its source.
In cases where this particular source frame has to be dropped,
enforce the next available frame to become a key frame instead.
@end table
Note that forcing too many keyframes is very harmful for the lookahead

6
fftools/ffmpeg.c
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@ -1287,6 +1287,7 @@ static void do_video_out(OutputFile *of,
}
}
ost->last_dropped = nb_frames == nb0_frames && next_picture;
ost->dropped_keyframe = ost->last_dropped && next_picture && next_picture->key_frame;
/* duplicates frame if needed */
for (i = 0; i < nb_frames; i++) {
@ -1347,6 +1348,11 @@ static void do_video_out(OutputFile *of,
&& in_picture->key_frame==1
&& !i) {
forced_keyframe = 1;
} else if ( ost->forced_keyframes
&& !strncmp(ost->forced_keyframes, "source_no_drop", 6)
&& !i) {
forced_keyframe = (in_picture->key_frame == 1) || ost->dropped_keyframe;
ost->dropped_keyframe = 0;
}
if (forced_keyframe) {

1
fftools/ffmpeg.h
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@ -504,6 +504,7 @@ typedef struct OutputStream {
char *forced_keyframes;
AVExpr *forced_keyframes_pexpr;
double forced_keyframes_expr_const_values[FKF_NB];
int dropped_keyframe;
/* audio only */
int *audio_channels_map; /* list of the channels id to pick from the source stream */