Commit 4ad08021 authored by Nicolas George's avatar Nicolas George Committed by Stefano Sabatini
Browse files

Add a -force_key_frames option to ffmpeg.

The option is useful to ensure that there is a seek point exactly at a
place the user will probably want to jump precisely sometime, the
major example would be the end of an opening and the beginning of a
chapter. The scene change detection system will often make it happen,
but not always for example if there is a fade-in.

See the thread:
Subject: [FFmpeg-devel] [PATCH] -force_key_frames option
Date: Tue, 12 Oct 2010 15:16:26 +0200

Patch by Nicolas George -mail nicolas,george,normalesup,org.

Originally committed as revision 25526 to svn://svn.ffmpeg.org/ffmpeg/trunk
parent 43945b27
......@@ -48,6 +48,7 @@ version <next>:
- cropdetect filter
- ffmpeg -crop* options removed
- transpose filter added
- ffmpeg -force_key_frames option added
version 0.6:
......
......@@ -495,6 +495,12 @@ Bitstream filters available are "dump_extra", "remove_extra", "noise", "h264_mp4
@example
ffmpeg -i h264.mp4 -vcodec copy -vbsf h264_mp4toannexb -an out.h264
@end example
@item -force_key_frames @var{time}[,@var{time}...]
Force key frames at the specified timestamps, more precisely at the first
frames after each specified time.
This option can be useful to ensure that a seek point is present at a
chapter mark or any other designated place in the output file.
The timestamps must be specified in ascending order.
@end table
@section Audio Options
......
......@@ -225,6 +225,7 @@ static int nb_frames_drop = 0;
static int input_sync;
static uint64_t limit_filesize = 0;
static int force_fps = 0;
static char *forced_key_frames = NULL;
static int pgmyuv_compatibility_hack=0;
static float dts_delta_threshold = 10;
......@@ -272,6 +273,11 @@ typedef struct AVOutputStream {
int original_height;
int original_width;
/* forced key frames */
int64_t *forced_kf_pts;
int forced_kf_count;
int forced_kf_index;
/* audio only */
int audio_resample;
ReSampleContext *resample; /* for audio resampling */
......@@ -1189,6 +1195,11 @@ static void do_video_out(AVFormatContext *s,
big_picture.pts= ost->sync_opts;
// big_picture.pts= av_rescale(ost->sync_opts, AV_TIME_BASE*(int64_t)enc->time_base.num, enc->time_base.den);
//av_log(NULL, AV_LOG_DEBUG, "%"PRId64" -> encoder\n", ost->sync_opts);
if (ost->forced_kf_index < ost->forced_kf_count &&
big_picture.pts >= ost->forced_kf_pts[ost->forced_kf_index]) {
big_picture.pict_type = FF_I_TYPE;
ost->forced_kf_index++;
}
ret = avcodec_encode_video(enc,
bit_buffer, bit_buffer_size,
&big_picture);
......@@ -1837,6 +1848,29 @@ static int copy_chapters(int infile, int outfile)
return 0;
}
static void parse_forced_key_frames(char *kf, AVOutputStream *ost,
AVCodecContext *avctx)
{
char *p;
int n = 1, i;
int64_t t;
for (p = kf; *p; p++)
if (*p == ',')
n++;
ost->forced_kf_count = n;
ost->forced_kf_pts = av_malloc(sizeof(*ost->forced_kf_pts) * n);
if (!ost->forced_kf_pts) {
av_log(NULL, AV_LOG_FATAL, "Could not allocate forced key frames array.\n");
ffmpeg_exit(1);
}
for (i = 0; i < n; i++) {
p = i ? strchr(p, ',') + 1 : kf;
t = parse_time_or_die("force_key_frames", p, 1);
ost->forced_kf_pts[i] = av_rescale_q(t, AV_TIME_BASE_Q, avctx->time_base);
}
}
/*
* The following code is the main loop of the file converter
*/
......@@ -2578,6 +2612,7 @@ static int transcode(AVFormatContext **output_files,
av_fifo_free(ost->fifo); /* works even if fifo is not
initialized but set to zero */
av_free(ost->pict_tmp.data[0]);
av_free(ost->forced_kf_pts);
if (ost->video_resample)
sws_freeContext(ost->img_resample_ctx);
if (ost->resample)
......@@ -3333,6 +3368,9 @@ static void new_video_stream(AVFormatContext *oc, int file_idx)
video_enc->flags |= CODEC_FLAG_PASS2;
}
}
if (forced_key_frames)
parse_forced_key_frames(forced_key_frames, ost, video_enc);
}
if (video_language) {
av_metadata_set2(&st->metadata, "language", video_language, 0);
......@@ -3342,6 +3380,7 @@ static void new_video_stream(AVFormatContext *oc, int file_idx)
/* reset some key parameters */
video_disable = 0;
av_freep(&video_codec_name);
av_freep(&forced_key_frames);
video_stream_copy = 0;
frame_pix_fmt = PIX_FMT_NONE;
}
......@@ -3644,6 +3683,7 @@ static void opt_output_file(const char *filename)
set_context_opts(oc, avformat_opts, AV_OPT_FLAG_ENCODING_PARAM, NULL);
nb_streamid_map = 0;
av_freep(&forced_key_frames);
}
/* same option as mencoder */
......@@ -4094,6 +4134,7 @@ static const OptionDef options[] = {
{ "qphist", OPT_BOOL | OPT_EXPERT | OPT_VIDEO, { (void *)&qp_hist }, "show QP histogram" },
{ "force_fps", OPT_BOOL | OPT_EXPERT | OPT_VIDEO, {(void*)&force_fps}, "force the selected framerate, disable the best supported framerate selection" },
{ "streamid", OPT_FUNC2 | HAS_ARG | OPT_EXPERT, {(void*)opt_streamid}, "set the value of an outfile streamid", "streamIndex:value" },
{ "force_key_frames", OPT_STRING | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void *)&forced_key_frames}, "force key frames at specified timestamps", "timestamps" },
/* audio options */
{ "ab", OPT_FUNC2 | HAS_ARG | OPT_AUDIO, {(void*)opt_bitrate}, "set bitrate (in bits/s)", "bitrate" },
......
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