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ffplay: adjust external clock speed based on buffer fullness for realtime sources

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This provides a means to synchronize the player clock to the clock of the
encoder.

Signed-off-by: Marton Balint <cus@passwd.hu>
This commit is contained in:
Marton Balint 2012-11-01 18:26:45 +01:00
parent a04698c4a9
commit 747c749d42
1 changed files with 35 additions and 2 deletions
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37
ffplay.c
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@ -78,6 +78,11 @@ const int program_birth_year = 2003;
/* maximum audio speed change to get correct sync */
#define SAMPLE_CORRECTION_PERCENT_MAX 10
/* external clock speed adjustment constants for realtime sources based on buffer fullness */
#define EXTERNAL_CLOCK_SPEED_MIN 0.900
#define EXTERNAL_CLOCK_SPEED_MAX 1.010
#define EXTERNAL_CLOCK_SPEED_STEP 0.001
/* we use about AUDIO_DIFF_AVG_NB A-V differences to make the average */
#define AUDIO_DIFF_AVG_NB 20
@ -157,6 +162,7 @@ typedef struct VideoState {
int64_t seek_rel;
int read_pause_return;
AVFormatContext *ic;
int realtime;
int audio_stream;
@ -164,6 +170,7 @@ typedef struct VideoState {
double external_clock; ///< external clock base
double external_clock_drift; ///< external clock base - time (av_gettime) at which we updated external_clock
int64_t external_clock_time; ///< last reference time
double external_clock_speed; ///< speed of the external clock
double audio_clock;
double audio_diff_cum; /* used for AV difference average computation */
@ -1107,7 +1114,8 @@ static double get_external_clock(VideoState *is)
if (is->paused) {
return is->external_clock;
} else {
return is->external_clock_drift + av_gettime() / 1000000.0;
double time = av_gettime() / 1000000.0;
return is->external_clock_drift + time - (time - is->external_clock_time / 1000000.0) * (1.0 - is->external_clock_speed);
}
}
@ -1159,6 +1167,25 @@ static void check_external_clock_sync(VideoState *is, double pts) {
}
}
static void update_external_clock_speed(VideoState *is, double speed) {
update_external_clock_pts(is, get_external_clock(is));
is->external_clock_speed = speed;
}
static void check_external_clock_speed(VideoState *is) {
if (is->video_stream >= 0 && is->videoq.nb_packets <= MIN_FRAMES / 2 ||
is->audio_stream >= 0 && is->audioq.nb_packets <= MIN_FRAMES / 2) {
update_external_clock_speed(is, FFMAX(EXTERNAL_CLOCK_SPEED_MIN, is->external_clock_speed - EXTERNAL_CLOCK_SPEED_STEP));
} else if ((is->video_stream < 0 || is->videoq.nb_packets > MIN_FRAMES * 2) &&
(is->audio_stream < 0 || is->audioq.nb_packets > MIN_FRAMES * 2)) {
update_external_clock_speed(is, FFMIN(EXTERNAL_CLOCK_SPEED_MAX, is->external_clock_speed + EXTERNAL_CLOCK_SPEED_STEP));
} else {
double speed = is->external_clock_speed;
if (speed != 1.0)
update_external_clock_speed(is, speed + EXTERNAL_CLOCK_SPEED_STEP * (1.0 - speed) / fabs(1.0 - speed));
}
}
/* seek in the stream */
static void stream_seek(VideoState *is, int64_t pos, int64_t rel, int seek_by_bytes)
{
@ -1261,6 +1288,9 @@ static void video_refresh(void *opaque)
SubPicture *sp, *sp2;
if (!is->paused && get_master_sync_type(is) == AV_SYNC_EXTERNAL_CLOCK && is->realtime)
check_external_clock_speed(is);
if (is->video_st) {
if (is->force_refresh)
pictq_prev_picture(is);
@ -2542,6 +2572,8 @@ static int read_thread(void *arg)
}
}
is->realtime = is_realtime(ic);
for (i = 0; i < ic->nb_streams; i++)
ic->streams[i]->discard = AVDISCARD_ALL;
if (!video_disable)
@ -2591,7 +2623,7 @@ static int read_thread(void *arg)
goto fail;
}
if (infinite_buffer < 0 && is_realtime(ic))
if (infinite_buffer < 0 && is->realtime)
infinite_buffer = 1;
for (;;) {
@ -2769,6 +2801,7 @@ static VideoState *stream_open(const char *filename, AVInputFormat *iformat)
is->continue_read_thread = SDL_CreateCond();
update_external_clock_pts(is, 0.0);
update_external_clock_speed(is, 1.0);
is->audio_current_pts_drift = -av_gettime() / 1000000.0;
is->video_current_pts_drift = is->audio_current_pts_drift;
is->av_sync_type = av_sync_type;