At present, if reading from a readrate-limited input is stalled,
then upon resumption, ffmpeg will read the input without any
throttle till the average readrate matches the specified readrate.
This new option allows to set a speed limit when reading is resumed
until the average readrate matches the primary readrate.
Fixes #11469
---
doc/ffmpeg.texi | 5 ++++
fftools/ffmpeg.h | 1 +
fftools/ffmpeg_demux.c | 62 ++++++++++++++++++++++++++++++++++++------
fftools/ffmpeg_opt.c | 3 ++
4 files changed, 63 insertions(+), 8 deletions(-)
diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index da6549f043..fca220a334 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -2325,6 +2325,11 @@ Read input at native frame rate. This is equivalent to
setting @code{-readrate 1
@item -readrate_initial_burst @var{seconds}
Set an initial read burst time, in seconds, after which @option{-re/-readrate}
will be enforced.
+@item -readrate_catchup @var{speed} (@emph{input})
+If either the input or output is blocked leading to actual read speed falling
behind the
+specified readrate, then this rate takes effect till the input catches up with
the
+specified readrate. Must not be lower than the primary readrate.
+
@item -vsync @var{parameter} (@emph{global})
@itemx -fps_mode[:@var{stream_specifier}] @var{parameter}
(@emph{output,per-stream})
Set video sync method / framerate mode. vsync is applied to all output video
streams
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 9439be0f41..c37a085029 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -163,6 +163,7 @@ typedef struct OptionsContext {
int loop;
int rate_emu;
float readrate;
+ float readrate_catchup;
double readrate_initial_burst;
int accurate_seek;
int thread_queue_size;
diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
index 5ff75eed1a..4a4a134afa 100644
--- a/fftools/ffmpeg_demux.c
+++ b/fftools/ffmpeg_demux.c
@@ -94,6 +94,12 @@ typedef struct DemuxStream {
uint64_t nb_packets;
// combined size of all the packets read
uint64_t data_size;
+ // latest wallclock time at which packet reading resumed after a stall -
used for readrate
+ int64_t resume_wc;
+ // timestamp of first packet sent after the latest stall - used for
readrate
+ int64_t resume_pts;
+ // measure of how far behind packet reading is against spceified readrate
+ int64_t lag;
} DemuxStream;
typedef struct Demuxer {
@@ -127,6 +133,7 @@ typedef struct Demuxer {
float readrate;
double readrate_initial_burst;
+ float readrate_catchup;
Scheduler *sch;
@@ -495,16 +502,42 @@ static void readrate_sleep(Demuxer *d)
(f->start_time_effective != AV_NOPTS_VALUE ?
f->start_time_effective * !start_at_zero : 0) +
(f->start_time != AV_NOPTS_VALUE ? f->start_time : 0)
);
- int64_t burst_until = AV_TIME_BASE * d->readrate_initial_burst;
+ int64_t initial_burst = AV_TIME_BASE * d->readrate_initial_burst;
+ int resume_warn;
+
for (int i = 0; i < f->nb_streams; i++) {
InputStream *ist = f->streams[i];
DemuxStream *ds = ds_from_ist(ist);
- int64_t stream_ts_offset, pts, now;
+ int64_t stream_ts_offset, pts, now, wc_elapsed, elapsed, lag, max_pts,
limit_pts;
+
+ if (ds->discard) continue;
+
stream_ts_offset = FFMAX(ds->first_dts != AV_NOPTS_VALUE ?
ds->first_dts : 0, file_start);
pts = av_rescale(ds->dts, 1000000, AV_TIME_BASE);
- now = (av_gettime_relative() - d->wallclock_start) * d->readrate +
stream_ts_offset;
- if (pts - burst_until > now)
- av_usleep(pts - burst_until - now);
+ now = av_gettime_relative();
+ wc_elapsed = now - d->wallclock_start;
+ max_pts = stream_ts_offset + initial_burst + wc_elapsed * d->readrate;
+ lag = FFMAX(max_pts - pts, 0);
+ if ( (!ds->lag && lag > 0.3 * AV_TIME_BASE) || ( lag > ds->lag + 0.3 *
AV_TIME_BASE) ) {
+ ds->lag = lag;
+ ds->resume_wc = now;
+ ds->resume_pts = pts;
+ av_log_once(ds, AV_LOG_WARNING, AV_LOG_DEBUG, &resume_warn,
+ "Resumed reading at pts %0.3f with rate %0.3f after a
lag of %0.3fs\n",
+ (float)pts/AV_TIME_BASE, d->readrate_catchup,
(float)lag/AV_TIME_BASE);
+ }
+ if (ds->lag && !lag)
+ ds->lag = ds->resume_wc = ds->resume_pts = 0;
+ if (ds->resume_wc) {
+ elapsed = now - ds->resume_wc;
+ limit_pts = ds->resume_pts + elapsed * d->readrate_catchup;
+ } else {
+ elapsed = wc_elapsed;
+ limit_pts = max_pts;
+ }
+
+ if (pts > limit_pts)
+ av_usleep(pts - limit_pts);
}
}
@@ -1859,9 +1892,22 @@ int ifile_open(const OptionsContext *o, const char
*filename, Scheduler *sch)
d->readrate_initial_burst);
return AVERROR(EINVAL);
}
- } else if (o->readrate_initial_burst) {
- av_log(d, AV_LOG_WARNING, "Option -readrate_initial_burst ignored "
- "since neither -readrate nor -re were given\n");
+ d->readrate_catchup = o->readrate_catchup ? o->readrate_catchup :
d->readrate;
+ if (d->readrate_catchup < d->readrate) {
+ av_log(d, AV_LOG_ERROR,
+ "Option -readrate_catchup is %0.3f; it must be at least
equal to %0.3f.\n",
+ d->readrate_catchup, d->readrate);
+ return AVERROR(EINVAL);
+ }
+ } else {
+ if (o->readrate_initial_burst) {
+ av_log(d, AV_LOG_WARNING, "Option -readrate_initial_burst ignored "
+ "since neither -readrate nor -re were given\n");
+ }
+ if (o->readrate_catchup) {
+ av_log(d, AV_LOG_WARNING, "Option -readrate_catchup ignored "
+ "since neither -readrate nor -re were given\n");
+ }
}
/* Add all the streams from the given input file to the demuxer */
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index 3c0c682594..27a9fc9e42 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -1639,6 +1639,9 @@ const OptionDef options[] = {
{ "readrate_initial_burst", OPT_TYPE_DOUBLE, OPT_OFFSET | OPT_EXPERT |
OPT_INPUT,
{ .off = OFFSET(readrate_initial_burst) },
"The initial amount of input to burst read before imposing any
readrate", "seconds" },
+ { "readrate_catchup", OPT_TYPE_FLOAT, OPT_OFFSET | OPT_EXPERT |
OPT_INPUT,
+ { .off = OFFSET(readrate_catchup) },
+ "Temporary readrate used to catch up if an input lags behind the
specified readrate", "speed" },
{ "target", OPT_TYPE_FUNC, OPT_FUNC_ARG | OPT_PERFILE |
OPT_EXPERT | OPT_OUTPUT,
{ .func_arg = opt_target },
"specify target file type (\"vcd\", \"svcd\", \"dvd\", \"dv\" or
\"dv50\" "
--
2.46.1
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