@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2023-02-09
API changes, most recent first:
+2024-03-05 - xxxxxxxxxx - lavf 60.25.100 - avformat.h
+ Add AVFormatContext.duration_probesize
+
2024-03-05 - xxxxxxxxxx - lavf 60.24.100 - avformat.h
Add avformat_stream_group_name().
@@ -225,9 +225,23 @@ Specifies the maximum number of streams. This can be used to reject files that
would require too many resources due to a large number of streams.
@item skip_estimate_duration_from_pts @var{bool} (@emph{input})
-Skip estimation of input duration when calculated using PTS.
+Skip estimation of input duration if it requires an additional probing for pts at end of file.
At present, applicable for MPEG-PS and MPEG-TS.
+@item durationprobesize @var{integer} (@emph{input})
+Set probing size for input duration estimation when it actually requires an additional probing
+for pts at end of file.
+At present, applicable for MPEG-PS and MPEG-TS.
+It is aimed at users interested in better durations probing for itself, or indirectly
+for specific use cases like using the concat demuxer.
+Files with high bitrates and ending cleanly (as opposed to live captures), can lead
+to a large physical gap between the last video packet and the last audio packet,
+so many bytes have to be read in order to get a video stream duration.
+Setting this value has a performance impact even for small files because the probing size is fixed.
+Default behaviour is a trade-off, largely adaptive: the probing size may range from
+250K up to 16M, but it is not extended to get streams durations at all costs.
+Must be an integer not lesser than 1, or 0 for default behaviour.
+
@item strict, f_strict @var{integer} (@emph{input/output})
Specify how strictly to follow the standards. @code{f_strict} is deprecated and
should be used only via the @command{ffmpeg} tool.
@@ -1952,6 +1952,8 @@ typedef struct AVFormatContext {
* Skip duration calcuation in estimate_timings_from_pts.
* - encoding: unused
* - decoding: set by user
+ *
+ * @sa duration_probesize
*/
int skip_estimate_duration_from_pts;
@@ -1994,6 +1996,16 @@ typedef struct AVFormatContext {
* Freed by libavformat in avformat_free_context().
*/
AVStreamGroup **stream_groups;
+
+ /**
+ * Maximum number of bytes read from input in order to determine stream durations
+ * when using estimate_timings_from_pts in avformat_find_stream_info().
+ * Demuxing only, set by the caller before avformat_find_stream_info().
+ * Can be set to 0 to let avformat choose using a heuristic.
+ *
+ * @sa skip_estimate_duration_from_pts
+ */
+ int64_t duration_probesize;
} AVFormatContext;
/**
@@ -1836,8 +1836,9 @@ static void estimate_timings_from_bit_rate(AVFormatContext *ic)
"Estimating duration from bitrate, this may be inaccurate\n");
}
-#define DURATION_MAX_READ_SIZE 250000LL
-#define DURATION_MAX_RETRY 6
+#define DURATION_MAX_READ_SIZE_DEFAULT 250000LL
+#define DURATION_MAX_RETRY_DEFAULT 6
+#define DURATION_MAX_RETRY_USER 1
/* only usable for MPEG-PS streams */
static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
@@ -1845,6 +1846,8 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
FFFormatContext *const si = ffformatcontext(ic);
AVPacket *const pkt = si->pkt;
int num, den, read_size, ret;
+ int64_t duration_max_read_size = ic->duration_probesize ? ic->duration_probesize >> DURATION_MAX_RETRY_USER : DURATION_MAX_READ_SIZE_DEFAULT;
+ int duration_max_retry = ic->duration_probesize ? DURATION_MAX_RETRY_USER : DURATION_MAX_RETRY_DEFAULT;
int found_duration = 0;
int is_end;
int64_t filesize, offset, duration;
@@ -1880,7 +1883,7 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
filesize = ic->pb ? avio_size(ic->pb) : 0;
do {
is_end = found_duration;
- offset = filesize - (DURATION_MAX_READ_SIZE << retry);
+ offset = filesize - (duration_max_read_size << retry);
if (offset < 0)
offset = 0;
@@ -1889,7 +1892,7 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
for (;;) {
AVStream *st;
FFStream *sti;
- if (read_size >= DURATION_MAX_READ_SIZE << (FFMAX(retry - 1, 0)))
+ if (read_size >= duration_max_read_size << (FFMAX(retry - 1, 0)))
break;
do {
@@ -1943,7 +1946,7 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
}
} while (!is_end &&
offset &&
- ++retry <= DURATION_MAX_RETRY);
+ ++retry <= duration_max_retry);
av_opt_set_int(ic, "skip_changes", 0, AV_OPT_SEARCH_CHILDREN);
@@ -108,6 +108,7 @@ static const AVOption avformat_options[] = {
{"max_streams", "maximum number of streams", OFFSET(max_streams), AV_OPT_TYPE_INT, { .i64 = 1000 }, 0, INT_MAX, D },
{"skip_estimate_duration_from_pts", "skip duration calculation in estimate_timings_from_pts", OFFSET(skip_estimate_duration_from_pts), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, D},
{"max_probe_packets", "Maximum number of packets to probe a codec", OFFSET(max_probe_packets), AV_OPT_TYPE_INT, { .i64 = 2500 }, 0, INT_MAX, D },
+{"durationprobesize", "maximum number of bytes to probe the durations of the streams in estimate_timings_from_pts", OFFSET(duration_probesize), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, D},
{NULL},
};
@@ -31,7 +31,7 @@
#include "version_major.h"
-#define LIBAVFORMAT_VERSION_MINOR 24
+#define LIBAVFORMAT_VERSION_MINOR 25
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
Yet another probesize used to get the durations when estimate_timings_from_pts is required. It is aimed at users interested in better durations probing for itself, or because using avformat_find_stream_info indirectly and requiring exact values: for concatdec for example, especially if streamcopying above it. The current code is a performance trade-off that can fail to get video stream durations in a scenario with high bitrates and buffering for files ending cleanly (as opposed to live captures): the physical gap between the last video packet and the last audio packet is very high in such a case. Default behaviour is unchanged: 250k up to 250k << 6 (step by step) Setting this new option has two effects: - override the maximum probesize (currently 250k << 6) - reduce the number of steps to 1 instead of 6, this is to avoid detecting the audio "too early" and failing to reach a video packet. Even if a single audio stream duration is found but not the other audio/video stream durations, there will be a retry, so at the end the full user-overriden probesize will be used as expected by the user. Signed-off-by: Nicolas Gaullier <nicolas.gaullier@cji.paris> --- doc/APIchanges | 3 +++ doc/formats.texi | 16 +++++++++++++++- libavformat/avformat.h | 12 ++++++++++++ libavformat/demux.c | 13 ++++++++----- libavformat/options_table.h | 1 + libavformat/version.h | 2 +- 6 files changed, 40 insertions(+), 7 deletions(-)