Re: [FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
On 2023-01-11 01:40 am, Michael Niedermayer wrote: On Tue, Jan 03, 2023 at 03:52:17PM +0530, Gyan Doshi wrote: At present, the offset for discontinuity adjustment is applied per-file but the check for discontinuity is intra-stream so the same discontinuity when seen in multiple streams with copyts, leads to compounded adjustment of the discontinuity offset. This introduces gaps in streams, leading to loss of sync or even de facto loss of stream. The ts_offset_discont parameter is transferred to InputStream and adjusted based on intra-stream gaps. --- Here's a simulated example to demonstrate the issue: 1) generate input ffmpeg -f lavfi -i nullsrc=s=32x32:r=1,format=gray -f lavfi -i anullsrc=cl=mono:r=8000 -c:v libx264 -preset superfast -bf 0 -crf 50 -c:a aac -b:a 64k -muxpreload 0 -muxdelay 0 -output_ts_offset 95000 -t 10 src-10s.ts 2) demo ffmpeg -copyts -i "src-10.ts" -vf "showinfo=checksum=0" -af "ashowinfo" -f null - -report ==Before patch== timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, new offset= 95443717689 timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, new offset= 190887435378 [Parsed_ashowinfo_0 @ 02700af98800] n:0 pts:759998976 pts_time:94999.9 [Parsed_ashowinfo_0 @ 02700af98800] n:1 pts:76000 pts_time:95000 ... [Parsed_ashowinfo_0 @ 02700af98800] n:745202 pts:1523085824 pts_time:190386 [Parsed_ashowinfo_0 @ 02700af98800] n:745203 pts:1523086848 pts_time:190386 [Parsed_ashowinfo_0 @ 02700af98800] n:745204 pts:2286637614 pts_time:285830 [Parsed_ashowinfo_0 @ 02700af98800] n:745205 pts:2286638638 pts_time:285830 [Parsed_showinfo_0 @ 02700ec34700] n: 0 pts:855000 pts_time:95000 [Parsed_showinfo_0 @ 02700ec34700] n: 1 pts:855009 pts_time:95001 ... [Parsed_showinfo_0 @ 02700ec34700] n:95380 pts:1713420 pts_time:190380 [Parsed_showinfo_0 @ 02700ec34700] n:95381 pts:1713429 pts_time:190381 [Parsed_showinfo_0 @ 02700ec34700] n:95382 pts:25724314592 pts_time:285826 [Parsed_showinfo_0 @ 02700ec34700] n:95383 pts:25724404592 pts_time:285827 ==After patch== timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, new stream offset= 95443717689 timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, new stream offset= 95443717689 [Parsed_ashowinfo_0 @ 023c773c8880] n:0 pts:759998976 pts_time:94999.9 [Parsed_ashowinfo_0 @ 023c773c8880] n:1 pts:76000 pts_time:95000 ... [Parsed_ashowinfo_0 @ 023c773c8880] n:745202 pts:1523085824 pts_time:190386 [Parsed_ashowinfo_0 @ 023c773c8880] n:745203 pts:1523086848 pts_time:190386 [Parsed_ashowinfo_0 @ 023c773c8880] n:745204 pts:1523087872 pts_time:190386 [Parsed_ashowinfo_0 @ 023c773c8880] n:745205 pts:1523088896 pts_time:190386 [Parsed_showinfo_0 @ 023c795d07c0] n: 0 pts:855000 pts_time:95000 [Parsed_showinfo_0 @ 023c795d07c0] n: 1 pts:855009 pts_time:95001 ... [Parsed_showinfo_0 @ 023c795d07c0] n:95380 pts:1713420 pts_time:190380 [Parsed_showinfo_0 @ 023c795d07c0] n:95381 pts:1713429 pts_time:190381 [Parsed_showinfo_0 @ 023c795d07c0] n:95382 pts:1713438 pts_time:190382 [Parsed_showinfo_0 @ 023c795d07c0] n:95383 pts:1713447 pts_time:190383 fftools/ffmpeg.c | 12 ++-- fftools/ffmpeg.h | 8 2 files changed, 10 insertions(+), 10 deletions(-) I havent looked into this but i have a slightly ungood feeling about this change Yes, this is a hack. Ideal is to track and sync discontinuities at both file and stream level to avoid compound adjustments. Let me rework this. Regards, Gyan ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
On Tue, Jan 03, 2023 at 03:52:17PM +0530, Gyan Doshi wrote: > At present, the offset for discontinuity adjustment is applied per-file but > the check for discontinuity is intra-stream so the same discontinuity when > seen in multiple streams with copyts, leads to compounded adjustment of the > discontinuity offset. This introduces gaps in streams, leading to loss of sync > or even de facto loss of stream. > > The ts_offset_discont parameter is transferred to InputStream and adjusted > based on intra-stream gaps. > --- > Here's a simulated example to demonstrate the issue: > 1) generate input > ffmpeg -f lavfi -i nullsrc=s=32x32:r=1,format=gray -f lavfi -i > anullsrc=cl=mono:r=8000 -c:v libx264 -preset superfast -bf 0 -crf 50 -c:a aac > -b:a 64k -muxpreload 0 -muxdelay 0 -output_ts_offset 95000 -t 10 > src-10s.ts > > 2) demo > ffmpeg -copyts -i "src-10.ts" -vf "showinfo=checksum=0" -af "ashowinfo" > -f null - -report > > ==Before patch== > > timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, > new offset= 95443717689 > timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, > new offset= 190887435378 > > [Parsed_ashowinfo_0 @ 02700af98800] n:0 pts:759998976 pts_time:94999.9 > [Parsed_ashowinfo_0 @ 02700af98800] n:1 pts:76000 pts_time:95000 > ... > [Parsed_ashowinfo_0 @ 02700af98800] n:745202 pts:1523085824 > pts_time:190386 > [Parsed_ashowinfo_0 @ 02700af98800] n:745203 pts:1523086848 > pts_time:190386 > [Parsed_ashowinfo_0 @ 02700af98800] n:745204 pts:2286637614 > pts_time:285830 > [Parsed_ashowinfo_0 @ 02700af98800] n:745205 pts:2286638638 > pts_time:285830 > > > [Parsed_showinfo_0 @ 02700ec34700] n: 0 pts:855000 pts_time:95000 > [Parsed_showinfo_0 @ 02700ec34700] n: 1 pts:855009 pts_time:95001 > ... > [Parsed_showinfo_0 @ 02700ec34700] n:95380 pts:1713420 pts_time:190380 > [Parsed_showinfo_0 @ 02700ec34700] n:95381 pts:1713429 pts_time:190381 > [Parsed_showinfo_0 @ 02700ec34700] n:95382 pts:25724314592 pts_time:285826 > [Parsed_showinfo_0 @ 02700ec34700] n:95383 pts:25724404592 pts_time:285827 > > ==After patch== > > timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, > new stream offset= 95443717689 > timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, > new stream offset= 95443717689 > > [Parsed_ashowinfo_0 @ 023c773c8880] n:0 pts:759998976 pts_time:94999.9 > [Parsed_ashowinfo_0 @ 023c773c8880] n:1 pts:76000 pts_time:95000 > ... > [Parsed_ashowinfo_0 @ 023c773c8880] n:745202 pts:1523085824 > pts_time:190386 > [Parsed_ashowinfo_0 @ 023c773c8880] n:745203 pts:1523086848 > pts_time:190386 > [Parsed_ashowinfo_0 @ 023c773c8880] n:745204 pts:1523087872 > pts_time:190386 > [Parsed_ashowinfo_0 @ 023c773c8880] n:745205 pts:1523088896 > pts_time:190386 > > > [Parsed_showinfo_0 @ 023c795d07c0] n: 0 pts:855000 pts_time:95000 > [Parsed_showinfo_0 @ 023c795d07c0] n: 1 pts:855009 pts_time:95001 > ... > [Parsed_showinfo_0 @ 023c795d07c0] n:95380 pts:1713420 pts_time:190380 > [Parsed_showinfo_0 @ 023c795d07c0] n:95381 pts:1713429 pts_time:190381 > [Parsed_showinfo_0 @ 023c795d07c0] n:95382 pts:1713438 pts_time:190382 > [Parsed_showinfo_0 @ 023c795d07c0] n:95383 pts:1713447 pts_time:190383 > > > > fftools/ffmpeg.c | 12 ++-- > fftools/ffmpeg.h | 8 > 2 files changed, 10 insertions(+), 10 deletions(-) I havent looked into this but i have a slightly ungood feeling about this change thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Dictatorship naturally arises out of democracy, and the most aggravated form of tyranny and slavery out of the most extreme liberty. -- Plato signature.asc Description: PGP signature ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
On 2023-01-10 04:32 pm, Anton Khirnov wrote: Quoting Gyan Doshi (2023-01-03 11:22:17) At present, the offset for discontinuity adjustment is applied per-file but the check for discontinuity is intra-stream so the same discontinuity when seen in multiple streams with copyts, leads to compounded adjustment of the discontinuity offset. This introduces gaps in streams, leading to loss of sync or even de facto loss of stream. The ts_offset_discont parameter is transferred to InputStream and adjusted based on intra-stream gaps. I never had much use for this feature, but I wonder if adding different offsets to different streams isn't going against the whole point of timestamps, which is synchronizing them. A robust method would have to look at the inter-stream delta among first packets in each stream after the jump, which neither the existing code nor my changes do. The existing code compares dts against next_dts for the stream where the jump is first seen, and derives the offset from that. That offset adjustment applied to all other streams may not preserve the inter-stream deltas for the packets after the jump since inter-frame intervals in each stream will be different. In practice, the discrepancy is going to be minor, except for pathological inputs. But this patch avoids the compounded adjustment currently being applied, which makes the output defunct, or worse frozen and a CPU/memory hog if video encoding is CFR. Regards, Gyan ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
Quoting Gyan Doshi (2023-01-03 11:22:17) > At present, the offset for discontinuity adjustment is applied per-file but > the check for discontinuity is intra-stream so the same discontinuity when > seen in multiple streams with copyts, leads to compounded adjustment of the > discontinuity offset. This introduces gaps in streams, leading to loss of sync > or even de facto loss of stream. > > The ts_offset_discont parameter is transferred to InputStream and adjusted > based on intra-stream gaps. I never had much use for this feature, but I wonder if adding different offsets to different streams isn't going against the whole point of timestamps, which is synchronizing them. Also, this could REALLY use tests. -- Anton Khirnov ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
On 2023-01-07 09:50 am, Gyan Doshi wrote:
On 2023-01-03 03:52 pm, Gyan Doshi wrote:
At present, the offset for discontinuity adjustment is applied
per-file but
the check for discontinuity is intra-stream so the same discontinuity
when
seen in multiple streams with copyts, leads to compounded adjustment
of the
discontinuity offset. This introduces gaps in streams, leading to
loss of sync
or even de facto loss of stream.
The ts_offset_discont parameter is transferred to InputStream and
adjusted
based on intra-stream gaps.
Comments?
Plan to push in 48h.
Regards,
Gyan
---
Here's a simulated example to demonstrate the issue:
1) generate input
ffmpeg -f lavfi -i nullsrc=s=32x32:r=1,format=gray -f lavfi -i
anullsrc=cl=mono:r=8000 -c:v libx264 -preset superfast -bf 0 -crf 50
-c:a aac -b:a 64k -muxpreload 0 -muxdelay 0 -output_ts_offset 95000
-t 10 src-10s.ts
2) demo
ffmpeg -copyts -i "src-10.ts" -vf "showinfo=checksum=0" -af
"ashowinfo" -f null - -report
==Before patch==
timestamp discontinuity for stream #0:1 (id=257, type=audio):
-95443717689, new offset= 95443717689
timestamp discontinuity for stream #0:0 (id=256, type=video):
-95443717689, new offset= 190887435378
[Parsed_ashowinfo_0 @ 02700af98800] n:0 pts:759998976
pts_time:94999.9
[Parsed_ashowinfo_0 @ 02700af98800] n:1 pts:76000 pts_time:95000
...
[Parsed_ashowinfo_0 @ 02700af98800] n:745202 pts:1523085824
pts_time:190386
[Parsed_ashowinfo_0 @ 02700af98800] n:745203 pts:1523086848
pts_time:190386
[Parsed_ashowinfo_0 @ 02700af98800] n:745204 pts:2286637614
pts_time:285830
[Parsed_ashowinfo_0 @ 02700af98800] n:745205 pts:2286638638
pts_time:285830
[Parsed_showinfo_0 @ 02700ec34700] n: 0 pts:855000
pts_time:95000
[Parsed_showinfo_0 @ 02700ec34700] n: 1 pts:855009
pts_time:95001
...
[Parsed_showinfo_0 @ 02700ec34700] n:95380 pts:1713420
pts_time:190380
[Parsed_showinfo_0 @ 02700ec34700] n:95381 pts:1713429
pts_time:190381
[Parsed_showinfo_0 @ 02700ec34700] n:95382 pts:25724314592
pts_time:285826
[Parsed_showinfo_0 @ 02700ec34700] n:95383 pts:25724404592
pts_time:285827
==After patch==
timestamp discontinuity for stream #0:1 (id=257, type=audio):
-95443717689, new stream offset= 95443717689
timestamp discontinuity for stream #0:0 (id=256, type=video):
-95443717689, new stream offset= 95443717689
[Parsed_ashowinfo_0 @ 023c773c8880] n:0 pts:759998976
pts_time:94999.9
[Parsed_ashowinfo_0 @ 023c773c8880] n:1 pts:76000 pts_time:95000
...
[Parsed_ashowinfo_0 @ 023c773c8880] n:745202 pts:1523085824
pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745203 pts:1523086848
pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745204 pts:1523087872
pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745205 pts:1523088896
pts_time:190386
[Parsed_showinfo_0 @ 023c795d07c0] n: 0 pts:855000
pts_time:95000
[Parsed_showinfo_0 @ 023c795d07c0] n: 1 pts:855009
pts_time:95001
...
[Parsed_showinfo_0 @ 023c795d07c0] n:95380 pts:1713420
pts_time:190380
[Parsed_showinfo_0 @ 023c795d07c0] n:95381 pts:1713429
pts_time:190381
[Parsed_showinfo_0 @ 023c795d07c0] n:95382 pts:1713438
pts_time:190382
[Parsed_showinfo_0 @ 023c795d07c0] n:95383 pts:1713447
pts_time:190383
fftools/ffmpeg.c | 12 ++--
fftools/ffmpeg.h | 8
2 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 881d6f0af2..b967055059 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -3418,13 +3418,13 @@ static void ts_discontinuity_detect(InputFile
*ifile, InputStream *ist,
if (fmt_is_discont) {
if (FFABS(delta) > 1LL * dts_delta_threshold *
AV_TIME_BASE ||
pkt_dts + AV_TIME_BASE/10 < FFMAX(ist->pts,
ist->dts)) {
- ifile->ts_offset_discont -= delta;
+ ist->ts_offset_discont -= delta;
av_log(NULL, AV_LOG_DEBUG,
"timestamp discontinuity for stream #%d:%d "
- "(id=%d, type=%s): %"PRId64", new offset=
%"PRId64"\n",
+ "(id=%d, type=%s): %"PRId64", new stream
offset= %"PRId64"\n",
ist->file_index, ist->st->index, ist->st->id,
av_get_media_type_string(ist->par->codec_type),
- delta, ifile->ts_offset_discont);
+ delta, ist->ts_offset_discont);
pkt->dts -= av_rescale_q(delta, AV_TIME_BASE_Q,
ist->st->time_base);
if (pkt->pts != AV_NOPTS_VALUE)
pkt->pts -= av_rescale_q(delta, AV_TIME_BASE_Q,
ist->st->time_base);
@@ -3447,10 +3447,10 @@ static void ts_discontinuity_detect(InputFile
*ifile, InputStream *ist,
fmt_is_discont && ifile->last_ts != AV_NOPTS_VALUE) {
int64_t delta = pkt_dts -
Re: [FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
On 2023-01-03 03:52 pm, Gyan Doshi wrote:
At present, the offset for discontinuity adjustment is applied per-file but
the check for discontinuity is intra-stream so the same discontinuity when
seen in multiple streams with copyts, leads to compounded adjustment of the
discontinuity offset. This introduces gaps in streams, leading to loss of sync
or even de facto loss of stream.
The ts_offset_discont parameter is transferred to InputStream and adjusted
based on intra-stream gaps.
Comments?
---
Here's a simulated example to demonstrate the issue:
1) generate input
ffmpeg -f lavfi -i nullsrc=s=32x32:r=1,format=gray -f lavfi -i
anullsrc=cl=mono:r=8000 -c:v libx264 -preset superfast -bf 0 -crf 50 -c:a aac
-b:a 64k -muxpreload 0 -muxdelay 0 -output_ts_offset 95000 -t 10
src-10s.ts
2) demo
ffmpeg -copyts -i "src-10.ts" -vf "showinfo=checksum=0" -af "ashowinfo" -f
null - -report
==Before patch==
timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, new
offset= 95443717689
timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, new
offset= 190887435378
[Parsed_ashowinfo_0 @ 02700af98800] n:0 pts:759998976 pts_time:94999.9
[Parsed_ashowinfo_0 @ 02700af98800] n:1 pts:76000 pts_time:95000
...
[Parsed_ashowinfo_0 @ 02700af98800] n:745202 pts:1523085824 pts_time:190386
[Parsed_ashowinfo_0 @ 02700af98800] n:745203 pts:1523086848 pts_time:190386
[Parsed_ashowinfo_0 @ 02700af98800] n:745204 pts:2286637614 pts_time:285830
[Parsed_ashowinfo_0 @ 02700af98800] n:745205 pts:2286638638 pts_time:285830
[Parsed_showinfo_0 @ 02700ec34700] n: 0 pts:855000 pts_time:95000
[Parsed_showinfo_0 @ 02700ec34700] n: 1 pts:855009 pts_time:95001
...
[Parsed_showinfo_0 @ 02700ec34700] n:95380 pts:1713420 pts_time:190380
[Parsed_showinfo_0 @ 02700ec34700] n:95381 pts:1713429 pts_time:190381
[Parsed_showinfo_0 @ 02700ec34700] n:95382 pts:25724314592 pts_time:285826
[Parsed_showinfo_0 @ 02700ec34700] n:95383 pts:25724404592 pts_time:285827
==After patch==
timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, new
stream offset= 95443717689
timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, new
stream offset= 95443717689
[Parsed_ashowinfo_0 @ 023c773c8880] n:0 pts:759998976 pts_time:94999.9
[Parsed_ashowinfo_0 @ 023c773c8880] n:1 pts:76000 pts_time:95000
...
[Parsed_ashowinfo_0 @ 023c773c8880] n:745202 pts:1523085824 pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745203 pts:1523086848 pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745204 pts:1523087872 pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745205 pts:1523088896 pts_time:190386
[Parsed_showinfo_0 @ 023c795d07c0] n: 0 pts:855000 pts_time:95000
[Parsed_showinfo_0 @ 023c795d07c0] n: 1 pts:855009 pts_time:95001
...
[Parsed_showinfo_0 @ 023c795d07c0] n:95380 pts:1713420 pts_time:190380
[Parsed_showinfo_0 @ 023c795d07c0] n:95381 pts:1713429 pts_time:190381
[Parsed_showinfo_0 @ 023c795d07c0] n:95382 pts:1713438 pts_time:190382
[Parsed_showinfo_0 @ 023c795d07c0] n:95383 pts:1713447 pts_time:190383
fftools/ffmpeg.c | 12 ++--
fftools/ffmpeg.h | 8
2 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 881d6f0af2..b967055059 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -3418,13 +3418,13 @@ static void ts_discontinuity_detect(InputFile *ifile,
InputStream *ist,
if (fmt_is_discont) {
if (FFABS(delta) > 1LL * dts_delta_threshold * AV_TIME_BASE ||
pkt_dts + AV_TIME_BASE/10 < FFMAX(ist->pts, ist->dts)) {
-ifile->ts_offset_discont -= delta;
+ist->ts_offset_discont -= delta;
av_log(NULL, AV_LOG_DEBUG,
"timestamp discontinuity for stream #%d:%d "
- "(id=%d, type=%s): %"PRId64", new offset= %"PRId64"\n",
+ "(id=%d, type=%s): %"PRId64", new stream offset=
%"PRId64"\n",
ist->file_index, ist->st->index, ist->st->id,
av_get_media_type_string(ist->par->codec_type),
- delta, ifile->ts_offset_discont);
+ delta, ist->ts_offset_discont);
pkt->dts -= av_rescale_q(delta, AV_TIME_BASE_Q,
ist->st->time_base);
if (pkt->pts != AV_NOPTS_VALUE)
pkt->pts -= av_rescale_q(delta, AV_TIME_BASE_Q,
ist->st->time_base);
@@ -3447,10 +3447,10 @@ static void ts_discontinuity_detect(InputFile *ifile,
InputStream *ist,
fmt_is_discont && ifile->last_ts != AV_NOPTS_VALUE) {
int64_t delta = pkt_dts - ifile->last_ts;
if (FFABS(delta) > 1LL * dts_delta_threshold * AV_TIME_BASE) {
-
[FFmpeg-devel] [PATCH] ffmpeg: apply discontinuity adjustment per-stream
At present, the offset for discontinuity adjustment is applied per-file but
the check for discontinuity is intra-stream so the same discontinuity when
seen in multiple streams with copyts, leads to compounded adjustment of the
discontinuity offset. This introduces gaps in streams, leading to loss of sync
or even de facto loss of stream.
The ts_offset_discont parameter is transferred to InputStream and adjusted
based on intra-stream gaps.
---
Here's a simulated example to demonstrate the issue:
1) generate input
ffmpeg -f lavfi -i nullsrc=s=32x32:r=1,format=gray -f lavfi -i
anullsrc=cl=mono:r=8000 -c:v libx264 -preset superfast -bf 0 -crf 50 -c:a aac
-b:a 64k -muxpreload 0 -muxdelay 0 -output_ts_offset 95000 -t 10
src-10s.ts
2) demo
ffmpeg -copyts -i "src-10.ts" -vf "showinfo=checksum=0" -af "ashowinfo" -f
null - -report
==Before patch==
timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, new
offset= 95443717689
timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, new
offset= 190887435378
[Parsed_ashowinfo_0 @ 02700af98800] n:0 pts:759998976 pts_time:94999.9
[Parsed_ashowinfo_0 @ 02700af98800] n:1 pts:76000 pts_time:95000
...
[Parsed_ashowinfo_0 @ 02700af98800] n:745202 pts:1523085824 pts_time:190386
[Parsed_ashowinfo_0 @ 02700af98800] n:745203 pts:1523086848 pts_time:190386
[Parsed_ashowinfo_0 @ 02700af98800] n:745204 pts:2286637614 pts_time:285830
[Parsed_ashowinfo_0 @ 02700af98800] n:745205 pts:2286638638 pts_time:285830
[Parsed_showinfo_0 @ 02700ec34700] n: 0 pts:855000 pts_time:95000
[Parsed_showinfo_0 @ 02700ec34700] n: 1 pts:855009 pts_time:95001
...
[Parsed_showinfo_0 @ 02700ec34700] n:95380 pts:1713420 pts_time:190380
[Parsed_showinfo_0 @ 02700ec34700] n:95381 pts:1713429 pts_time:190381
[Parsed_showinfo_0 @ 02700ec34700] n:95382 pts:25724314592 pts_time:285826
[Parsed_showinfo_0 @ 02700ec34700] n:95383 pts:25724404592 pts_time:285827
==After patch==
timestamp discontinuity for stream #0:1 (id=257, type=audio): -95443717689, new
stream offset= 95443717689
timestamp discontinuity for stream #0:0 (id=256, type=video): -95443717689, new
stream offset= 95443717689
[Parsed_ashowinfo_0 @ 023c773c8880] n:0 pts:759998976 pts_time:94999.9
[Parsed_ashowinfo_0 @ 023c773c8880] n:1 pts:76000 pts_time:95000
...
[Parsed_ashowinfo_0 @ 023c773c8880] n:745202 pts:1523085824 pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745203 pts:1523086848 pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745204 pts:1523087872 pts_time:190386
[Parsed_ashowinfo_0 @ 023c773c8880] n:745205 pts:1523088896 pts_time:190386
[Parsed_showinfo_0 @ 023c795d07c0] n: 0 pts:855000 pts_time:95000
[Parsed_showinfo_0 @ 023c795d07c0] n: 1 pts:855009 pts_time:95001
...
[Parsed_showinfo_0 @ 023c795d07c0] n:95380 pts:1713420 pts_time:190380
[Parsed_showinfo_0 @ 023c795d07c0] n:95381 pts:1713429 pts_time:190381
[Parsed_showinfo_0 @ 023c795d07c0] n:95382 pts:1713438 pts_time:190382
[Parsed_showinfo_0 @ 023c795d07c0] n:95383 pts:1713447 pts_time:190383
fftools/ffmpeg.c | 12 ++--
fftools/ffmpeg.h | 8
2 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 881d6f0af2..b967055059 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -3418,13 +3418,13 @@ static void ts_discontinuity_detect(InputFile *ifile,
InputStream *ist,
if (fmt_is_discont) {
if (FFABS(delta) > 1LL * dts_delta_threshold * AV_TIME_BASE ||
pkt_dts + AV_TIME_BASE/10 < FFMAX(ist->pts, ist->dts)) {
-ifile->ts_offset_discont -= delta;
+ist->ts_offset_discont -= delta;
av_log(NULL, AV_LOG_DEBUG,
"timestamp discontinuity for stream #%d:%d "
- "(id=%d, type=%s): %"PRId64", new offset= %"PRId64"\n",
+ "(id=%d, type=%s): %"PRId64", new stream offset=
%"PRId64"\n",
ist->file_index, ist->st->index, ist->st->id,
av_get_media_type_string(ist->par->codec_type),
- delta, ifile->ts_offset_discont);
+ delta, ist->ts_offset_discont);
pkt->dts -= av_rescale_q(delta, AV_TIME_BASE_Q,
ist->st->time_base);
if (pkt->pts != AV_NOPTS_VALUE)
pkt->pts -= av_rescale_q(delta, AV_TIME_BASE_Q,
ist->st->time_base);
@@ -3447,10 +3447,10 @@ static void ts_discontinuity_detect(InputFile *ifile,
InputStream *ist,
fmt_is_discont && ifile->last_ts != AV_NOPTS_VALUE) {
int64_t delta = pkt_dts - ifile->last_ts;
if (FFABS(delta) > 1LL * dts_delta_threshold * AV_TIME_BASE) {
-ifile->ts_offset_discont -= delta;
+ist->ts_offset_discont -= delta;
