On Fri, 20 Dec 2019, Michael Niedermayer wrote:
On Tue, Dec 17, 2019 at 03:15:09PM +0200, Martin Storsjö wrote:
Keep all the existing data fields as they are (there's lots and
lots of nontrivial calculation and heuristics based on them in
their current form), but derive the duration as the difference
between the pts of the first packet to the maximum pts+duration
(not necessarily the last packet); use this duration in any box
where the actual presentation duration is supposed to be.
Fixes: 8420
---
Fixed to fetch the duration for tmcd tracks from their designated
source track.
---
libavformat/movenc.c | 35 ++++++++++++++++++++++++++++-------
1 file changed, 28 insertions(+), 7 deletions(-)
I found another case that changes, again dont know which is more correct
make -j12 && ./ffmpeg -i ~/tickets/3453/mov_with_tmcd.mov -y -bitexact -codec
copy -map 0 -t 2 file.mov ; ./ffprobe -v 0 file.mov -show_packets -print_format compact
> /tmp/before
--- /tmp/before 2019-12-20 23:28:04.009327038 +0100
+++ /tmp/after 2019-12-20 23:27:17.213326052 +0100
@@ -188,7 +188,7 @@
packet|codec_type=audio|stream_index=1|pts=88320|pts_time=1.840000|dts=88320|dts_time=1.840000|duration=1024|duration_time=0.021333|convergence_duration=N/A|convergence_duration_time=N/A|size=4096|pos=408905|flags=K_
packet|codec_type=data|stream_index=2|pts=46|pts_time=1.840000|dts=46|dts_time=1.840000|duration=1|duration_time=0.040000|convergence_duration=N/A|convergence_duration_time=N/A|size=4|pos=413001|flags=K_
packet|codec_type=audio|stream_index=1|pts=89344|pts_time=1.861333|dts=89344|dts_time=1.861333|duration=896|duration_time=0.018667|convergence_duration=N/A|convergence_duration_time=N/A|size=3584|pos=413005|flags=K_
-packet|codec_type=video|stream_index=0|pts=26624|pts_time=2.080000|dts=24064|dts_time=1.880000|duration=512|duration_time=0.040000|convergence_duration=N/A|convergence_duration_time=N/A|size=776|pos=416589|flags=_D
+packet|codec_type=video|stream_index=0|pts=26624|pts_time=2.080000|dts=24064|dts_time=1.880000|duration=512|duration_time=0.040000|convergence_duration=N/A|convergence_duration_time=N/A|size=776|pos=416589|flags=__
packet|codec_type=audio|stream_index=1|pts=90240|pts_time=1.880000|dts=90240|dts_time=1.880000|duration=1024|duration_time=0.021333|convergence_duration=N/A|convergence_duration_time=N/A|size=4096|pos=417365|flags=K_
packet|codec_type=data|stream_index=2|pts=47|pts_time=1.880000|dts=47|dts_time=1.880000|duration=1|duration_time=0.040000|convergence_duration=N/A|convergence_duration_time=N/A|size=4|pos=421461|flags=K_
packet|codec_type=audio|stream_index=1|pts=91264|pts_time=1.901333|dts=91264|dts_time=1.901333|duration=896|duration_time=0.018667|convergence_duration=N/A|convergence_duration_time=N/A|size=3584|pos=421465|flags=K_
I would say the new behaviour is more correct here.
This command writes a truncated sequence; the sequence of muxed packets
is this:
pts=0|pts_time=0.000000|dts=-1024|dts_time=-0.080000|duration=512|duration_time=0.040000
...
pts=26624|pts_time=2.080000|dts=24064|dts_time=1.880000|duration=512|duration_time=0.040000
pts=25600|pts_time=2.000000|dts=24576|dts_time=1.920000|duration=512|duration_time=0.040000
pts=25088|pts_time=1.960000|dts=25088|dts_time=1.960000|duration=512|duration_time=0.040000
Based on DTS, this previously wrote a total duration of 1.96 + 0.04 -
(-0.08) = 2.08.
This duration also was set in the edit list, which then made the last
frame (in presentation order) with a pts of 2.08 to be outside of the edit
list, and thus be marked discardable.
With the patch, the duration of the file gets written as 2.08 + 0.04 -
0.00 = 2.12, and thus the last frame no longer is marked as discardable.
If the reordering sequene wasn't truncated, if the following packet also
would be included, the duration would end up calculated the same with both
DTS and PTS:
pts=26112|pts_time=2.040000|dts=25600|dts_time=2.000000|duration=512|duration_time=0.040000
// Martin
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