On Wed, Oct 01, 2014 at 03:07:19PM +0200, wm4 wrote: > On Wed, 1 Oct 2014 12:58:32 +0200 > Michael Niedermayer <michae...@gmx.at> wrote: > > > On Wed, Oct 01, 2014 at 01:36:58PM +0300, Petri Hintukainen wrote: > > > On ti, 2014-09-30 at 16:09 +0200, wm4 wrote: > > > > On Tue, 30 Sep 2014 12:01:33 +0300 > > > > Petri Hintukainen <phint...@gmail.com> wrote: > > > > > > > > > Hello, > > > > > > > > > > Missing DTS combined with non-monotonic PTS seems to cause some > > > > > problems. This is with the file from ticket #2208 (I added dumping > > > > > timestamps to demuxer and muxer): > > > > > > > > > > > > > > > $ ../ffmpeg -i orig/track_06\ -\ Subtitle.sup -scodec copy 6.sup > > > > > ffmpeg version N-66546-gea74007 Copyright (c) 2000-2014 the FFmpeg > > > > > developers > > > > > built on Sep 30 2014 11:10:08 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1) > > > > > configuration: > > > > > libavutil 54. 7.101 / 54. 7.101 > > > > > libavcodec 56. 1.101 / 56. 1.101 > > > > > libavformat 56. 7.101 / 56. 7.101 > > > > > libavdevice 56. 1.100 / 56. 1.100 > > > > > libavfilter 5. 1.102 / 5. 1.102 > > > > > libswscale 3. 1.100 / 3. 1.100 > > > > > libswresample 1. 1.100 / 1. 1.100 > > > > > IN pts 00255314 dts 00000000 > > > > > Input #0, sup, from 'orig/track_06 - Subtitle.sup': > > > > > Duration: N/A, start: 2.836822, bitrate: N/A > > > > > Stream #0:0: Subtitle: hdmv_pgs_subtitle, 1920x1080 > > > > > Output #0, sup, to '6.sup': > > > > > Metadata: > > > > > encoder : Lavf56.7.101 > > > > > Stream #0:0: Subtitle: hdmv_pgs_subtitle, 1920x1080 > > > > > Stream mapping: > > > > > Stream #0:0 -> #0:0 (copy) > > > > > Press [q] to stop, [?] for help > > > > > OUT pts 00000000 dts 00000000 > > > > > IN pts 00255037 dts 00000000 > > > > > OUT pts 00000000 dts 00000000 > > > > > IN pts 00249205 dts 00000000 > > > > > [sup @ 0x241f4e0] Application provided invalid, non monotonically > > > > > increasing dts to muxer in stream 0: -277 >= -6109 > > > > > av_interleaved_write_frame(): Invalid argument > > > > > size= 0kB time=00:00:00.00 bitrate=N/A > > > > > video:0kB audio:0kB subtitle:1kB other streams:0kB global headers:0kB > > > > > muxing overhead: unknown > > > > > Conversion failed! > > > > > > > > The DTS in this file are indeed decreasing sometimes. > > > > > > No, there are no DTS timestamps in this file. > >
> > > those dts's are generated by ffmpeg, probably in mux.c > > > compute_pkt_fields2(). that could be > > Ouch. Yeah, I think this function used to corrupt perfectly fine h264 > mpegts timestamps in the past or so... which trac ticket is that ? or do you mean by "past" that this is not relevant anymore as it has been fixed already ? > > > > > > Also note that timestamps are re-positioned to start from 0. This may > > > > > be > > > > > problematic, it requires manually synchronizing subtitles to the > > > > > video. > > > > > > > > "Rebasing" the timestamps is apparently the normal operation of > > > > ffmpeg.c, there's probably a way to make it stop doing that. > > > > > > Yes, -copyts seems to do the trick. > > > I think all pts timestamps in .sup file should be relative to video > > > start, i.e. if video starts at pts 12345, corresponding .sup file starts > > > at pts = pts_of_first_subtitle - 12345. > > > > > > > > Remuxing from the original .m2ts file works just well: > > > > > > > > > > > > > > > $ ffmpeg -i orig/00038.m2ts -map 0:6 -scodec copy 6.sup > > > > > ffmpeg version N-66546-gea74007 Copyright (c) 2000-2014 the FFmpeg > > > > > developers > > > > > built on Sep 30 2014 11:10:08 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1) > > > > > configuration: > > > > > libavutil 54. 7.101 / 54. 7.101 > > > > > libavcodec 56. 1.101 / 56. 1.101 > > > > > libavformat 56. 7.101 / 56. 7.101 > > > > > libavdevice 56. 1.100 / 56. 1.100 > > > > > libavfilter 5. 1.102 / 5. 1.102 > > > > > libswscale 3. 1.100 / 3. 1.100 > > > > > libswresample 1. 1.100 / 1. 1.100 > > > > > [NULL @ 0x1bf9ba0] start time for stream 6 is not set in > > > > > estimate_timings_from_pts > > > > > [NULL @ 0x1c146e0] start time for stream 7 is not set in > > > > > estimate_timings_from_pts > > > > > [NULL @ 0x1c151c0] start time for stream 8 is not set in > > > > > estimate_timings_from_pts > > > > > [mpegts @ 0x1bf1ca0] Could not find codec parameters for stream 6 > > > > > (Subtitle: hdmv_pgs_subtitle ([144][0][0][0] / 0x0090)): unspecified > > > > > size > > > > > Consider increasing the value for the 'analyzeduration' and > > > > > 'probesize' options > > > > > [mpegts @ 0x1bf1ca0] Could not find codec parameters for stream 7 > > > > > (Subtitle: hdmv_pgs_subtitle ([144][0][0][0] / 0x0090)): unspecified > > > > > size > > > > > Consider increasing the value for the 'analyzeduration' and > > > > > 'probesize' options > > > > > [mpegts @ 0x1bf1ca0] Could not find codec parameters for stream 8 > > > > > (Subtitle: hdmv_pgs_subtitle ([144][0][0][0] / 0x0090)): unspecified > > > > > size > > > > > Consider increasing the value for the 'analyzeduration' and > > > > > 'probesize' options > > > > > Input #0, mpegts, from 'orig/00038.m2ts': > > > > > Duration: 00:00:43.90, start: 11.650667, bitrate: 35145 kb/s > > > > > Program 1 > > > > > Stream #0:0[0x1011]: Video: h264 (High) (HDMV / 0x564D4448), > > > > > yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 90k tbn, > > > > > 47.95 tbc > > > > > Stream #0:1[0x1100]: Audio: truehd (AC-3 / 0x332D4341), 48000 Hz, > > > > > 7.1, s32 (24 bit) > > > > > Stream #0:2[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, > > > > > 5.1(side), fltp, 640 kb/s > > > > > Stream #0:3[0x1101]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, > > > > > stereo, fltp, 320 kb/s > > > > > Stream #0:4[0x1102]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, > > > > > stereo, fltp, 320 kb/s > > > > > Stream #0:5[0x1200]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] > > > > > / 0x0090), 1920x1080 > > > > > Stream #0:6[0x1201]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] > > > > > / 0x0090) > > > > > Stream #0:7[0x1202]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] > > > > > / 0x0090) > > > > > Stream #0:8[0x1203]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] > > > > > / 0x0090) > > > > > Output #0, sup, to '6.sup': > > > > > Metadata: > > > > > encoder : Lavf56.7.101 > > > > > Stream #0:0: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] / 0x0090) > > > > > Stream mapping: > > > > > Stream #0:6 -> #0:0 (copy) > > > > > Press [q] to stop, [?] for help > > > > > OUT pts 00255255 dts 00249146 > > > > > OUT pts 00254978 dts 00249146 > > > > > OUT pts 00249146 dts 00249146 > > > > > OUT pts 00249699 dts 00249146 > > > > > OUT pts 00249699 dts 00249699 > > > > > ... > > > > > > > > > > > > > > > Also, remuxing this file again (.sup->.sup) with ffmpeg works. Well, > > > > > except that timestamps are again repositioned. > > > > > > > > > > > > > > > Is this something that can be handled in muxer ? > > > > > > > > Not sure what's going on here at all. Normally, DTS as stored in a file > > > > should never decrease, except on timestamp resets, which doesn't happen > > > > here. > > > > > > ffmpeg uses PTS as DTS when there is no DTS. This does not work well > > > with non-monotonic PTS (that's why DTS should be kept in those > > > files ...). I think there are also some players that do not display PGS > > > subtitles without DTS. > > > > > > Using AVFMT_NOTIMESTAMPS in .sup muxer kind of works, but incorrect DTS > > > is still written to output file, and there are lot of error messages. I > > > could probably hack the muxer to drop those invalid DTS timestamps, but > > > it doesn't feel the right solution (and does not work with other output > > > formats). > > > > > > One possible solution in demuxer (or parser) could be reading all > > > segments until segment 0x80 is found, and using the smallest PTS value > > > found as DTS for every segment in display set. I'm not sure if this > > > would be 100% compilant, but I can try to check it. > > > In any case, there's no way one could guess/calculate DTS from PTS of > > > first segment. Some upper limit / "safety distance" for PTS-DTS > > > difference could possibly be found from full-screen display update, but > > > I don't know if that could cause overflowing graphics buffers with high > > > frame rate animations. > > > > > > Probably the best solution would be to not output DTS when it is not > > > present in input (and maybe refusing to mux such files to containers > > > that require DTS), but I have no idea how to implement it :) > > > > i didnt follow this thread closely but > > why is this dts calculation so hard ? > > consider a matching encoder, how would it generate DTS ? > > it has to, to function, a encoder just has pts and durations for its > > raw input and needs dts on its output encoded bitstream packets > > If we can't reconstruct a correct DTS if it's missing, we definitely > should prevent the generic libavformat code from filling in completely > broken DTS. Is there a flag for this? dts are not optional in mpeg* if you have no dts you wont have a mpeg-TS They are a integral part of the muxing process used both in the buffering model as well as in stream interleaving. that said its quite easy to add a flag to disable the code that sets the DTS if someone really wants such flag [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Awnsering whenever a program halts or runs forever is On a turing machine, in general impossible (turings halting problem). On any real computer, always possible as a real computer has a finite number of states N, and will either halt in less than N cycles or never halt.
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