[FFmpeg-devel] [PATCH v7] Add SUP/PGS subtitle demuxer

[wm4]

On Tue, 30 Sep 2014 12:01:33 +0300
Petri Hintukainen <phintuka at 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.

First packet:

pts=255314
pts_time=2.836822
dts=255314
dts_time=2.836822

Second packet:

pts=255037
pts_time=2.833744
dts=255037
dts_time=2.833744

> 
> 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.

> 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.