[FFmpeg-user] Keeping A/V sync during telecine

Carl Zwanzig cpz at tuunq.com
Sat Dec 30 21:11:14 EET 2017


On 12/30/2017 5:01 AM, Carl Eugen Hoyos wrote:
>> -vf framerate=24000/1001,telecine
> Should have been: -vf fps=24000/1001,telecine

I have tried both of those, but there was no discernible difference or 
improvement in the output a/v sync. (Do they interact with the "-r 
ntsc-film" before the input file?)

(only ran this long enough to produce a couple minutes of output)
cpz at video-proc-0:/mnt/videofiles % ffmpeg -hide_banner -r ntsc-film -i 
INFILE.vob -vf fps=24000/1001,telecine -async 1 -dc 9 -target ntsc-dvd 
-flags +ilme+ildct -alternate_scan 1 -top 0 OUTFILE.mpg
Input #0, mpeg, from 'INFILE.vob':
   Duration: 01:55:53.25, start: 0.084000, bitrate: 5061 kb/s
     Stream #0:0[0x1bf]: Data: dvd_nav_packet
     Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, bt470bg, top 
first), 720x480 [SAR 8:9 DAR 4:3], 29.97 fps, 59.94 tbr, 90k tbn, 59.94 tbc
     Stream #0:2[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 256 kb/s
File 'OUTFILE.mpg' already exists. Overwrite ? [y/N] y
Stream mapping:
   Stream #0:1 -> #0:0 (mpeg2video (native) -> mpeg2video (native))
   Stream #0:2 -> #0:1 (ac3 (native) -> ac3 (native))
Press [q] to stop, [?] for help
[Parsed_telecine_1 @ 0x80c23e9c0] Telecine pattern 23 yields up to 2 frames 
per frame, pts advance factor: 4/5
-async is forwarded to lavfi similarly to -af 
Output #0, dvd, to 'OUTFILE.mpg':
     encoder         : Lavf57.71.100
     Stream #0:0: Video: mpeg2video (Main), yuv420p, 720x480 [SAR 8:9 DAR 
4:3], q=2-31, 6000 kb/s, 29.97 fps, 90k tbn, 29.97 tbc
       encoder         : Lavc57.89.100 mpeg2video
     Side data:
       cpb: bitrate max/min/avg: 9000000/0/6000000 buffer size: 1835008 
vbv_delay: -1
     Stream #0:1: Audio: ac3, 48000 Hz, stereo, fltp, 448 kb/s
       encoder         : Lavc57.89.100 ac3
frame= 5352 fps=462 q=2.0 Lsize=  107994kB time=00:02:58.51 
bitrate=4955.9kbits/s speed=15.4x
video:96191kB audio:9567kB subtitle:0kB other streams:0kB global headers:0kB 
muxing overhead: 2.114477%
Exiting normally, received signal 2.
cpz at video-proc-0:/mnt/videofiles%

Other that dumping the packet headers to a large text file, are there any 
tools for looking at the PTS? While I'd like to solve the problem and get 
the content processed, I'd also like to understand what's going on.



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