[mythtv-users] File format problem from one DVB-T mux

John Pilkington johnpilk222 at gmail.com
Mon Jan 25 18:23:49 UTC 2021

I first saw this some time ago, and posted about it here:


The mux uses QPSK and carries a 'local' TV channel and 3 Sony Movies 
channels, often at 544x576 resolution;  but there is some confusion 
about the encoding.  mediainfo and ffprobe give opposite results for the 
field order and 'mythcommflag --rebuild' finds only half the number of 
frames in the original seektable  - 25 fps instead of 50 fps 
(field/frame mixup).  Playback in mythfrontend, and cutting, works ok 
with both kinds - although my usual cutting program using the ProjectX 
demuxer reports bad timestamps and drops every GOP as defective.

My main reason for coming back to this relates to the 'leanfront' 
player, which now gives good smooth and controllable playback of most of 
my other files.  In contrast, although playback starts well, any 
skipping or pausing enters a flickery mode with segments of different 
frames being displayed while the audio continues as normal.

Googling shows that the mediainfo/ffmpeg field-order detection is known 
to be unreliable, and an attempt to change it using

ffmpeg -hide_banner -i infile.ts -vf "fieldorder=tff" outfile_tff.ts

(or xxx_bff.ts) dropped the video bitrate and stopped video playback in 
leanfront altogether.  Room for more experimentation there, but not hopeful.

I'm posting a clip here.  Helpful comments welcome!


John P

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