[mythtv-users] Why does channel 4 transmit a silent audio track as well as the normal audio?

Charlie Brej mythtv at brej.org
Wed Aug 31 11:11:25 UTC 2005


George Styles wrote:
> The PID 231 contains the actual audio for the show, but the PID 232
> seems to contain only silence. Anyone know why C4 broadcast silence?
> is it a different codec? ac3 perhaps?

It is mp3 but it is silent. I think they keep a silent track running all 
the time and only sometimes use it for other languages or that 'audio 
describe' thing.

> Anyway, as sods law would have it, mencoder encodes the second, broken
> audio track, and I end up with a silent movie :(
> 
> Anyone know how to remove a pid from a ts? or maybe just re-label it
> as non-audio so mencoder doesnt pick it up?

I use "replex". then you can pick which audio stream you want and then pass 
that straight to an mpeg file for a DVD.

> Should the program association table stream tell mencoder which one to
> use? is mencoder broken in that respect?

I think mencoder just picks whichever stream comes first ignoring the tags 
on the stream stating if it is in english or w'eva.

> what do others use to convert TS's to xvid? i may try ffmpeg, as that
> seems to pick the correct audio stream...

So after you use replex and manually pick the audio stream (you can scan 
for streams with -s). you can re encode nicely into something else.


-- 
         Charlie Brej
APT Group, Dept. of Computer Science, University of Manchester
Web: http://brej.org/                 Tel: +44 (0)161 275 6177
Mail: IT303, University of Manchester, Manchester, M13 9PL, UK


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