[mythtv-users] Extracting MP3s

mythtv at ripnet.co.uk mythtv at ripnet.co.uk
Fri Jul 30 05:59:57 EDT 2004


Ive now got Myth working great and recording all my programs.

My ultimate aim is to have programs transcoded to smaller normal format (non .nuv) files and moved to a directory and removed from MythTV

Can mythtv do this on its own? can it be set to transcode my programs to divx (for tv channels) and mp3 (for my radio channels)?

I have been playing with nuvexport to try and do this, and have several observations

1. mythexport doesnt seem to export correctly from the actual .nuv files - it works fine when using the channel and start time to find the nuv, but if you use the actual .nuv file, it give the following output (sorry, mythtranscode, not mythexport - and im typing this from a shell so cant edit :( )

Stream: 0 Type: 0
Stream: 1 Type: 1
Input #0, mpeg, from '1003_20040729210000_20040729220000.nuv':
  Stream #0.0: Video: mpeg2video, 704x576, 25.00 fps
  Stream #0.1: Audio: mp2, 48000 Hz, stereo, 192 kb/s
Only MP2 audio is currently supported
mythtranscode: mpeg2trans.cpp:377: uint32_t MPEG2trans::process_mp2_audio(AVPacket*): Assertion `0' failed.

The same program works fine if I specify -c -s to find the program.

2. nuvexport MP3 output seems to actually give mpeg layer 2 (mp2?) as it uses toolame to encode it. Ive tried using lame instead, telling it its raw PCM input (by altering the perl script that calls mythtranscode etc), but I just get white noise - what format does mythtranscode output? not raw pcm?

Ive also tried to use lame to re-code from mp2 to mp3 (telling Lame its a mp2 input) - that nearly works, but I get lots of artifacts in the sound (wierd whining noises, distorted speach etc - reminds me of when I addidently encoded a stream interleaved with other output to stdout.

3. Finally, whats up with the .nuv format? is it a container format similar to mpg and avi? is there a utility that will just move it to a .avi or .mpeg container without re-encoding it?

Once I have this sorted, my MythTV system will be perfect - many thanks to the developers for creating such a cool package. I wish it ran on my hardware Tivo :)

So, ideally, I would be able to tell MythTV to always transcode channels x,y,z to divx and channels a,b,c to mp3, then I would use a utility to convert this to .mpeg or .avi format, so I can use on my MP3 player and PocketPC (audio and video)

thanks in advance


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