[mythtv-users] Mytharchive errors

Rod Smith mythtv at rodsbooks.com
Fri Dec 5 05:54:34 UTC 2008

On Thursday 04 December 2008 08:12:25 pm Harry Devine wrote:
> I'll give your script a try, but in the mean time, maybe you can clear
> up some confusion for me.  I had the recording use the Autodetect
> transcoder.  I'm actually transcoding the recording that I want to
> archive again now just to see what happens.  I guess I'm not really sure
> if I need to change anything in the Transcoder settings, or transcode
> the recording using another transcoder before archiving it.  I won't
> archive every recording, but if I think I might want to, I could set it
> up to record using another one other than Autodetect.

The MythTV transcoders can all be customized, so it's impossible to say for 
certain what the autodetect transcoder does on any given system without 
checking its settings. On *MY* system, the autodetect transcoder does a 
lossless transcode, meaning that it just cuts out anything that's flagged for 
removal via manual editing and does some minor cleanup. Lossless transcodes 
run quickly but don't change resolution or bitrate. I don't recall if 
autodetect doing a lossless transcode is the default or if I changed that.

When burning to DVD, there's little point in transcoding via MythTV ahead of 
time, except possibly for a lossless transcode to cut out unwanted material. 
A non-lossless MythTV transcode will convert to MPEG-4 or RTjpeg, depending 
on how it's configured, but DVDs must be burned in MPEG-2 format -- and with 
a limited set of options for resolution and some other parameters, too. Thus, 
if you plan to burn to DVD, it's best to do one of two things:

1) Record directly in MPEG-2 format at 720x480 resolution (for NTSC; IIRC,
   it's 720x576 for PAL) and burn that to DVD without transcoding it, or
   at most do a lossless transcode on the material.

2) Record in whatever format is an option for your hardware and transcode just
   once. This transcode can be:
   a) In MythArchive
   b) Prior to using MythArchive, using a non-MythTV transcode tool (such
      as mencoder or ffmpeg directly)

Note that even if you record in a DVD-ready format, you may need to transcode 
if your recording is too big for your DVD.

I hope this makes sense; it's getting late for me, so I might not be writing 
as clearly as I'd like.

Rod Smith

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