[mythtv] transcoder documentation.

Geoffrey Hausheer ou401cru02 at sneakemail.com
Fri Aug 8 23:53:09 EDT 2003

Okay, maybe I'm just an idiot, but what is the best way to submit
documentation patches?
Do I just add my text to the sgml file, and do a diff against that?  Do I
just submit the text I want added?  i know nothing about sgml (though
looking at the syntax, it doesn't look too hard).

Anyhow I'd like to add something like this (it is a work in progress, and
isn't really complete yet, but it is better than no docs at all)

19.16 My system is too slow for realtime MPEG4, how do I use the
The transcoder reencodes files from one mythtv format to another.  Its
main purpose is to allow users who have either hardware encoders (PVR250)
or systems that can only record in RTJpeg due to performance reasons
(multiple capture cards, slow system, etc) to create MPEG4 streams to
save space.

The transcoder can be used in two ways:
(1) Automatically reencode every file once it has completed recording
(2) After marking commercials, the transcoder can be run manually to
delete the commercials from the file (thus further saving space)

the second method can be used on already transcoded files, and only the
frames immediately following a cut section will be reencoded (thus there
is very minimal quality loss)

To enable the transcoder, do the following:
   start the setup program
   under the host-specific settings:
      set the MaxTranscoders >= 1 (1 is the recommended, and safest,
      setting.  This option MUST be set if you plan to ever use the
      set the Transcoder Autorun checkbox if you'd like the transcoder to
      run automatically after each recording
      set the Use Cutlist checkbox if you plan to ever use the manual
      transcoding option.

   start mythbackend
   start mythfrontend
   select setup, and the Transcoding recording profile.
      now select either RTJPEG or MPEG4 (selecting any of the hardware
      encoders will result in the transcoder not working).
      set the other parameters as you'd like.  For best performance, you
      should match the audio to the 'Default' profile.  If you plan to
      only use the manual transocder, you can choose to set the video to
      be the same as the default profile too.

Everything should now be setup properly.  If you elected to use the
Auto-Run feature, the transcoder will automatically launch afeter each
recording is complete (don't worry, it runs niced-down, so it shouldn't
impact any critical tasks).
If you want to manually transcode a program, simply press X while
watching a recording (you should have already finished marking all
commericals).  this will queue a new transcoding, which will start once
you have finished watching the program.

Once the transcode is complete, mythbackend will replace the old file
with the new as soon as it is no longer in use.
  Geoffrey Hausheer

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