[mythtv-users] Transcoding HD-PVR Recordings

Doug Vaughan r.d.vaughan at rogers.com
Mon Sep 20 19:39:33 UTC 2010

John and Kirk,
     I regularly edit and transcode HDPVR recordings. There are some 
restrictions which may not suit you but here is what I do.

1) I locked my STB to 1280x720p output. This keeps the recording size 
down but allows me to reliably use a video editor.
2) I use a compiled version of Avidemux 2.4 as I found at least the 
Ubuntu packaged version could not handle the audio AC3 tracks. Avidemux 
has not worked for me with 1920x1080i HDPVR recordings. I have reliably 
edited up to 8Gb files if the 1280x720p restriction is adheared to. 
Although I rarely record more than 6Gb HDPVR file.
3) I edit the HDPVR recording as needed then save as an avi with copy 
audio and copy video settings.
4) I run a ffmpeg copying the audio and video tracks to change the 
container from avi to mkv. This also sets a seek table that reliably 
works with the MythTV internal player.
5) If you want to transcode the mkv file use HandBrake either the GUI or 
the CLI. I have several presets for various sizes of transcoded video. 
Handbrake already has iPod presets that you can use. I transcode the 
output to mkv files. If you want to use the cli then you can cut and 
paste their iPod presets from the GUI. That was my starting point when 
building my customized presets.
6) Occasionally the audio can be out of sync which I correct with a 
feature of MKV File Creator GUI. MKV File Creator will not accept the 
HDPVR recordings directly you need to at least change their container 
type with a ffmpeg copy.

As I can write python and bash scripts, outside of the manual editing or 
audio resync, the whole process has been automated. I even initiate the 
process as a right click script in Nautilus. The transcoding occurs as 
an overnight cron job.

This would not be what everyone would want but has worked well for my 
needs almost two years now.


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