[mythtv-users] Transcode to only remove commercials

Pieter Arentz pieter at arentz.eu
Mon Feb 9 00:00:56 UTC 2009


Hi all,

So far, I'm well on my way to a nice mythtv-setup, but I'm having  
problems with the cutting of commercials. I think the problem might  
very well be between the chair and keyboard, as I'm still a bit  
confused about mythtv's transcoding process. If someone would be so  
kind to explain things, please do.

I don't really need to transcode to a different codec, as I don't  
record enough to fill up the available space, so the original  
recordings are fine the way they are. Also, if I want to archive  
something to dvd, I don't want to transcode a transcoded recording  
*again*. However, I understand that I need transcoding to remove  
commercials from recordings.

When I set all the neccesary cut points and start transcoding, it  
transcodes to a different codec anyway. As a test, I placed cutpoints  
to remove about 30 secs from a recording, but after transcoding the  
recording is about 25% smaller in filesize than the original. (And the  
30 secs are cut, so that works.) However, I have no idea how to check  
on what codec is used on the original recording or the transcoded  
recording.

So I'm not sure how to configure the transcoder to NOT to transcode to  
a different codec, just cut the commercials. I tried setting the  
lossless transcoding checkbox, but that didn't work.

When selecting "Begin Transcoding" from the menu while watching a  
recording, I can choose between Default, Autodetect, High quality,  
Medium quality, Low quality (and the Default Transcoder in the  
settings appears to be "Autodetect". However, I'm not sure what to do  
about the transcoders. I went to the Transcoder settings, found the  
Autodetect from RTjpeg/MPEG4, Autodetect from MPEG2, High/Medium/Low  
quality profiles there, but I'm not sure what I should change there.

I added a new transcoder profile, however this one doesn't even show  
up when selecting "Begin transcoding" from the menu. I also edited the  
two Autodetect profiles, and changed the video codec to MPEG-4, as  
recommended in http://www.mythtv.org/wiki/Removing_Commercials#Transcode_error_-_Transcode_failed_with_status 
:_247 but that didn't help. Enabling the "Lossless transcoding" didn't  
help either, the result after transcoding was about 25% smaller than  
the original.

Also, how does transcoding work when you press X while watching a  
recording? Is the "Default" transcoder used? Transcoding starts,  
according to mythweb's backend status page, but I'm still watching the  
un-transcoded show. What happens when transcoding finishes while I'm  
still watching the untranscoded recording? Will it replace the  
original recording with the transcoded one when I stop watching?

I'm using Mythbuntu 8.10 (mythtv 0.21), with a Technotrend S-1500 to  
record from DVB-S.

Any help would be greatly appreciated.

Thanks,
Pieter


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