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Lossless MPEG2 Transcoding in mythtv 0.19
http://forums.linhes.org/viewtopic.php?f=17&t=8719		 Page 1 of 3
Author:  Greg Frost [ Mon Feb 27, 2006 3:55 am ]
Post subject:  Lossless MPEG2 Transcoding in mythtv 0.19
For those that have upgraded to 0.19 and those that are about to, you may be interested in the fact that it includes lossless MPEG2 transcoding.

To enable it simply:
Utilities/Setup->Setup->TV Settings->Recording Profiles->Transcoders->Autodetect from MPEG2
and check the Lossless Transcoding checkbox.

There have been some reports of audio sync problems after using it (in the earlier days. Those issues may well have been resolved before 0.19), but it has worked fine for the few DVB recordings I have tried it on.

Geoff Hausheer from the mythtv-dev list is the author and has been quite helphul in resolving people's problems, so if you have any, swing on over there and help make it better for all of us.
Author:  Girkers [ Mon Feb 27, 2006 3:59 am ]
Post subject: 
Greg,
Have you tested this on upgraded files? What I mean is recordings that were on the box prior to upgrading to 0.19?

Thanks

Girkers
Author:  Greg Frost [ Mon Feb 27, 2006 4:44 am ]
Post subject: 
I don't think I have. (And I dont think I have any such recordings anymore). I have been running svn since soon after A22.
Author:  ryanpatterson [ Mon Feb 27, 2006 8:52 am ]
Post subject: 
What does this do exactly? Is it for cutting commerials out of recordings? Or for transcoding into a smaller file size?
Author:  snaproll [ Mon Feb 27, 2006 11:15 am ]
Post subject: 
How many gig/hr. does it use ?
Author:  Greg Frost [ Mon Feb 27, 2006 2:25 pm ]
Post subject: 
It is for removing commercials without actually trascoding the parts that it doesn't need to. Keeps the quality identical (except for small sections around the cutpoints that need transcoding). If you have a large pre and post roll because the programming in your area is unreliable, you can chop off those as well. So it will save space because it removes the unwanted parts of the recording but without changing quality.
Author:  nigelpearson [ Sat Mar 04, 2006 2:08 am ]
Post subject: 
I have had good results with the built-in "lossless" transcoding so far. Haven't tried it on really bad ones yet, though (i.e. ones with lots of pops and skips).

Only problem now is that my wife still needs the ability to to extract multiple small parts from a recording (ideally renaming them at the same time). Looks like another update to commercial_cut will be forthcoming -
maybe using mythtranscode to actually do the cutting?

Greg, you got any spare time to play around with this in your script?

Ideally, I think an enhancement to the "Delete Recordings" screen is in order, to allow text input for the renaming, but that is a bit far off, for now :-(
Author:  Greg Frost [ Sat Mar 04, 2006 2:52 am ]
Post subject: 
Commercial cut isn't a script, its a program. A script would probably be better suited to what you want to do.

I'd also like the ability to join recordings. I also wish you could tell myth to merge the recording schedule for two consecutive programs so you end up with a single recording.

Sadly, I probably wont find time to make this happen any time soon.

Nigel, have you ever used the keep original when transcoding option? Perhaps this would help.
Author:  nigelpearson [ Sat Mar 04, 2006 9:58 am ]
Post subject: 
Greg Frost wrote:
Commercial cut isn't a script, its a program.


Sorry, yes - I remember now. C and a Makefile, and markup table based chopping.

Quote:
Nigel, have you ever used the keep original when transcoding option? Perhaps this would help.


I have it set. To make use of it I have to:
Code:
mv file.old newfile
SQL to insert newfile into DB
mythcommflag --rebuild -f newfile
Your program was so much easier :wink:

I might be able to use a script as a JobFile which immediately pops up and prompts for the new details (in the same way nuv2disk does), and then does the transcoding in the background.
Author:  tjc [ Sat Mar 04, 2006 10:26 am ]
Post subject: 
So far the lossless transcode has been giving me great results with old PVR-x50 recordings. I've only noticed one miscut where I ended up with 2-3 frames of junk in the resulting clean recording. It does help to review your cutpoints before kicking it off however, since 0.19 seems to have fixed some things in the cut point seeking, and a number of mine were up to a second and a half off from where they should have been as a result.
Author:  Greg Frost [ Sat Mar 04, 2006 2:59 pm ]
Post subject: 
nigelpearson wrote:
Quote:
Nigel, have you ever used the keep original when transcoding option? Perhaps this would help.


I have it set. To make use of it I have to:
Code:
mv file.old newfile
SQL to insert newfile into DB
mythcommflag --rebuild -f newfile

Ughh!! I have never used it and assumed that it would do that automatically.
Author:  paul.lessard [ Thu Mar 09, 2006 3:11 pm ]
Post subject:  Trying to upgrade to 0.19
How did you go about installing 0.19? I just grabbed the source and compiled it down, but when I install it I get mixed results. It's probably because the deb puts things in different dirs or something like that, but I'm sure you all have a smooth way of doing it (apt-get maybe?? it's been a while since I used debian).

--Paul
Author:  paul.lessard [ Thu Mar 09, 2006 3:14 pm ]
Post subject:  Oops...
Just found the thread talking about the upgrade... srry for the post here...
Author:  WattoToydarian [ Sun Apr 09, 2006 12:39 pm ]
Post subject: 
Hey guys, I upgraded to R5B7 and I found that commercial_cut doesn't work anymore.
I tried looking for this lossless transcode but it's not there...
All i see in Recording Profiles is a recording profile for my PVR-150 and create a new profile group. I dont see any autodetect from mpeg2 in any of the menus. :?
Author:  tjc [ Sun Apr 09, 2006 12:59 pm ]
Post subject: 
Try looking under the transcoding profile group...
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