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 Post subject: hdpvr honor cutlist
PostPosted: Wed Aug 10, 2011 10:19 pm 
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Joined: Sun Nov 12, 2006 3:15 pm
Posts: 21
Short Version:
This script will honor the cutlist for a HDPVR recording and make frame accurate cuts. Yes it does encode and resize the recording and change the AAC audio to AC3. It will require FFmpeg, Mencoder, and MKVmerge. This has not been tested on an actual LINhes box but it should work. Make sure to open the script and set the user options before use. This is a modified brfransen myth2h264 script. I have had 100% success rate on my myth box with it. Constructive feedback is welcome.

hdpvr2mkv.sh

Long Version:
First of all my development box is broken. Yes, fixing it is on my list of things to do. So the development was done on my main myth box. But it is set up like a LINhes box. The main one runs Gentoo x64 with a KDE desktop and Myth 25pre on it. So I believe this should be a good script but it is not LINhes tested. If someone would like to try it and give back some constructive feedback I would appreciate it. I took a brfransen myth2x264 script and modified it with the help of my son. Since mythtranscode does not cut h264 I had to find another way. FFmpeg seemed to work the best and it did not depend on keyframes for the cuts. However, it would not hold A/V sync all the time. Some of my tests had the audio and video at different lengths by almost 400 msec. So I solved this by making every frame a keyframe, making my cuts, and then putting it back together and re-indexing it. I have never had it miss on me using this method. I have about 20+ runs on it with no A/V sync issues so far.

I also had issues with my HDPVR. Sometimes it would record at 60 fps and sometimes at 59.94 fps. When I updated the HDPVR firmware it would stay at 59.94 fps for a while and then go back to 60 fps. The script was modified to detect the fps of the recording and adjust accordingly.

FFmpeg and the AAC audio would not play nice when I tried to cut the AAC audio. Since I don't use AAC audio I really didn't try hard to fix this. I just convert the AAC audio to AC3 when I do the keyframe conversion. This may be just a problem with my myth box but I am unsure. This might be something to look at in the future. If anyone has knowledge doing this please speak up.

File size could be an issue. The recordings are kind of large. The script uses about triple the recording size for file manipulations. So if the recording is 2Gb then the script will need up to 6Gb of hard drive to work. Be careful and make sure you have enough hard drive space.

I really believe this script cuts frame accurate. Since I do not have a test video with 200,000 frames and each frame numbered, I could not do a complete and thorough test. However, I did make many cuts at scene changes and it appeared to work accurately and very well.

I tried to encode the cuts using FFmpeg but FFmpeg did not scene change well. I could tell every cut. The video would have blocking, artifacts, and other strange creatures. Using Mencoder seemed to work very well. The scene changes across the cuts came out very well. So I stayed with FFmpeg for the cuts and Mencoder for the encoding and resizing.

I hope this is usable and helps.


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