[mythtv-users] Announcement: Looking for Alpha testers for a generic Lossless cut solution

Doug Vaughan r.d.vaughan at rogers.com
Thu Oct 11 10:46:00 UTC 2012


Stephen,
     I appreciate you getting back to me on this problem video. So far I 
have seen these other problems that have a slightly similar ring to them.

1) An HDHomrun recording device with one specific TV station whose 
recordings consistently get cut with only the audio track. I have been 
provided samples and will be looking at this issue today. Every other 
channel that is recorded on the same device works well with Lossless Cut.
2) A specific UK DVB usb device creates recorded files whose audio track 
cause mkvmerge to output a flood of "No audio header found" until 
mkvmerge has a malloc() error and aborts. I suggested that this user 
communicate with the MKVToolNix developers on their forum.

I would like to investigate your situation but can only provide more 
help if I get a sample of the video. Please do two things. Update 
Lossless Cut to v0.1.4 as a number if important bugs were fixed. Second 
provide a sample specific to the video that Lossless Cut cannot process.

I know you already supplied one sample but I understood that to be an 
issue over subtitle extraction and not a problem with interpreting track 
information. In any event I tried the test described below on the sample 
you had supply and the video and audio track was copied without issue. I 
would need a recording sample from this other recording to do any more 
investigating.

You can try to simplify the investigation with this set of tests. 
Basically use mkvmerge to convert your whole video to a mkv file. No 
cuts no other Lossless Cut processes. If mkvmerge can successfully take 
the recording and copy the tracks to a mkv container then I can likely 
fix Lossless Cut.
Try:
 > mkvmerge -v -o "test.mkv" "/path to problem/recordedfile.mpg"
 > mediainfo "/path to problem/recordedfile.mpg"
 > mediainfo "test.mkv"

That will tell you definitively if mkvmerge can handle your recording 
and what tracks (video, audio and subtitle) it recognises and copies to 
the output mkv container. The two mediainfo commands will shows you what 
tracks are in the original recording and what tracks mkvmerge copied to 
the new mkv container. Expect the subtitle tracks to be dropped but 
focus on the video and audio tracks.

Lossless Cut is totally dependant on mkvmerge to recognise audio and 
video tracks. When it cannot Lossless Cut has reached a limit and that 
recording device or at least a description on the circumstances needs to 
be added to the Unsupported device list or Known limitations section.

Thanks for your help.

Doug


More information about the mythtv-users mailing list