2011-04-04, 13:19
I've just solved a transcoding problem that's been driving me nuts for a couple of weeks, so I thought I'd share in case anyone else is having similar issues. Also, my method is slightly clunky, so I'd love some feedback on how to do it in one pass...
The issue is deinterlacing, and the solution turns out to be not to deinterlace...
The video in question is using WVC1 interlaced, but it seems XBMC's DVDPlayer under Linux doesn't support that (side note - mplayer does play this video OK, so maybe it's not a particularly difficult fix). When I play this video, I get only sound - no video... 'mkvmerge -i' identifies it like this:
Track ID 1: video (V_MS/VFW/FOURCC, WVC1)
Track ID 2: audio (A_DTS)
Track ID 3: subtitles (S_HDMV/PGS)
I spent many hours trying to transcode this, but always hit the same problem - suggested solutions always seem to revolve around deinterlacing, but deinterlacing caused audio sync problems, and try as I might I couldn't find the right formula to get them back into sync (and/or the video ended up pretty jerky and unpleasant to watch anyway).
I finally stumbled on a better solution more or less by accident, which was this...
I was trying to use 'RipBot264' to transcode, but for some reason it failed when re-muxing the audio/video. For this run, I had left the deinterlace setting on 'Do not deinterlace'. After it bombed, I was left with two files in the temp folder: audio.aac and video.264. Both of these files played with mplayer, so I though what the hell - I'll try muxing them back together and see if XBMC likes it:
mkvmerge -o test.mkv audio.aac video.264
'mkvmerge -i' now identifies it as:
Track ID 1: audio (A_AAC)
Track ID 2: video (V_MPEG4/ISO/AVC)
and it plays perfectly within XBMC. Sweet!
The final step was to re-mux it with the original soundtrack, as that didn't really need transcoding:
mkvextract tracks title00.mkv 2:audio.dts
mkvmerge -o test.mkv audio.dts video.264
so now it looks like this:
Track ID 1: audio (A_DTS)
Track ID 2: video (V_MPEG4/ISO/AVC)
video plays perfectly and there are no audio sync problems. Job done!
So, my question is - is there an 'mencoder' command line that would have done the same thing - i.e. transcode the video without deinterlacing it? I've tried numerous options but I always seem to get dropped or duplicate frames so it looks like it alwways tried to deinterlace no matter what...
The issue is deinterlacing, and the solution turns out to be not to deinterlace...
The video in question is using WVC1 interlaced, but it seems XBMC's DVDPlayer under Linux doesn't support that (side note - mplayer does play this video OK, so maybe it's not a particularly difficult fix). When I play this video, I get only sound - no video... 'mkvmerge -i' identifies it like this:
Track ID 1: video (V_MS/VFW/FOURCC, WVC1)
Track ID 2: audio (A_DTS)
Track ID 3: subtitles (S_HDMV/PGS)
I spent many hours trying to transcode this, but always hit the same problem - suggested solutions always seem to revolve around deinterlacing, but deinterlacing caused audio sync problems, and try as I might I couldn't find the right formula to get them back into sync (and/or the video ended up pretty jerky and unpleasant to watch anyway).
I finally stumbled on a better solution more or less by accident, which was this...
I was trying to use 'RipBot264' to transcode, but for some reason it failed when re-muxing the audio/video. For this run, I had left the deinterlace setting on 'Do not deinterlace'. After it bombed, I was left with two files in the temp folder: audio.aac and video.264. Both of these files played with mplayer, so I though what the hell - I'll try muxing them back together and see if XBMC likes it:
mkvmerge -o test.mkv audio.aac video.264
'mkvmerge -i' now identifies it as:
Track ID 1: audio (A_AAC)
Track ID 2: video (V_MPEG4/ISO/AVC)
and it plays perfectly within XBMC. Sweet!
The final step was to re-mux it with the original soundtrack, as that didn't really need transcoding:
mkvextract tracks title00.mkv 2:audio.dts
mkvmerge -o test.mkv audio.dts video.264
so now it looks like this:
Track ID 1: audio (A_DTS)
Track ID 2: video (V_MPEG4/ISO/AVC)
video plays perfectly and there are no audio sync problems. Job done!
So, my question is - is there an 'mencoder' command line that would have done the same thing - i.e. transcode the video without deinterlacing it? I've tried numerous options but I always seem to get dropped or duplicate frames so it looks like it alwways tried to deinterlace no matter what...