maemo.org - Talk - Transcoding problems with DVDs

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- - Transcoding problems with DVDs (https://talk.maemo.org/showthread.php?t=20520)

Re: Transcoding problems with DVDs

Quote:

Originally Posted by vbrilon (Post 188311)

As Ace said, it definitely sounds like a keyframe issue. I am not sure what we can do about this if you're already using the "best" quality. On OS X we're relying on the underlying QT codecs to manage this kind of stuff, whereas on Windows we actually ship very high quality commercial codecs that seems to be better quality wise for certain types of videos.

QuickTime's mpeg4 encoding pretty much sucks, unfortunately. The biggest problem I've always had with QuickTime Pro exporting is keyframing, the defaults always give you the pulsing picture quality. You might try extending the keyframe interval a bit to see if that helps (as that made the pulsing go away for me, at least until I moved to mencoder ;)).

Re: Transcoding problems with DVDs

Quote:

Originally Posted by vbrilon (Post 188311)

I think you definitely have a more sensitive eye for this than most people (and I mean that as a compliment).

Hehehe. Thanks! As I said, I have a sensitivity to flashing lights and such, so it stuck out for me.

Quote:

Originally Posted by vbrilon (Post 188311)

Would it be possible for you to try the Windows version of ITVC and see if the results are better to your eyes? Also, can you reproduce this problem with all types of video sources (i.e., high quality and with different codecs)?

I've tried a number of different files, ranging from DVDs that I ripped using Handbrake and movie files I downloaded off the 'net, and I seem to get the same results (one "off" frame every second) regardless of the file type (mp4 vs mov). I haven't done much with AVI files, so that's worth checking.

I can probably give the Windows version a go on my office PC, but that might not happen for a while, as I'm away from my office a good chunk of time. Still, when I have a chance, I'll try it and report back.

Sorry about the thread-jacking! That wasn't my intent at all! :o

Re: Transcoding problems with DVDs

Quote:

Originally Posted by GeneralAntilles (Post 188315)

QuickTime's mpeg4 encoding pretty much sucks, unfortunately.

Yeah that does suck and unfortunately I am not quite sure what we can do about it :/

Quote:

You might try extending the keyframe interval a bit to see if that helps (as that made the pulsing go away for me, at least until I moved to mencoder ;)).

You *do* know that with a small amount of perl, java, or python, it's fairly trivial to write a plug-in for ITVC that will let it use an external encoder, right? :)

Re: Transcoding problems with DVDs

Quote:

Originally Posted by vbrilon (Post 188328)

You *do* know that with a small amount of perl, java, or python, it's fairly trivial to write a plug-in for ITVC that will let it use an external encoder, right? :)

No, not particularly, but Jaffa already wrote that code for me. :p

Talk somebody else into making the awesome mencoder plugin! :D

Re: Transcoding problems with DVDs

Quote:

Originally Posted by vbrilon (Post 188328)

You *do* know that with a small amount of perl, java, or python, it's fairly trivial to write a plug-in for ITVC that will let it use an external encoder, right? :)

I've got a prototype thingy around tablet-encode which acts as an encoder for ITVC - wasn't sure how valuable it really was, but might look at it again; especially if QT's mpeg4 encoding is crap.

Re: Transcoding problems with DVDs

Quote:

Originally Posted by Jaffa (Post 188624)

especially if QT is crap.

Well, all of QuickTime isn't crap, just its mpeg4 encoder (for instance, h.264 encoding fine and it does fine at playback). ;)

Re: Transcoding problems with DVDs

Quote:

Originally Posted by GeneralAntilles (Post 188635)

Well, all of QuickTime isn't crap, just its mpeg4 encoder (for instance, h.264 encoding fine and it does fine at playback). ;)

Indeed, I was being lazy and slack with my language. Edited post to clarify :-)