AVIdemux differences with DVD lavc and DVD

[syeager]

I have been experimenting with AVIdemux and it is an excellent tool. Some of its filters are wonderful for noisy video (even better than TMPGenc's filter and faster) and it has a good interface.

However, it has both a DVD and a DVD lavc method to encode to mpeg2 for DVD. If I use DVD, it encodes with a filesize as expected and looks good. If I use DVD lavc, the filesize can be much smaller. Instead of about 4gb for video only, I have had files as small as 1.8 or 2.8 gb. And I cannot see any visual quality difference between them. Does anyone have any experience with this or have any ideas? I would hate to use the smaller filesize (which is almost twice as fast with the DVD lavc as opposed to DVD - and I can use Quantize at maximum and encode in one pass instead of two, making it even faster) and later find the quality was missing.

[celtic_druid]

For DVD I believe it uses MPEG2Enc with XviD's rate control. This is quite slow, but libavcodec's rate control doesn't work perfectly.

[syeager]

So, what would be the visible results of the imperfect rate control? And I assume the libavcodec is the DVD lavc, correct?

[celtic_druid]

Yep, lavc = libavcodec. Well the problems with rate control could mean that your output is not 100% DVD compliant, buffer underuns, etc.

libavcodec is definatly much faster though and you can use CQM's (Custom Quant Matrix) if you want to increase quality/filesize.

QuEnc, FreeEnc, ffmpeg, mencoder, etc. also use libavcodec. NuEnc was an attempt to fix some of the rate control issues.