Detailed info about why MPEG-2/XviD isn't good for editing?

elvirasweeney · Post by **elvirasweeney** » Sun Apr 20, 2008 5:54 pm

I know, I know that it isn't. I use a Mac for my video editing most of the time, and edit in DV MOV.

I've researched the a-m-v.org Guide and about MPEG, it says this: "the editing will not be frame accurate and you may find that the cut you thought was spot-on actually pops into the next scene when editing. This is very bad, not to mention that the quality will be pretty aweful when it's all done too."

I also found this page which explains why MPEG editing isn't the best solution.

I gather that it's the GOP (Group of Pictures) thing that makes it a problem—not each frame is a keyframe, so you can't do frame-by-frame editing. Editing with MPEG-2 and XviD both use "interframe" (instead of "intraframe"), right?

What are the other reasons? Don't get me wrong, I'm not looking to be convinced myself (Final Cut likes DV MOV very much and I have no inclination to use anything else), but I'd like to understand all the nuances and details about why, rather than just saying, "We're not supposed to do it."

I appreciate any information you can give me.

elvirasweeney · Post by **elvirasweeney** » Sun Apr 20, 2008 5:57 pm

Oh, and something I forgot—has anything changed (software/hardware-wise) since those articles that I linked to above (about MPEG editing)? Is the latest non-linear software able to handle MPEG-2 better now, than before? (Again, not looking for an "excuse" to use MPEG—I don't want to use it! I just am curious to know if anything is changing or developing in this area, or are all the articles I found still holding true with current software and hardware.)

Kariudo · Post by **Kariudo** » Sun Apr 20, 2008 6:49 pm

this page sums it all up

this thread is pretty much a case file for trying to edit with divx/xvid

Pwolf · Post by **Pwolf** » Sun Apr 20, 2008 7:05 pm

that page mentions using avisynth... Using avisynth to serve a divx/xvid encoded video DOES NOT make it any more frame accurate. It helps some times, but doesn't always work.

Pwolf

elvirasweeney · Post by **elvirasweeney** » Mon Apr 21, 2008 2:00 am

Thank you for the links. This is very helpful.

Zarxrax · Post by **Zarxrax** » Mon Apr 21, 2008 6:07 am

Pwolf wrote:that page mentions using avisynth... Using avisynth to serve a divx/xvid encoded video DOES NOT make it any more frame accurate. It helps some times, but doesn't always work.

Pwolf

If you use avisource, it should be frame accurate, though directshowsource definitely isn't frame accurate. That page ought to be updated to mention as much. I'll tell scintilla to change it or something.

Phantasmagoriat · Post by **Phantasmagoriat** » Mon Apr 21, 2008 4:12 pm

ffmpegsource() should work too. I'm just assuming this has something to do with the cache file it makes.