Editing demuxed video, dropped frames problem...

[beansandjeans]

I wasn’t sure exactly which section to post this in, but decided on this one, as this is ultimately an editing issue. I’ve spent some time searching through posts and doing research, but have yet to find a solution that works.

Ok, so here’s the situation – I’m working on video production, and I have some footage on DVD that I want to edit and mix with other footage (don’t have the original DV tape). We do have a DV capture deck with A/V inputs that we can plug a DVD player into for re-digitizing, but I’d really like to avoid the generational loss of going from digital to analog and then back to digital. (I’ve also yet to find any DVD player with firewire outputs).

So what I’ve been trying to do is demux the DVD (I’ve been using DoItFast4U for demuxing and then an AC3 converter to convert the audio to WAV or mp3) and then import the audio and video files for editing. We’re working on Mac G5s, and I’ve so far been using iMovie and Final Cut Pro. Avid X Pro is also installed, but I haven’t used that yet.

The problem comes when the imported video (M2V file) is rendered. In iMovie the rendering is done automatically when the video is imported and in Final Cut the rendering is done manually. But in both cases, the result is the same – dropped frames! When I import and render an hour and a half of video, the footage ends up being about five seconds shorter than it originally was (which translates into around 150 frames lost – about 100 per hour). I was able to solve the obvious problem of audio synching by using Audacity to make precise adjustments to the audio’s speed. But when I burned the final product to DVD and watched it on my tv, the dropped fames made the video very noticeably jittery and just watching it gave me a headache. So obviously this won’t work for any production.

So does anyone know of any good solutions for this?...

Is there a way to render without losing frames?

Also, I don’t really know why rendering or any sort of transcoding should be necessary in the first place, since we’re starting out with MPEG-2 video from DVD, and we ultimately want to end up with MPEG-2 to burn on DVD. I’m thinking that maybe the software I’ve been using insists on rendering just so they can keep it in their own proprietary format so that we have to keep using their software… Are there any good non-linear video editing programs that can import, edit, and then export M2V/MPEG-2 video without having to do any sort of rendering or transcoding??...

If anyone can give me any good suggestions I’d really appreciate!

Thanks

[stl]

Haven't tried it yet but I hear that premiere pro can handle mpg/m2v files without problems.

I've had various problems with premiere 6.5 and mpg/m2v files. The work around I use consists of exporting to AVI then using a good mpg encoder like CCE or TMPG to convert to DVD compliant MPG. The only downside besides the extra time and effort is that the AVI can take up tons of disk space.

[beansandjeans]

Haven't tried it yet but I hear that premiere pro can handle mpg/m2v files without problems.

Does this mean that Premiere Pro imports and edits mpeg-2 without transcoding or "redering" it to a different format, or that it does a good job at the transcoding/redering and doesn't drop any frames? If it's the former, is premiere the only software that can do this, or are there any other good NLE programs that can import and export mpeg-2/m2v without any sort of transcoding and can do other basic video editing stuff like adding titles and basic transitions like cross-disolves?

I've had various problems with premiere 6.5 and mpg/m2v files. The work around I use consists of exporting to AVI then using a good mpg encoder like CCE or TMPG to convert to DVD compliant MPG. The only downside besides the extra time and effort is that the AVI can take up tons of disk space.

I've never worked with AVI format... There wouldn't be any loss of resolution going to and from AVI? When you say a lot of disk space, do you mean like the 2GB/hr of standard bitrate DVD mpeg-2, or is it more like the 14GB/hr of raw DV video? (Actually the last question more out of curiousity, as I've got plenty of disk space - my main priority is just the best possible quality for this production.)

Thanks again for the help!

[stl]

Actually, out of my own curiosity, I tested this out in Premeire Pro. I imported and dropped into the timeline a 470MB .m2v file. PP took this with no problem, no transcoding to proprietary formats. PP 6.5 (previous version) would freeze at times during import or when placing in timeline or if you managed to get that far, when trying to "scroll" through the clip. No problems with PP. One of the improvements to the prog was better mpeg support.

Off the top of my head, I can't say for certain which other NLEs can handle mpeg, but I'm sure there are others, probably Avid can, although I really don't like that prog and don't have much experience with it.

Yes, .avi like raw DV footage. You mention "going down to .avi" When you export your project what format do you get? Premeire 6.5 exported to .avi (you had options to set as well if you wanted to) So to answer your question, no loss as this was the native format. I would then re-encode to DVD spec mpeg-2.

I'm just starting to mess with PP but I see that you can export to "movie" (avi) and to DVD (either through an encoder, or right to the disk via a burner) nice if it works well, if not, then my old method (avi then encode with Tmpeg)

[mic]

Hope this might be of interest, though it is PC based, as am I. :)

In NLEs when you look at mpg2, you're seeing the same sort of video as something like PowerDVD, ie. a rendered view. Support for this does vary quite a bit, though in my opinion and experience you do better with something like DGIndex to serve the video rather then rely solely on the NLE's code. Any editing rewrites the mpg2, though there is at least one app that will only encode the changes as with DV video files.

DVD video can very often be demuxed and used as is, but individual DVD results can vary quite a bit. DVD files can make the process more difficult by intention. Quite a few apps insist on re-encoding mpg2, and more then a few will not recognize a DVD spec mpg2 as such.

Be aware that DVD mpg2 can have one fps, but use flags to in effect achieve another. Some software will not preserve this.

I'm not sure what software is available for MAC (or Linux that might be adapted -- another avenue?). But the general process I think would be to create basic, decoded video using the original mpg2 in vob files, for editing. On a PC I would use DGIndex to serve the video & V/Dub or Avisynth to render. The alternative is one app that can deal with mpg2 without re-encodeing everything, but I'm afraid I con't recall the name let alone if it is ported to anything but win32.

If you want to use mpg2 without editing, then the process would be de-mux and use as is, or something like DVD shrink to easily reduce the size &/or isolate clips, that normally should be imported into a DVD authoring app without any conversion. Lower end programs may not do it, but everything I've seen mid to high end will -- when there's a prob., it's often with the header or format of the mpg2... DVDA for example will only accept full mpg2 without audio, DVDLab likes a clean (demuxed if nec) video stream.

[beansandjeans]

Actually, out of my own curiosity, I tested this out in Premeire Pro. I imported and dropped into the timeline a 470MB .m2v file. PP took this with no problem, no transcoding to proprietary formats. PP 6.5 (previous version) would freeze at times during import or when placing in timeline or if you managed to get that far, when trying to "scroll" through the clip. No problems with PP. One of the improvements to the prog was better mpeg support.

Off the top of my head, I can't say for certain which other NLEs can handle mpeg, but I'm sure there are others, probably Avid can, although I really don't like that prog and don't have much experience with it.

Yes, .avi like raw DV footage. You mention "going down to .avi" When you export your project what format do you get? Premeire 6.5 exported to .avi (you had options to set as well if you wanted to) So to answer your question, no loss as this was the native format. I would then re-encode to DVD spec mpeg-2.

I'm just starting to mess with PP but I see that you can export to "movie" (avi) and to DVD (either through an encoder, or right to the disk via a burner) nice if it works well, if not, then my old method (avi then encode with Tmpeg)

Hey - thanks for checkin that out. If anyone else knows of other video editing software that would be good for this - preferably cheap or free - please let me know. I'm gonna try out a few more things before I pony up and spend $250 for Premire Pro (with student discount). Right now I'm downloading the free traial of Power Director, which specifically advertises that it can import VOB (actually the only software I've seen that's specifically stated that), so I'll see how that works. I've read through a few reviews of that, and some like it some don't. Don't know if anyone here has used it much....

But thanks everyone for the advice!

[beansandjeans]

Hope this might be of interest, though it is PC based, as am I. :)

In NLEs when you look at mpg2, you're seeing the same sort of video as something like PowerDVD, ie. a rendered view. Support for this does vary quite a bit, though in my opinion and experience you do better with something like DGIndex to serve the video rather then rely solely on the NLE's code. Any editing rewrites the mpg2, though there is at least one app that will only encode the changes as with DV video files.

Does anyone know which app that is?...
Is that MPEG2VCR, or a different one?
That would deffinately be a big plus for me, both for preserving video quality and for saving a lot of time, since my Windows computer just has a fairly slow Celeron proccesor.

Thanks again!

[mic]

re: Prem Pro, once heard of someone who did something he's not supposed to... Got ahold of a copy off the web, then bought the upgrade.

I think if you google on mpg2 editing software you'll get a few hits on software that doesn't re-encode when when it doesn't need to -- more are adding this capability it seems. I think even Hauppage has a free version for their customers -- don't know if it works without their hardware, or just what it's capable of though.:(