4 Replies Latest reply on Aug 18, 2010 6:40 AM by MikeLip

    mpg/DVI and AV Out of Sync

    MikeLip

      Hi folks, this is my first post, and I'm looking for some advice on how best to handle mpg AV sources. I've read many of the posts here regarding mpg/oos. Very helpful, thanks!

       

      I have 3Gb 45min PAL .MOD mpeg2 (720x576, 25fps, 48kHz compressed audio) from a JVC Everio camera (I'm in Australia). The file is copied to my Media hdd. Bringing the raw file into PrE8 the audio gets out of sync further along the timeline - i.e. first song is fine, last song is ~.5s video lags audio. No suprise here from what I've read in respect to PrE8 engine and compressed files. I tried to export DV-AVI from PrE8 but that didnt help.

       

      Exporting to DV-AVI from Vista32 MovieMaker helped a lot, but still in PE8 the last song's audio is ever so slightly ahead of the video. In WinMediaPlayer it is perfectly aligned.

       

      So I then split the file in MovieMaker and exported only the last song to DV-AVI. PE8 sees this small DV-AVI perfectly in sync.

       

      So this begs me to ask for advice:
      -Does PE8 normally sync degrade with large (DV-AVI) files? (the file is 10GB in DVI format)
      -Is it typical workflow to split larg-ish mpg's into smaller (say 10 min) DV-AVI chunks and then stick back together in PrE8?

      -Should I split large DV-AVI's for that matter for PE8 to stay in sync? (or is this a symptom of something wrong).
      -My camera can't record at DV-AVI so I stuck with this source for now.

       

      Thanks for any advice, I'm just trying to lock down a workflow I can move forward with.

       

      Some system specs: I can post a Sandra report or similar if anyone believes it is a problem with my rig.
      PrE8.01; i7 930; Giga UD3R; nvidia GT240 512; Vista 32Ult; 12GB ram; C:Sys (300GB 7200rpm); D:Media (1TB WDCaviarBlack 64Mg). Running in min spec, 3GB switch, no network/antivirus/etc. This is brand new formatted system, only Vista and PrE8 and PhotoshopE8 originally. Both hdd's are >80% empty. In trying to resolve this I have since installed Quicktime; Roxio 2010; and Divx. These made no difference. I have an Acronis backup of virgin Vista with just Adobe software. I also have a 4GB E6600 Core2Duo with dual 512Mg nvidia cards (my game pc) and my Media hdd is swappable. I'm seeing the out of sync symptoms in PrE8 with mpg and DVI on both machines. My i7 is normally running Pro Tools (seperate C: drive) so I'm very familiar with tweaking, etc.

       

      Thanks in advance for any help,

      Mike.
      P.S. Interestingly Elements Organizer shows the .MOD file as NTSC 29.97 fps but I believe this to be a cosmetic bug. PE8 File/Show Properties correctly recognises PAL/25fps.

        • 1. Re: mpg/DVI and AV Out of Sync
          MikeLip Level 1

          Since my post above, I've been thinking and so checked Win Media Player on the 10GB DV-AVI file. Indeed it gets oos in the last song ever so slightly, which I must put down to the WMM conversion.

           

          So to paraphrase my entire original thread:

           

          Should I be chopping up files into small (~10min) AV-DVI clips as a matter of practice or is this a symptom of a larger problem?

           

          Thank you,

          Mike.

          • 2. Re: mpg/DVI and AV Out of Sync
            nealeh Level 5

            No, PE8 does not normally sync degrade with large (DV-AVI) files so this is a symptom of something wrong. DV-AVI runs at around 12GB per hour so your file is represents less than an hour.

             

            To diagnose your problem I'd be inclined to, first, uninstall Divx (you can always reinstall if it is proven to not be the cause) as it adds codecs to your system that may interfere with PRE, then uninstall/reinstall PRE.

             

            Re Roxio - check you did not install the packet writing feature. Depending on version this might be called 'Drag2Disk' 'DLA' or 'Roxio Burn'. If you did, uninstall it.

             

            For the DV-AVI created out of WMM you should be using the standard Project Presets PAL> DV> Standard. When you place a clip on the timeline there should not be any redlines at the top of the timeline - is this so?

             

            Re your PostScript, try with an NTSC project and load your clip into that. Do you have a redline? What happens to your sync?

             

            Your machine is 'brand new'. This means that it is out of date - disk masters are created well before product distribution. So, some basics:

            • Install all Windows updates.
            • Check your updated QuickTime is v7.6.7.
            • Install most recent graphics and sound drivers from the manufacturers web sites.
            • Run Disk Cleanup.
            • Run Defragmenter.
            • Post back here with any additional information (not already provided) described here: Got a Problem? How to Get Started (especially details of your clip processed through GSpot).

             

            Re your workflow, converting to DV-AVI through WMM and loading to PRE is a good workflow.

             

            Cheers,
            --
            Neale
            Insanity is hereditary, you get it from your children

             

            Updated to reflect new QuickTime version

            • 3. Re: mpg/DVI and AV Out of Sync
              the_wine_snob Level 9

              One of the issues with MPEG (and many other GOP file structures) is that there are only I-frames about every 15th Frame. The ones in between are Difference Frames. In a Frame-accurate editor, like PrE, those Difference Frames must be converted to 100% I-frames. Then, with MPEG Audio, the block size for the Audio differs very slightly from the block size of the Video. These two factors can add up to drifting sync, especially in longer Clips.

               

              My workflows, given the material would be:

               

              1.) Convert the muxed MPEG AV file to DV-AVI Type II w/ PCM/WAV 48KHz 16-bit Audio in a good conversion program

               

              2.) Rip the muxed Audio to PCM/WAV 48KHz 16-bit Audio in a program like, Audition, or the free Audacity, and just replace the muxed MPEG Audio on the Timeline

               

              3.) Cut the long muxed MPEG Clip into segments by song. Think that you have 3 in your example. Manually adjust the sync, by slipping the Audio or Video by a Frame, or so. If you Cut the Clip into 3 sections, to adjust each, and find that the sync is still drifting, the technique would be to cut THAT into smaller parts. Now, if you have continuous Video, and obviously the music, it becomes a bit more difficult, as you will either be removing a Frame, or two, from the Video, to allow the visuals to sync to the music. This can be very work intensive, as you will likely not have neat Cuts to just trim a Frame here, or there. Let's hope that with the 3 sections, you can get sync close enough on each segment.

               

              This ARTICLE will give you some tips on adjusting for OOS.

               

              This ARTICLE offers links to some interesting threads on JVC MOD files. Be sure to follow those, to see especially the comments from Chris at JVC, who responds to using PrE to edit. Might be some interesting and useful tips in the other replies, along the way. Happy reading.

               

              This ARTICLE will give you a bit more background on GOP file structures.

               

              Good luck,

               

              Hunt

              • 4. Re: mpg/DVI and AV Out of Sync
                MikeLip Level 1

                Just dropping a line to say thanks to nealeh and Bill. I'll check out everything you replied. I should've mentioned the machine is updated and patched, etc - not just raw Vista. Much appreciated.

                Best regards,

                Mike.