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Audio Sync Problems Recording Mkv File To Dvd Disk


vipassananow
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I have had many problems with slightly out of sync audio when recording MKV or MP4 movie files to standard DVD's on my Mac 10.6.8. I copy them to to Disk Image first before recording to DVD in case of problems. Recently, a movie with perfect audio sync on the MKV file became 6 seconds early when transferred to Disk Image. The file info read as follows: Video: AVC/H.264, 1280 X 532, 23.98 fps Audio: AAC, Stereo, 24000 Hz, How can I overcome this sync problem? As I said, it has happened many times, but usually only about 8-10 frames out. Any suggestions would be most appreciated.

Edited by vipassananow
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When Toast encoded that video it changed the frame rate to 29.97 fps and resampled the audio to 48 kHz (unless that 24 kHz you mentioned is per channel and therefore 48 kHz for both channels). Toast also needed to rescale to standard definition. There are some combinations that Toast doesn't get right and yours is apparently one of them. It may work for you to first use Toast's Convert window to convert the original video to 16:9 DV. The play the DV video to see if the audio is still in sync. If not there is a freeware app called QT Sync that can correct the audio timing. Then add the video to Toast. This way Toast doesn't have to do anything except convert the video to MPEG 2 and the audio to AC-3 because all the other specs will be right for DVD.

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Thanks for your response Digital Guru. I tried using Toast's Covert window to convert the original video to 16:9 DV. It has a 15 second preview window (very handy) which I used to see what it would look like. The sound was still way out. I have used QT Sync many times but it does not accept the MKV file because it says it has more than one video track (?), and it doesn't respond to the .Toast file at all. I wondered if I could use Handbrake to convert it to an MP2 NTSC file with an MP3 Codec, the sound was still out. The sound is in sync on the original MKV file. Any other suggestions?

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I don't use Handbrake but there must be a way for it to create separate audio and video streams where the audio stream is a QuickTime-playable format and not mp3. If the audio is AIFF or PCM and the video also is not mpeg 2 then you could use QuickTime or maybe Toast to convert the audio to 16-bit 48 kHz while retaining the correct length in time. One reason I was thinking of converting to DV is that QT Sync can work with that format. Maybe you could export a 5-minute segment as DV to see what you can do with it When the audio and video are separate streams just drag the video stream to Toast's Video window to prepare the DVD and Toast will either automatically find the matching audio or ask you to locate it.

Edited by tsantee
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I followed your advice and created a 3 minute .dv scene on Toast which went onto QT Sync without a problem. I advanced the audio 175 frames to sync up with the picture. However, I didn't like the look of the 16:9 .dv transfer since it made the actors faces look too thin compared to the 2.35:1 original. So I played around on QT Sync and increased the ratio from 720 X 480 to 900 X 480 which made the faces appear more normal again on the 3 minute test. I'm now re-recording the whole movie on Toast to a .dv file which I will then adjust by 175 frames on QT Sync as well as increase the ratio to 900 X 480 and save that as a Reference .mov file which I will then use to record the DVD on Toast. This will all take some time and I'm hopeful that it will work out. Your help is much appreciated tsantee.

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Good job working that out. There is a QuickTime export option with Toast where you probably could manually create all the best ratio. Instead of using DV you'd use DVCPRO-25 as the codec. I mention this in case you run into similar problems with future videos. You seem to be a lot like me in your determination to find a solution. Glad my suggestion pointed in a workable direction.

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The only problem with my solution in my last post is that the picture ends up looking somewhat jerky. I imagine this is because a few still frames have to be inserted every 25 seconds or so to adjust for either the enlarged ratio or adjusted audio... I'm not sure. The slight pauses are quite annoying, especially in slow pan shots. Thanks tsantee,I will play with DVCPRO (now -50) next time I have problems.

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There may be QuickTime settings for the frame rate as well as everything else. The problem, though, is when Toast encodes the MPEG 2 for DVD video it always makes it 29.97 fps regardless of the source. There is a shareware program called MPEG2 Works that may be able to make the MPEG 2 video at the original frame rate. If so it could be just multiplexed rather than encoded when making the DVD video in Toast thereby retaining the original frame rate. Some people use HandBrake for lots of video work but I have no experience with it. So it may also be an option.

 

One other thing, here's a QuickTime setting that I've used with good results. Note that I chose Progressive rather than Interlaced scaling even though the source was interlaced. It really smooths things out in the final DVD video; especially reducing the shimmering around areas with high contrast.

post-120-0-85072300-1360343354_thumb.png

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Forgive me.....I am so out of my depth with all this! When you write about QuickTime settings and show the screen "Movie Settings", what app is that from? There seem to be dozens of QuickTime Converters out there. Which one is best?

 

You also mentioned MPEG2 Works which can keep the original frame rate rather than 29.97fps. Since I live in North America, I actually want NTSC encoding, not PAL.

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Go to mpeg2works.com where you'll see a lot of information about it. It does either PAL or NTSC and can convert one to the other. I see there a question & response about MKV conversions going out of Sync and a suggestion to use either of two freeware tools to remultiplex the MKV video. That may be the answer to your problem.

 

The window I displayed in my previous post is Apple's QuickTime export settings window. Several applications can access those custom settings. To do it with Toast choose QuickTime Movie from the list of formats that Toast presents when you click the Convert button, and then click Change... next to the Quality setting. It may not be necessary to bother with this if the tip described at the MPEG2 Works site solves the problem.

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