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| Unofficial VirtualDub Support Forums > Newbie Questions > Audio Sync Issues When Joining Avis |
| Posted by: ilitirit Jul 3 2012, 02:53 PM |
| I'm trying to join 720p H.264 AVI files using VirtualDub. When I open the first file it gives the normal VBR warning and says the audio may be 0ms out of sync (128kbps VBR). I trim the ends off the AVIs and join them at the different spots. The problem is that no matter which options I choose (Direct Stream Copy, Full Compression, etc) the audio *always* goes out of sync after the 3rd or 4th clip. Each clip is about 2 minutes long. What is the recommended way of dealing with this situation? VirtualDub 1.9.11 |
| Posted by: Abrazo Jul 3 2012, 05:05 PM |
| This is a known problem. Encoders do split up the video and the audio in small parts and compress them. Unfortunately these parts (or chunks) are not exactly equal in time for video and for audio. So there will always be a little difference in length. You can verify this by opening one of your (partial) files and look via File > File information... Compare the 'Length' in the Video Stream with that in the Audio Stream and normally you should see a little difference. For every separate file this is not a real problem, but if you join them, than at the end the audio will result in an "out of sync". SOLUTION: For every separate file: (trim the end and) do a File > Save as AVI... with: - the Audio-menu set to "Full Processing" and - the Audio > Compression... set to "No compression" - you can leave the Video-menu set to "Direct stream copy" When the audio is not compressed it should have the same Length as the video (verify the resulting file via File Information...) Once you have made the different parts that you want to join, open the first part and than via File > Append AVI segment... open the second part, and so on... Now you can make the final videofile with: - Video-menu set to Direct stream copy and - Audio-menu set to Full Processing AND Audio > Compression set to the codec and bitrate that you prefere. EXTRA INFO in other threads (SEARCH for 'Append AND Join'): http://forums.virtualdub.org/index.php?act=ST&f=15&t=20591&hl=append,and,join (Thanks to dloneranger and phaeron). |