I'm trying to add an audio track to an existing MKV. I'm trying to add the Italian audio track (extracted from another MKV with lower video quality) to a high quality MKV with only the English track. For the whole procedure I'm using MKVToolnix
The resultant file has audio not in sync with video. I tried to fix it delaying the audio track but unfortunately I discovered that even if I fix the sync near the beginning of the movie, however the sync is not kept throughout the whole movie: that means that I should stretch the audio track (or the video track).
Is there a way to fix the sync in 2 different points (i.e. near the beginning and near the end of the movie) and stretch consequently one of the 2 tracks?
Or, is there any other way to stretch one of the tracks to get them in sync?
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Try setting the Video frame rate to 25fps (Default Duration=40000).
Last edited by ndjamena; 1st Sep 2014 at 12:20.
Even stretching the audio may not work because movies released in different regions are often different cuts --- ie, scenes are added or removed.
But you can try using the stretch feature of MKV. Some players will respect that. MPCHC and VLC for example. If that works and you want to permanently alter the audio (for other players) you can open the audio in an audio editor like Audacity and stretch it similarly. Then remux the new audio with the video.