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  1. Member
    Join Date: Sep 2005
    Location: Israel
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    Hi,

    I tried to merge a MKV file with an additional MP3 track and stretched it in about 1.04xx.
    The resulted soundtrack is synched but has some noises (clicks and pops). I tried to use a WAV track and there are no noises, but this increased the MKV size by 1GB.

    Any solution for that?

    Thanks
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  2. Yeah, successfully stretching the audio (no noises or clicks on playback) seems to depend on the type of audio and how much you stretch it. I'd either re-encode the audio while stretching it (so it doesn't need to be stretched when muxing) or instead of stretching the audio to match the video, I'd try doing it the other way around. You might be able to adjust the video frame rate so it matches the audio instead.

    If you want to adjust the audio, MeGUI's audio encoder has settings for adjusting it while re-encoding, although you can't specify a percentage, but you can specify conversion from NTSC to PAL or FILM to PAL etc and the speed will be adjusted accordingly.
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  3. Member
    Join Date: Sep 2005
    Location: Israel
    Search Comp PM
    Thanks for the reply.

    How do i re-encode the audio track through MKVmerge?

    As for changing the video length, i assume it will take a long time and i need to retry several times until i reach a synched audio/video file.

    PAL/NTSC conversion won't help me, i need more flexible values.
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  4. How do i re-encode the audio track through MKVmerge?
    you can't, mkvmerge can't re-encode.
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  5. Originally Posted by zilbermm View Post
    As for changing the video length, i assume it will take a long time and i need to retry several times until i reach a synched audio/video file.
    It can be trial and error. But is you've already worked out how much to stretch the audio to sync it, it shouldn't be hard to adjust the frame rate by a similar percentage. Although depending on where the video and audio came from there's no guarantee they'll ever sync without editing.

    There's a plugin for foobar2000 called SoundTouch which will let you specify a percentage to stretch the audio on playback, and the same DSP can be added to the conversion setup, allowing foobar2000 to time stretch the audio while it's being converted, but if you're not a foobar2000 user it'll probably take a little time to become familiar with it, you need to manually download encoders such as LAME, NeroAAC or AFTEN AC3 etc, and adjusting the frame rate numerous times can actually be quite speedy compared to re-encoding the audio numerous times until you get it right.
    There's also another DSP plugin for foobar2000 here which includes time stretching amongst it's tricks, but I've not used it myself. There may be another program which will make time stretching/converting nice and easy. If so, hopefully someone can suggest it. foobar2000 is a really good player/converter though, so it probably wouldn't be a waste of time getting to know it if you don't use it already. Depending on the format of the original audio, you may also need to download the appropriate decoder plugin from the foobar2000 site.

    PS I just had a quick play with the second DSP I linked to and it seems it'll only make adjustments in 1% increments, so SoundTouch would probably be the better option as it can make adjustments in increments of 0.01%.
    Last edited by hello_hello; 22nd Jul 2013 at 18:09.
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  6. Member
    Join Date: Sep 2005
    Location: Israel
    Search Comp PM
    I eventually user the 'Change tempo' option through Audacity to stretch the MP3 file and then merged it through MKVmerge to the MKV file with not stretch. Worked well, no noises.

    Thanks
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