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  1. Does anyone know of a good (and fairly easy to use) program that can change the speed of a MPG or VOB files WITHOUT having to convert/demux etc to anything else before working with the file?
    The audio editing software Sound Forge has a feature called Pitch, which can be applied to audio by selecting Pitch > Shift and then there is a preview "final time" calculated realtime as you increase / decrease the semitones or cents of the audio file.
    I need a program that can do this to MPG files, by changing the speed by an exact percentage while simultaneously showing what the final time will be. Can for example Sony Vegas do this or are there better alternatives? It must be possible to save the file back to it's original format (MPG) after applying the speed change.
    PS: I rather pay for a user friendly and simple to understand program than deal with some hard to understand (for a novice) freeware program.
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  2. Marsia Mariner
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    Does anyone know of a good (and fairly easy to use) program that can change the speed of a MPG or VOB files WITHOUT having to convert/demux etc to anything else before working with the file?
    ............
    It must be possible to save the file back to it's original format (MPG) after applying the speed change.
    Not possible, because the MPG container and the MPEG-1 + MPEG-2 codecs are very-restrictive with respect to video playback rates (fps). If you don't want to re-encode the video stream, you will have to mux it into a different container (MKV or MP4) and set the custom fps value in the container itself. Also, you'll have to use a software decoder that is not picky, i.e., that does not enforce the fps info which is hardcoded in the MPEG-2 video stream itself.
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  3. Member hech54's Avatar
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    I usually load the audio from the original MPG(and my new audio) into Reaper, change the NEW audio speed to match the original audio speed, them remux back to the MPG with AviDemux so there is no re-encoding necessary to the video.
    The speed matching can get quite time consuming(and frustrating) but hey....spit happens. And if there is a glitch in the video....that SUCKS even more.
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  4. Member Bernix's Avatar
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    enforce the fps info which is hardcoded in the MPEG-2 video stream itself.
    I have read on internet, there is possibility to change it in some hex editor. It was on Mac forum, but problem is I don't know if it was for mpeg1 or mpeg2, but in hex editor it should doesn't matter.
    But OP question seems to me to be attempt to add different audio track to video track. And it doesn't fit. If this is the case, The speed change will not most probably helps.
    So try find how change fps mpeg in hex editor. But there are more operation needed.

    Bernix
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  5. Marsia Mariner
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    ^ Yeah, the OP was not clear enough --- not to me, at least. Indeed it is possible to change the pitch of an audio track without changing the playback speed (and therefore the duration). Also, if what the OP wants is, let's say, correct the audio of a PAL movie, then it is possible to flag the video stream as 23.976 fps (OR 24 fps) and keep using the .MPG container.
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  6. Originally Posted by Bernix View Post
    I have read on internet, there is possibility to change it in some hex editor.
    Yes, but MPG uses a four bit flag to encode the frame rate, with only 23.976, 24, 25, 29.97, 30, 50, 59.94 and 60 fps defined. You cannot set any other frame rates.
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  7. Member Bernix's Avatar
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    Hi jagabo,
    thanks for clarification!
    Bernix
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  8. Thanks for all your replies. I'll try to explain a bit more in detail what it is that I want to achieve:
    I have two videos. They essentially contain the same footage, but the audio is different (different languages). One video is in NTSC format (the one I want to use the video from) and the other is an old VHS rip in PAL format (the one I want to use the audio from). They play at different speeds. If the contents were 100% identical and the only obstacle was the PAL/NTSC difference, I would simply extract the audio out of the PAL video, and change the speed to match the length of the NTSC video, unfortunately this is not possible because some scenes are missing in the PAL video (or edited slighly different), so I must change the PAL video's speed as well, so I have the two video stream to match up with side by side in the video editor I use, as some editing of the NTSC video will be necessary. It's too difficult for me to simply edit according to the audio stream by itself. I'm picky and the two video/audio streams must match frame perfect, not just "close enough".
    PS: I might also add, I want to actually change the SPEED / "pitch", i don't want to use a "time stretch" kind of effect, as it ends up containing clicks and other annoying artifacts.
    This is the best I can explain it, I hope you understood what I mean.

    PS 2: I don't think simply changing the fps of the PAL video will make it match the NTSC perfectly. I tried this one time in the past with an old PAL VHS recording, where I changed the fps from 25 to 29.97, and even though the two video streams would play more evenly, they would still not match up 100% frame perfect.
    Last edited by guy24s; 18th Dec 2017 at 04:50.
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  9. If you load both audio tracks into a DAW (Hech suggested Reaper earlier or Audacity) you can slice, align and stretch/shrink your tracks using the waveforms for music and effects as a guide. (Obviously the dialogue will not match. )
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  10. Member Bernix's Avatar
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    Yes. Audio is independent on video framerate. So as Smrpix said and earlier mentioned, extract both audios, visually compare them and delete unwanted parts is best way to do it from my point of view.
    EDIT:With stretching audio, you get nowhere. If only one version has more content no problem. If both contain parts, that second video hasn't inserting silent would be better to achieve right duration (inserting silence I mean in the exact position, not at the end).

    Bernix
    Last edited by Bernix; 18th Dec 2017 at 06:56. Reason: EDIT and Smrpix instead of Sneaker :)
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  11. Thank you for all your replies. I think I've finally figured it out now.
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