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  1. Member
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    Hey all,

    As the informative title states, I have some mkv's that are the wrong frame rate. These are for playback on my PC, i have the k-lite codecs which will play back the mkv file. However, I've tried, unsuccessfully, several thigns including popcorn audioconverter (from this site, can't select the frame rate argument in converting video w/o reencode), avisynth with both the assumefps and the convertfps arguments (audio unsyncs), mkvextract with other programs (couldn't get it figured out), and avidemux (created 2 files that idk what to do with, no extension).

    I'm running the beta of windows 7, build 7000, amd64.

    Please, how do I change the frame rate on these videos without losing the audio sync? Is there perhaps a european media player out there that will play the 25fps video at the correct rate?

    Thanks in advance!
    ~Lag
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  2. Always Watching guns1inger's Avatar
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    Why, if you are playing them on your PC, do you need to change the framerate ?
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  3. I'm assuming they are supposed to be 23.976 in the first place? ie the source was 23.976, not 25 ?

    mkvmergegui, select the video file, format specific options tab, fps 24000/1001

    You have to do this on the raw files (so extract, then use mkvmerge)

    If the audio is from a 25fps source, you have to do a reverse pal speedup in eac3to , ie. 25.000 -> 24.000/1.001 fps

    e.g. for 192kbps ac3:
    eac3to input.eac3 output.ac3 -slowdown -192

    EDIT: gunslinger has a good point... why not leave it?
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  4. Always Watching guns1inger's Avatar
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    You might also have to look at just how the speed up was done. Is it a simple speed up, or is it done with blended frames or duplicate frames. It may not be as simple as just slowing it down.
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    afaik it originated in europe making the video originally 25fps (correct me if i'm wrong), however everything is a bit sped up.

    Gunslinger:
    The reason I'm looking at converting them is that music is a big part of the vids and i want to hear it "as it was intended" which is kind of hard to do 4% faster and at a higher pitch. If there is a way to slow down the playback or convince my media player that I'm in europe I'd love to do that as it doesn't have the time overhead of what poison is suggesting.


    To make sure I understand the process you're suggestiong, poison:
    MKVExtract, command line: eac3to.exe input.ac3 output.ac3 -slowdown 0192

    What kind of time would it take to re-encode these 8gb files? Running an athlon 5200 oc'd to 3.0 in a 64bit win7 with 4gb of low latency ram, 1tb raid WD Caviar blacks, but I imagine it would take some time to encode...?
    Also, I have a geforce 8800 if there is a cuda port of any of these tools...that would, likely, speed things up significantly.

    Thanks for your swift replies!
    ~Lag
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  6. I'm a Super Moderator johns0's Avatar
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    Use multiAVCHD which comes with uncrop mkv,encodes 25fps to 23.976 with no slowdown,works good for me.
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  7. If it was a simple pal speedup, you shouldn't have to re-encode the video which would take probably 8-10hours on your system, and you would lose quality. The audio re-encoding would only take a few minutes

    You can also try the "stretch by" option in mkvmergegui, for both the audio & video, so the container controls the playback. It's also in the format specific options tab. There is no re-encoding capability in mkvmerge, so the quality would be preserved and it would be much faster. Not sure if this 2nd method will work or how the audio will sound, but it's usually better to try the non-destructive methods first
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  8. Member
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    Poison:
    I have the mkv open in mkvmerge, but I can't seem to find a "stretch by " option. Where is this?

    Johns:
    If poison's non destructive method fail's I'll give the complete re-encoding a go

    Thanks again!
    ~Lag
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  9. You have to highlight the video or audio track, and format specific options tab. There is one for each. To access fps options, the video has to be raw, not in a container



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  10. Member
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    Ah, that makes sense. Thanks for the screenie. What stretch factor should I be using, 2400/1001? Also, once I enter in the factors do I start muxing or is there something else I need to do to get the desired stretch?


    ~lag
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  11. I'm guessing 23976/25000 for the audio, no strech for the video, just the fps change to 24000/1001

    If that doesn't work, you can try fiddling with other options, then maybe even doing the audio conversion with eac3to.
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  12. Member
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    You're probably getting tired of my dumb questions =/, but how do I set the video's framerate without stretch?
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  13. Originally Posted by lag
    You're probably getting tired of my dumb questions =/, but how do I set the video's framerate without stretch?
    It has to be raw avc video, you can't do it with the original mkv container, so use mkvextractgui to get the video, then use mkvmergegui, highlight the video track, format specific options tab, fps will be activated with a drop down menu

    The key is highlighting either the raw video or audio track before using the format specific options tab



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  14. Member
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    Oh, so extract then merge. In hindsight that makes sense :P

    I'll play around with this and post back in an hour or two.

    Thank you for your patience!
    ~lag
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    Nice! Not only did it work (with 25000/23976 for w/e reason), it worked in literally 5 minutes. That beats the 7 hours (not 8-10, thank you very much :P) that re-encoding it was projected to take.

    If only every forum had some amazing n00b keeper like poison

    Thanks again!
    ~Lag
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  16. Member spiritgumm's Avatar
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    I tried this (and didnt need to separate the audio and video) which worked as long as you use 25/23.976 for the audio stretch (and 24000/1001 only for the video). Plays fine on my blu-ray player, but the audio pitch didnt change which is actually the goal. Does the audio need to be re-encoded, or can this be solved with an additional command line in mkvmergegui? Maybe a resample command? In Avisynth, the audio pitch is changed while simply previewing the script with MPC: AssumeFPS(23.976,true).Resampleaudio(48000).
    Last edited by spiritgumm; 20th Aug 2014 at 16:20.
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