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Reducing MP4 video playback speed incl. audio sync

Discussion in 'Other video questions' started by jsvez2010, Sep 16, 2011.

  1. jsvez2010

    jsvez2010 Member

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    Newbie here, with a question, hoping one of the experts out there can assist with. I have been just getting into some editing, I have a couple videos, just short ones I have downloaded for my grandson, I have been using VLC mostly for playback of videos on the computer for him. He likes to sit on grandpas knee and watch them.

    Well recently I tried hitting the << arrows to mess with the playback speed. I hit it once on a couple of the videos, and they area actually pretty cool just slowed down a little bit. The speed indicator on the lower right of the player says it was reduced to 67% of the normal speed.

    When I try to use the record feature on VLC the audio is all chopped up, and using movie maker, no sound at all, I have been trying to tinker with some other programs too. I understand that once you reduce the playback, it throws the audio out of sync and such.

    Is there a program out there that will allow me to reduce the playback, and keep the audio and video in sync?

    Will like virtualdub work or something like that?

    I can pretty much make the video to any format I wish, so if there is a better format to work with I can do that too.

    Any help would be greatly appreciated.

    Thank all.
     
  2. attar

    attar Senior member

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    You want to slow down the playback and keep the audio in sync (it slows down too)?
    Can be done using VirtualDub.
     
  3. jsvez2010

    jsvez2010 Member

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    Yes that is what I'm looking to do. I was playing the videos using VLC and hit the arrows that reduce the speed and or tempo, it read at 67% of normal speed on the right side of the playback slider. It sounded really good, my grandson loved it, so I tried the record feature, to record the video, during the reduced speed or tempo playback and it did play in slower speed, but the audio was all broken up, so the record feature was not an option I guess.

    Ok so try Virtualdub then, is the process pretty much automatic? What would be the best format, if I may ask? MP4, MKV, AVI, FLV I can work with any and or convert any, currently it is an HD download, MP4.

    Hey thanks for responding.
     
  4. attar

    attar Senior member

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    VirtualDub saves in AVI format, so the source should be the same.

    I'll do a short writeup of the steps and repost.
     
  5. attar

    attar Senior member

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    Drag the source AVI into VirtualDub.

    Click:
    Video > Direct stream copy
    Video > Frame rate

    Source rate adjustment pane > Change frame rate to (fps):16.75
    (this assumes that the source frame rate is 25fps and 25 x 67% = 16.75)

    Frame rate conversion pane > Convert to fps:25
    (25 is the original source rate)

    'OK' to main screen.

    Audio > Full processing mode
    Audio > Use advanced filtering
    Audio > Filters...
    Add the following filters in sequence - they should join automatically.
    input (add)
    time stretch (add)
    output (add)

    In the filters window, the filters should be joined, click on the 'time stretch' box and input the value 1.4925373
    (25 divided by 16.75 = 1.4925373)
    You can click the test button to hear the slowed down audio, click 'OK' to exit the filters pane back to the main screen.

    Click 'Audio' > 'Compression' and select a compressor:
    (assuming the source was MP3 48000,128,CBR,Stereo, I select the Lame mp3 compressor with the same values).
    'OK' back to the main screen.

    Click 'File' > 'Save as AVI...'


    [​IMG]


    [​IMG]


    Short clip normal speed and 67%
    http://www.mediafire.com/?t37ti4dib9izs09
     
    Last edited: Sep 17, 2011
  6. jsvez2010

    jsvez2010 Member

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    Hey Thanks a lot, I am going to try this in just a bit.. I really appreciate it.
     
  7. jsvez2010

    jsvez2010 Member

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    Excellent Dude... Worked like a charm... thank you very much
     
  8. jsvez2010

    jsvez2010 Member

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    Hey I have an additional question... I followed the instructions, the original file was 14mb in size.. OMG the file that was created is over 5GB in size.... What the hell did I do wrong?
     
  9. jsvez2010

    jsvez2010 Member

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    Oh here is one also... I am using any dvd converter, it does a pretty good job, but one of the files I want to edit has the following info:

    Format: H264
    Frame Size: 640x360
    FPS = 60fps (I assume this is the frame rate).

    When I created the avi, the video is very fast, out paces the audio. The max setting for video frame rate in the any dvd software appears to be 30, can you suggest another way to make the avi file, I guess to keep the same rate?
     
  10. attar

    attar Senior member

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    You didn't select 'Direct stream copy' under 'Video' ?
     
  11. attar

    attar Senior member

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    I don't use AnyDvd and have little experience, so far, of h624.
    I would need a few seconds of the source, h624 file uploaded to Mediafire.
     
  12. jsvez2010

    jsvez2010 Member

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    Ok, I will upload the file (The MP4) file in a bit.... I can also give you the link. It is the "Mister Gummybear" song, my grandson loves these, I have to play them for him everyday, it has become like a ritual, I have my morning coffee, and he gets a couple videos as he sits on my knee at my desk.

    Here is the main site link (there are others on YouTube) I figured better to get right from the source. I pulled the HD version, I have the FLV but the conversion is a pain in the butt. I was able to convert the MP4 to AVI without too much problem.

    (typical http stuff here) (dot) "gummibar" (dot) net (Forward Slash) "videos" (Forward Slash)

    The first one is the one I am trying to do the same reduction on. I use a YouTube down-loader to Grab the file. Those are the MP4 files.

    Thanks for the advice on the other, yep, I did miss the Direct Stream Copy, did that and got a reasonable sized conversion.
     
  13. attar

    attar Senior member

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    I downloaded the World Cup video and did the following:

    Installed the X264 codec for VFW, to use with VirtualDub.

    http://sourceforge.net/projects/x264vfw/


    Converted the downloaded video to avi (leaving the existing codec intact, but with mp3 audio) so that VirtualDub can handle it.

    http://sourceforge.net/projects/mp4...32 binary v2.91/MP4Cam2AVI_v2.91.zip/download


    Loaded the converted file in VirtualDub.

    Followed the previous steps to slow the video/audio.

    Since the new X264VFW codec is available to VirtualDub, the video can still be saved as 'Direct stream copy' - thus no re-encodeing is required.
     
    Last edited: Sep 18, 2011
  14. jsvez2010

    jsvez2010 Member

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    Ok, fantastic, so you used the mp4cam2 to do your conversion, keep the codec, but select mp3 audio if I understand it. I will give it a shot.

    I have been going back and re-downloading his little videos in mp4 format, seems to easiest to work with, the flv files are just to much a pain in the butt.

    Thanks.

    John
     
  15. jsvez2010

    jsvez2010 Member

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    Sorry to be a pain in the ass, but a couple questions:

    1. With regards to the codec, I assume I just install this to the default directory and Vdub will find it?
    2. The converter, there is no install for this, just unzip, place into my programs directory and create a shortcut right?
     
  16. attar

    attar Senior member

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    The codec is installed (and can be uninstalled) on the system.
    VirtualDub will find it and use it to decompress the source video.
    Note that this codec will also be available to save the output from VirtualDub if you select 'Full processing mode' and 'Compression.' - but since you will be selecting 'Direct stream copy', it it wont apply in this case.

    There is no installation for the the converter, simply run from the .exe file or convenient shortcut.
     

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