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Replace audio without re-rendering!!

I made a video that was 5 hours long.   

Rendering it took about 18 hours.

After it was done rendering, I discovered a short audio bug (a 2-minute region was duplicated) and fixed the bug.   Now I need to get the corrected audio back into the video.

I have tried exporting the audio all by itself, and then using Logic Pro X to replace the audio in the movie, but Logic doesn't allow exporting audio to movies when they're this long.   it's beyond the AIFF file size limit of 2gb and beyond the WAV file size limit of 4GB. 

Rather than burning another 18 hours rendering with the corrected audio, I'm just going to tell people in advance about the issue. 

But it would be awesome if we could easily replace audio in a video without re-rendering the video side of things.  Logic Pro X lets us do this easily, so I know the APIs for writing mp4 files to disk allow replacing the audio track without re-rendering the video track in an existing file.

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    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 1 yr ago
    • Reported - view
    Charles Schiermeyer said:
    But it would be awesome if we could easily replace audio in a video without re-rendering the video side of things. 

     Rendering as in encoding export?

    You could export H.264 with AAC and disable the video (and do likewise to export video only) in the encoder and then join the audio with the video in Quicktime Player. I believe Apple Compressor may do this as well. The export from ScreenFlow would be MP4.

     
     

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  • Unfortunately, QuickTime Player X won't allow me to export at the original video resolution of 4096*2304 (iMac 27" display).  It only allows 4K which is a slightly smaller dimension.   It was worth a try, though.

     

    And yes, I meant re-encoding. Your engineers should find a way to copy video data from the previous encoded file directly to the new file without re-encoding it.  I believe audio is stored as a separate stream in these mp4/mov container file formats.   This is how Logic Pro is able to replace the audio in a video without re-encoding the video. 

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    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 1 yr ago
    • Reported - view
    Charles Schiermeyer said:
    It only allows 4K which is a slightly smaller dimension. 

     And I think you'll find the same limitation in Apple Compressor but Compressor should have video pass through but I'm not sure if that gets around the issue.

    Charles Schiermeyer said:
    Your engineers should find a way to copy video data from the previous encoded file directly to the new file without re-encoding it.

     While it's not uncommon for a compression app to have a video pass-through mode, given ScreenFlow is an editor it would be uncommon. 

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    • CraigS Thanks.

      I don't know if Compressor gets around the issue as Apple wants $49.99 to upgrade the previous version that came on OS X for free to the version that is compatible with Catalina. 

      I'm sure if you took a poll of your userbase, you would find that many of them would benefit from the ability to edit only the audio of an existing video. 

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    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 1 yr ago
    • Reported - view
    Charles Schiermeyer said:
    Apple wants $49.99

     Apple has a free 90 day trial for FCP but apparently not for Compressor. 

    Charles Schiermeyer said:
    I'm sure if you took a poll of your userbase, you would find that many of them would benefit from the ability to edit only the audio of an existing video. 

    They'll be able to vote right here of course.
    You may want to explain that workflow so users would understand it. Keep in mind some ScreenFlow users may not have the experience.

    Also, explain how you envision the feature would work. Keep in mind that for many users a timeline consists of multiple separate files including screen recordings, camera and audio recordings, imported files so they may need to understand how you envision the workflow.

    Perhaps give a step-by-step so users can see the utility of it.

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    • CraigS 

      You add a video to a project.  If you don't make any edits to the video other than modifying the audio, when you export, the video track is passed through to the final export.

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      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 1 yr ago
      • Reported - view

      Charles Schiermeyer Thanks for that description. Investigating feature request FLOW-10957

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