Audio

Replace A Video’s Audio Track In Three Minutes or Less

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KdenLive

The Problem – Switching Out Your Audio Track

It’s common for those recording musical or other performances to record audio separately from the video. For instance, the video may be recorded using an Iphone which gives good video quality. The audio however may be recorded using an external mic for either duplication reasons (in case the hookup to the Iphone or other video camera goes bad, or because one doesn’t have the proper connectors to pipe the microphone audio to the camera). To replace the audio track manually might cost you hours of time trying to sync the new audio to the video.

Automatic Syncing of New Audio with Video Track

If you find yourself in a position of wanting to replace the audio track recorded with the Iphone or other video camera with the audio recorded by an external mic, here’s a dead simple way of achieving the replacement without manually re-syncing to the video.

KDEN Live – An Open Source Solution

KDENLive is a free and open source video editing software for Linux which offers an easy way to replace the audio track while automatically syncing the new track to the old.

Steps to Replace Audio Track

  1. Install KDENLive. Go to the download page and install per the instructions.
  2. Copy the video file from your camera or mobile phone (in my case it was a .MOV file from the Iphone) and the audio file from your microphone recording (probably a .wav file) to the same folder on your computer.
  3. Open KDENLive, Select “Project” from the menu and then “Add Clip or Folder”

    Add Clip to KDENLive

  4. Select the folder that contains the video file and microphone audio file.
  5. The files should appear in your “Project Bin” on the top left of the KDENLive screen. Drag the video file to the time line below. It will create two tracks, one for the audio only track recorded by the microphone, and one for the audio associated with the video file (in my case the audio that was recorded by the Iphone).
  6. Drag the Microphone .wav file to the time line right below the Iphone’s audio track. In my case, the Iphone’s Video track was assigned V1, the audio track assigned A1, and the Microphone audio track was assigned A2.
  7. Mute the video file’s audio track (A1) by clicking on the speaker on that track.
  8. Now select the audio track from the Iphone (A1). Right click and select “Set Audio Reference”. Below is a screenshot showing the tracks, the muted audio, and setting the audio reference:

    KDENlive Set Audio Reference

  9. Now right click on the A2 track (the microphone’s wav file) and select “Align Audio”:

    KDENLive Audio Tracks

    KDENLive will automatically move the A2 track to match the audio in the A1 track. You are done. Play back the video using the preview and confirm that the audio is satisfactory then save your project and/or render your video.

    KDENLive does offer a Windows binary version for download but I have not tested as it is reportedly buggy. I would be interested if somebody would try and it and respond in the comments as to how well the audio sync feature works.

Record Live Radio Station Stream to Mp3 in WIndows

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This method is ideal to record long period of time from a radio station (e.g. talk radio). There are many ways to do this but this uses free tools.

These are very “quick and dirty” instructions that assume basic computer knowledge.

  1. Download VLC: http://www.videolan.org/vlc/index.html
  2. Find a radio station that broadcasts in mp3 audio stream. This is the hardest part. Many radio stations do not but a few still do. The url sometimes ends with a “m3u” or “pls” extension. Like this:
    http://www.publicbroadcasting.net/kmfa/ppr/index.shtml

    Copy and paste youre radio stream into VLC by opening Media->Open Network Stream->copy in the url. If it starts playing, go to Tools->codec information in VLC and make sure it says “mpeg” audio or something similar. In any event if VLC plays it shoudl work. If the url ends with “m3u” or “pls” right click on the link, download the file and open it in note pad and get the real link. For example, in the example above the real link to the stream is: http://pubint.ic.llnwd.net/stream/pubint_kmfa

  3. Open up a text editor and paste in the following making the appropriate changes for your radio stream (using the above as an example):

    The stop time is the number of seconds to record. Here it is set for one hour (60 x 60). The c:\audio line is the path to your output file with some extra batch variables thrown in to automatically add date and time of recording.

  4. Save the text file something descriptive like “Record KMFA Radio Station.bat”.
  5. Open up the Task Scheduler in Windows and Create a new task to run the batch file at the time your program starts.

    I won’t go into details on this but here’s link that gives general instructions:

Also, some written instructions on using the task manager from LifeHacker.

That’s it!