Naturally a cheapskate like me is only interested in free solutions, so the software tools for this project are Avidemux for video and Wavosaur for audio. With these two tools we can tweak our camera audio by raising volume, adding reverb, adjusting tone, and so on.

Trim Video and Extract Audio

We start by opening the video in Avidemux. Next we trim the video to eliminate alternate takes and start and stop activity that we don’t need to display. The A and B markers in Avidemux make this an easy task, just be sure to only set these markers on I frames, not P frames. Then set the container format to match the original video, and save the file, preferably to a new name, retaining the original. Avidemux will only save the portion of the video within the A and B markers. As always with Avidemux we must enter the file extension, and it should match the container format.

Next, open the newly saved trimmed file. We want to save the audio as an uncompressed WAV file in most cases, so set the Audio codec to PCM. Then save the audio from this video using the Audio : Save menu option, being sure to add the .WAV extension. Close Avidemux.

Enhance Audio with Wavosaur

Now start Wavosaur and open the newly extracted audio file. In our example we’ll only adjust the volume, and we’ll do that in the simplest way, by normalizing the file to -3dB. (Maximum volume in a digital audio file is called 0dB, so all volume levels are expressed as negative numbers.) Use the Process : Normalize menu option, then select Custom and set the value to -3. The audio file is now noticeably louder. Save the file and close Wavosaur.

Merge Enhanced Audio with Avidemux

Restart Avidemux and open the trimmed clip. Set the container Format to match the file type. Now merge the enhanced audio file using the Audio : Main Track menu option. Set the source to External WAV and Open the file we just ehanced in Wavosaour. We’re almost done, but we need to recompress the audio – it’s currently an uncompressed WAV file and we need to return it to the AAC format (or other as appropriate) that we started with. So set the Audio field to the AAC codec and save the file. Now you’re ready to upload your video with its enhanced audio.

Of course it’s a lot easier to follow these steps in a video demonstration, so please check this one out.

Audio Enhancement Using Avidemux and Wavosaur from Fran Guidry on Vimeo.

VST Plugins

Wavosaur is a handy audio tool with a simple interface and good performance, but it needs a little help from some other free software tools called VST plugins. These are software tools for audio that can be added to any program that knows how to be a VST host, and Wavosaour is just such a program.

Some of my favorite VST plugins are created by Kjaerhus Audio. The Classic series of effects are all free downloads, and no one should be without Classic EQ and Classic Reverb.

While I was perusing the Wavosaur tutorials I discovered another EQ tool, called PushTec 5.1 and I was startled by the excellent selection of presets. Be sure to spend a few moments going through the tutorials to better understand the power of Wavosaur and of this terrific free utility.

A Free Video Editor – and a Good One

In the past I’ve used Windows Movie Maker to combine my audio and video streams, but WMM is not compatible with the MP4 720P file created by the Flip. I was happy to find Avidemux, a free video editor. The program comes with a wide range of codecs and works on the compressed files without decompressing for simple operations like trimming length and replacing audio. And since that’s almost all I do to my music videos, it’s perfect for the job.

Avidemux is simple both in concept and use. You can peruse and search the Wiki and ask questions in the forum but there’s no substitute for a little experimenting.

For a simple music video I replace the camera audio with my separate recording and trim the start and end points of the clip. Naturally, when I shoot the video I clap in front of the camera so I have an obvious point to synchronize the two streams. As funny as it seems, getting a good clap important because it makes synchronization so much easier. Try to face the camcorder directly so the instant of contact is easy to see.

Synch Video with External Audio

To sync the video first File : Open the video file and find the “clap” point. Note the time. Then load the external audio file by going to the Audio : Main Track menu selection, choosing the format for the external audio file, and open the file. Now when you play the video, the external audio will play instead of the audio recorded by the camcorder. Find the “clap” on the audio track and note the time.

Take the difference between the two “clap” points in milliseconds. Check the Shift option box, and enter the difference value in the milliseconds value field. If the clap happens first on the external audio file, enter the difference as a positive number. If the clap happens first on the video stream, enter the difference as a negative number, with a minus sign preceding.

Now play the video the audio and video “clap” should be synchronized.

Trim the Video

Next, trim the video to length. Avidemux provides two markers, the A and B marker, which can be placed at any frame in the video. After the markers are set, any save, delete, cut, or copy will affect the section between the markers. My technique for trimming a video is to set the “A” marker to the beginning of the good stuff, and the “B” marker to the end of the portion I want to keep. When I save the video only the portion between the markers is saved.

Before saving, confirm that the Format field is set to the proper container format. If you’re not converting to a new format, it should be the same as the input video. You may need to set a codec for the audio stream, depending on the container format and the format of the external audio file. Once again, the format used in the original video file is a good choice.

When saving files, Avidemux has a quirk – probably because it’s a port from a Linux implementation – it does not automatically insert the extension on the saved file. You need to specify an extension that matches the container format when you save the video, and you should choose the appropriate extension for audio files and frame exports as well. And one more tip, I always save the file to a new name, so I can re-use the original file if needed.

Here’s a video demonstrating all the steps I’ve described. A few moments watching the procedure should make things much more clear. Try the full screen option in the lower right hand corner of the video control bar.

Audio for Video using Avidemux from Fran Guidry on Vimeo.

I’ve had a lot of fun learning and using Avidemux. If you need a nifty video tool that works quickly with minimal resources and minimal damage to your video quality, you should give this program a try.