Quickest way to increase audio gain on a video

[HippoMan]

I'm looking for the quickest way under MacOSX 10.8 to increase the audio gain in videos, without altering the original video track at all. These are .MP4 videos, not .MOV videos.

In principle, I think the following should work ...

1. Using Audacity, import the audio from the .MP4 file.

2. In Audacity, increase the gain on the audio track and save it as an AAC (.M4A suffix).

3. Back in the .MP4 video, delete the audio track and import the newly created .M4A audio track.

Steps 1 and 2 are quick and easy. However, I don't know how to perform step 3.

Could someone suggest some MacOSX software that allows me to quickly remove a video's audio track and replace it with a new audio track?

I know that I can do something like this within QuickTime Player 7, but the resulting video file will be a .MOV file, which I don't want. If I export to an .MP4 from QuickTime Player 7, this is slow; furthermore, the original video track gets altered.

Also, there are a number of software packages (Handbrake, Avidemux, MPEG Streamclip, etc.) which allow me to increase a video's audio gain. However, to get a new video out of these packages, the video gets totally re-encoded, which is a very time-consuming process, and which alters that original video track.

I want the original, unaltered video track combined with the new .M4A audio track (or at least some sort of amplified version of the video's original audio track), and the result to be pasted together as an .MP4, and I'd like this to require a minimum amount of time.

Any suggestions?

Thank you in advance.

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[HippoMan]

Well, I no sooner asked this question than I figured out the answer. I'm posting it here in case this helps others ...

I can do what I want strictly within the Avidemux utility. I do it as follows ...

1. Import the .MP4 video into Avidemux.

2. Set the Video operation to Copy.

3. Set the Audio operation to AAC, MP3, or whatever is appropriate.

4. In the the Audio operation section, select Filters.

5. In the Audio Filters section, set Gain mode to Manual, and set the Gain value below it. Then, select OK.

6. In the Format section on the main Avidemux screen, select MP4.

7. Do a Save as to save new video file. It will be a new .MP4 files which contains the original video track with the altered audio track. This is a quick operation, since only the audio track is modified.

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[waynewhite]

This method is amazing. I downloaded Avidemux can import MP4 file but I cannot configure audio. Any ideas?

[HippoMan]

Quote: Originally Posted by waynewhite This method is amazing. I downloaded Avidemux can import MP4 file but I cannot configure audio. Any ideas?

I'm sorry that I didn't get back to you sooner.

After loading the *.MP4 file, did you click on the Copy button in the Audio section? Doing that should cause a list of audio formats to drop down: AAC (Faac), MP3 (lame), AC3 (lav), MP2 (lav), PCM, MP2 (Twolame), and Vorbis. Select one of these (AC3 usually seems to work well), and then the Filters button should become un-greyed out. This will let you select Filters, as I described in step 4.

If the Copy button is greyed out after loading the video or the Filters button remains greyed out after selecting a video format, can you try it with a different *.MP4?

Also, I did this with the following Avidemux version: avidemux2_qt4.

If this still doesn't work for you, then I'm at a loss. I'm sorry.

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