Extract audio from mp4

[tttulio]

Gosh, I have the same question, Just trying to split the already encoded file.
Most posters here don't grab this notion.
If you don't know the answer, stop telling people to re-encode it.

Thanks.

Originally Posted by Canubis

Sorry, maybe I just don't get it or you don't actually understand what I intend to do.

If I understand you right, FCP.guru.guy, you tell me to convert the video to AIFF to just get the audio out and then convert it back to AAC for a smaller filesize. But this is definitely not lossless and its reencoding for two times.

What I am looking for is a direct way of splitting the audio from the video track and saving it to disk as is. In the same format. No reencoding.

I apologize honestly if I just didn't understand what you told me.

[Cjsimmons0]

If you are looking to extract the audio from a mp4, just use ffmpegX to convert the mp4 into a FLV file. Once you have converted, use the program iExtractMP3 to convert to mp3. Works well and is VERY fast!

[justytylor]

Okay: I'm assuming you have access to QuickTime Pro 7 (where the Command-J command works).

You will open the movie in QTPro 7.

Type Command-J (or choose "View -> Show Movie Properties").

The top pane of that window will have all the resources within the .mp4 file listed. You'll have a Video track and a sound track. Click on the sound track.

Click the "Extract" button. This will open just the sound track in a new QuickTime document window.

Choose "Export..." from the File menu.

In the Export dialog box, in the Export: pull down menu, choose "Movie to MPEG-4". Click the "Options..." button next to that pull-down menu.

In the next window, choose the "Audio" tab."

In the "Audio Format:" pull-down menu, choose "pass-through".

Click "OK" to commit that change and exit this dialog box.

Name your file, click "Save" and you'll have exactly what you want: an audio-only .mp4 file with no reencoding.

[bleater]

Originally Posted by justytylor

Okay: I'm assuming you have access to QuickTime Pro 7 (where the Command-J command works).

You will open the movie in QTPro 7.

Type Command-J (or choose "View -> Show Movie Properties").

The top pane of that window will have all the resources within the .mp4 file listed. You'll have a Video track and a sound track. Click on the sound track.

Click the "Extract" button. This will open just the sound track in a new QuickTime document window.

Choose "Export..." from the File menu.

In the Export dialog box, in the Export: pull down menu, choose "Movie to MPEG-4". Click the "Options..." button next to that pull-down menu.

In the next window, choose the "Audio" tab."

In the "Audio Format:" pull-down menu, choose "pass-through".

Click "OK" to commit that change and exit this dialog box.

Name your file, click "Save" and you'll have exactly what you want: an audio-only .mp4 file with no reencoding.

I can confirm that this is the best way to achieve the desired result of extracting AAC audio from an MP4 file without re-encoding it and using only Apple-provided tools.

I would add only one more thing, which is when saving the file, give it the .m4a extension (or rename it with this extension once exported). That way, iTunes will correctly list it as "AAC audio file" rather than "MP4 video file" (even though it has no video track).

[Sami.]

Use TSmuxer.

[CJYetman]

great ideas.... thanks. but couldn't you just extract directly from the video file? another words, skip to the "Choose "Export.."" step and just make sure in the Options that on the "Video" tab you have the video format set to "none"?

I think that would do the same thing and make this a bit less complicated.
-cj

Originally Posted by justytylor

Okay: I'm assuming you have access to QuickTime Pro 7 (where the Command-J command works).

You will open the movie in QTPro 7.

Type Command-J (or choose "View -> Show Movie Properties").

The top pane of that window will have all the resources within the .mp4 file listed. You'll have a Video track and a sound track. Click on the sound track.

Click the "Extract" button. This will open just the sound track in a new QuickTime document window.

Choose "Export..." from the File menu.

In the Export dialog box, in the Export: pull down menu, choose "Movie to MPEG-4". Click the "Options..." button next to that pull-down menu.

In the next window, choose the "Audio" tab."

In the "Audio Format:" pull-down menu, choose "pass-through".

Click "OK" to commit that change and exit this dialog box.

Name your file, click "Save" and you'll have exactly what you want: an audio-only .mp4 file with no reencoding.

[SkwidSpawn]

Here's how it worked for me under Mountain Lion, for anyone who finds this on Google and simply wants to pull the audio out of a movie file:

Open the file in Quicktime Player, then go to:
File->Export… (or hit command-shift-S)


Then select "Audio Only" from the Format drop-down:


Then Save it:


It appears to work as a pass-through rip, and I don't know if it works on every file, but it worked a charm on this one, pulling out 256kb/s aac audio.

[smaghe]

Hi everybody,

Thanks to the previous messages I was able to succeed in splitting the audio from the video.
However, I needed to automate the steps, as I had a lot of videos to split.

Here's the script that I wrote :

#!/bin/bash
for f in *.mp4; do
./ffmpeg -i "$f" -vn -acodec copy "${f%.mp4}.m4a"
done


For people who aren't so much into scripts, open Terminal, type "Nano"
Paste the script. Type Ctrl + X to close the editor, a prompt asking what to do will appear, save the file with ".sh" suffix.
Assuming you saved it in a convenient folder, navigate to the directory where the script is with the terminal. For example, script being in the Resources folder (mentioned in page 2), type :
cd Desktop/Resources/
Being in the folder, where your script and videos are, you then have to make the script executable; type :
chmod u+x nameofscript.sh
Then you just have to run the script in the same folder of the videos, to do so type :
./nameofthescript.sh


Thanks for the help that you gave me.
Cheers.


Stas

[Elias Hedberg]

Originally Posted by halfthelaw

No, FCP.guru.guy, you really don't get what Canubis is trying to do.

Canubis, here's how I do what you're describing:
1. Get Rogue Amoeba's Fission
http://rogueamoeba.com/fission/
2. Open the movie file with Fission
3. Go to File > Save Audio and you will be able to save the audio track losslessly

Small update to halfthelaw’s post: with the latest version of Fission (2+) there is no "Save Audio" option, just use "Save as…" and it will save the audio separately and, as far as I can tell, without doing any recompression (hence it should be the original aac track).