How to swap audio Channel from left to right on AVI files.

[noon]

Hi all,
I am new on videohelp, and have a problem to ask to you.

Is there is a batch program to swap audio between Left and Right Channel for an AVI file?

Cause in all my AVI file, 5% of those files have the voice channel at the left side. They are AVI Karaoke files.
And it will be more convenient for me if I could have all of my AVI Karaoke files with the voice channel affected at the Right Channel.
A Batch programm will really help me, cause I have an huge files in that case.

Thank you in advance for all your helps.

Noon.

[Baldrick]

I doubt you will find ONE software that does this.

But you could use ffmpeg(demux and multiplex) and sox(swap channels) and write a custom batch file for this. They are command lines tools.

Something like

ffmpeg -i video.avi -acodec copy audio.mp3
sox audio.mp3 audioswap.mp3 swap 2 1
ffmpeg -i video.avi -i audioswap.mp3 -vcodec copy -acodec copy newvideo.avi

WHen you get that working you can make it in a batch/bat file.

[noon]

Thank Baldrick. But I am not so good to write those code.
Are those line there usable? or there is just a sample from you?

I have seen the place to download there are static version, dev version which one I have to use, there are also 32 bits and 64 bits...
I am a novice in high level computerize...

[Baldrick]

I guess it will work. If now the audio is in mp3 format. I have never tried the sox swap command though.

You can try it. Put the ffmpeg.exe and sox.exe in for example c:\temp together with a video.avi file. Open a command prompt. Type cd c:\temp . Then copy and paste each command line and see what it says.

[noon]

Thanks, I will try it and keep you update.

[Baldrick]

Try the 32 bit static versions for windows. It will work fine in both 32bit and 64bit systems.

[noon]

After a first test I have an error for the second command line as below



1. ffmpeg -i video.avi -acodec copy audio.mp3
executed
OK

2. sox audio.mp3 audioswap.mp3 swap 2 1
Executed
Error The Application was unable to start correctly (0xc000007b)

3. ffmpeg -i video.avi -i audioswap.mp3 -vcodec copy -acodec copy newvideo.avi
Not yet test

[Baldrick]

Try just run sox without any commands. Just type sox

You might need the entire sox folder.

[Baldrick]

You need a sox version with mp3 support also.

Try

[noon]

I have copy all sox directory files to my temp1 directory, there is an message error as attached :

41.jpg

[Baldrick]

Download the sox version I posted above. It works with a test mp3 I just tried.

[noon]

Ok, I will uninstall and try the new version

[Baldrick]

You can just copy all the files in the version above to the temp folder.

[noon]

After test with the new version
Here is error message for 2. case
"sox WARN swap: Invoking this effect with parameters is deprecatedl; use 'remis' instead."

[Baldrick]

That is just a warning and it should have made a newaudio.mp3. It can take some minutes.

[noon]

In the 2. case line code I use Remix instead of SWAP It's works
for MP3 new file is works, the voice is on the right channel (on the MP3 files)

But the 3. case line command, after executed, the sound come back to the left side again.

[Baldrick]

I see. It doesn't use the new audio. It should look like

ffmpeg -i video.avi -i newaudio.mp3 -map 0 -map 1 -codec copy newvideo.avi

[noon]

the swap MP3 filename is audioswap.mp3
I have change it in your new command line, after executed.
I have the same video from the beginning (voice on the left channel).
But my audioswap.mp3 file play right (voice on the right channel)... we are nearly succeed...

I think I know the problem, cause I hear the VOICE on boths channel, Left and Right.
So the command line copy the newaudio.mp3 to the video.avi of the beginning.
that already have VOICE on left channel.
So we have VOICE on both channel with a delay created by the process.

But I don't know who to write the command line for that.
Perhaps it might have for command line.
cause it is needed a video.avi without any sound.
then mix with the newaudio.mp3 that have the right sound that I need.

[Baldrick]

Hmm...they have changed it a bit. Try

ffmpeg -i audioswap.mp3 -i video.avi -map 0.0 -map 1.0 -acodec copy -vcodec copy newvideo.avi

(from http://cfc.kizzx2.com/index.php/muxing-audio-and-video-with-ffmpeg/ )

[noon]

I have tried there is a message error "Invalide stream speficier: .0.


But Baldrick, how about my idea to have a command line to create a video_unsound.avi file then mix with the audioswap.mp3 file that is what I really need?

[Baldrick]

Try then

ffmpeg -i video.avi -vcodec copy -an video_unsound.avi

and

ffmpeg -i video_unsound.avi -i audioswap.mp3 -vcodec copy -acodec copy newvideo.avi

[noon]

Yes, GREAAAAAAAAAAAAT!
It works Baldrick.
I can have it with all your helps. Thank you soooooo MUCH!
It is the first time that I am member of videohelp, you are so kind and helpfull to me. Thank you, thank you.

[Baldrick]

You can now make a .bat batch for that to fix all avi files. I can help write it also.

[noon]

Thank you in advance for that.
I have just send you a private message for a Web Media player, just in case...

[Baldrick]

FOR %%f IN (*.avi) DO (
ffmpeg -i %%~nf.avi -acodec copy %%~nf.mp3
ffmpeg -i %%~nf.avi -vcodec copy -an %%~nf_unsound.avi
sox %%~nf.mp3 %%~nf-swap.mp3 swap 2 1
ffmpeg -i  %%~nf_unsound.avi -i %%~nf-swap.mp3 -vcodec copy -acodec copy c:\temp\newfolder\%%~nf-new.avi
)

Make a folder named newfolder in c:\temp
Make a file called swap.bat in the c:\temp folder and open in notepad. Copy and paste the code above. Save.
Run the swap.bat file from the command line and you will see if you get any errors.
If it creates a video-new.avi in the folder it works.
Copy some more avi files to the c:\temp folder and test run the swap.bat.

[noon]

for 3rd line I replace SWAP by REMIX, it works (sox %%~nf.mp3 %%~nf-swap.mp3 remix 2 1)
There is an error on 4th Line (final step). But I don't know where?


Here is the one that work by manual for mix video and audio swapped.


ffmpeg -i video_unsound.avi -i audioswap.mp3 -vcodec copy -acodec copy newvideo.avi

[Baldrick]

Does it look like

ffmpeg -i %%~nf_unsound.avi -i %%~nf-swap.mp3 -vcodec copy -acodec copy c:\temp\newfolder\%%~nf-new.avi

and you have the correct folder path?

[noon]

Yes now it works.
The mistake from my side was : new folder (per default windows create it with a space).

You are a Master with the bath code Baldrick
Now I will try with few avi in one time

[noon]

Well Mr.Baldrick, you have just created for me a bath to swap Audio for AVI for me. It works good.
I will save time in front of my computer.
Thank you so much...
Wishing helping all of those people like me always.
Wishing a good luck and a good heath for such kindness you give to other people like me.

Have a nice day.


Noon.

[Baldrick]

Great!


If anyone else finds this thread it might be good to know that you could also swap channels directly when you play, in for example vlc media player, audio->audio channels->reverse stereo. But you have do it manually for each file then.