Mix 2 Mono Audio Stream in 1 Stereo Stream

[Michael Rampe]

Merging two mono streams into a left/right panned single stream….

short answer is: not yet;-)

I found this task on the google summer of code wiki related to ffmpeg:

Implement negotiation of sample format and number of channels analogously to the libavfilter colorspace negotiation
* Does this imply a channel mixing filter? This would be the second most desirable basic audio filter in my opinion.

https://wiki.multimedia.cx/index.php?title=FFmpeg_Summer_Of_Code_2010

As this states, this is a work in progress and a very much needed feature.

My question for you is: what are you trying to do with the output file?

If you intend to edit it in a NLE later, you CAN map two streams to two new streams. They will both be mono but will be separate tracks which will work in an NLE. I recreated a 4channel movie to test with similar in stream layout to your .gxf file. I then used this command line to map audio channel 1 and 2 to two new streams in the output file.

ffmpeg -i input.mov -map 0:0 -map 0:1 -map 0:2 -vcodec dvvideo -s 720×576 -aspect 5:4 -acodec copy output.mov -acodec copy -newaudio

This came into my NLE (Final Cut Pro) as two center panned mono tracks. It is then simple to pan them left and right respectively in the NLE. NOTE: I could not get it working with the .dv wrappper or -target dv50 settings which is why I set the codec/size/aspect myself.

Finally, from the research I have done, mencoder (another free command line tool) DOES have a pan function so you may want to investigate that.

Michael

“half-way to world domination A.K.A. the belligerent blue bike shed”

[Lormeau Bertrand]

Mickael,

Thank you for your reply.

I’m looking to convert GXF files in TS H264/AAC.

For this I use Carbon Coder which has a channel mixing, but i have problems with the de-interlacing filter.

So I’m looking for another way to get a better result.

That’s why I wanted to convert GXF files in DV50 files for testing the ffmpeg de-interlacing filter. ( The result is not better 🙁 )

It is at this moment that I discovered that ffmpeg did not allow to select multiple single stream for make a stereo stream.

FFmpeg take the first stream mono and duplicate it in a stereo stream.

I’ll try mencoder, and the yadif filter.

I hope he will accept GXF files in source.

I tried your command line, but it does not work with the GXF and dv.

Respectfully

BobTheChinese

[Alex Nesterov]

Hi Michael!
Sorry I’m not an ffmpeg expert and not intend to be.
Everything works perfectly- i just want to send mic mono input to both channels out. Like normally programs do on default.
It’s crazy: in my stupid project having 3 not so bad computers -including mac and windows- only ffmpeg does the job.
Here is the command which works great- I just don’t know how.

ffmpeg -f oss -i /dev/audio3 -f video4linux2 -s 320×240 -i /dev/video1 out.mpg

Thank You in advance!
I simply don’t know how to write the script. Sorry.