Currently I'm running with the following setup.

ffmpeg \
 -i http://pub1.di.fm:80/di_vocaltrance \
 -f x11grab -s 1920x1080 -r 25 -i :0.0 \
 -c:v libx264 -preset fast -pix_fmt yuv420p -s 1280x800 \
 -c:a libmp3lame -ab 96k -ar 22050 \
 -threads 0 \
 -f flv "rtmp://...."

What I want to bake in:

 -f alsa -ac 2 -i hw:0 -acodec pcm_s32le -aq 1 -ab 128k\

Is this possible? And perhaps even mix in "what I hear" (aka playback) so to speak?

I've tried something along the lines of (but not fully understanding -map)

 -i http://pub1.di.fm:80/di_vocaltrance -map 0:1 \
 -f x11grab -s 1920x1080 -r 25 -i :0.0 -map 0:0 \

But that didn't really go so well.

I'm so close now, this gives me sound channels, but everything sounds like I'm inside a small tin-can of sorts.

KEY=`cat key.db`

ffmpeg \
 -i http://pub1.di.fm:80/di_vocaltrance \
 -f alsa -ac 2 -i hw:0 -acodec mp3 -aq 1 -ab 128k \
 -f x11grab -s 1920x1080 -r 25 -i :0.0 \
 -c:v libx264 -preset fast -pix_fmt yuv420p -s 1280x800 \
 -c:a mp3 -ab 96k -ar 22050 \
 -threads 0 \
 -map 0:0 -map 1:0 -map 2:0 \
 -f flv "rtmp://live.twitch.tv/app/$KEY"

It only appears when I mix the two sounds together. Trying to get JACK in here as well, but without any actual results (I thought I'd pass everything via a mixer board to unload ffmpeg from the mixing).

Running with:

 -f alsa -ac 2 -i jack \

Gives this however:

[alsa @ 0x1399280] cannot set sample format 0x10000 2 (Invalid argument)

jack: Input/output error

  • Just a suggestion, but Sox is a simply implemented cli utility designed for this kind of thing. frozen does seem to have a pretty firm handle on it though.
    – mikeserv
    Mar 12, 2014 at 12:09

1 Answer 1


You should be able to use the amix filter to mix together your audio.


ffmpeg \
  -i http://pub1.di.fm:80/di_vocaltrance \ # internet radio
  -f alsa    -i hw:0 \                     # microphone
  -f x11grab -i :0.0 \                     # computer desktop
  -f v4l2    -i /dev/video0 \              # webcam or
  # -f iec61883 -i auto \                  # firewire camcorder
  -filter_complex '[0:a:0][1:a:0]amix=inputs=2;[3:v:0]scale=200:-1[webcam],[2:v:0][webcam]overlay=main_w-overlay_w-10:main_h-overlay_h-10' \

I added a webcam overlay also, to remove it, take off the webcam line, the semi-colon and the definitions after the semi-colon.

Be ware that you might have to define -maps if you add any input that has multiple streams to remove the extraneous ones.


defines filters with multiple inputs or outputs
Input 0's audio stream number 0. (internet radio)
Input 1's audio stream number 0. (microphone)
Mix together two audio streams, if no input streams are defined, it autoselects two, so in this instance, you should be able to leave out the above two definitions.
Start a new filter chain
Input 3's video stream number 0. (webcam)
Scale the video to 200x???, -1 keeps aspect ratio, so a 600x480 video becomes 200x160.
Call the scaled output "webcam".
Continue to the next filter in this chain.
Input 2's video stream number 0. (desktop)
The scaled webcam stream.
Overlay the second input over the first input, placing the second input 10 pixels from right, and 10 pixels from the bottom.

Also, you can set the sound card capture source to mix to get what the computer outputs, and you can often unmute the microphone to get a microphone monitor loopback, but to get it to work properly you have to use jack or pulse. I do not know why jack did not work for you, so I can not help you with that, sorry.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .