How to overlay/downmix two audio files using ffmpeg

Question

Can I overlay/downmix two audio mp3 files into one mp3 output file using ffmpeg?

Solution 1

stereo + stereo → stereo

Normal downmix

Use the amix filter:

ffmpeg -i input0.mp3 -i input1.mp3 -filter_complex amix=inputs=2:duration=longest output.mp3

Or the amerge filter:

ffmpeg -i input0.mp3 -i input1.mp3 -filter_complex amerge=inputs=2 -ac 2 output.mp3

Downmix each input into specific output channel

Use the amerge and pan filters:

ffmpeg -i input0.mp3 -i input1.mp3 -filter_complex "amerge=inputs=2,pan=stereo|c0<c0+c1|c1<c2+c3" output.mp3

---

mono + mono → stereo

Use the join filter:

ffmpeg -i input0.mp3 -i input1.mp3 -filter_complex join=inputs=2:channel_layout=stereo output.mp3

Or amerge:

ffmpeg -i input0.mp3 -i input1.mp3 -filter_complex amerge=inputs=2 output.mp3

---

mono + mono → mono

Use the amix filter:

ffmpeg -i input0.mp3 -i input1.mp3 -filter_complex amix=inputs=2:duration=longest output.mp3

---

More info and examples

See FFmpeg Wiki: Audio Channels

Solution 2

Check this out:

ffmpeg -y -i ad_sound/whistle.mp3 -i ad_sound/4s.wav -filter_complex "[0:0][1:0] amix=inputs=2:duration=longest" -c:a libmp3lame ad_sound/outputnow.mp3

I think it will help.

Solution 3

The amix filter helps to mix multiple audio inputs into a single output.

If you run the following command:

ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT

This command will mix 3 input audio streams (I used two mp3 files, in the example below) into a single output with the same duration as the first input and a dropout transition time of 3 seconds.

The amix filter accepts the following parameters:

• inputs: The number of inputs. If unspecified, it defaults to 2.

• duration: How to determine the end-of-stream.

  • longest: The duration of the longest input. (default)

  • shortest: The duration of the shortest input.

  • first: The duration of the first input.

• dropout_transition: The transition time, in seconds, for volume renormalization when an input stream ends. The default value is 2 seconds.

For example, I ran the following command in Ubuntu: FFMPEG version: 3.2.1-1 UBUNTU 16.04.1

ffmpeg -i background.mp3 -i bSound.mp3 -filter_complex amix=inputs=2:duration=first:dropout_transition=0 -codec:a libmp3lame -q:a 0 OUTPUT.mp3

-codec:a libmp3lame -q:a 0 was used to set a variable bit rate. Remember that, you need to install the libmp3lame library, if is necessary. But, it will work even without the -codec:a libmp3lame -q:a 0 part.

Reference: https://ffmpeg.org/ffmpeg-filters.html#amix

Solution 4

For merging two audio files with different volumes and different duration following command will work:

ffmpeg -y -i audio1.mp3 -i audio2.mp3 -filter_complex "[0:0]volume=0.09[a];[1:0]volume=1.8[b];[a][b]amix=inputs=2:duration=longest" -c:a libmp3lame output.mp3

Here duration can be change to longest or to shortest, you can also change the volume levels according to your need.

If you're looking to add background music to some voice use the following command as in the gaps the music will become loud automatically:

ffmpeg -i bgmusic.mp3 -i audio.mp3 -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress=threshold=0.003:ratio=20[bg]; [bg][mix]amerge[final]" -map [final] final.mp3

In this threshold is something whose value will decide how much loud the audio should be, the less the threshold more the audio will be. Ratio gives how much the other audio should be compressed, the more the ratio the more the compression is.

Solution 5

If they are different length, you can use apad to add a silent sound to the shortest one

View more solutions

Comments

[Andriy Tylychko]

You can decode both of them, mix (pretty simple operation) and encode again

[Faisal]

Can you please mention commands to do that. I checked the other post you mentioned in your link but it did not help.

[TheFlash]

@Faisalcan u please guide me..how to build ffmpeg on ubuntu? if yes then i will post new question on Stackoverflow with all the necessary details..

[Faisal]

Thanks it helped. what if length of both files is different?

[Faisal]

Thanks, it really helped and done without errors. But my audio files are different in length. Do you have any idea that how to generate output file to the maximum length of input files?

[Ahmad Arslan]

please can you give the example by putting fake path and value . It will be appreciated

[Ahmad Arslan]

Will it be using like this ?? {"ffmpeg","-i", Audio,"-i",Audio2, "-filter_complex" ,"amerge", "-c:a", "libmp3lame","-q:a","4" ,filenameVideoReplace};

[Admin]

@LordNeckbeard: Your code is not working for Merging two audio files.

[sonida]

It worked for me. It's perfect and faster "ffmpeg -y -i input1.mp3 -i input2.mp3 -filter_complex amerge -c:a libmp3lame -q:a 4 output.mp3"

[Ahmad Arslan]

it throws me error in log Unknown encoder 'libmp3lame'

[llogan]

@ArslanAhmad Without your actual command and the complete console output I can only guess that your ffmpeg was not configured with --enable-libmp3lame and therefore cannot use this encoder.

[cesarpachon]

this worked better for me, as take care of the differences in lenght.. this is how I mixed three sounds: ffmpeg -i flute_long.ogg -i gallop.ogg -i wind.ogg -filter_complex "[0:0][1:0] amix=inputs=3:duration=longest" main.ogg

[EnriMR]

Perfect explanation of amix :)

[chovy]

Is there anyway to adjust the volume on one of the input files down say 20%?

[dastan]

@chovy ffmpeg -y -i A.mp3 -i B.mp3 -filter_complex "[0:0]volume=0.2[a];[1:0]volume=0.5[b];[a][b]amix=inputs=2:d‌​uration=longest" -c:a libmp3lame output1.mp3

[Hermann]

amerge creates one multi-channel which is then "squashed" into a stereo stream by -ac 2. @Ehsan's answer utilising amix is the better way to go.

[llogan]

@Hermann amerge is more flexible in this regard because you can choose the desired downmix channel layout, but either should be fine for the general user.

[ychaouche]

Works perfectly well AND is also available for avconv, contrary to the amerge plugin which didn't work for my version of avconv (avconv version 9.20-6:9.20-0ubuntu0.14.04.1)

[Shino Lex]

Thanks a lot, worked perfectly for me. I wanted to combine 2 different sound's into 1 file that has different durations.

[Asif Sb]

@llogan, I tried using this cmd but it goes to the failure callback method.

[llogan]

@AsifSb I don't know what that means.

[Asif Sb]

@llogan, I tried using this command for merging two audios using FFMPEG, It is not working.If it is working for you can you please share some code?

[llogan]

@AsifSb Use a pastebin link to show your ffmpeg command and the complete log from the command.

[llogan]

@AsifSb Is the problem with the script or the ffmpeg command? If the problem is ffmpeg then get rid of the extra layer of complexity from the scripting. Just run the ffmpeg command manually, unscripted and provide the complete log from the ffmpeg command. Once you verify that ffmpeg runs only then should you attempt to script it.

[Asif Sb]

I don't think the problem is with the FFmpeg but command. Because when I try to execute another command it gives me success.

[llogan]

@AsifSb The command works for me. I can't help you because you never provided the log from ffmpeg.