<p>I use ffmpeg to:</p>

<ol>
<li>add multiple audio into a video file and offset them </li>
<li>discard original audio in the video </li>
</ol>

<p>Everything is OK <strong>except</strong> that 
1. the audio volume in the <code>result.mp4</code> is remarkably lower than the volumes in each individual input audio
2. sound quality in <code>mp3</code>(which is a background music) also drops</p>

<p>I listened to each <code>3gp</code> and the <code>mp3</code> files, can confirm that the two issues above.</p>

<p>Why is this happening?</p>

<pre><code>ffmpeg -i 1.mp4 -i 1.3gp -i 2.3gp -i 1.mp3
  -filter_complex "[2]adelay=10000|10000[s2];[3:a][1:a][s2]amix=3[a]"
  -map 0:v -map "[a]" -c:v copy result.mp4
</code></pre>

CC BY-SA 3.0
2017-07-24T13:09:57.773Z
See https://stackoverflow.com/a/38714779/5726027
Gyan
CC BY-SA 3.0
2017-07-24T15:27:59.740Z
Thanks, I was also checking that thread. The command there works better, but still it does generate an optimal result. For example, at the begin of 5 secs, there is only one mp3 file as audio input, but the volume is still very low. From a noob point of view, why can't ffmpeg just stack these audios up then generate result?
Xi Xiao
CC BY-SA 3.0
2017-07-24T15:46:20.570Z
I checked your explanation @Mulvya in that thread. In my case, there is always two active audio inputs at any given time, one is the mp3, the other one is a 3gp, i.e. none 3gp files overlaps.
Xi Xiao
<ffmpeg>
Audio volume lower, quality drops after ffmpeg amix multiple audio inputs
Xi Xiao
# Audio volume lower, quality drops after ffmpeg amix multiple audio inputs

(Asked by: username_0 on 2017-07-24)

I use ffmpeg to:

add multiple audio into a video file and offset them 
discard original audio in the video 

Everything is OK except that 
1. the audio volume in the result.mp4 is remarkably lower than the volumes in each individual input audio
2. sound quality in mp3(which is a background music) also drops
I listened to each 3gp and the mp3 files, can confirm that the two issues above.
Why is this happening?
ffmpeg -i 1.mp4 -i 1.3gp -i 2.3gp -i 1.mp3
  -filter_complex "[2]adelay=10000|10000[s2];[3:a][1:a][s2]amix=3[a]"
  -map 0:v -map "[a]" -c:v copy result.mp4

**Tags:** ffmpeg

> **Comments:**
> **username_1**: See https://stackoverflow.com/a/38714779/5726027  
> **username_0**: Thanks, I was also checking that thread. The command there works better, but still it does generate an optimal result. For example, at the begin of 5 secs, there is only one mp3 file as audio input, but the volume is still very low. From a noob point of view, why can't ffmpeg just stack these audios up then generate result?  
> **username_0**: I checked your explanation @Mulvya in that thread. In my case, there is always two active audio inputs at any given time, one is the mp3, the other one is a 3gp, i.e. none 3gp files overlaps.  

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## 0 answers

