user38683: I used some complex filters on a audio file and did some re-encoding.
ffmpeg -f lavfi -t 5 -i anullsrc=channel_layout=stereo:sample_rate=192000 -i file1.mp3 -filter_complex "[1:a][0:a]concat=n=2:v=0:a=1[audio_silence],amovie=file2.mp3:loop=0,asetpts=N/SR/TB,volume=0.1[music];[audio_silence][music]amix=duration=shortest,volume=1" out.mp3

Everytime I do this the audio gets worse. The audio is some speech recording and there are a lot of hisses and high frequency noices in the output.
How can this be prevented or equalized afterwards?
I tried some low pass filters but that doesn't seem to work.
Cheers

user38683: Problem found. The input quality was already very bad. I used higher quality input which sounded already better.
Also minimizing the amount of conversions helped to increase output quality. Nothing too special but when I asked the question it was not obvious to me.
Hope it helps. Cheers.

38683: <p>I used some complex filters on a audio file and did some re-encoding.</p>
<pre><code>ffmpeg -f lavfi -t 5 -i anullsrc=channel_layout=stereo:sample_rate=192000 -i file1.mp3 -filter_complex &quot;[1:a][0:a]concat=n=2:v=0:a=1[audio_silence],amovie=file2.mp3:loop=0,asetpts=N/SR/TB,volume=0.1[music];[audio_silence][music]amix=duration=shortest,volume=1&quot; out.mp3
</code></pre>
<p>Everytime I do this the audio gets worse. The audio is some speech recording and there are a lot of hisses and high frequency noices in the output.
How can this be prevented or equalized afterwards?
I tried some low pass filters but that doesn't seem to work.</p>
<p>Cheers</p>
 38683: <p>Problem found. The input quality was already very bad. I used higher quality input which sounded already better.
Also minimizing the amount of conversions helped to increase output quality. Nothing too special but when I asked the question it was not obvious to me.</p>
<p>Hope it helps. Cheers.</p>
