Most flv files are mono with an audio frequency of 22050 Hz. For example, the videos from youtube.com.
You can add these options to ffmpeg to improve the sound.
ffmpeg -i file.flv -f mp3 -ab 128k -ar 44100 -ac 2 file.mp3
-ab is the audio bitrate
-ar is the frequency
-ac is 2 channels or stereo
There are times when we rip the flv file, the volume is low. A better way is to convert the flv file to a wav file, normalize it and then convert the wav to an mp3 file. Example:
ffmpeg -i file.flv -f wav file.wav
normalize file.wav
ffmpeg -i file.wav -f mp3 -ab 128k -ar 44100 -ac 2 file.mp3
If you have many flv files, you can create a for loop shell script and use variables in place of the file(s).
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