问题
I want to first decode a MP3 audio file, and then increase the volume of the audio, and then encode it again into a new MP3 file. I want to use libavformat or libavcodec for this. Can you help me how I can do this? Any example?
回答1:
You can use the "-filter" parameter with the "volume" option to set a multiplier for the audio. More info: http://ffmpeg.org/ffmpeg-filters.html#volume
Since you are dealing only with MP3 files (that have only one audio track), you can use the "-af" parameter, which is an alias for "-filter:a".
For instance,
ffmpeg -i input.mp3 -af 'volume=1.5' output.mp3
would increase the volume in 50% and create the output file with the same codec as input (MP3).
来源：https://stackoverflow.com/questions/21496031/decode-mp3-then-increase-the-audio-volume-and-then-encode-the-new-audio