ffmpeg_commands.txt

extract mp3 from mp4:

option 1:
	link: https://stackoverflow.com/a/36324719

	To encode a high quality MP3 or MP4 audio from a movie file (eg AVI, MP4, MOV, etc) or audio file (eg WAV), I find it's best to use -q:a 0 for variable bit rate and it's good practice to specify -map a to exclude video/subtitles and only grab audio:

	ffmpeg -i sample.avi -q:a 0 -map a sample.mp3

	If you want to extract a portion of audio from a video use the -ss option to specify the starting timestamp, and the -t option to specify the encoding duration, eg from 3 minutes and 5 seconds in for 45 seconds:

	ffmpeg -i sample.avi -ss 00:03:05 -t 00:00:45.0 -q:a 0 -map a sample.mp3

	    The timestamps need to be in HH:MM:SS.xxx format or in seconds.

	    If you don't specify the -t option it will go to the end.

	    You can use the -to option instead of the -t option, if you want to specify the range, eg for 45 seconds: 00:03:05 + 45 = 00:03:50

option 2:
	link: https://stackoverflow.com/a/27413824
	
	To extract the audio stream without re-encoding:

	ffmpeg -i input-video.avi -vn -acodec copy output-audio.aac

	    -vn is no video.
	    -acodec copy says use the same audio stream that's already in there.

	Read the output to see what codec it is, to set the right filename extension.



boost audio through filter:
	ffmpeg -i sample.mp3 -filter:a "volume=5" sample.mp3