First I tested Jahzzar_-02-_FM.mp3:
and I found out that it was encoded with 224 kbps:
Duration: 00:02:15.11, start: 0.025056, bitrate: 224 kb/s
I encoded Jahzzar_-02-_FM.mp3 with 128 kbps:
ffmpeg -i Jahzzar_-_02_-_FM.mp3 -b:a 128k output128.aac
and then I tested again:
I get the following statement:
Duration: 00:02:36.34, bitrate: 113 kb/s Stream #0:0: Audio: aac (LC), 44100 Hz, stereo, fltp, 113 kb/s
- Why is the duration changed?
What is the difference between the first bitrate (from Duration: ) and the second one (from Stream: )? For some tracks they are different, here for instance:
Duration: 00:02:15.11, start: 0.025056, bitrate: 138 kb/s Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 128 kb/s
Why is it encoded with 113 kbps (I used b:a 128k)?