Changes between Version 1 and Version 2 of Encode/MP3
- Timestamp:
- Nov 25, 2012, 11:43:59 PM (6 years ago)
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Encode/MP3
v1 v2 1 To encode VBR mp3 audio with FFmpeg, using libmp3lame library, we would specify a command like this:1 To encode VBR mp3 audio with `ffmpeg`, using libmp3lame library, we would specify a command like this: 2 2 {{{ 3 ffmpeg -i input.wav - aq2 out.mp33 ffmpeg -i input.wav -q:a 2 out.mp3 4 4 }}} 5 5 6 Option "-aq" needs a parameter, that tells FFmpeg something about expected "audio quality" (of course, this parameter has a different meaning for each audio encoder used, and we are now describing the libmp3lame encoder).6 Option `-q:a` needs a parameter, that tells `ffmpeg` something about expected "audio quality". This parameter has a different meaning for each audio encoder used, and we are now describing the libmp3lame encoder. 7 7 8 The table for LAME option "-V <num>" is shown here (and that option is mapped to FFmpeg's "-aq" option): 9 [http://wiki.hydrogenaudio.org/index.php?title=LAME#VBR_.28variable_bitrate.29_settings] 8 The table for LAME option `-V <number>` is shown here (and that option is mapped to the `-q:a` option in `ffmpeg`): [http://wiki.hydrogenaudio.org/index.php?title=LAME#VBR_.28variable_bitrate.29_settings VBR (variable bitrate) settings for LAME]. 10 9 11 {{{ 12 Switch Kbit/s Bitrate range kbit/s 13 -b 320 320 320 CBR 14 -V 0 245 220...260 15 -V 1 225 190...250 16 -V 2 190 170...210 17 -V 3 175 150...195 18 -V 4 165 140...185 19 -V 5 130 120...150 20 -V 6 115 100...130 21 -V 7 100 80...120 22 -V 8 85 70...105 23 -V 9 65 45...85 24 }}} 10 ||= Switch =||= Kbit/s =||= Bitrate range kbit/s =|| 11 || -b 320 || 320 || 320 CBR || 12 || -V 0 || 245 || 220...260 || 13 || -V 1 || 225 || 190...250 || 14 || -V 2 || 190 || 170...210 || 15 || -V 3 || 175 || 150...195 || 16 || -V 4 || 165 || 140...185 || 17 || -V 5 || 130 || 120...150 || 18 || -V 6 || 115 || 100...130 || 19 || -V 7 || 100 || 80...120 || 20 || -V 8 || 85 || 70...105 || 21 || -V 9 || 65 || 45...85 || 25 22 26 So, in our example above, we selected "-aq 2", meaning we used LAME's option "-V 2", which gives a VBR mp3 audio in the range of 170-210 kbit/s.23 So, in our example above, we selected `-q:a 2`, meaning we used LAME's option `-V 2`, which gives a VBR mp3 audio in the approximate range of 170-210 kbit/s. 27 24 28 If you want constant bit rate (CBR) mp3 audio, instead of using "-aq" option, you need to use "-ab" option to set the preferred "audio bit rate" in bps, like "-ab 256k"if you want 256 kbit/s audio.25 If you want constant bit rate (CBR) mp3 audio, instead of using `-q:a` option, you need to use the `-b:a` option to set the preferred "audio bit rate" in bits per second, like `-b:a 256k` if you want 256 kbit/s audio.