Or possibly that the input was CBR, and the VBR aspect is able to reduce bitrate by a considerable amount.With VBR it could be due to the input already in being a lower bitrate than requested, in which case, it basically just re-encodes it at the bitrate of the input.With CBR it could be due to the chosen value being in-between allowable settings (it defaults down to the next lower acceptable bitrate).Sometimes the output will consist of fewer bits per second than requested: be any input type supported by encoding, including layer I,II,III (MP3) and OGG files. See Hydrogen Audio: Recommended LAME Encoder Settings for more info.ĪBR is something of a mixture between VBR and CBR, see the official documentation for details on use. To encode a stereo PCM input file as mono, use lame -m s -a. MP3 is lossy anyway, so if you really want the highest quality use a lossless format such as FLAC.-q:a 0 – -q:a 3 will normally produce transparent results. ![]() Note: Using -b:a 320k is generally considered wasteful because: So to get the highest quality setting use -b:a 320k (but see note below). Here you can specify the number of bits per second, for example -b:a 256k if you want 256 Kbit/s (25.6 KB/s) audio. If you need constant bitrate (CBR) MP3 audio, you need to use the -b:a option instead of -qscale:a. In our example above, we selected -qscale:a 2, meaning we used LAME's option -V 2, which gives us a VBR MP3 audio stream with an average stereo bitrate of 170-210 kBit/s. q:a 0 (NB this is VBR from 220 to 260 KB/s) ![]() b:a 320k (NB this is 32KB/s, or its max) The option -qscale:a is mapped to the -V option in the standalone lame command-line interface tool. 0-3 will normally produce transparent results, 4 (default) should be close to perceptual transparency, and 6 produces an "acceptable" quality. Values are encoder specific, so for libmp3lame the range is 0-9 where a lower value is a higher quality. See also other codecs you could use, and FFmpeg AAC Encoding Guide if you want AAC instead, and the official documentation.Įxample to encode VBR MP3 audio with ffmpeg using the libmp3lame library:įfmpeg -i input.wav -codec:a libmp3lame -qscale:a 2 output.mp3Ĭontrol quality with -qscale:a (or the alias -q:a). This page describes how to use the external libmp3lame encoding library within ffmpeg to create MP3 audio files ( ffmpeg has no native MP3 encoder).
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