That's why your output is larger than the input, because in contrast to MP3, ALAC is still compressed, but it needs to be lossless – that's why it needs to store more data. ALAC is the Apple Lossless Audio Codec, whereas AAC is Advanced Audio Coding. 5.0 you will not hear any sound artifacts. 4.0 you will hear faintly discernible sound artifacts.
3.0 you will hear distinctly audible but tolerable sound artifacts. 2.0 you will hear unpleasant sound artifacts. There were some problems with your original approach:Īlac is not AAC. In most cases using this device/technology: 1.0 you will hear heavily distorted sound.
Good mp3 encoder install#
When you follow the compilation guides and install the appropriate libraries before, FFmpeg now gives you the option to use libfdk_aac. Compiling is easy on Linux, moderately easy on OS X, and rather hard on Windows. You can compile ffmpeg yourself and add libfdk_aac support. This encoder does not support VBR properly, so if you need that or HE-AAC, read on. If that's the case, you can use the built-in AAC encoder: ffmpeg -i input.mp3 -c:a aac -b:a 192k output.m4a Some versions of FFmpeg do not have libfdk_aac (for licensing reasons). You can also use HE-AAC (v1/v2) instead of the default AAC-LC (low complexity) profile, which is best suited for low bitrates: ffmpeg -i input.mp3 -c:a libfdk_aac -profile:a aac_he_v2 -b:a 32k output.m4a ffmpeg -i input.mp3 -c:a libfdk_aac -b:a 128k output.m4a You can often choose something lower as well.
128 kBit/s should be good enough for most situations. ffmpeg -i input.mp3 -c:a libfdk_aac -vbr 4 output.m4aįor fixed bitrate (CBR), use the -b:a option, for example -b:a 128k. For example, -vbr 4 is a good choice (roughly 128 kBit/s for stereo audio). To change the quality, you have two options:įor variable bitrate (VBR), use the -vbr option. ffmpeg -i input.mp3 -c:a libfdk_aac output.m4a libfdk_aac is the Fraunhofer AAC encoder, and it is available when you compiled FFmpeg with support for it. This is the most basic FFmpeg command to convert input to AAC audio using the highest quality AAC FFmpeg has.
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