Apple - How to I go from .flac to .mp3 using LAME & FLAC using the Terminal alone?

Converting a single file without preserving tags

brew install lame
flac --decode --stdout test.flac | lame --preset extreme - test.mp3
  • --decode --stdout = -dc
  • lame - $outfile = input from STDIN
  • --preset extreme = ~245 kbit/s VBR

A shell script that preserves some ID3 tags

#!/bin/bash

for f in "$@"; do
    [[ "$f" != *.flac ]] && continue
    album="$(metaflac --show-tag=album "$f" | sed 's/[^=]*=//')"
    artist="$(metaflac --show-tag=artist "$f" | sed 's/[^=]*=//')"
    date="$(metaflac --show-tag=date "$f" | sed 's/[^=]*=//')"
    title="$(metaflac --show-tag=title "$f" | sed 's/[^=]*=//')"
    year="$(metaflac --show-tag=date "$f" | sed 's/[^=]*=//')"
    genre="$(metaflac --show-tag=genre "$f" | sed 's/[^=]*=//')"
    tracknumber="$(metaflac --show-tag=tracknumber "$f" | sed 's/[^=]*=//')"

    flac --decode --stdout "$f" | lame --preset extreme --add-id3v2 --tt "$title" --ta "$artist" --tl "$album" --ty "$year" --tn "$tracknumber" --tg "$genre" - "${f%.flac}.mp3"
done

To use the script, just save it somewhere like ~/bin/flac2mp3 and make it executable with chmod +x ~/bin/flac2mp3.

This would convert all flac files in your Music folder:

find ~/Music/ -name '*.flac' -exec ~/bin/flac2mp3 {} \;

Or slightly faster, since it only calls flac2mp3 once:

find ~/Music/ -name '*.flac' -print0 | xargs -0 ~/bin/flac2mp3

ffmpeg would preserve tags (but not cover art) by default.

for f in *.flac; do ffmpeg -i "$f" -aq 1 "${f%flac}mp3"; done

-aq 1 corresponds to -V 1 in lame. -acodec libfaac would convert the files to AAC:

for f in *.flac; do ffmpeg -i "$f" -acodec libfaac -aq 200 "${f%flac}m4a"; done

i took what you guys had, but then made it run even faster by using xargs to parallelize the jobs.

find <directory> -name '*.flac' -print0 | xargs -0 -P8 -n1  /usr/local/bin/flac2mp3

Then this is the script from above /usr/local/bin/flac2mp3 

#!/usr/bin/env bash

for f in "$@"; do
  [[ "$f" != *.flac ]] && continue
  album="$(metaflac --show-tag=album "$f" | sed 's/[^=]*=//')"
  artist="$(metaflac --show-tag=artist "$f" | sed 's/[^=]*=//')"
  date="$(metaflac --show-tag=date "$f" | sed 's/[^=]*=//')"
  title="$(metaflac --show-tag=title "$f" | sed 's/[^=]*=//')"
  year="$(metaflac --show-tag=date "$f" | sed 's/[^=]*=//')"
  genre="$(metaflac --show-tag=genre "$f" | sed 's/[^=]*=//')"
  tracknumber="$(metaflac --show-tag=tracknumber "$f" | sed 's/[^=]*=//')"

  flac --decode --stdout "$f" \ 
         | lame --preset extreme \
                --add-id3v2 \
                 --tt "$title" \
                 --ta "$artist" \
                 --tl "$album" \
                 --ty "$year" \
                 --tn "$tracknumber" \
                 --tg "$genre" \
                 - "${f%.flac}.mp3"
done

and heres some stats for the performance speedup using parallelism.

find <dirOfFlac24s> -name '*.flac -print0 | xargs -0 -P8 -n1 /usr/local/bin/flac2mp320  

0.00s user 0.00s system 60% cpu 0.002 total
115.94s user 1.40s system 359% cpu 32.655 total

time /usr/local/bin/flac2mp320 <dirOfFlac24s>/*.flac
96.63s user 1.46s system 109% cpu 1:29.98 total

you can see it also utilized my CPUs more effectively, i have an intel i7, so 8 is probably the right number of processes.

Tags:

Terminal

Encoding

Mp3

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