MP3ファイルを無音部分で分割する (Macのコマンドライン)

MP3ファイルの最後の部分に、「10秒くらいの無音区間」＋「無関係な音楽」がくっついているものがあって聞きづらい。 GUIで波形データを直接編集したり、編集後にコードするのは面倒なので、コマンドラインから自動的に削除したいと思っていました。

mp3spltというプログラムをつかうと簡単にできました(github repo: mp3splt/mp3splt)。作者の方に感謝です。

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# Install:
brew install mp3splt

# Usage:
mp3splt -s -pmin=<無音区間の秒数>,th=<無音判定の判定位レベル(dB)。-48くらいがよいとのこと> <mp3ファイル名>

# Example:
mp3splt -s -pmin=10,th=-54 ラジオ.mp3

# Output:
ラジオ_silent_1.mp3 # <== このファイルが、ほしい出力。
ラジオ_silent_2.mp3 # <== このファイルが、無音区間後の無関係な音楽。消してしまってよい。

ヘルプメッセージ

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mp3splt 2.6.2 (09/11/14) - using libmp3splt 0.9.2
	Matteo Trotta <mtrotta AT users.sourceforge.net>
	Alexandru Munteanu <m AT ioalex.net>
THIS SOFTWARE COMES WITH ABSOLUTELY NO WARRANTY! USE AT YOUR OWN RISK!

USAGE:
      mp3splt [OPTIONS] FILE1 [FILE2] ... [BEGIN_TIME] [TIME] ... [END_TIME]
      TIME FORMAT: min.sec[.0-99], even if minutes are over 59
                   or EOF-min.sec[.0-99] (or EOF for End Of File).

OPTIONS (split mode options)
 -t + TIME: to split files every fixed time len. (TIME format same as above).
 -c + file.cddb, file.cue or "query" or "query{album}" or "internal_sheet".
      Get splitpoints and filenames from a .cddb or .cue file or from Internet
      ("query"). Use -a to auto-adjust splitpoints.
 -s   Silence detection: automatically find splitpoint. (Use -p for arguments)
 -w   Splits wrapped files created with Mp3Wrap or AlbumWrap.
 -l   Lists the tracks from file without extraction. (Only for wrapped mp3)
 -e   Error mode: split mp3 with sync error detection. (For concatenated mp3)
 -r   Trim using silence detection (Use -p for arguments)
 -A + AUDACITY_FILE: split with splitpoints from the audacity labels file
 -S + SPLIT_NUMBER: split in SPLIT_NUMBER equal time files
 -v   Prints current version and exits
 -h   Shows this help

(other options)
 -T + TAGS_VERSION: for mp3 files, force output tags as version 1, 2 or 1 & 2.
      TAGS_VERSION can be 1, 2 or 12
      (default is to set the same version as the file to split)
 -m + M3U_FILE: Appends to the specified m3u file the split filenames.
 -f   Frame mode (mp3 only): process all frames. For higher precision and VBR.
 -b   [Experimental] Bit reservoir handling for gapless playback (mp3 only).
 -a   Auto-Adjust splitpoints with silence detection. (Use -p for arguments)
 -p + PARAMETERS (th, nt, off, min, rm, gap, trackmin, shots, trackjoin): user arguments for -s, -a, -t.
 -o + FORMAT: output filename pattern. Can contain those variables:
      @a: artist tag, @p: performer tag (might not exists), @b: album tag
      @t: title tag, @n: track number identifier, @N: track tag number
      (a digit may follow the 'n' or 'N' for the number of digits to output),
      @f: original filename, @g: genre
 -g + TAGS: custom tags for the split files.
      TAGS can contain those variables:
         @a, @b, @t, @y, @c, @n, @g, @o (set original tags),
         @N (auto increment track number).
      TAGS format is like [@a=artist1,@t=title1]%[@o,@N=2,@a=artist2]
       (% means that we set the tags for all remaining files)
 -G + regex=REGEX: set tags from input filename. REGEX defines how to extract
      the tags from the filename. It can contain those variables:
         (?<artist>), (?<album>), (?<title>), (?<tracknum>), (?<year>), (?<comment>), (?<genre>)
 -d + DIRNAME: to put all output files in the directory DIRNAME.
 -k   Consider input not seekable (slower). Default when input is STDIN (-).
 -O + TIME: Overlap split files with TIME (slower).
 -n   No Tag: does not write ID3v1 or vorbis comment. If you need clean files.
 -x   No Xing header: does not write the Xing header. Use with -n if you wish
      to concatenate the split files
 -N   Don't create the 'mp3splt.log' log file when using '-s'.
 -P   Pretend to split: simulation of the process, without creating any
      files or directories
 -E + CUE_FILE: export splitpoints to CUE file (use with -P if needed)
 -q   Quiet mode: try not to prompt (if possible) and print less messages.
 -Q   Very quiet mode: don't print anything to stdout and no progress bar
       (also enables -q).
 -D   Debug mode: used to debug the program.

      Please read man page for complete documentation.