CUE splitter using ffmpeg (to mp3)

cue_to_mp3.py

# Changes over the original:
#
# + Support both Python 2 & 3.
# * fixed location of bitrate parameters.
# * Fixed track duration so it does't cuts tracks short, nor starts them early
#   (Margin of error for .flac source files should at most be around +/- 0.013 secs).
# + Added pre_gap support.

cue_file = 'file.cue'

d = open(cue_file).read().splitlines()

general = {}

tracks = []

current_file = None


def index2seconds(line):
    mm, ss, ff = list(map(int, ' '.join(line.strip().split(' ')[2:]).replace('"', '').split(':')))
    return 60 * mm + ss + ff / 75.0 # each FF is 1/75 of a sec


def replace_chars(string, chars=r':\/|<>?*"', replacement='_'):
    """
    Return `string` with any char in the `chars` replaced by `replacement`.

    Defaults to replace problematic/invalid chars for filenames/paths.
    """
    for c in string:
        if c in chars:
            string = string.replace(c, replacement)
    return string


for line in d:
    if line.startswith('REM GENRE '):
        general['genre'] = ' '.join(line.split(' ')[2:])
    if line.startswith('REM DATE '):
        general['date'] = ' '.join(line.split(' ')[2:])
    if line.startswith('PERFORMER '):
        general['artist'] = ' '.join(line.split(' ')[1:]).replace('"', '')
    if line.startswith('TITLE '):
        general['album'] = ' '.join(line.split(' ')[1:]).replace('"', '')
    if line.startswith('FILE '):
        current_file = ' '.join(line.split(' ')[1:-1]).replace('"', '')

    if line.startswith('  TRACK '):
        track = general.copy()
        track['track'] = int(line.strip().split(' ')[1], 10)

        tracks.append(track)

    if line.startswith('    TITLE '):
        tracks[-1]['title'] = ' '.join(line.strip().split(' ')[1:]).replace('"', '')
    if line.startswith('    PERFORMER '):
        tracks[-1]['artist'] = ' '.join(line.strip().split(' ')[1:]).replace('"', '')
    if line.startswith('    INDEX 00 '):
        tracks[-1]['pre_gap'] = index2seconds(line)
    if line.startswith('    INDEX 01 '):
        tracks[-1]['start'] = index2seconds(line)

for i in range(len(tracks) - 1):
    if 'pre_gap' in tracks[i + 1]:
        tracks[i]['duration'] = tracks[i + 1]['pre_gap'] - tracks[i]['start']
    else:
        tracks[i]['duration'] = tracks[i + 1]['start'] - tracks[i]['start']

for track in tracks:
    metadata = {
        'artist': track['artist'],
        'title': track['title'],
        'album': track['album'],
        'track': str(track['track']) + '/' + str(len(tracks))
    }

    if 'genre' in track:
        metadata['genre'] = track['genre']
    if 'date' in track:
        metadata['date'] = track['date']

    cmd = 'ffmpeg'
    cmd += ' -i "%s"' % current_file
    cmd += ' -b:a 320k'
    cmd += ' -ss %.2d:%.2d:%09.6f' % (track['start'] / 60 / 60, track['start'] / 60 % 60, track['start'] % 60)

    if 'duration' in track:
        cmd += ' -t %.2d:%.2d:%09.6f' % (track['duration'] / 60 / 60, track['duration'] / 60 % 60, track['duration'] % 60)

    cmd += ' ' + ' '.join('-metadata %s="%s"' % (k, v) for (k, v) in metadata.items())
    cmd += replace_chars(' "%.2d - %s - %s.mp3"' % (track['track'], track['artist'], track['title']))

    print(cmd)

@maye9999, hi! Thanks for the feedback!

The .cue files I had for testing, either had NO pre-gap in any track, or had pre-gap in ALL the tracks, even for track 1 with a zero pregap (ie: INDEX 00 00:00:00), so using either if 'pre_gap' in tracks[i]: or if 'pre_gap' in tracks[i+1]: didn't actually changed the calculated durations.

Does your .cue file has pre-gaps (INDEX 00) for all the tracks EXCEPT for the first one? Like the examples on this wiki?

Not really sure which case is more common. I guess that I'll go with your suggestion until I come up with something more reliable :-D

Thanks again!

I'll go ahead and also change that silly looking code:

for i in range(len(tracks)):
    if i != len(tracks) - 1:

for

for i in range(len(tracks) - 1):

@OscarL Hi, thanks for your reply.
Yes, there are pre-gaps for all tracks EXCEPT for the first one, just like the example.
By the way, there is a little bug when ':' exists in TITLE. Maybe because ffmpeg uses ':' as a special token?

@maye9999: that seems to be not so much of a problem with ffmpeg, as to with the under-laying filesystem. AFAIK, Macs forbid ":", Linux forbids "/", and Windows forbids a ton of characters and names (<, >, /, . |, ", *, ?) , and ":" is used in NTFS for alternate datastreams.

Workaround: manually replace ":" for " - " in the TITLE lines of your .cue file (or see if the program that created it has an option to do it automatically, most ripping software I used to use had an option like that).

Some more info on stackoverflow.

We should escape such characters to make sure we are using valid filenames, but I feel that it its out of scope for this little gist.

I have a work-in-progress version that actually calls ffmpeg, lets you select the output format, choose if you want metadata or not, things like that... and a bit more error correction. I'll do my best to keep this issue in mind.

I will create a proper git repository for that script, as I want it to have tests, docs, and things like that... all while being a small, easy to follow project for beginners and old timers, like me, that are just a bit rusty :-D

I'll add a comment here when I upload that code.

Thanks again!

@maye9999, I just added a basic "replace invalid chars in filenames with _" (Untested), just in case I take too long to move this into a proper git repo.

@OscarL Thank you very much❤