MP3FS 0.07

&MP3FS is A read-only FUSE filesystem which transcodes audio formats (currently FLAC) to MP3 on the fly when opened and read. This was written to enable me to use my FLAC collection with software and/or hardware which only understands MP3. e.g. gmediaserver to a netgear MP101 mp3 player.
MP3FS is also a novel alternative to traditional mp3 encoder applications. Just use your favorite file browser to select the files you want encoded and copy them somewhere!
How it Works:
When a file is opened, the decoder and encoder are initialised and the file metadata is read. At this time the final filesize can be determined as we only support constant bitrate mp3s.
ID3v2 tags are created from the vorbis comments in the flac file. They are located at the start of the file. As such, an application scanning a directory to read tags should not cause too much of a performance hit as the actual encoder does not need to be invoked (depending on how much data the read asks for).
A special exception to this is when an application tries to read the very last block first. Many applications do this to look for an id3v1 tag (stored in the last 128 bytes of the file). When this is detected, the filesystem simply return zeros (I dont support id3v1 tags). This dramatically speeds up applications, however it could potentially lead to corrupt mp3 files if the zeros are still in kernel cache when the application comes back to read the actual audio sequentially. In my experimentation this has not happened, I always get another read for the final block.
As the file is read, it is transcoded into an internal per-file buffer. This buffer continues to grow while the file is being read until the whole file is transcoded in memory. The memory is freed only when the file is closed. This simplifies the implementation.
Seeking within a file will cause the file to be transcoded up to the seek point (if not already done). This is not usually a problem since most programs will read a file from start to finish. Future enhancements may provide true random seeking.
For build instructions see INSTALL
Usage:
mount your filesystem like this: (you will probably have to be root)
mp3fs musicdir bitrate mountpoint [-o fuse_options]
e.g.:
mp3fs /mnt/music 256 /mnt/mp3 -o allow_other,ro
Here are the original files:
dave@bender:~/mp3fs$ ls -l /mnt/music/Smashing Pumpkins/Pisces Iscariot/
total 345732
-rw-r--r-- 1 mythtv mythtv 10267876 2005-06-19 18:36 01 - Soothe.flac
-rw-r--r-- 1 mythtv mythtv 23512276 2005-06-19 18:36 02 - Frail And Bedazzled.flac
-rw-r--r-- 1 mythtv mythtv 23332187 2005-06-19 18:36 03 - Plum.flac
-rw-r--r-- 1 mythtv mythtv 26402936 2005-06-19 18:36 04 - Whir.flac
-rw-r--r-- 1 mythtv mythtv 21591252 2005-06-19 18:36 05 - Blew Away.flac
-rw-r--r-- 1 mythtv mythtv 16719855 2005-06-19 18:36 06 - Pissant.flac
-rw-r--r-- 1 mythtv mythtv 33454889 2005-06-19 18:36 07 - Hello Kitty Kat.flac
-rw-r--r-- 1 mythtv mythtv 32073747 2005-06-19 18:36 08 - Obscured.flac
-rw-r--r-- 1 mythtv mythtv 17614217 2005-06-19 18:36 09 - Landslide.flac
-rw-r--r-- 1 mythtv mythtv 65406696 2005-06-19 18:36 10 - Starla.flac
-rw-r--r-- 1 mythtv mythtv 18651734 2005-06-19 18:36 11 - Blue.flac
-rw-r--r-- 1 mythtv mythtv 25055200 2005-06-19 18:36 12 - Girl Named Sandoz.flac
-rw-r--r-- 1 mythtv mythtv 28060023 2005-06-19 18:36 13 - La Dolly Vita.flac
-rw-r--r-- 1 mythtv mythtv 11432008 2005-06-19 18:36 14 - Spaced.flac
And now you can use the (virtual) mp3 files from the MP3FS mountpoint:
dave@bender:~/mp3fs$ ls -l /mnt/mp3/Smashing Pumpkins/Pisces Iscariot/
total 345732
-rw-r--r-- 1 mythtv mythtv 2446849 2005-06-19 18:36 01 - Soothe.mp3
-rw-r--r-- 1 mythtv mythtv 3197934 2005-06-19 18:36 02 - Frail And Bedazzled.mp3
-rw-r--r-- 1 mythtv mythtv 3467503 2005-06-19 18:36 03 - Plum.mp3
-rw-r--r-- 1 mythtv mythtv 4003745 2005-06-19 18:36 04 - Whir.mp3
-rw-r--r-- 1 mythtv mythtv 3414845 2005-06-19 18:36 05 - Blew Away.mp3
-rw-r--r-- 1 mythtv mythtv 2413413 2005-06-19 18:36 06 - Pissant.mp3
-rw-r--r-- 1 mythtv mythtv 4348572 2005-06-19 18:36 07 - Hello Kitty Kat.mp3
-rw-r--r-- 1 mythtv mythtv 5132656 2005-06-19 18:36 08 - Obscured.mp3
-rw-r--r-- 1 mythtv mythtv 3099704 2005-06-19 18:36 09 - Landslide.mp3
-rw-r--r-- 1 mythtv mythtv 10542719 2005-06-19 18:36 10 - Starla.mp3
-rw-r--r-- 1 mythtv mythtv 3210041 2005-06-19 18:36 11 - Blue.mp3
-rw-r--r-- 1 mythtv mythtv 3449127 2005-06-19 18:36 12 - Girl Named Sandoz.mp3
-rw-r--r-- 1 mythtv mythtv 4098213 2005-06-19 18:36 13 - La Dolly Vita.mp3
-rw-r--r-- 1 mythtv mythtv 2337344 2005-06-19 18:36 14 - Spaced.mp3
dave@bender:~/mp3fs$ id3info /mnt/mp3/Smashing Pumpkins/Pisces Iscariot/01 - Soothe.mp3
*** Tag information for /mnt/mp3/Smashing Pumpkins/Pisces Iscariot/01 - Soothe.mp3
=== TSSE (Software/Hardware and settings used for encoding): LAME v3.96.1
=== TIT2 (Title/songname/content description): Soothe
=== TPE1 (Lead performer(s)/Soloist(s)): Smashing Pumpkins
=== TALB (Album/Movie/Show title): Pisces Iscariot
=== TRCK (Track number/Position in set): 1
*** mp3 info
MPEG1/layer III
Bitrate: 128KBps
Frequency: 44KHz
dave@bender:~/mp3fs$ time cp /mnt/mp3/Smashing Pumpkins/Pisces Iscariot/01 - Soothe.mp3 /tmp/
real 0m12.917s
user 0m0.004s
sys 0m0.020s
dave@bender:~/mp3fs$ xmms /mnt/mp3/Smashing Pumpkins/Pisces Iscariot/*
Enhancements:
- A segfault and several memory leaks were fixed.