OK, as an experiment, I looked at the album with the smallest difference between FLAC and MP3 file sizes:
Code:
TYRIAN FLAC MP3
200.63 MB 138.28 MB
I downloaded both ZIPs and looked at the individual tracks. While the vast majority of these tracks had smaller MP3 files than FLAC, there were a few where the 320Kbps CBR MP3 was bigger.
Code:
FLAC MP3
07 - Deli Shop Quartet No 2 1352 KB 1557 KB
10 - End Of Level 330 KB 385 KB
11 - Game Over Solo 553 KB 636 KB
31 - Zanac3 219 KB 282 KB
40 - Composition In Q 4716 KB 5329 KB
Keep in mind that 76KB of each file is the album art. For tracks 10, 11, and 31, these are very short tracks (5-14 seconds), around half of which is silence. The FLAC file can drop the bitrate during the silence to near 0, while the 320Kbps CBR MP3 is stuck recording the silence at 320Kbps CBR. For the other two tracks, 07 and 40, I think the repetitiveness of the tracks helped the FLAC encoding to be more efficient somewhat.
I think this shows the inefficiency of 320Kbps CBR for MP3s. While 320Kbps is the highest bitrate possible for MP3, forcing the encoder to encode
every frame at this bitrate, regardless of if it's needed, can lead to large file sizes that, occasionally, even rival a non-lossy FLAC file of the same track. Encoding in VBR is likely much better if you're looking for a small file size of good quality. For example, running track 10 (uncompressed from the FLAC) through LAME on preset extreme gave this result:
Code:
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
301/301 (100%)| 0:00/ 0:00| 0:00/ 0:00| 19.414x| 0:00
32 [ 0]
40 [ 0]
48 [ 0]
56 [ 0]
64 [ 0]
80 [ 0]
96 [ 0]
112 [ 0]
128 [181] *********************************************************************
160 [110] ******************************************
192 [ 9] ****
224 [ 1] *
256 [ 0]
320 [ 0]
-------------------------------------------------------------------------------
kbps MS % long switch short %
141.9 100.0 97.5 1.3 1.2
After adding in album art and ID3 tag info, the file size as 215 KB.
BTW, I don't think there's anything "wrong" with the 320Kbps CBR encodes for these tracks. They're exactly the size you'd expect when encoding at 320Kbps CBR. As a test, I also re-encoded track 10 in LAME at 320Kbps CBR, and got the same file size. The problem isn't the files, but the concept of using 320Kbps CBR in the first place.
So yes, if you have the space, download the FLACs and re-encode them into VBR MP3s at whatever quality setting fits you preferences for size/quality.
