Large Batch conversion - is it possible ALAC file size is half the size of FLAC??

[glevethan]

I have been in the process of doing a large batch conversion project. CD's were originally ripped in dBpoweramp to FLAC compression set at 0. Approximately 8800 tracks. The resulting FLAC folder is 390 GB.

The first batch conversion to AAC 320 yielded 81 GB - makes sense.

I then converted the original FLAC's to ALAC lossless - total folder size 199GB. How is it possible that the ALAC folder (198gb) is half the size of FLAC (390gb)? I was under the impression that file size for FLAC and ALAC were approximately the same.

The only thing I can think of is my choice on the initial rip of FLAC compression set to 0 resulted in rather large file sizes? Perhaps leaving the default compression of 5 would have resulted in a smaller size - but half??? Would compression set to 5 have resulted in 200gb instead of 390??

[crawler9]

I have a significantly smaller library than you, but FLAC compression can offer considerable space savings. Uncompressed FLAC will obviously be faster to encode/decode than compressed FLAC, but will result in larger files every time. I don't have any devices which struggle to decode FLAC at level 8 in realtime for playback, so using compression is a no brainer for me. FLAC's compression is lossless, so regardless of the compression level, audio remains identical. The only difference is the encoding/decoding speed/efficiency. I just took a look at my library and checked it's uncompressed size vs its compressed size (using FLAC compression level 8) and the difference in my case is about 30% (64.82 GB compressed vs 91.92 GB original size across 2,458 files). This will probably vary on a case by case basis depending on your library's content, and the codec which offers the better compression might vary as well. I'm not especially familiar with ALAC's compression rate. A quick bit of searching leads me to believe that FLAC generally results in slightly better compression, and ALAC offers less intensive decoding, though I have found a few sources which state the exact opposite, and this would likely be impacted by the compression level selected as well.

[glevethan]

Thank you for the reply and analysis. It appears that my initial thoughts were correct and uncompressed FLAC is resulting in larger files. I have and will continue to rip in FLAC compression 0. My thoughts have always been that hard disk drive storage costs are effectively zero so why not apply zero compression and lighten the load on the transcoding end. My player is a Linn KDS and, while I do not subscribe to it, there has been talk on both the Linn and Naim forums that different file formats (uncompressed) sound different. Naim even goes as far to declare that WAV files sound better. Linn do not make that statement and maintain that all uncompressed file formats sound the same (although they frequently mention FLAC as their flavor of choice).

This was an interesting finding for me as the reason for my large batch encoding project was to generate files to put on my iPhone 7 256gb storage. Interesting to note that while my initial ripped folder at FLAC 0 compression could not fit on my phone (400gb) - the same library encoded in ALAC or FLAC compression 5 or 8 or whatever - will now be able to fit.