[Gberg]

Hey there, I'm trying to convert my growing collection of FLAC to ALAC, but I'm having trouble using dbpoweramp. I'm not sure if I'm using it right... because the bit rate I'm getting is around 1000kbps.. and its variable.. it also says that the files are around 30% compressed. That doesn't seem right to me.

Can someone help me out?
Thanks

 

[Gberg]

anyone?

 

[Duggeh]

Whats the bit depth and sample rate of the audio and what sort of music is it?

 

[m1abrams]

The bitrate will be variable and somewhere around the number you have. while 1000 is on the high side that is not unusual. The bitrate is referring to the data stream AFTER compression.

The 30% number not sure what that is in relation to? Are your files only 30% smaller than the PCM data? If so that is kinda low compression for FLAC atleast, not sure how much ALAC is able to compress.

 

[krmathis]

Seems about right to me!

 

[Gberg]

sample rate is 44.1KHz,

I'm just confused, from what it says when I check out the audio specs of a song (after FLAC to ALAC conversion)

Size: 12.08mb (35% compressed)
Original Size: 18.53mb

It also says the bit rate is 1411kbps, but when loaded into itunes it says slightly under 1000.
Is ALAC supposed to be compressed compared to FLAC?

 

[krmathis]

Yes, Apple Lossless and FLAC have comparable compression rates. Some some kind of music Apple Lossless have an edge on FLAC, while for different music its the other way around.

A compression rate of 60-70% of the source material is what most lossless codecs do on average.

 

[m1abrams]

Quote:

Originally Posted by Gberg /img/forum/go_quote.gif sample rate is 44.1KHz, I'm just confused, from what it says when I check out the audio specs of a song (after FLAC to ALAC conversion) Size: 12.08mb (35% compressed) Original Size: 18.53mb It also says the bit rate is 1411kbps, but when loaded into itunes it says slightly under 1000. Is ALAC supposed to be compressed compared to FLAC?

ok 1411kbps is the bitrate for uncompressed data, 16bit/44.1khz stereo PCM, you can get to that number with simple math. 16*44.1*2 = 1411kbps. The bitrate itunes is reporting is that of the compressed file and this is a variable bitrate.

ALAC uses different compression than FLAC I do not know how the compare in how much they compress. Most likely their is not a huge difference between the two. The 35% compressed number is probably how much smaller the compressed file is versus the raw PCM data (wav file). Do not know the numbers for ALAC but for FLAC most of my FLAC files are probably compress to about 40%. Rock does not compress as well as Classical since the signal is more complex. My concert piano songs where only a single piano is playing gets compress to about 70%.