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ALAC bit rate

Hi everyone,

I've been converting FLAC files to ALAC using XLD. The options are set to keep the same bit rate and depth as in original files. When I check the bit rate for resulting ALAC files in iTunes, most of them are in 500-800 kbps range, but for some of them it showed bit rates under 300kbps, which seems very low for a lossless file. I wonder if I missed something during conversion, which degraded the files.

Thanks.

ALAC bit rate

Reply #1
but for some of them it showed bit rates under 300kbps,


Probably they have a lot of silence, or else the software you're using can't compute the bitrate correctly.

I wonder if I missed something during conversion, which degraded the files.


I don't even think thats possible unless you accidentally encoded them as some other format (e.g. AAC).

ALAC bit rate

Reply #2
really easy to check - convert them back to FLAC, then use metaflac.exe --list to compare the MD5 signatures. If they match, you didn't lose anything.

ALAC bit rate

Reply #3
The options are set to keep the same bit rate and depth as in original files.

You mean sample rate. It is different from bit rate.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?


ALAC bit rate

Reply #5
but for some of them it showed bit rates under 300kbps,


Probably they have a lot of silence, or else the software you're using can't compute the bitrate correctly.

I wonder if I missed something during conversion, which degraded the files.


I don't even think thats possible unless you accidentally encoded them as some other format (e.g. AAC).


I see, thanks.

ALAC bit rate

Reply #6
Binary compare the FLAC with the ALAC in foobar, you'll be fixed.


ALAC bit rate

Reply #8
but for some of them it showed bit rates under 300kbps,


Probably they have a lot of silence, or else the software you're using can't compute the bitrate correctly.


Or possibly they are mono.

There are various reasons why lossless encoding can some times require a surprisingly low bitrate. Especially for older (not recently remastered) music apparently. I have seen reports of someone having a <300 kBps FLAC file of a 1970's Pink Floyd song.

What matters in this particular case is whether the original lossless file had a significantly higher bitrate. The difference between the various lossless codecs isn't that big and a significant drop in bitrate converting from one to the other could indicate a problem instead of increased efficiency. If the original FLAC had 290 kBps and the new ALAC has 280 kBps there is probably nothing to worry about, if it's a drop from 800 to 280 there might be a problem.
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

ALAC bit rate

Reply #9
but for some of them it showed bit rates under 300kbps,


Probably they have a lot of silence, or else the software you're using can't compute the bitrate correctly.


Or possibly they are mono.

There are various reasons why lossless encoding can some times require a surprisingly low bitrate. Especially for older (not recently remastered) music apparently. I have seen reports of someone having a <300 kBps FLAC file of a 1970's Pink Floyd song.

What matters in this particular case is whether the original lossless file had a significantly higher bitrate. The difference between the various lossless codecs isn't that big and a significant drop in bitrate converting from one to the other could indicate a problem instead of increased efficiency. If the original FLAC had 290 kBps and the new ALAC has 280 kBps there is probably nothing to worry about, if it's a drop from 800 to 280 there might be a problem.


Thank you, this makes a lot of sense. It was an old chamber music recording from the 60's with a piano and a cello in mono.

ALAC bit rate

Reply #10
I have an Édith Piaf compilation FLACing in at a bitrate of 251 - that is average over a 41 min CD. Lowest track: 234.  It is mono or near-mono.

http://www.hydrogenaud.io/forums/index.php...st&p=800823
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