AAC Bitrate and sound quality
07-28-2005, 10:03 PM
#13
when you create an mp3, jpeg or any other type of 'lossy' compression format, data is lost. a 5 minute song (<-- roughly) is about 50-60MB straight from the CD, in aiff format. make a mp3 at 128k, and it works out to about 1mb per minute. Data from the original track is lost to compress the file.
AAC does handle the compression better but data is still lost. If you play around with the settings, and understand what all the options do in the encoding software, you can minimize the amount of audiable data that is lost, thus creating a compressed file that is about as close to the original as possible, while still compressing enough to be a acceptable size.
higher the bitrate the more data is preserved, and sticking to 192k, or 256k, should give you a compressed file that is very, very close to the original; I would be surprised if you could tell the difference between a 256k AAC / MP3, and the original CD.
regards, Mark
AAC does handle the compression better but data is still lost. If you play around with the settings, and understand what all the options do in the encoding software, you can minimize the amount of audiable data that is lost, thus creating a compressed file that is about as close to the original as possible, while still compressing enough to be a acceptable size.
higher the bitrate the more data is preserved, and sticking to 192k, or 256k, should give you a compressed file that is very, very close to the original; I would be surprised if you could tell the difference between a 256k AAC / MP3, and the original CD.
regards, Mark
07-28-2005, 10:06 PM
#14
one thing that has to be noted, there is no curret 'lossless' compression for music, at least that I am aware of.
When you compress a ZIP file, what winzip does is instead of having five zero's, ten one's, it makes a note that there were 5 0's, and 10 1's, thus saving room. once the file is expanded, winzip reads that header file, and puts stuff where it belongs. this is why raw txt files compress very little, if any because they are txt to begin with.
MP3, or AAC compression doesn't work this way, it actually removed data to save space. Think of it this way, rip a track at 256k, and then another at 64k, mp3, or AAC. there is a huge difference in sound quality, and file size. This is the trade off. do you want small file sizes, or hi quality songs... This is where knowing what all the options, and bitrate combinations comes in handy, because then you can find the happy medium between quality, and size that best fits your needs.
if you had a 60 gig ipod, then hell go nuts, rip everything in 320k, and be done with it, if you had a 20 gig ipod, then you have to sacrafice sound quality to get the same songs onto the smaller ipod.
hope that makes sense, and or helps, Mark
[ July 28, 2005, 11:14 PM: Message edited by: SQ Civic ]
When you compress a ZIP file, what winzip does is instead of having five zero's, ten one's, it makes a note that there were 5 0's, and 10 1's, thus saving room. once the file is expanded, winzip reads that header file, and puts stuff where it belongs. this is why raw txt files compress very little, if any because they are txt to begin with.
MP3, or AAC compression doesn't work this way, it actually removed data to save space. Think of it this way, rip a track at 256k, and then another at 64k, mp3, or AAC. there is a huge difference in sound quality, and file size. This is the trade off. do you want small file sizes, or hi quality songs... This is where knowing what all the options, and bitrate combinations comes in handy, because then you can find the happy medium between quality, and size that best fits your needs.
if you had a 60 gig ipod, then hell go nuts, rip everything in 320k, and be done with it, if you had a 20 gig ipod, then you have to sacrafice sound quality to get the same songs onto the smaller ipod.
hope that makes sense, and or helps, Mark
[ July 28, 2005, 11:14 PM: Message edited by: SQ Civic ]
07-29-2005, 06:17 AM
#15
^^ I wasn't talking about MP3 or AAC anymore. I was talking about Apple LossLess format, which was developed by Apple to satisfy those demanding a higher quality format. There are several formats out there now that are apparently lossless and work similar to .zip files. Apple LossLess is one and Flac is another. They all claim to be the exact same in quality as the original CD but at half the size.
07-29-2005, 09:05 AM
#16
1000 Watt CAFz'r
Join Date: Jun 2002
Posts: 1,242
Flac is most definatly lossless.
in fact there are actually quite a few lossless formats, (Free Lossless Audio Codec - FLAC, Monkey's audio - APE, Meridian Lossless Processing - MLP)
For more info chat with some of the people over at:
http://www.hydrogenaudio.org/forums/index.php
for more info on FLAC see:
http://wiki.hydrogenaudio.org/index.php?title=FLAC
in fact there are actually quite a few lossless formats, (Free Lossless Audio Codec - FLAC, Monkey's audio - APE, Meridian Lossless Processing - MLP)
For more info chat with some of the people over at:
http://www.hydrogenaudio.org/forums/index.php
for more info on FLAC see:
http://wiki.hydrogenaudio.org/index.php?title=FLAC
07-29-2005, 05:37 PM
#17
I don't see how any compressed file can be lossless. it may for all intents and purposes be undetectable from the original, but if it's compressed, something had to be removed. Now unless the compression codec replaces every bit during expansion, then there is some loss of info, however small. Please enlighten me if I am incorrect.
