aac recompression

[destrolennox]

Quick question. I have downloaded a bunch of aac files, from local bands around my area. The songs were avaliable for download in 320 or 192 kbps and i chose 320 because they werent much bigger, and only cost a bit more to download.

However, recently I purchased an Ipod, and wanted to fit more songs on it. obviously, 192kbps is much smaller, and since I dont need the better quality on my ipod i wanted to recompress the aac files.

I have read on this website that recompressing a mp3 to aac will create quality problems, but is it a problem to recompress an aac file to a lower bitrate? it seems that this would just remove more information from the song and make it identical to an aac file compressed originally to 192kbps.


thanks for the info!

-Brendan

[WinterMute]

Quick question. I have downloaded a bunch of aac files, from local bands around my area. The songs were avaliable for download in 320 or 192 kbps and i chose 320 because they werent much bigger, and only cost a bit more to download.

However, recently I purchased an Ipod, and wanted to fit more songs on it. obviously, 192kbps is much smaller, and since I dont need the better quality on my ipod i wanted to recompress the aac files.

I have read on this website that recompressing a mp3 to aac will create quality problems, but is it a problem to recompress an aac file to a lower bitrate? it seems that this would just remove more information from the song and make it identical to an aac file compressed originally to 192kbps.


thanks for the info!

-Brendan

There's no problem re-coding to AAC from MP-3 unless there is a problem with the original MP-3 coding, so downsampling an AAC file in AAC isn't going to hurt unless you run it through good speakers and have the ears to hear the difference. I code at 160 AAC for my iPod and it sounds fine for everyday use, I'll use the Apple lossless codec for more critical work, and I'll stay with uncompressed PCM for the pro stuff, 24-bit if I have the system avaliable.

160 AAC is very musical and obviously half the size of 320. I have around 1400 songs on a 10 gig rev 2 iPod, with about 2 gig left.

Downsampling is always going to give you more noticable artifacts, just think of your target evironment.

[destrolennox]

I guess more specifically I am asking: is there going to be a difference in quality from a 192kbps aac file compressed directly from a .wav file from a 192kbps aac file compressed from a 320kbps aac file?

[lavar78]

I guess more specifically I am asking: is there going to be a difference in quality from a 192kbps aac file compressed directly from a .wav file from a 192kbps aac file compressed from a 320kbps aac file?
There will definitely be a difference. The question is whether you'll be able to hear it.

[WinterMute]

I guess more specifically I am asking: is there going to be a difference in quality from a 192kbps aac file compressed directly from a .wav file from a 192kbps aac file compressed from a 320kbps aac file?

It still depends on the quality of the original file and what you're listening through, I doubt you'd hear the differences on ear-buds, but you'll hear it on good speakers.