AAC Sample Rate and Bit Rate for High Quality Audio?

Question

What are the AAC Sample Rate and Bit Rate settings to set in order to encode an audio track with a quality comparable to MP3 320kbps?

I need to backup a DVD movie, the default settings for AAC are

Bitrate (KB/s) 128 
Sample Rate (HZ) 44100

should I set

Bitrate (KB/s) 320
Sample Rate (HZ) 48000

or the default are already good?

Answer 1

AAC has different ratios against MP3, so thats good question to ask. AAC has slightly better quality than MP3 in higher bitrates, and is superior to in lower bitrates.

Sample rate: You should keep sample ratio, as resampling looses some quality and up-sample wouldnt do any good.

Bitrate: If you like to have quality comparable to MP3, choose lower when using AAC. For example, for 320kbps MP3 like, I would choose 192 to about 226. This doesn apply to speech in which AAC has better compression ratio, hence same bitrate would yield higher quality.

For higher quality (not highest) movies generally rippers use 192kbps AAC. That would suit good even movies with lots of music and background sounds and effects. For general use and mediocre DVD films 128kbps would do the thing. Regular person should choose 128kbps, audiophile or movie lover may choose slightly more.

Answer 2

Keep the sample rate the same as the original, but you can get away with reducing the bit rate somewhat, as AAC is more efficient than MP3.