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M4A Bit Resolution Confusion
John 31415926
post Jun 2 2012, 02:52
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I'm reading up on M4A (aka MP4 audio) and how for the same bit rate, it's superior to MP3 in sound quality.

I've already begun converting some of my large FLAC files to MP4 so I can have more music on my hard drive. I'm using XLD to convert, set at 256 kbps VBR.

I thought I got this ... now I'm seeing some FLACs with bit rates of 800-900 and beyond. And a whole album encoded at that rate will still be 280 mb or so, still less than a FLAC of the same album.

I was raised on MP3 bit rates ... 96 for spoken word ... 128 for straightforward listening ... 256 for audiophile listening ... 320 just for the heck of it.

Now I'm seeing 920 kbps M4A and I'm confused. I would get if this was something entirely different than MP3, but I keep reading "a MP4 encoded at (insert number) kbps will sound superior to an MP3 encoded at the same bit rate.

Okay, a 128 M4A will sound better than a 128 MP3. Got it.

Now what on earth is a 920 kbps MP4? XLD, my conversion software, doesn't even go higher than 320 kbps.

(By the way, I'm referring to the bit rate shown in my iTunes window when I display an M4A album's contents.)
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Gregory S. Chudo...
post Jun 2 2012, 03:00
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M4A is a container format. The confusion comes from the fact that it can contain codecs of very different nature.
Some .m4a files use ALAC codec, which is a lossless codec similar to FLAC.
Some .m4a files use AAC lossy codec, which is comparable to MP3.

CUETools 2.1.4
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