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:-( MP3 destroys Surround Sound encoding
post Dec 3 2002, 00:18
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I've been experimenting with MP3 and converting my CDs to MP3-320 compressed files. Unfortunately, I've discovered that the MP3 encoding process destroys the Rear Channel Sound. In a few cases I can still hear music in the rear, but for most songs the rear speaker just produces garbage sound... rather disappointing compared to the rich sound produced from the original CD!

I suppose MP3 considers the rear channel information to be "inaudible" which it would be in a standard 2-speaker stereo arrangement, but the addition of the rear speaker makes these types of sounds *very* audible. It's basically an echo effect that is audible when listening to the CD and places the listener *inside* the music, but sadly lacking on the MP3 rip. The stripping of that rear channel echo dramatically diminishes the experience.


P.S. I'm using CDex for ripping and LAME for encoding with the following settings: q=0;Very High Quality, Stereo, 320kbps.
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post Dec 4 2002, 12:11
Post #2

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Hi TheAveng

I've actually done a fair amount of testing on this. Please have a look at the post in the MPC section at http://www.hydrogenaudio.org/forums/index....=ST&f=11&t=4109.

I've done comparisons between a number of encoders at various bitrates.

I concur that MP3 (have only tested lame, but suspect this may be generally true of the MP3 model) is terrible at encoding the stereo image for samples with surround information. It only APPROACHES acceptibility at --alt-preset insane.

MPC does a great job at (--quality 6), or at (--quality 5 --ms 15). However, both AAC and Ogg Vorbis gets it right at the "standard" quality settings.

My recommendation: switch to MPC and encode surround tracks with the settings above. You can still encode your other tracks at (--quality 5) and save space (and improve quality!) over MP3.

If you are encoding movie clips, have a look in stead at Ogg Vorbis, for which I believe there exists a Windows CODEC capable of decoding Ogg Vorbis streams.

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