24 bit playback questions

[jlscoson]

I've tried searching the forums but i haven't been able to find a 24bit playback guide so i have a few questions that need answering, since im confused about the 24 bit playback thing:

1. Does the 24bit playback option in winamp also depend on the source of the audio? I thought CDs are 16bit/44khz so would 24bit playback even make a difference with ripped mp3s?

2. Would this mean that 24bit playback in winamp and in soundcards that support 24bit playback would kind of be useless in playing mp3 ripped from regular CDs? Would stuff like only SACDs and DVD Audio benefit?

[DJ Egg]

The main benefit is that true 24bit soundcards output at 24bit, therefore the soundcard won't need to upsample 16bit to 24bit if Winamp is already sending it a 24bit audio stream.

[Benski]

Because MP3's are a mathematically representation of the audio, they aren't really "16bit" in the same sense as CD's. When MP3's are decoded for playback, 64bits of precision are used (think of more bits of precision are doing math with more numbers after the decimal point). The 64bit numbers are then truncated to 16bits (or 24) before outputting to the soundcard.

As DJ Egg said, the main advantage is that most modern sound cards want 24bit audio anyway, so why go to 16bit and then have to fill up the extra 8 bits with 0's? But in most situations, you won't hear the difference.

Also, there is an advantage to using 24bit output when using Replay Gain, the EQ, and a DSP effects plugin, because 24bit samples can retain more of the precision lost from doing the extra processing.