Audio PCM 16bit or 24bit?

Verified answer

PCM stands for pulse-code modulation, a digital representation of an analog signal (in this case, sound waves). The more bits you use, the more accurate the digital representation. But in addition to bits, there's another thing that influences the quality. It's the frequency, which is measured in kilohertz (kHz)

Audio CD quality is 16 bit and 44.1 kHz, so if you're ripping to WAV files that's the highest quality you need to use. Any higher and you'll just be using more space without improving quality. So 24 bit would take up useless space.

But it sounds like you're ripping to MP3, AAC, WMA, or some other compressed file. The quality of these files is usually measured in kbps (kilobits per second), which is the bitrate. It's found by multiplying the bits by the kHz, and then multiplying by 2 if it's stereo. So we can convert CD quality (16 bits, 44.1 kHz) into kbps (bitrate) by multiplying 16 bits x 44.1 kHz x 2 (stereo) and we get 1411 kbps.

So at 1411 kbps, CD quality contains much more information than a 128 kbps MP3 file. The higher the bitrate of the MP3, the closer it sounds to CD quality, but it never quite achieves CD quality, because it uses "lossy" compression.

128 kbps sounds pretty good, and some people can't hear the difference between that and CD quality. But personally, I can. So I usually rip at 192 or 256 kbps. It's an individual thing. Try ripping at different rates and see if you can tell the difference. If not, then you might want to go for the lower bitrate, unless space is no object. If you want full CD quality, rip to WAV, FLAC, or Apple Lossless (iTunes).

Here's a couple good articles that explain PCM, bits, kHz, bitrate, and 16-bit vs 24-bit:

http://en.wikipedia.org/wiki/Pulse-code_modulation

http://www.tweakheadz.com/16_vs_24_bit_audio.htm

http://www.bestmp3links.com/faq/kbps-and-kHz-rate-...