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Is compression used in CDs?
plazz
post Jul 10 2002, 18:48
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Is any kind of compression at all used in audio CD's? I know that there is on DVD's, just at a huge bitrate.
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gdougherty
post Jul 11 2002, 04:46
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QUOTE
Originally posted by bryant
And the data is also truncated to 16 bits, which is yet another form of compression. No wonder CDs sound so bad!


First, on topic comment. *Some* CD's do use compression, but they're not really considered CD's even though they use CD in their name. DTS CD's use DTS compression and are recorded on CD media. Standard CD's that conform to Red Book and are playable on any CD player do not use any compression.

Now, the off-topic reply to Bryant's comment.

Due to the distortion inherent in any PCM sampled audio, 44.1Khz requires a low pass filter, which, if poorly designed and implemented, does have an effect on the audio. 96, or 88.2Khz sampling rates move these distortions way up into the inaudible range and negate the need for a low pass filter. Arguably a very well designed 44.1 DAC would sound as good as any decent 96Khz DAC unless you're one of the extremely rare people who can hear above 20Khz.

Bit depth shouldn't make any real difference except in edit calculations. 24bit over 16bit just gives you more headroom before the signal clips, so a proper 16-bit recording is capable of having just as much audible dynamic range. Most equipment (both recording and playback) has enough inherent noise that the dynamic range issue is truly moot. The public expects music to be squashed down these days anyways, and 14dB of average dynamic range is considered to be a good amount of dynamics that far exceeds the average of any modern pop or rock album. Classical and Jazz are the real bastions of dynamic range and even there 16-bit as a playback medium is very adequate.

Contrary to your statement there isn't any inherent bit truncation that occurs with 16-bit files. Music properly recorded at 16-bit and never digitally amplified past the zero mark of 16-bit would never be truncated as I understand things. Generally 24-bit resampled down to 16-bit using a very good algorithm doesn't necessarily truncate the signal and toss out the dynamic range in the 24-bit sample. Anything in the dynamics that would be tossed are likely inaudible unless you've got things up so loud that the louder sections would make your ears bleed (ie, it drops the bottom, not the top of the signal).

Listening tests have shown that good digital equipment is on par with analog while also having better s/n ratios. Crappy analog often "fails" more gracefully than digital, which is the major difference. Really, digital or analog, good equipment sounds good, bad equipment sounds bad. IMO, most of the people who ooh and aah over analog are generally hearing what they want to hear or simply prefer the distortions, compression and "warm" inaccuracies often added by analog equipment.

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Posts in this topic
- plazz   Is compression used in CDs?   Jul 10 2002, 18:48
- - rjamorim   QUOTE Originally posted by plazz Is any kind of c...   Jul 10 2002, 18:50
- - Speek   Yes, there are only 44100 samples per second (per ...   Jul 10 2002, 19:47
- - bryant   QUOTE Originally posted by Speek Yes, there are o...   Jul 10 2002, 20:05
- - rjamorim   QUOTE Originally posted by bryant No wonder CDs s...   Jul 10 2002, 20:09
- - fewtch   QUOTE Originally posted by rjamorim WHA? Are y...   Jul 10 2002, 20:22
- - The Belgain   Can anyone tell the difference between 16bit 44.1 ...   Jul 10 2002, 20:27
- - rjamorim   QUOTE Originally posted by The Belgain Can anyone...   Jul 10 2002, 20:41
- - Pio2001   It's a bit like the sound of CDR : there is the sa...   Jul 10 2002, 21:05
- - bryant   QUOTE Originally posted by rjamorim Be prepared, ...   Jul 10 2002, 21:29
- - Frank Klemm   QUOTE Originally posted by bryant Very true, Spee...   Jul 10 2002, 21:38
- - plazz   QUOTE Originally posted by rjamorim I would bel...   Jul 10 2002, 22:12
- - [JAZ]   QUOTE was developed in the 1920's or 30's Man! at...   Jul 10 2002, 22:38
- - Frank Klemm   QUOTE Originally posted by plazz Sony and Phili...   Jul 10 2002, 22:39
- - smg   QUOTE Originally posted by Frank Klemm Refutabl...   Jul 10 2002, 22:41
- - bryant   QUOTE Originally posted by plazz Sony and Philips...   Jul 10 2002, 22:47
- - plazz   I stand corrected. I has thinking of Alec H. Reeve...   Jul 11 2002, 00:02
- - Frank Klemm   QUOTE Originally posted by [JAZ] Man! at that t...   Jul 11 2002, 01:44
- - SometimesWarrior   Thank you for the history lesson, Mr. Klemm! It's...   Jul 11 2002, 02:57
- - gdougherty   QUOTE Originally posted by bryant And the data is...   Jul 11 2002, 04:46
- - JonPike   QUOTE Originally posted by plazz Is any kind of c...   Jul 11 2002, 04:55
- - godzilla525   I have a portable CD player that has anti-skip mem...   Jul 11 2002, 06:30
- - bryant   QUOTE Originally posted by gdougherty Contrary to...   Jul 11 2002, 06:45
- - JonPike   QUOTE Originally posted by godzilla525 I have a p...   Jul 11 2002, 07:02
- - godzilla525   RightMark's test tones are way too short. They do...   Jul 11 2002, 07:57
- - Mr. Mulder   QUOTE Originally posted by godzilla525 RightMark'...   Jul 11 2002, 09:59
- - westgroveg   So then if vinyl records are not compressed they s...   Jul 11 2002, 10:05
- - JonPike   I'll have to go looking thru some bookmarks.. In ...   Jul 11 2002, 10:40
- - KikeG   QUOTE Originally posted by bryant And when 24-bit...   Jul 11 2002, 14:18
- - KikeG   QUOTE Originally posted by westgroveg So then if ...   Jul 11 2002, 14:27
- - godzilla525   Thanks for the links.   Jul 11 2002, 18:32
- - westgroveg   QUOTE Originally posted by KikeG Vinyl records ...   Jul 12 2002, 08:33


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