Talk:Sampling rate
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[edit] Name of article
Question: should this be at Sampling frequency or Sampling rate? The latter seems to be linked a bit more often. (Or is there some obscure difference between the meaning of the two terms that I'm not aware of?) --Brion
- Google reveals far more hits for "sampling rate" than "sampling frequency", so I have moved the page there per Wikipedia:Use common names. —Lowellian (reply) 09:25, 7 July 2006 (UTC)
[edit] CCDs
Regarding video: the sampling frequency is the frame/field rate, rather than the notional pixel clock. All modern TV cameras use CCDs, and the image sampling frequency is the repetition rate of the CCD integration period. -- Anon.
—The preceding unsigned comment was added by 217.158.229.208 (talk • contribs) 16:57, March 18, 2003 (UTC)
- "All modern TV cameras use CCDs" - Not true: some modern TV cameras use CMOS sensors. Ikegami's new HD cameras come to mind. Ehusman 23:40, 8 April 2006 (UTC)
[edit] DVD/BD-ROM/HD-DVD
Regarding:
- 96,000 or 192,400 Hz - DVD, BD-ROM (Blu-ray Disc), and HD-DVD (High-Definition DVD) Audio
They seriously are doing 192.4 KHz sampling rate for audio? Or is 192 two-channel 96 KHz or something? I seriously can't believe they would waste that much space on audio considering that's many times higher than our hearing can hear. Cburnett 04:35, 25 Feb 2005 (UTC)
- You may be surprized, but many professional recorders digitize sound at 192kHz. Remember that recording at a higher resolution will better sample the soundwave and therefore less interpolation is required to recreat the sound when you play it back. A standard cd can only play back sound up to 20,500 Hz in theory, but if you have sound at 20,000 Hz you only have two samples representing the sound wave. Hopefully you can appreciate that 192kHz, although capable of reproducing every high pitched sounds, is used to produce more accurate sound in the range of human hearing. --129.173.105.28 21:34, 29 November 2005 (UTC)
- A good rule of thumb for high fidelity sampling is to sample 7-10 higher than the highest frequency of interest.--User:Ehusman 23:14, 30 November 2005 (UTC)
192.4 kHz is wrong, it should be even 192.0 kHz. I guess someone has mixed this up with 176.4 kHz.
[edit] Audio vs. video sampling rates
Question: Usually, voice is sampled at 8000 samples per second, but video may be sampled at 6000000 samples per second. Why do the two types of signal require different sampling rates? —The preceding unsigned comment was added by 58.106.251.53 (talk • contribs) 04:20, April 3, 2006 (UTC)
- Human hearing operates between 20 Hz and 20 kHz, so the human voice operates well within these two extremes. The human eye only gets "refreshed" about 24 times per second; anything that happens more frequently than that gets blurred together (known as "persistence"). You must sample at a frequency twice the highest frequency you wish to store (something called Nyquist's sampling theorem). Thus, sound is sampled at relatively low rates (you can probably still preserve most voices at 8000 Hz), but video is only at 60 Hz. Your figure of 6000000 Hz is way off - unless you are counting individual pixels or ultra high speed photography, which is a specialized field. Ehusman 23:40, 8 April 2006 (UTC)
