Related: Digital Cinema uses a 48Khz sample rate which gives exactly 2000 samples per frame, per channel. That makes it very easy to sync the audio to the film.
Explanation of 44.1 kHz CD sampling rate
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Re: Explanation of 44.1 kHz CD sampling rate
#32Earlier quoted context omitted.
Actually 44.1kHz is unhelpful for that... a lot of infrastructure exists that expects things to work on 10 and 20ms intervals (and multiples there-of), e.g. the normal windows audio apis work in 10ms chunks. 10ms of 44.1kHz is 441 samples, which is odd and thus a not really fantastic size for easily implemented factorizations. Of course, if you can pick your own analysis interval you can pick some nice power of two o…
Almost all ASR engines use 25ms windows, not 10ms (they typically overlap and are processed every 10ms).
25ms of 44.1kHz isn't even an integer. So the original argument is even less compelling with 25ms windows than it was with 10ms windows.
Re: Explanation of 44.1 kHz CD sampling rate
#33Related: Digital Cinema uses a 48Khz sample rate which gives exactly 2000 samples per frame, per channel. That makes it very easy to sync the audio to the film.
At 25fps and 48Khz you rather neatly have 1920 samples per frame, which is coincidentally the width of an HD picture. At least I think it's a kind of a coincidence... I believe the number 1920 was derived from the 720 horizontal pixels of Rec. 709, which doubled give a 1440 pixel 4:3 picture and hence a 1920 pixel 16:9 picture.
The 48Khz rate used by everything apart from CDs also came from video standards according to http://www.tvtechnology.com/opinions/0087/digital-audio-samp...
Here's some more about the number-theory used in digital video, from 1990 during the standardisation of HD: http://www.poynton.com/papers/SMPTE_90_Magic_Numbers.html
Re: Explanation of 44.1 kHz CD sampling rate
#34https://www.youtube.com/watch?v=GAE-c7aksxI shows what audio recorded this way looks like when you play it back as video.
I'm only guessing but it looks like 3 stereo samples per line plus some extra data (ECC?) on the right. Its quite interesting to see how the pattern changes when the music fades out (around 3:50, 9:20, and 13:25).
I wonder what kind of sound you could extract given only the low-quality YouTube video as a source.
Re: Explanation of 44.1 kHz CD sampling rate
#35It's also convenient that highest frequencies a human ear can detect is about 20khz, so the sampling rate needs to be at least 40khz (see "Nyquist Rate")
Re: Explanation of 44.1 kHz CD sampling rate
#36Earlier quoted context omitted.
Why are you splitting 44100 samples into windows? That's the number of samples in one second. Where did you get one second from? You could have started from any duration.
I see what you mean, but since the 1970s speech researchers have been splitting seconds into 10ms or 25ms intervals, that's not my decision. They could have started from any duration but they haven't. And you could start to express time with the Aztec calendar if you wanted. But you won't.
It's not (entirely) arbitrary. Speech is variable, our vocal tract shape changes all the time, but not arbitrarily fast. From a source-filter theory perspective it does make sense to consider speech production over short time frames as linear time-invariant systems.
What this has to do with 44.1 kHz is beyond me, however..
Re: Explanation of 44.1 kHz CD sampling rate
#37This confuses me because the vertical rate is not 60 Hz, it's 3579545 Hz / (525/2 * 455/2) = 59.94 Hz. In other words it's odd that they would have chosen to be compatible with black and white instead of color.. instead of 44.1 KHz, it would be 44.056 KHz. Edit: Well it turns out that 44.056 KHz was used for the "EIAJ digital-audio-on-videotape standard" http://recordingtheworld.infopop.cc/eve/forums/a/tpc/f/22260...
Keen. Sony was originally proposing 44.056 kHz (NTSC - popular in Japan) with 16 bits while Philips was pushing for 44.1 kHz (PAL - popular in Europe) with 14 bits. The two reconciled their differences at the 4th Red Book meeting in 1980[1]. Sony was further ahead in developing the CD players but Philips supposedly was in the lead when it came to making the CD's[2]. Sony insisted on 16 bit vs while Philips was pushin…
Quite a lot of early CD players were actually 14 bits. Many early CDs were probably mastered with 14 bits in mind too, as they have a noticeably low average mix level.
Re: Explanation of 44.1 kHz CD sampling rate
#38Earlier quoted context omitted.
Keen. Sony was originally proposing 44.056 kHz (NTSC - popular in Japan) with 16 bits while Philips was pushing for 44.1 kHz (PAL - popular in Europe) with 14 bits. The two reconciled their differences at the 4th Red Book meeting in 1980[1]. Sony was further ahead in developing the CD players but Philips supposedly was in the lead when it came to making the CD's[2]. Sony insisted on 16 bit vs while Philips was pushin…
Quoting your first link [ http://www.realhd-audio.com/?p=2197 ]... ❝Of course, lots of CDs were released with the original 44.056 kHz rate simple reclocked at 44.1 kHz. This resulted in a very slight speed increase AND a pitch shift of less than a quartertone.❞ While technically true (less than a quartertone), it's much, much, much less than a quartertone. It's 1.7cent (1.7 percent of a half-tone, or 1/30th of a quar…
Here's what happens when you do mix up 44.1 khz and 48 khz.
Van Halen - Jump (Greensboro): http://youtu.be/Mjx_GjyXCs4
Re: Explanation of 44.1 kHz CD sampling rate
#39Earlier quoted context omitted.
Keen. Sony was originally proposing 44.056 kHz (NTSC - popular in Japan) with 16 bits while Philips was pushing for 44.1 kHz (PAL - popular in Europe) with 14 bits. The two reconciled their differences at the 4th Red Book meeting in 1980[1]. Sony was further ahead in developing the CD players but Philips supposedly was in the lead when it came to making the CD's[2]. Sony insisted on 16 bit vs while Philips was pushin…
Quite a lot of early CD players were actually 14 bits. Many early CDs were probably mastered with 14 bits in mind too, as they have a noticeably low average mix level.
That makes no sense at all. A 14-bit player would play the top 14-bit.
Playing the bottom 14-bits would make anything with nonzero top two bits sound mostly like noise.
Re: Explanation of 44.1 kHz CD sampling rate
#40In the Wikipedia it states that the CD's capacity target was to hold Beethoven's Ninth Symphony on one CD. There was a tale that this and the desire to fit a CD in a standard Japanese car stereo form factor determined the sampling rate. Submitted for your amusement.