[opendtv] Re: Precision
- From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 26 May 2007 10:20:15 -0700
Sure, "aliasing" first entered the video lexicon when people tried to put
graphics on top of video, or tried to superimpose video. Those come from
the 1950's and 1960's, perhaps earlier.
Audio aliasing wasn't something that I heard about until the mid/late
1970's, when PCM encoding (u-law and A-law) and quantization error came up
against analog audio as the input source and output target, with PCM in
between.
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de negrjp
Enviado el: Friday, May 25, 2007 2:52 AM
Para: opendtv
Asunto: [opendtv] Re: Precision
Very Interesting!
In video domain is possible aliasing phenomenom?
For LP records nostalgia, Look this :
http://www.elpj.com/index.html
Jonas
In video, how much precision is enough?
Let us take audio as an example. Audio can be sampled at 48,000 samples per
second, 16 bit, and it is "CD" quality. But sample at 192Khz at 24 bit,
process, downconvert, encode, etc., and the quality is markedly better than
when produced at the previously stated format. Of course, we are only
dealing with one axis, representing pressure, and time (or are we?).
However, if we sample audio at 384Khz at 48 bits, I bet not but three people
in the world could tell a difference from the audio produced at 192Khz at 24
bits. So there is a point to which we have human limitations and there is no
reason to sample higher or with more "precision" (Law of diminishing
returns), save research areas.
However, there is a weak link to this aforementioned audio recording:
spatial offset. Even with 7.1 surround sound, there is still spatial gaps to
fill with audio. So there is still room for improvement. But it is not in
sampling frequency or bit depth that will make the difference.
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