Hi,
On 13-Jun-01 Christopher Ross wrote:
>
> The 4:2:0 is a standard format, derived from CCIR-601 (1982).
> To quote Benoit (ch2 Digitization of Video Signals):
>
> For applications that are less demanding in terms of resolution,
> and in view of the bit-rate reduction, a certain number of
by-products
> of the 4:2:2 standard have been defined as follows:
>
> The 4:2:0 format
> This format is obtained from the 4:2:2 format by using the same
> chroma samples for two successive lines, in order to reduce the
> amount of memory required in processing circuitry while at the
> same time giving a vertical resolution of the same order as the
> horizontal resolution. Luminance and horizontal chrominance
> resolutions are the same as for the 4:2:2 format
> [...snip...]
[snip]
Okay, interesting stuff, but it still fails to address the most basic
question: in what order are the bytes (supposed to be) arranged? It seems
nobody dared to propose a specific format.
> Oh, in searching Amazon to get the above reference for you I found
> that of the two customer reviews the second (5*) is also from a Philips
> employee. This is clearly the book we crib all our stuff from ;-)
*heh*
> I've tried but failed to find the ITU specification itself online (not
> least
> because their website seems to hate Mozilla - but that's a different
> problem). There's a useful summary (with a link to the 4:2:0 variation)
> at http://www.electric-words.com/dict/9/601ccir.html
You have to pay for most ITU documentation, and that�s why you won�t find
it online. And they aren�t cheap. I recall looking for documentation on the
H.263 protocol, etc. and arrived at their site (www.itu.ch), and found that
in order to get enough information about video conferencing stuff, I�d need
a dozen pieces of documentation, ranging in price from CHF 20 to CHF 65
(Swiss franks).
- Nemosoft
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