引用:

原帖由 猫猫猫 于 2009-12-16 21:23 发表


愿闻其详

谈画质，谈VGA，谈DVI离不开RAMDAC，貌似没人说到这个嘛，居然直接就说数模转换，还损失，损失具体有多少知道么，怎么看的知道么，笑死了
VGA九年前轻松上到2560*1600*120HZ的路过
以前没外置RAMDAC的DVI能上到多少呢？:D
能看懂么

麻烦喷之前把相关的白皮书看几遍，别那么业余...

TGFC伪高手真多啊:D :D :D

潜潜水算了

[ 本帖最后由 Zico2003 于 2009-12-18 21:45 编辑 ]

今天线到了，HDMI画面绝赞，不过360的设计太脑残了，居然没有单独的音频输出，俺把色差线大卸八块才勉强把HDMI线插了进去。。。。。

引用:

原帖由 Zico2003 于 2009-12-18 21:42 发表


谈画质，谈VGA，谈DVI离不开RAMDAC，貌似没人说到这个嘛，居然直接就说数模转换，还损失，损失具体有多少知道么，怎么看的知道么，笑死了
VGA九年前轻松上到2560*1600*120HZ的路过
以前没外置RAMDAC的DVI能上到 ...

牛逼哄哄的专业淫士垒猴, 牛逼哄哄的专业淫士拜拜

别说1080P, 就算1680的分辨率,  觉得VGA已经干扰严重, 不胜负荷的小白用户飘过

[ 本帖最后由 猫猫猫 于 2009-12-18 22:08 编辑 ]

引用:

原帖由 OpEth 于 2009-12-18 21:48 发表
今天线到了，HDMI画面绝赞，不过360的设计太脑残了，居然没有单独的音频输出，俺把色差线大卸八块才勉强把HDMI线插了进去。。。。。

其实我用的是分量....
哈哈哈


老版本豪华版, 无HDMI接口, 只能用分量了, 原配线. 平时只用720P分辨率(接电视机47inch)

为什么XO开始没有HDMI至今也没有DVI, 原因一就是伪卵短视, 二就是因为DVI/HDMI效果太牛逼
它怕大家数字无损复制盗版. 所以只给大家VGA和分量, AV

最后仿天师大喊一声, 统统垃圾!!　　ＲＧＢ最高！！

[ 本帖最后由 猫猫猫 于 2009-12-18 22:12 编辑 ]

转篇不错的文章

e.271828.p.31415@gmail.com wrote:
>> The VGA connector has no limit. I have a CRT monitor that will do 2048x1536,
>> so no worries there.
>
> How does this relate to the fact that some 30'' LCD monitors require a
> dual connector in a higher end graphics card in order to run?
>

There are a couple ways to interface to a monitor.

The analog way, is via a 15 pin VGA connector. The
RGB signals on the VGA, send the three primary colors
to the screen.

As the resolution increases on the VGA interface, the
analog "bandwidth" requirement of the components has to improve
to keep up. Many video cards have a 400MHz DAC on the VGA
connector, which appears to be suitable for 2048x1536 or so.
(At least that is a typical maximum number listed.) The
cabling used, also has a bandwidth spec, which is why,
if you use a long cable, the maximum resolution that works
well, will drop. Even the connectorization can play a part,
and if you wanted a really high quality interface, you'd want
set of coax cables, instead of the VGA connector. (This is
because the VGA connector is not a perfect transmission line
environment, and using coax connectors would be better.)
So while VGA is theoretically unlimited, the effects of PI
filters, DAC bandwidth, cable bandwidth, connector quality,
all take their toll on image quality.

You might not find the visual quality of a 2048x1536 analog
connection to be that good. One compromise, is on the video
card itself. The designers use "PI filters", to remove
EMI from the video signals. Doing so, will degrade the
sharpness of the display. And this becomes more obvious
at higher resolutions. While 1280x1024 may look good, there
are no guarantees as you go higher.

So while the video card maker may claim 2048x1536 resolution
is possible over a VGA connection, the resultant image may
not be usable.

A second alternative, is a digital connection via a DVI connector.
Here, all that matters, is that the digital data move across
the cable, without the bit values being corrupted. As far as
I know, DVI has no error correction, so if some of the bits
arrive flipped, you would get colored "snow" on the screen.
That would tell you that the DVI cable is poor quality, or
that the digital bandwidth of the output interface, is not
sufficient for the job. There are articles, where various
brands of video cards, have their DVI digital output
checked, and the test used, is to look at the "eye opening"
of the signal. That spec tells you whether the receiver will
be able to pick up the digital signal OK. A good or bad
"eye" is shown in pictures here. The six-sided blue area
in the picture, is the zone to stay out of.

http://www.siliconimage.com/docs/Sit...-CTC_FINAL.pdf

In terms of DVI resolution support, there are single and
dual link DVI connections. A dual link DVI carries twice the
data of a single link, by virtue of using more of the pins.

DVI has a "clock" spec of maximum around 165MHz. During one
clock period, something like 10 data bits are passed on the
cable. Which means the data rate on the cable, is something
like 1650Mbit/sec. This is a pretty high rate, and is why
the cable quality or length can make a difference.

There are some entries in a table on this page, showing
possible resolution settings, and the data rates involved.

http://en.wikipedia.org/wiki/Dvi

A dual link DVI card (you have to check the spec to see if
it is so-equipped), can do 2048x1536 @ 75Hz. But to do it,
the link "clock rate" is 170MHz. Which demands a good
quality DVI output device on the video card. Also, a cheap
or longish cable, could cause an attempt to run this
way, to have "snow" on the screen.

QXGA (2048 × 1536) @ 75 Hz with GTF blanking (2×170 MHz)

But chances are, if you compare attempting to transmit
2048x1536 over analog, versus via DVI, the DVI will win
on visual quality. To make the analog work, you'd probably
have to take your soldering iron, and remove the PI filters
from the RGB signal path, in order to get a clean signal
from the VGA connector. The DVI should be sharper, as there
is no analog bandwidth degradation along the way. As long
as a bit is received digitally, without corruption, the
monitor now has exactly the same info content, as was present
at the output connector of the video card.

Paul

引用:

原帖由 Zico2003 于 2009-12-18 21:42 发表


谈画质，谈VGA，谈DVI离不开RAMDAC，貌似没人说到这个嘛，居然直接就说数模转换，还损失，损失具体有多少知道么，怎么看的知道么，笑死了
VGA九年前轻松上到2560*1600*120HZ的路过
以前没外置RAMDAC的DVI能上到 ...

数字输出不需要ramdac