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- TV Tuner / Laptop Hardware Question...
- Ray Garcia
November 21, 2005, 10:12 pm
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spring so in order to save space, I will be buying a new laptop in the
coming month. In doing my research, I've run into a couple problems...
Ideally I'd like a desktop replacement system so Im looking for
something reasonable powerfull. Im not interested in gaming at all,
but I occassionally do some video, and frequently do some photo,
Since my main concern is SAVING SPACE in my room. My ideal setup is a
laptop with a 14 inch screen and my 19 inch LCD attached to it so I can
move programs from my laptop screen to my LCD screen when neccesary.
More importantly though, I want my laptop to have a TV tuner so I can
use my 19 inch monitor to watch TV and play my XBox through my laptop,
allowing me to skip buying a TV. My question is if I get a laptop with
a TV tuner, will watching TV and playing my XBox through my laptop onto
my 19 inch screen use up much processing power?
I plan on getting a top Pentium M processor (Which I beleive is 2.16
now) and 1 GB of RAM, so I figure I should have a reasonable amount of
power, but I dont want to open up a window on my laptop to watch TV,
move it over to my LCD monitor, and have it slow down my system a
If this is the case, I will most likely buy an external TV Tuner box
that I can plug the cable, XBox, and my laptop into to use my monitor,
but I would much rather NOT do this. I'd rather have the ability to
control the size of the window playing the TV on my 19" monitor as
opposed to it taking up the whole screen.
If anyone has any suggestions or is aware of whether or not a TV tuner
uses the CPUs processing power, please let me know.
Re: TV Tuner / Laptop Hardware Question...
It is pretty hard to to generalize, but I would guess a typical
TV Tuner would be:
1) A mini-PCI card, sitting on the PCI bus.
2) Tuner card captures video, stream is then compressed for easy
movement to system memory. MPEG or MJPEG might be the format.
3) By using DMA, transfer of the stream to system memory, and from
system memory to disk, is a reasonably lightweight process.
That means PVR style recording is invisible to you.
4) Decoding the stream, and reconstituting the image, takes some
kind of processing power. Decoding could be done by a chip on
the TV tuner card itself (meaning something like 27MB/sec data
would have to come across the PCI bus, to get to the video card).
It could be done by the processor only (pretty heavyweight). It
can be assisted by the video card. Most GPUs support IDCT (inverse
discrete cosine transform), which aids the decompression process.
Newer GPUs now have programmable video engines, but these
haven't been impressive to date (not sure if they are bug free
yet). I haven't seen any update on the state of the programmable
video engines, since they were first introduced.
Sample mini-PCI tuner:
Considering how lazy the average designer is, I would expect a
measurable load on your laptop CPU while watching TV. Just picking
a number out of thin air, I'll guess 20%-30% loading, at least
until I see some evidence that programmable video processor technology
inside the GPU is doing what it claims to be able to do.
Marketing or reality ? Hard to say...
So, to research this yourself, try to find a review of some
of the mobile GPUs currently being made, and see if the reviews
benchmarked CPU utilization for video playback. That might
give you some idea as to how mature the programmable video
processor block is, in a modern GPU.
This could end up being mainly a software issue. Say the TV tuner
application, isn't smart enough to use the programmable video engine
on the video card. The TV tuner application that comes with the laptop,
might use its own software-only decoder. In which case, buying a
third party TV application might help, if the tuner card has a
standard API, and the third party TV application knows about the
capabilities of the video card.
This program, looks to me like it uses IDCT on playback.
(Based on the kind of video cards it can use for playback.)
Look for programs like this, but ones that can tap into the
programmable video processor on the GPU.
Hope that is some help,