TV through wireless LAN

Hi.
I'd like to get TV on my laptop through my home LAN.
Should I aim at W-Fi 5 or is 11 MB fast enough ?
Thanks.
Alain

Could you be more vague?

It is hard to answer the question without more details. What is the encoding
scheme, framerate, etc?

Jeremy

"Alain" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi.
> I'd like to get TV on my laptop through my home LAN.
> Should I aim at W-Fi 5 or is 11 MB fast enough ?
> Thanks.
> Alain
>

Well, I'm not sure of the details, but maybe this will help.
There are several ways ot transmit video. Among others that come to mind
are SVCD, Mpeg1, MPeg2 and MPeg4, not to mention variants of things like
RealVideo and WMV.

As a truly overgeneralized statement, MPEG1 and MPEG2 really do like
bandwidth. 802.11b and b+ really do have trouble with this. Yes, it can be
done, but the video quality will be noticably poor and that doesn't include
effects of interference. 802.11a has a chance at an average of 20Mbs
(802.11a v.2) but even it needs better QOS support.

Compressed video such as the the real or WM formats, can be done over
802.11a or g, but the real question remains:

- What video quality are you looking for?
- What wireless network are you planning to employ?

"Alain" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi.
> I'd like to get TV on my laptop through my home LAN.
> Should I aim at W-Fi 5 or is 11 MB fast enough ?
> Thanks.
> Alain
>

John,
Thanks for your answer.

<<What wireless network are you planning to employ?>>

I'm aiming at 802.11g (54MB compatible 11b).
I'm just hesitating concerning the brand : SMC vs. DLINK particularly.
SMC seems particularly nice.

<< What video quality are you looking for>>

Well, I'd just like to have the "non-numeric" TV standard quality.

<<bandwidth>>

Below, I tried to reproduce an embryo of computation of the necessary
bandwitdth that I read somewhere, but I'm not sure of the logic:

Assuming a 640 * 480 resolution = 307'200 bits.
Let's make it 400'000 for the (probable) control bits, the tip for the
waiter, blahblah.

400'000 * 24 images per sec = 9'600'000 bits p/sec,

9'600'000 bits p/sec divided by 8 = 1'200'000 bytes which sounds like
a bit more than 1 MB.

Sounds really inexpensive in terms of bandwith. And I did not even
mention the compression.
Where is the bug ? Does a pixel equal a bit ? Or am I mixing things
up ?

<<conversion TV signal - MPEGx possible>>
Hallelujah.
What hardware and program will I have to acquire :-) ? Any trap I
should be aware of ? Buffering e.g. ?

Thanks a lot for your help.
Alain



On Thu, 10 Jul 2003 13:19:13 -0700, "John Antypas" <(E-Mail Removed)> wrote:

>Well, I'm not sure of the details, but maybe this will help.
>There are several ways ot transmit video. Among others that come to mind
>are SVCD, Mpeg1, MPeg2 and MPeg4, not to mention variants of things like
>RealVideo and WMV.
>
>As a truly overgeneralized statement, MPEG1 and MPEG2 really do like
>bandwidth. 802.11b and b+ really do have trouble with this. Yes, it can be
>done, but the video quality will be noticably poor and that doesn't include
>effects of interference. 802.11a has a chance at an average of 20Mbs
>(802.11a v.2) but even it needs better QOS support.
>
>Compressed video such as the the real or WM formats, can be done over
>802.11a or g, but the real question remains:
>
>- What video quality are you looking for?
>- What wireless network are you planning to employ?
>
>"Alain" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> Hi.
>> I'd like to get TV on my laptop through my home LAN.
>> Should I aim at W-Fi 5 or is 11 MB fast enough ?
>> Thanks.
>> Alain
>>
>
>

Here is some software to check out, you can stream live TV with it.. It uses
WMV for streaming. Works well for me.

http://snapstream.com/

"Alain" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi.
> I'd like to get TV on my laptop through my home LAN.
> Should I aim at W-Fi 5 or is 11 MB fast enough ?
> Thanks.
> Alain
>

> 740x480 uncompressed priceless

Like you said, he hadn't taken colour into account and if you assume 24
bit then you're looking in the order of 25Mbytes/sec. That starts to
get tough on other components like disks too, as well as storage space.

Not worth it unless you're in the industry.

> I'm not sure exactly how mpeg2 would do but afaik dvds are in mpeg2 so
> something like:
>
> 2GB/hr / 360s/hr * 8bits/byte = 4.4Mb/s

Which doesn't take into account variable bit rate compression, DVD spec
MPEG2 is allowed a peak bitrate of 9Mbps which is going to be a push for
WLAN's too.

David.

Dear David,
Tnx for your answer.

<<Might manage it with the g.>>

That's my intention.
54 MB for two users should be acceptable I hope :-)

Concerning the bandwith required by the feed : I'm reading a book in
French which indicates that high definition TV is based on
"luminance", which requires a 720x480 pixels resolution, where
"chrominance" (normal TV) only requires 360x240. So the color aspect
(mentionned in another post) does not seem to be show stopper, does
it?

<<I used to use a TV card feeding into RealServer and would send that
around the wireless network to my laptop.>>

That's exactly what I'm looking for. So you installed the TV card onto
a PC, fed RealServer, and were able to get live TV using a connected
laptop? Congratulations.
Did you face any problem or do you have any recommendation for the
setup / parameters ?

Tnx
Alain



On Fri, 11 Jul 2003 09:13:42 +0100, David Taylor
<(E-Mail Removed)> wrote:

>> 9'600'000 bits p/sec divided by 8 = 1'200'000 bytes which sounds like
>> a bit more than 1 MB.
>>
>> Sounds really inexpensive in terms of bandwith. And I did not even
>> mention the compression.
>> Where is the bug ? Does a pixel equal a bit ? Or am I mixing things
>> up ?
>
>You're saying there 1MByte/sec. You'll be lucky to get 500kbytes/sec
>with domestic 802.11b gear. Might manage it with the g.
>
>I used to use a TV card feeding into RealServer and would send that
>around the wireless network to my laptop.
>
>That worked very well. A high bitrate (we're talking 300kbytes/sec for
>Real) on 352 x 288 (25fps) was a great picture.
>
>David.

On Fri, 11 Jul 2003 15:01:29 +0200, Alain <(E-Mail Removed)> wrote:

>Concerning the bandwith required by the feed : I'm reading a book in
>French which indicates that high definition TV is based on
>"luminance", which requires a 720x480 pixels resolution, where
>"chrominance" (normal TV) only requires 360x240. So the color aspect
>(mentionned in another post) does not seem to be show stopper, does
>it?

An NTSC DVD is (AIRC) 720x480 x 29.97 fps. PAL is 720x576 x 25 fps.

At 24 bits per pixel that's 720 x 480 x 29.97 x 24 = 248,583,168 bits
per second for NTSC and 720 x 576 x 25 x 24 = 248,832,000 bits per
second for PAL. That's pretty big. But that's uncompressed video
for you.

As another poster has said, DVDs peak at around 9 Mbit/second. It's
amazing that such good quality is achieved with such extreme compression.

Digital satellite TV channels (here in the UK anyway) tend to peak at
about 4 Mbit/sec, which should be just about doable on 802.11b.

--
Jim Hatfield

With digital TV signal only part of the picture information is transmitted -
the first picture is sent then only the infomation that has changed since
the first picture is transmitted - so if you are watching a news program
where the presenter is seated down in front of a fixed backdrop not much
information is needed to be transmitted - the problem occurs when lots of
fast moving images have to be sent - sometimes you can see this on DVD's
when the pictures break up as they use the same princples.

This helps to keep the bandwidth down.

Jim Hatfield wrote:
> On Fri, 11 Jul 2003 15:01:29 +0200, Alain <(E-Mail Removed)>
> wrote:
>
>> Concerning the bandwith required by the feed : I'm reading a book in
>> French which indicates that high definition TV is based on
>> "luminance", which requires a 720x480 pixels resolution, where
>> "chrominance" (normal TV) only requires 360x240. So the color aspect
>> (mentionned in another post) does not seem to be show stopper, does
>> it?
>
> An NTSC DVD is (AIRC) 720x480 x 29.97 fps. PAL is 720x576 x 25 fps.
>
> At 24 bits per pixel that's 720 x 480 x 29.97 x 24 = 248,583,168 bits
> per second for NTSC and 720 x 576 x 25 x 24 = 248,832,000 bits per
> second for PAL. That's pretty big. But that's uncompressed video
> for you.
>
> As another poster has said, DVDs peak at around 9 Mbit/second. It's
> amazing that such good quality is achieved with such extreme
> compression.
>
> Digital satellite TV channels (here in the UK anyway) tend to peak at
> about 4 Mbit/sec, which should be just about doable on 802.11b.

> With digital TV signal only part of the picture information is transmitted -
> the first picture is sent then only the infomation that has changed since
> the first picture is transmitted - so if you are watching a news program
> where the presenter is seated down in front of a fixed backdrop not much
> information is needed to be transmitted - the problem occurs when lots of
> fast moving images have to be sent - sometimes you can see this on DVD's
> when the pictures break up as they use the same princples.

MPEG Compression