One more try - cheap HDTV camcorder

Archived from groups: alt.tv.tech.hdtv (More info?)

I want to build my own HDTV camcorder by hooking up a high end webcam (or
other similar USB camera) to a laptop computer with a large hard drive. Is
this doable? Will the results be good?

Archived from groups: alt.tv.tech.hdtv (More info?)

THICK!.............. So what part of NO is difficult for you to understand?



"Bootstrap Bill" <wrcousert@yahoo.com> wrote in message
news:j2kSc.242271$IQ4.33702@attbi_s02...
>I want to build my own HDTV camcorder by hooking up a high end webcam (or
> other similar USB camera) to a laptop computer with a large hard drive. Is
> this doable? Will the results be good?
>
>
>
>

Archived from groups: alt.tv.tech.hdtv (More info?)

Bootstrap Bill wrote:
> I want to build my own HDTV camcorder by hooking up a high end webcam (or
> other similar USB camera) to a laptop computer with a large hard drive. Is
> this doable? Will the results be good?
>
>
>
>


USB Camera?

Let us assume that your "webcam" can capture HD resolution. And it
doesn't do MPEG2 compression in hardware (none do, AFAIK). That is
1920x1200 pixels, at 30 fps. Each pixel takes 4 bytes of storage
space to encode true color.

Now for some math!

1920 x 1200 x 4 x 30 = 276,480,000 bytes per second.

That's a spicy meatball!

Then you need to crunch that down using MPEG2 compression. In real
time. On a laptop. If a laptop is even capable of that kind of
computational power it'll set itself on fire.

I'd venture the answer to your question is "no".

;-)

Archived from groups: alt.tv.tech.hdtv (More info?)

"Michael J. Sherman" <msherman@dsbox.com> wrote:

>Let us assume that your "webcam" can capture HD resolution. And it
>doesn't do MPEG2 compression in hardware (none do, AFAIK). That is
>1920x1200 pixels, at 30 fps. Each pixel takes 4 bytes of storage
>space to encode true color.
>
>Now for some math!
>
>1920 x 1200 x 4 x 30 = 276,480,000 bytes per second.
>
I think there's something wrong here. A standard TV signal fits in a
4.5 MHz channel. The output of a DVD is about 6 Mbps (that's
megabits), and a full HDTV signal is about 20Mbps. That's too fast
for USB1, but could travel over USB2 or 802.11g.

A DVD movie is (say) 90 min * 60s/m * 6Mbps / 8 bits/byte = 4Gb.

For OTA broadcast, the 20Mbps HDTV signal is compressed into an Mpeg2
stream that fits into the same old 4.5MHz TV channel.

Archived from groups: alt.tv.tech.hdtv (More info?)

Guy Gordon wrote:

> "Michael J. Sherman" <msherman@dsbox.com> wrote:
>
>
>>Let us assume that your "webcam" can capture HD resolution. And it
>>doesn't do MPEG2 compression in hardware (none do, AFAIK). That is
>>1920x1200 pixels, at 30 fps. Each pixel takes 4 bytes of storage
>>space to encode true color.
>>
>>Now for some math!
>>
>>1920 x 1200 x 4 x 30 = 276,480,000 bytes per second.
>>
>
> I think there's something wrong here. A standard TV signal fits in a
> 4.5 MHz channel. The output of a DVD is about 6 Mbps (that's
> megabits), and a full HDTV signal is about 20Mbps. That's too fast
> for USB1, but could travel over USB2 or 802.11g.
>
> A DVD movie is (say) 90 min * 60s/m * 6Mbps / 8 bits/byte = 4Gb.
>
> For OTA broadcast, the 20Mbps HDTV signal is compressed into an Mpeg2
> stream that fits into the same old 4.5MHz TV channel.
>
>

That's because it is already compressed using MPEG2. The above
numbers were for an uncompressed stream.

Archived from groups: alt.tv.tech.hdtv (More info?)

"Hasenpfeffer" <hasenpfeffer@triad.rr.com> wrote in message
news:xqJSc.191720$tH1.9548396@twister.southeast.rr.com...
>
> "hunkahunkaburninluv" <some@where.come> wrote in message
> news:2nvb26F53cggU1@uni-berlin.de...
> >
> > "Michael J. Sherman" <msherman@dsbox.com> wrote in message
> > news:jp6qu1-tis.ln1@developers.dsbox.com...
> > > Bootstrap Bill wrote:
> > > > I want to build my own HDTV camcorder by hooking up a high end
webcam
> > (or
> > > > other similar USB camera) to a laptop computer with a large hard
> drive.
> > Is
> > > > this doable? Will the results be good?
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > > USB Camera?
> > >
> > > Let us assume that your "webcam" can capture HD resolution. And it
> > > doesn't do MPEG2 compression in hardware (none do, AFAIK). That is
> > > 1920x1200 pixels, at 30 fps. Each pixel takes 4 bytes of storage
> > > space to encode true color.
> > >
> > > Now for some math!
> > >
> > > 1920 x 1200 x 4 x 30 = 276,480,000 bytes per second.
> > >
> > > That's a spicy meatball!
> > >
> > > Then you need to crunch that down using MPEG2 compression. In real
> > > time. On a laptop. If a laptop is even capable of that kind of
> > > computational power it'll set itself on fire.
> > >
> > > I'd venture the answer to your question is "no".
> > >
> > > ;-)
> >
> > I'll bet that cell phones will be able to do all this and store ten
hours
> of
> > video internally within five years. Not only that, but they'll be able
to
> > dump their entire contents to an FTP server in less than ten minutes.
> >
>
> I take that bet! How much?
> I bet that things like that will probably take 50 years. Consider where
> technology has been in 1999....it really hasn't changed much, only more
> applications are available.

There are several devices on the horizon that promise to put as much as ten
terabytes of storage in a solid state device the size of a sugar cube in the
next few years. Wireless internet is available at T1 speed today. In five
years, it will probably be at least ten times faster. Look at how far
digital cameras have come in the past few years. They will almost certainly
be capapble of better than HDTV resolution in five years. Add that up and
you have something similar to what I predicted.

In five years, you'll be able to buy it for $1500. In ten years it will be
in the bargain bin at Kmart. In 20 years it will be at the dollar stores.

Archived from groups: alt.tv.tech.hdtv (More info?)

"hunkahunkaburninluv" <some@where.come> wrote in message
news:2o3e5dF5vlvcU1@uni-berlin.de...
>
> "Hasenpfeffer" <hasenpfeffer@triad.rr.com> wrote in message
> news:xqJSc.191720$tH1.9548396@twister.southeast.rr.com...
> >
> > "hunkahunkaburninluv" <some@where.come> wrote in message
> > news:2nvb26F53cggU1@uni-berlin.de...
> > >
> > > "Michael J. Sherman" <msherman@dsbox.com> wrote in message
> > > news:jp6qu1-tis.ln1@developers.dsbox.com...
> > > > Bootstrap Bill wrote:
> > > > > I want to build my own HDTV camcorder by hooking up a high end
> webcam
> > > (or
> > > > > other similar USB camera) to a laptop computer with a large hard
> > drive.
> > > Is
> > > > > this doable? Will the results be good?
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > > USB Camera?
> > > >
> > > > Let us assume that your "webcam" can capture HD resolution. And it
> > > > doesn't do MPEG2 compression in hardware (none do, AFAIK). That is
> > > > 1920x1200 pixels, at 30 fps. Each pixel takes 4 bytes of storage
> > > > space to encode true color.
> > > >
> > > > Now for some math!
> > > >
> > > > 1920 x 1200 x 4 x 30 = 276,480,000 bytes per second.
> > > >
> > > > That's a spicy meatball!
> > > >
> > > > Then you need to crunch that down using MPEG2 compression. In real
> > > > time. On a laptop. If a laptop is even capable of that kind of
> > > > computational power it'll set itself on fire.
> > > >
> > > > I'd venture the answer to your question is "no".
> > > >
> > > > ;-)
> > >
> > > I'll bet that cell phones will be able to do all this and store ten
> hours
> > of
> > > video internally within five years. Not only that, but they'll be able
> to
> > > dump their entire contents to an FTP server in less than ten minutes.
> > >
> >
> > I take that bet! How much?
> > I bet that things like that will probably take 50 years. Consider where
> > technology has been in 1999....it really hasn't changed much, only more
> > applications are available.
>
> There are several devices on the horizon that promise to put as much as
ten
> terabytes of storage in a solid state device the size of a sugar cube in
the
> next few years. Wireless internet is available at T1 speed today. In five
> years, it will probably be at least ten times faster. Look at how far
> digital cameras have come in the past few years. They will almost
certainly
> be capapble of better than HDTV resolution in five years. Add that up and
> you have something similar to what I predicted.
>
> In five years, you'll be able to buy it for $1500. In ten years it will be
> in the bargain bin at Kmart. In 20 years it will be at the dollar stores.
>
>
>

I bought a 3 megapixel camera in '99 for 800 bucks. That was five years ago.
So, now there are 6 megapixel cameras for 800 bucks. Big deal. By the way
1920x1080 is HD resolution, about 2 megapixels in camera terms.
T1 speed is 1.5 Mbit per second. Wireless G, 802.11g's max. rate is 54 Mbit
per second. Already 36 times faster - in less than a day for you.
Uncompressed HD is about 2000 Mbit per second.
I think the biggest problem is going to be the power source. If you had the
storage, and the wireless capability - cell phones probably operate on about
20 kbit per second - anyone know? and the computational power to compress in
realtime, you're not gonna do that with a 1000 mA/h battery for longer than
a minute.
According to Popular Science, we all should have been flying around with
nuclear powered personal levitating air-suits long time ago....