[MEncoder-users] tv tuner card suggestions?

[Dieter]

> > > it has to be a pci card,
> > 
> > There are USB tuners, Ethernet tuners and probably Firewire tuners.
> > These don't use up a valuable PCI slot.  Newer computers have fewer
> > and fewer PCI slots, due to having some PCIe slots instead.  And
> > USB/Ethernet/Firewire tuners can be used with a laptop.  If you go
> > this route you can have more than 2 tuners.
> 
> USB etc. probably requires a lot more cpu. I always get huge cpu load
> from using usb storage devices, and tv capture has similar or higher
> bandwidth requirements.

dd-ing from a USB disk to /dev/null for awhile gives

2944139264 bytes transferred in 180.379007 secs (16321962 bytes/sec)

with the CPU 97.5% Idle.  A US ATSC broadcast is 19392576 bits/sec.
So reading a maxed out channel over USB would use 0.37% CPU.
This assumes that reading from a USB TV tuner has the same CPU overhead
as reading from a USB disk, which might not be the case.  Add another
fractional percent for writing that data to disk.  This with a CPU that
was the bottom of the line 2 years ago and is probably no longer made.

> US essentially does not have digital TV.

In the US, the FCC has required all TV stations to broadcast digital for
quite awhile now.  I don't know if Jody is in the US or in some other country.

> Also the crappy signal degredation will
> mean that many people who could receive analog TV (far from the
> station) will be unable to get digital TV at all.

Some people have good analog reception and poor digital reception.
Other people have good digital reception and poor analog reception.
The point is that the FCC is requiring TV stations to shutdown analog
TV broadcasts on 2009-02-17.  Once that happens analog-only tuners
become useless for receiving broadcasts.  (You could still use them
for transferring your analog vacation tapes to the computer.)  If you
can convince the FCC to postpone the analog shutoff, good luck.  My
analog TVs and I will thank you.

> > > i want it to include an encoder on the card, so my cpu can be left in
> > > peace
> > 
> > Note that watching a recording requires decoding, which also requires a lot
> > of CPU, or decoding hardware.
> 
> This is misleading. Watching requires trivially small CPU load
> compared to encoding (like 100mhz vs 1.5ghz). In fact my experience is
> that just moving uncompressed video across the PCI bus is slower than
> decoding the same video and moving it across the video bus (AGP/etc.)!

Xbitlabs tested this.   AMD Athlon 64 FX-60 CPU (2x2.60GHz, 2x1MB L2) +
GeForce 7300 GS decoding 1080i takes 26.6% CPU.  A single CPU would thus
take about 53.2%, and more if you have a slower clock rate, which is likely,
since the FX chips are expensive high end chips.  And that is with whatever
hardware assist they are getting from the GPU.  Given the lack of
documentation on GPUs, the amount of hardware assist *BSD or Linux gets is
zero, so CPU requirements probably go up even more.  100 MHz?  No way.