[mythtv-users] HDMI capture card with linux drivers

[Mike Perkins]

Douglas Peale wrote:
>
> Lets do a bit of math here.
> 1920 pixels * 1080 pixels * 3 bytes * 30 frames/second = 186,624,000
> bytes/second.
> There are very few hard drives that can be written that fast.
> Your computer could do nothing else but write the disk, so there is no
> possibility of encoding while recording.
> So you want to record a 2 hour movie, that is 186,624,000 * 60 * 60 * 2
> = 1,343,692,800,000 bytes.
> So it would require most of one of the largest hard drives available
> today just to store the unencrypted file.
> 
It's not impossible. In 1997 I worked, briefly, on software for a professional 
video recorder/editor (which ran under a customised version of Windows NT4.0!) 
which offered recording rates up to 9 Gb/minute: how they did this with the 
hardware available at the time I have no idea, but I saw it working, so is 
obviously possible[1].

However, using a hardware encoder means that you write a much smaller stream to 
disk, which is obviously more sensible. You just have to pick your hardware and 
a suitable codec :)

[1] As I recall, it buffered to disk at one end while the other end frantically 
wrote it out to broadcast-quality betamax tapes. Go figure.

-- 

Mike Perkins