Originally Posted by BuffyzDead
bfdtv, you seem like you have a lot of knowledge, so here goes: So I have the DirecTV HR20-700. And I want to record HDTV and standard TV to my iMac. Why couldn't I record from the HDMI out (is that MPEG-4 Layer 2 or MPEG-4 Layer 10 (H.264)?)
HDMI is an encrypted connection for uncompressed video.
From satellite dish to receiver, you have an encrypted, DVB or DVB-S2 modulated signal containing all the MPEG-2 and MPEG-4 feeds. Once that signal enters the box, the MPEG-2 and MPEG-4 feeds are demodulated from the coax and decrypted. Those decrypted MPEG-2 and MPEG-4 feeds are then decoded (i.e. uncompressed) by the Broadcom chip in the STB or DVR. The result is a 1.0Gbps signal, which is then encrypted and output over HDMI.
of the DiretTV? Is it because that out needs to be converted to a signal I can input to my iMac? Couldn't I use an HDMI to USB/Firewire 'converter'?
There is no such thing. There is no MPEG signal of any kind on a HDMI cable. The uncompressed bitstream on HDMI is several times greater than Firewire and USB can support.
Some older STBs could be hardware-modified to add a Firewire output, which would output the MPEG-2 bitstream data before it was decoded (i.e. uncompressed). Unfortunately, none of those hacks work with DirecTV's more recent MPEG-4 hardware.
Once the content is encrypted on that HDMI cable, there isn't much you can legally do with it. There is illicit hardware out there that will remove the encryption on HDMI signals, but then you are faced with the prospect of storing Gbps of digital video on your PC. At 450 gigabytes per hour, that would require a massive storage array with tens of terabytes to be of much practical use.
There are some more affordable solutions to record component via HD, but even then, you are looking at $1000-$1500 in new hardware plus a new high-performance computer to do that.