Re: www.badvista.org

Quoting "Alan C." <r.andom@noshut.com>:

> I'm not 100% on this one but here is how I understand it and why there
> might be some confusion here. Note I haven't checked out any of the
> links below but have spent significant time mucking with high
> definition sources so this should apply to HD in general, not necessary
> Linux compatible HD devices:
>
> Most modern hardware implementations of digital HD content have some
> sort of DRM required. It maybe that some of the HD recording
> devices/software for Linux don't support modern DRM (HDCP in this case)
> and therefore can't record the content unless the provider (cable
> company/satellite provider/Blu-ray player, etc.) disables the HDCP
> negotiation. If HDCP is disabled then the receiving device can record
> the content but many of the hardware vendors are now requiring that
> HDCP be enabled and one by one cable/sat/etc. companies are enabling
> HDCP on their platforms.
>
> HDMI (and DVI in some cases) uses a protocol called HDCP in order to
> prevent unauthorized devices from receiving the high definition content
> stream. When the HDMI source is turned on it negotiates with the next
> HDMI aware device, etc. down the chain all the way to the recorder or
> display device. If a single device (other than a plain no-logic
> switch/relay) in-between doesn't support HDMI or they are running
> incompatible versions you will end up with no audio or video being
> transmitted since the entire chain must be authenticated for the video
> and audio to be sent over HDMI.
>
> One of the ways I avoided DRM early on when I didn't have HDCP
> compatible devices was to use source devices that did not enforce HDCP.
> Normally the combination that I used was SPDIF audio w/ DVI or
> Component video. Now I've given up and almost all my devices support
> HDCP since it was becoming increasingly difficult to integrate new
> components without it.
>
> Component, VGA/HD-15, DVI (in some cases - modern DVI interfaces are
> commonly HDCP enabled), analog audio, SPDIF/Coax interfaces etc. are
> all sources which do not have HDCP so this makes it so if you can get
> into the middle or have a device hanging off the cable or sat box you
> can record the content in high definition. Many people that experience
> compatibility issues with HDMI/HDCP between their products end up
> switching back to Component video and non-HDMI digital audio in order
> to record or display high definition content.
>
> -Alan
>

Good write up Alan. I know the DRM issue was twice shot down in =20
congress and the next step was to pressure the manufactures into =20
building it directly into their devices. There was a big rush to get =20
HD cards that did not have the restrictions before the first vote in =20
Congress. You can still get the equipment but it is becoming =20
increasingly more difficult to do so.

Jon

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Received on Mon Jul 9 14:04:24 2007