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I connected my android tablet (mini-HMDI) to my monitor (DVI) and I get:

  • weird colors
  • mis-aligned image
  • error message

http://postimage.org/image/5tdvmb5pz/

I tested the tablet on a new fancy tv with hdmi port at the local electonics store, it worked well. I also tested the monitor with a desktop pc through dvi, it worked well.

So I suspect (after reading about it) that the High-bandwidth Digital Content Protection is the guilty. So my monitor (1920x1080, DVI, VGA) probably does not support HDCP. And because the tablet recognizes that, it sends bad quality image on purpose (which of course is not encrypted, but annoying).

Note that I do not want to play any protected/encrypted/copyrighted content, just browse the web, read email, etc.

Is there anything that can be done in software (Linux kernel) so that the tablet is usable with that monitor?

(I have read in some forum/blogpost that HDCP is purely hardware driven, the software stack cannot even be aware of it. Is that true? Is there no way that I can couple these otherwise compatible devices?)

user1358
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  • since then I found this, although it is for a different device: https://android.googlesource.com/kernel/omap/+/android-omap-steelhead-3.0-ics-aah/drivers/video/omap2/hdcp/hdcp.h – user1358 Feb 08 '13 at 08:15

1 Answers1

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I would have expected you to get no image if it was HDCP, because it's an encrypted channel - no decryption of an encrypted feed = no useable image, not just a less than perfect one.

With HDCP the feed is supposed to remain encrypted until it reaches the TV/Monitor. I would not expect to find a software solution - software can indicate that HDCP is required, but without a root access no other software could override another piece to say not to encrypt an output. I would expect the output to normally be unencrypted, and only encrypted if the software demands it - so, for example, my desktop outputs just fine over HDMI to DVI normally, but won't play back BluRays using the bundled software as that demands HDCP.

HDCP decryption units are not that common, anyway - it would almost certainly be much cheaper to pick up a cheap Android stick computer, which is silent and sufficient for some basic websurfing, email, etc.

David Burton
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  • I thought that the source (tablet) recognizes that the sink (monitor) does not support HDCP and thats why it sends that downscaled/imperfect image (which of course is not encrypted, but of low quality). – user1358 Feb 07 '13 at 19:33
  • "to pick up a cheap Android stick computer", my tablet has the same SoC (namely allwinner A10) as those cheap sticks, so that would make no difference – user1358 Feb 07 '13 at 19:37