Teardown: Portta HDMI splitter

[NiHaoMike]

It all started with this post about HDMI splitters that can be hacked to bypass HDCP: http://hackaday.com/2015/03/12/hdmi-splitter-is-also-a-decrypter/

Out of curiosity, I decided to buy a cheap HDMI splitter to try the hack myself. What I got has a completely different design.


There's a PI3HDMI412AD dual output HDMI repeater, a Sil9187 HDMI receiver, and a ST microcontroller. The HDMI receiver seemed a little strange as the repeater could take the TMDS signals directly, but what info I could find seemed to indicate that it has built in HDCP decryption. Thus, it looks like it is being used as a HDCP stripper. Which basically means the unit works as a HDCP stripper with no mods needed. In fact, the DDC pins on the outputs are not connected to anything. It always gives a "generic" EDID table with a whole lot of resolutions up to 1080p60.

BTW, while trying to reverse engineer it, I looked up PI3HDMI412 and it returned the datasheet for the PI3HDMI412A, which is a HDMI switch that could only enable one path at a time. That confused me for a good while since I did connect two displays during testing and both did work at the same time. Pericom has a rather confusing part number system!

[amyk]

The Chinese attitude of not always getting things "right and proper" can benefit the user, like this.

Also, HDCP was thoroughly broken ever since the master key became public. No doubt a lot of no-name Chinese manufacturers are generating their own keys from it to put in devices like these.

[ConKbot]

oh no, how is hollywood going to protect the consumer from uh..., from uhh what was it that HDCP protected consumers from again? 

[NiHaoMike]

The irony is that DRM encourages piracy. The real irony is that real pirates don't even bother trying to break HDCP, but rather break some DRM further up in the chain. HDCP has annoyed a lot of legitimate users and few pirates were affected at all by it.

[reagle]

Yikes, anybody else notices a complete lack of ESD protection on the HDMI lines?

[turdferguson]

What is the manufacturer/model number of this?

Thanks.

[NiHaoMike]

http://www.amazon.com/Amplifier-Splitter-compatible-swither-Blu-ray/dp/B007K1KWTQ/ref=pd_ys_iyr28

[NiHaoMike]

I have now confirmed that the splitter does in fact strip HDCP. Beware that many (if not most) non HDCP monitors aren't compatible with the HD modes and therefore still won't work.

Yikes, anybody else notices a complete lack of ESD protection on the HDMI lines?

Both of the chips have built in ESD protection. With the contacts being recessed on HDMI connectors and the shield making connection first, ESD is a much lesser issue than on connectors that connect data lines first (e.g. RCA!) or with exposed data connections.