I know a little bit about microcontrollers. I want to first say this question will be over my head but I'd like to do the project anyway...

I want to have a HDMI input, add effects to the sound, then output to HDMI out(all the while receiving the video, if there is any, on the other end). Through this guys post Microcontroller to process HDMI frames I learned I need a DSP. Can anyone step me in the right direction, I cannot find any tutorials or references online how to even get HDMI in to HDMI out on a board. If anyone has any references for that or even how to take the audio and effect it that would be very helpful.

I need to do more research on DSP's since I really just heard of them... but I'm having trouble finding HDMI components(for the in & out connection) and which type of processor or hardware would be used to process the sound...

I have seen the Raspberry Pi but I need an HDMI in & out and would like to find out how to do this strictly using the components rather than using a prebuilt microcontroller like that if at all possible.

Any information is very much appreciated!

  • 2
    \$\begingroup\$ I'm not sure this is a trivial task at all. HDMI standard exists to avoid ripping of high quality video and audio, I think that to build and HDMI device you need to buy the specification and comply to it... For example, extracting the HQ audio from your thing would be very easy, thus I don't think it's easily built. Not an expert here, just my two cents. Good luck. \$\endgroup\$ Commented Apr 9, 2014 at 8:27
  • \$\begingroup\$ I don't think you need a DSP, although for your audio processing/effects it may be the most suitable device. HDMI is (usually) copy-protected so you may have problems there, however there was a project some time ago that overlaid subtitles on un-broken copy-protected HDMI in a very clever way, a search through Hackaday's archives should turn it up. You might get lucky and be able to do the same sort of trick to extract / insert audio streams as HDMI separates video & audio packets. \$\endgroup\$
    – John U
    Commented Apr 9, 2014 at 8:37
  • \$\begingroup\$ Have a look at kosagi.com/w/index.php?title=NeTV_Main_Page (which may be the thing John U is referring to). It's not at all easy. \$\endgroup\$
    – pjc50
    Commented Apr 9, 2014 at 10:52

1 Answer 1


Don't implement the HDMI standard on a DSP, the standard isn't public and it's a waste of your time.

There's two ways to do this that I can think of. The "hard" way: get a receiver and a transmitter IC (ADI sells them, for example). Demod the HDMI data with a reciever, and pipe the video directly to the transmitter. Push the audio into a DSP like the ADI Blackfin, do your audio magic, then send it to the transmitter. This is not a trivial task: you need to design a PCB and you'll have to deal with high-frequency design concerns.

The "easy" way: just get a small Mini-ITX PC with an HDMI capture card and write some software do do what you want.

In both cases, you'll probably have to contend with HDCP, so you won't be able to use all media.

  • \$\begingroup\$ interesting, thank you! How do home theater amps deal with hdmi, this one says it will imporove the sound. tinyurl.com/n5vb5uj how do they get around HDCP you think? Also this is definitely over my head but I would love to figure it out...Im thinking maybe doing a version with simpler i/o like maybe 1/8th inch connecter to familiarize myself with the process or processing sound... do you know any resources where I could talk with a engineer and have them help me through every step of making this the "hard" way... I would be willing to pay some engineer but not sure where to find someone \$\endgroup\$
    – mike
    Commented Apr 9, 2014 at 17:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.