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I am curious what the main differences are between using the HDMI output or the DSI connector to hook up a screen?

I understand that HDMI carries audio while the DSI ribbon connection will not, and that the HDMI can scale to much larger screens, while the DSI is meant for smaller LCDS. But beyond that i have found very little info explaining WHY you might use one instead of the other.

Are there power or processing considerations involved?

This is meant as a general question. But as extra info for my situation i will share that my current project is to build a DJ controller with raspbian running the DJ software Mixxx on a pi 3. I would like ALL of the required hardware to be contained in a suit-case style housing.

closed as off-topic by Milliways, joan, tlhIngan, Steve Robillard, Darth Vader Aug 27 '18 at 10:39

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be specific to the Raspberry Pi within the scope defined in the help center." – Milliways, joan, tlhIngan, Steve Robillard, Darth Vader
If this question can be reworded to fit the rules in the help center, please edit the question.

  • After reviewing the help center guidelines as to what is off or on topic, i'd say this question is definitely on-topic. It matches the first 2 points of the on-topic list and maybe comes close to being one of the points from the off-topic list. Perhaps it could benefit from an earlier statement that i am specifically asking about these outputs on a raspberry pi (i figured the forum heading made that obvious), but beyond that, i really thought this was the best forum to post this. Lots of time on google could not find any answers to this. – Marshall Sep 6 '18 at 21:29
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HDMI

  • wide range of available screens, but small HDMI screens are very expensive
  • audio support

DSI

  • only a single supported screen !
  • no audio
  • touch support ( the only supported screen is a touchscreen ...)
  • very flimsy connector
  • the Pi can be "elegantly" mounted behind the official screen whilst the screen provides power the Pi

As of August 2018, beta software allows you to use both HDMI and DSI together. 2 simultaneous 1080p videos will probably be still impossible because of limited internal (memory ? HW compositor ?) bandwidth.

  • Thanks for the info! I have recently found some HDMI screens with touch capabilities which just have an extra component overlaying the screen with its own USB output. i assume that in such cases the DSI option must be "lighter" for both processing and power. – Marshall Aug 20 '18 at 15:58
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If you actually have a choice (that is, the same screen is sold with either HDMI or DSI), DSI will be a more power-efficient solution than HDMI. DSI is designed to be implemented directly by the LCD panel controllers, while HDMI is a more generic protocol which will have to be converted to something a particular LCD controller understands (which might as well be DSI), so you have to power an additional HDMI->DSI converter.

In reality, when you find a screen with the size and resolution you need, you often don't have a choice and get to use whatever interface that screen has.

  • Thanks for the details, your comment about needing that extra layer of encoding for HDMI is what i suspected about these options. In the end, it might be the short length of the DSI ribbon cable that will force me to go HDMI just to fit it all how i want. – Marshall Aug 20 '18 at 16:02

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