Mini Displayport to Displayport - Audio Out?

Question

Mini Displayport to Displayport - Audio Out?

Techies, I'd be grateful for some sage advice. So we know that Displayport supports audio pass-through as well as video, and that support for audio out of the mini-displayport was added to recent Macbook models (which I have).

However, Apple only specifies that audio is available via Mini Displayport to HDMI adapters. There seems to be no information on whether mini Displayport to Displayport adapters can also pass audio.

I know several users here successfully utilize these mini-DP to DP adapters (like this one: http://www.kanexlive.com/products/mdp_to_dp_mm.html); can anyone test if this type of connection will successfully pass audio? Does the Apple Sound Settings utility still detect the TV in question as an audio output option, as it does using the HDMI adapters?

This is frustrating because I have a screen whose HDMI port has to stay in use by another device, and my only means of getting audio and video to it otherwise is through the full sized DP port. There's no technical reason why this shouldn't function flawlessly, I have no idea why Apple doesn't document it one way or another.

Many thanks.

MacBook Pro

Posted on Jul 14, 2011 9:58 PM

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Answer 1

JaEvo

Level 2

395 points

Jul 14, 2011 10:03 PM in response to ronanosullivan

You should be able to get sound from a mdp to DVI connection... Does your tv have a DVI input? Displayport inputs don't accept audio.... similar to VGA but greater bandwidth.

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Answer 2

tjk

Level 9

51,116 points

Jul 14, 2011 10:05 PM in response to JaEvo

JaEvo wrote:

You should be able to get sound from a mdp to DVI connection... Does your tv have a DVI input? Displayport inputs don't accept audio.... similar to VGA but greater bandwidth.

DVI does not do audio.

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Answer 3

Jul 14, 2011 10:13 PM in response to tjk

Yes, unfortunately the first response is incorrect: Displayport DOES accept and carry audio. DVI does not (if it did I wouldn't have this dilemma in the first place).

A full sized Displayport to Displayport setup carries audio just fine with this screen. Mini-displayport now also carries audio, according to Apple - but they only say this is the case with a mini-DP to HDMI adapter. Does it also work with a mini-DP to DP connection? Can any resident techies speak to this? And/or anyone using a mini-DP to DP setup give it a quick test?

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Answer 4

JaEvo

Level 2

395 points

Jul 14, 2011 10:15 PM in response to ronanosullivan

Oh man you guyes are correct sorry about that my mistake...

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Answer 5

Jul 15, 2011 7:18 AM in response to JaEvo

No problem - thanks for trying.

Anyone have any thoughts on this? Frustrating to run into a question with seemingly no answer on the net. Can we ping Apple about it?

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Answer 6

eww

Level 9

53,028 points

Jul 15, 2011 7:27 AM in response to ronanosullivan

I suspect the surest way to get a definitive answer to this question will be to consult the maker and/or supplier of your MDP > DP adapter.

Just as there were a number of MDP > HDMI adapters in the early days that didn't support audio pass-through, there may be MDP > DP adapters with the same limitation. You may have one.

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Answer 7

Jul 18, 2011 9:50 PM in response to eww

All - Found my answer. I contacted the engineering depts of a few custom cable companies (ultimately settling on Circuit Assembly; they were extremely helpful and forthcoming about the details of which spec they utilized, and promised a full refund if the audio didn't work). My understanding is that to successfully carry audio from a Mac, you need to use a cable with the 1.1a or higher spec of Displayport.

MonoPrice, which uses an older 1.1 spec, claimed adamantly that their cables would not carry audio. I've heard of some people having success with their cables carrying audio, so it may be that they've started slipping some 1.1a spec ones in unbeknownst to the engineer I spoke with.

At any rate, if you find a 1.1a cable, the audio carries beautifully from Mini Displayport to Displayport.

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