javaboyuk
Posts: 18
Joined: Mon Mar 05, 2012 7:07 pm

Re: HDMI Audio - Supported Output (stero only I think)

Wed Mar 14, 2012 5:46 pm

Guys

A question to which I hope the answer is "you got it wrong!"

After looking at the "BCM2835 ARM Peripherals" manual page 119 it suggests that the output is only 2 channels (ie says "Frames can contain 1 or 2 audio/data channels in each direction. Each channel can be between 8 and 32 bits wide").

However the HDMI spec states it should "It transmits all ATSC HDTV standards and supports 8-channel, 192kHz, uncompressed digital audio and all currently-available compressed formats (such as Dolby Digital and DTS), HDMI 1.3 adds additional support for new lossless digital audio formats Dolby® TrueHD and DTS-HD Master Audio™"  The Raspberry Pi FAQ states its HDMI 1.3a compliant. BUT will the BCM2835 SOC gives us the audio streams with the current drivers?

So.... what *AUDIO* can I get over HDMI (would like DTS-HD Master Audio) do you have a list of what we can get out (like the list of support video resolutions but for audio!)

Many thanks

(yes this is proving educational had not looked at a control register function for a long time!)

javaboyuk
Posts: 18
Joined: Mon Mar 05, 2012 7:07 pm

Re: HDMI Audio - Supported Output (stero only I think)

Wed Mar 14, 2012 7:40 pm

Found a post from Liz, saying about licenceing costs for Dolby 5.1.

BUT a reply said that Raspberry Pi don't need it if we just Pass Through the audio stream for example..... So the question can we pass through the audio streams from say a video file, or an audio file straight out down the HDMI connection?

In other words send my HDMI Dobly, DTS, MP3, etc etc enable AMP the audio stream over HDMI to get it to play it?

User avatar
Jessie
Posts: 1754
Joined: Fri Nov 04, 2011 7:40 pm
Location: C/S CO USA

Re: HDMI Audio - Supported Output (stero only I think)

Wed Mar 14, 2012 9:02 pm

The answer to this is whatever the decoding device tells the R-Pi it supports than it will support that.  The audio is passed un-processed through the cable to whatever you plug it into (assuming you are using HDMI.)

If you are un-lucky enough to have a device (TV or reciever) that has no Dolby or DTS license then the R-Pi will have to software decode it and chances (but I don't know) that this will be just stereo because that is the fallback path for HD streams that can't verify that the content will be protected.  Who knows though I have heard software decode is pretty much trivial and that there may be a work around.

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