HDMI and CEC – Installment 024

Installment 024 is live.  It has been a while.  We decided to let the dust settle after CES before picking things up again.  It has been a year since our first installment.  Man, we have covered a lot of territory since then.

I decided to change the way I format the subject for these blog posts so that it is easier to find related topics instead of just having the Installment numbers to go by.  I hope it works out better now that we are getting quite a few posts out here.

We start this year out with Ian’s discussing some of his HDMI findings at CES and, like everyone else lately, we look at the implications of 3-D on the requirements – especially for HDMI 1.4.  We then start our dive into the Consumer Electronics Control (CEC) aspects of HDMI.

[mp3]http://media.libsyn.com/media/iandixon/TDL_Custom_20100129_024.mp3[/mp3]

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Before I write about what we cover, I need to clarify something that I said in the recording that is not entirely accurate (hopefully you know that I strive to provide correct information).  I will discuss this again in the next Installment (025), so keep an ear out for that.  The issue revolves around the need for HDMI 1.4 and 3-D.  Steve Venuti, President of the HDMI  Licensing, LLC organization, had stated that, theoretically, it would take 15 Gb/s to support full resolution per eye when delivering 3-D over HDMI.  I mistakenly interpreted that as a reason that high speed HDMI 1.4 is required.  Things get really confusing, but essentially they are not doing full resolution 3-D, so the bandwidth over the wire stays the same (assuming the Color Depth values are constant).  The format, as it is right now, is to provide only 1080i per eye when doing 3-D.  This is not full resolution per eye as one would get at 1080p/60 per eye, which would require the higher bandwidth.  Additionally, the Blu-ray 3-D specifications only go up to 24 frames per second per eye, or 48 Hz, so it is not 1080p/60 per eye either.  These limitations allow the current 10.2 Gb/s available via HDMI 1.3 to be sufficient for delivering 3-D.  I am sure it is crystal clear now, right?

Also, the way that the Consumer Electronics Control (CEC) aspects of HDMI 1.4 deal with devices exposing if they support the additional capabilities of HDMI 1.4 like the reverse audio channel and Ethernet are part of the extensions to the CEC command (and response) set.  Since we were just getting into these aspects of CEC, we will add those aspects to our discussion in Installment 025.

Following is the background information on CEC we cover.  It is important to note that the Features listed here are more like functional scenarios.  The CEC platform really is designed around tasks that are performed (similar to macros in universal remote controls) rather than just strings of command codes.  Once again, we will dive into this further in the next installment.

CEC

GLOSSARY OF TERMS

• Broadcast Message – This is a message, sent to logical address 15, on which all devices are expected to receive.
• Deck – The part of a recording device or playback device that provides playback functionality – usually from a removable media.
• Destination – The target device for a CEC message.
• Follower – A device that has just received a CEC message and is required to respond to it.
• Initiator – The device that is sending, or has just sent, a CEC message and, if appropriate, is waiting for a follower to respond.
• Logical Address – A unique address assigned to each device
• Menu Providing Device – A non-display device that may render a menu on a TV.
• Playback Device – A device that has the ability to play media, e.g. a DVD Player.
• Recording Device  –A device that has the ability to record a source such as an internal digital tuner or an external connection.
• Source Device – A device that is currently providing an AV stream via HDMI.
• Tuner Device – A device that contains a digital tuner, e.g. a STB or a Recording Device.
• Timer Setting Device – A device that has the ability to set the record timer blocks of a recording device.
• TV – A device with HDMI input that has the ability to display the input HDMI signal. Generally it has no HDMI output.

END-USER FEATURES

• One Touch Play – Allows a device to be played and become the active source with a single button press.
• System Standby – Enables the user to switch all devices to standby with one button press.
• One Touch Record – Offers a What You See Is What You Record (WYSIWYR) facility, meaning that whatever is shown on the TV screen is recorded on a selected recording device.
• Deck Control – Enables a device to control (play, fast forward, etc.) and interrogate a playback device (a deck).
• Tuner Control – Allows a device to control the tuner of another device.
• Device Menu Control – Enables a device to control the menu of another device by passing through user interface commands.
• Remote Control Pass Through – Enables remote control commands to be passed through to other devices within the system.

SUPPORTING FEATURES

• Device OSD Name Transfer – Enables devices to upload their preferred OSD name to the TV. The TV can then use this name in any menus associated with that device.
• Device Power Status – Allows the current power status of a device to be discovered.
• OSD Display – Enables a device to use the on-screen display of the TV to display text strings.
• Routing Control – Allows the control of CEC Switches for streaming of a new source device.
• System Information – Queries the system to determine device addresses and language.
• Vendor Specific Commands – Allows a set of vendor-defined commands to be used between devices of that vendor.

As mentioned, we will dig down deeper into CEC in Installment 025.  CEC is a much overlooked aspect of HDMI that really adds some value to its vision and capabilities and, like most of our topics, it is important to understand how it works on the wire so you can take advantage of it in your installations.

  =D-