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0 pointsgond1y ago0 comments

> DP is still missing HDMI features like ARC and CEC, which are important for TVs.

ARC could also be considered as a bug, a hindrance, or both.

ARC and its various implementations would not exist if the HDMI Forum would not be so fanatically force copy protection on everything. The whole problem, or feature that ARC is or is not, would disappear with the reliance of protecting every stream. The alternative would be a full datastream, decoded, going back to the device in question. The prerequisite would be to remove the shitshow that HDCP is and allow full-blown HDMI-in and outputs, which is the exact opposite of what the Forum wants.

HDMI in its current implementation hinders technological progress in the audio segment by forcing everyone to output analogue signals after the decoding stage or not allow decoding at all.

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gizmo1y ago

Don't you also need ARC because of video post-processing that adds frames of latency? The TV needs to send audio back to the receiver otherwise video and audio will not be in sync anymore. Receivers/amplifiers can process audio with practically no latency so it makes sense for them to be at the end of the chain.

toast01y ago

You don't need ARC to address a/v sync. HDMI has (optional) metadata somewhere (edid?) where the display device indicates its delay and the audio device can adjust accordingly. It's helpful if the display device has fixed delay for this feature to be most effective; it's fine if there's different modes with different delays and the current delay is communicated, but some modes have variable delay depending on content which is terrible in several ways.

IMHO, ARC is primarily useful when the display device is also acquiring the content: it's running the TV tuner or internet streaming or content off a usb drive. It's also useful if you have a 1080p capable receiver and upgrade to a 2160p(4k) display and sources: if you put the receiver in the middle, you lose on video quality, but with eARC the display can route full quality audio from all your sources. Some sources do have two HDMI outs, so you could wire to the display and the receiver, but that's not very common.

AstralStorm1y ago

Ugh, DisplayPort already has the audio channel. As far as sync, neither protocol provides for effective reclocking or supplies the audio clocks, and you need VRR to provide sort of display clocks.

realityking1y ago

DisplayPort has the audio channel but AFAIK has no _return_ channel. Which is not needed in the typical computer setup but quite useful in a TV + soundbar or AVR setup.

alt2271y ago

I admire your exasperation on this issue :)

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