HDMI Fail

HDMI was sold as a next generation connector, having used it a bit recently, some of the omissions surprise me.

  1. Explicit support for Audio and Video synchronisation only appeared in version 1.3. The forth revision of the standard. That’s a pretty big omission for a next generation audio-video connector; in the meantime every device seems to have optional delay values to tweak the setup.
  2. More generally the audio support is lacking. While you can deliver multiple audio formats, more with each revision, there isn’t (at least in early revisions) a way of sending both surround sound (AC3, DTS or better) and simple 2 channel PCM stereo at the same time. Devices have to elect which to send, and while some form of auto-negotiation is possible, devices like the HD TiVo require you to choose which form you send. And while your Amplifier can decode AC3/DTS, your TV potentially can’t. If the standard had just said from the beginning that you always send 2 channel PCM as a fallback/base level, and also any better standard if available, no negotiation or configuration would be needed.One workaround is to send Stereo audio to the HDMI connector, and send the AC3 audio out over S/PDIF connection, and get the surround sound amplifier to decode this. And then adjust various delays to provide lip-sync again. This is just faff that could so easily have been avoided by sending both, the connector is not lacking in bandwidth for audio.
  3. The inclusion of HDCP to provide the movie studios a misplaced sense of safety that content is protected. In reality all it does is cause sporadic errors when your Source, Amp and TV fail the negotiation and require you to power cycle everything. Meanwhile in the background is the threat that some studio somewhere could deem your TV insecure, and your expensive flat panel on the wall is prevented from showing certain HD content.

Having spent many years trying to get overly complicated SCART setups to work, I hoped that HDMI would be much better, and while impressed at the quality of HD, I’m disappointed at the level of user intervention and forethought required when they are setting equipment up, much of which could be avoided if some more pragmatic decisions were taken at the initial design meetings.

1 thought on “HDMI Fail”

  1. You can also add

    Stupdily long resync times
    The connector is a peice of shit and gets loose a lot. Especially, for example, in earthquake prone areas. *cough*
    HDCP syncing fails with distressing regularity and you get the multi coloured snow storm of death until you switch inputs and back and forth to force a resync. Which takes ages

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