audio delay lines are old tech as are regular video delay lines, but as far as I can find, no-one makes an HDMI delay line for home use in delaying the video to match the delayed audio that comes from things like using bluetooth speakers. There are very few HDMI products of any description out there because of the DRM mechanism, but I suspect it has not occurred to manufacturers (until reading this post :-) ) that you don't need to un-DRM an HDMI signal in order to delay it! Simply store the DRM'd data packets in RAM for a short time then pump them out the other side, still DRM'd. Video/audio synch for HDMI is really becoming a problem nowadays with so many systems inserting delays, especially in the audio path.
-- gtoal, Jul 15 2019

same principle https://www.crowdsu....com/alphamax/netv2
This kickstarter project seems to rely on the same principle of manipulating a DRM'd signal without actually decoding it. I think this confirms that the delay line idea would indeed be implementable. [gtoal, Jul 20 2019]

Why is not possible for the audio track to include time- markers that software can use to sync with corresponding markers in the video track?
-- MaxwellBuchanan, Jul 15 2019


Actually, @bigsleep, it was after buying a v4 BT transmitter/receiver pair that was advertised as having the lowest latency available that I posted this suggestion. Some people (such as my wife) don't hear the offset audio, but I definitely do and it's enough to continually annoy me whenever I watch TV on our projector. The lag may only be 2 or 3 frames but it's noticeable. And I looked around a lot and could not find anything (other that super expensive recording studio tech) that delayed the video - only the audio.
-- gtoal, Jul 16 2019


Does anyone know the name of the analog video effect where an image of say a dancing person is followed by a bunch of clones? I think it might have been used in the 1970's.

The lag modifying HDMI thing reminded me of that.
-- beanangel, Jul 16 2019


[beanangel] Stroboscopic motion? The waveform of dance in a mouse arrow tails sort of way.

Dig into the menu systems of the appliance, sometimes there are timing features.
-- wjt, Jul 18 2019


// the same principle of manipulating a DRM'd signal without actually decoding it //

Additionally (or not, if that link is to the same thing I'm remembering), I remember there was a few years ago some kind of device (open-source/diy/?) that overlaid a generated image (e.g. dashboard meters or the like) on top of an HDCP-protected HDMI video signal, so the generated image could be displayed superimposed on the video on an HDCP- supporting monitor/TV.
-- notexactly, Jul 20 2019



random, halfbakery