Originally Posted by rdgrimes
Audio delay should remain constant over different sources or material. If it doesn't, then the issue is clearly in the display and should be addressed there. IOW, once you set the delay you shouldn't need to change it. 24p image processing is one common source of lag in a display.
If it would be constant, it would be one time job to set it up manually, which is no big deal.
Reality is far from it. Different source materials take TVs different amount of time to process. And this is not because of their processors are too slow, but because there are actions just cannot be done without knowing upcoming video frame. For example, you cannot detect and reverse 3:2 pulldown without knowing a frame ahead. So it effectively adds delay. On the other hand 25fps material, you don't need to wait for next frame and can show it immediately.
We should not forget that audio processing is getting more and more complex as well and more and more data is being used to produce a quality sound. So there is also audio delay.
I would simply expect TV to tell receiver, that hey, I need 116 ms to process this video stream and receiver to tell that I need 32ms to process audio with current sound field, speaker positions and all the Adaptive DRC/DSP stuff.
So receiver knows that it has to hold back audio for 84ms and that's it.
Or achieving the same result by letting each other know which frame they are finished processing. Just like it is happening in DirectShow graph in your computer when you play back any video.
For some time I was under impression that HDMI 1.3 lipsync functionality takes care of it. My impression was backed up by friend of mine who runs Sony receiver with Sony TV. He confirmed not to encounter any lip sync issues. Is it possible, that Sony is using some proprietary method to get its equipment synchronized?