I presented an argument as to how the AVR is not simply passing data through, but rather is creating a new outbound stream. I have been told that my argument is wrong and that I am confused, but I don't believe anyone has yet provided any consistent and/or cogent explanation as to how I am mistaken.

Once again, here is the argument, which I will break down into numbered points to hopefully facilitate a counter argument. The context here is that a source is sending data over HDMI through an AVR to a display, and that the AVR is being used to strip out and play the audio portion of that data.

1. When a source sends HDCP protected data via HDMI to an AVR, the TMDS stream between the source and the AVR is encrypted using the keys of both the source and the AVR.

2. This stream, therefore, can only be decrypted by the AVR. That is, if any portion of the TMDS stream were forwarded bit for bit to the display, the display would be uneable to decrypt that data.

3. When the AVR sends the video portion of the data carried in this TMDS stream on to the display, it does so by taking the unencrypted video data extracted from that stream and then encrypting that data using the keys of both the AVR and the display.

4. The video stream portion of the TMDS stream sent from the source to the AVR is therefore comprised of an entirely different set of bits then the video sent in the TMDS stream from the AVR to the display.

(While the decrypted version of both streams would contain the same bits, the encrypted version - which is what appears on the line - contains entirely different bits because the bit streams result from applying encryption using different key sets.

That is:

a. The bit stream from the source to the AVR is derived by encrypting the original video stream with keys from the source and AVR.

b. The bit stream from the AVR to the display is derived by encrypting the original video stream with keys from the AVR and display.

So, again, these two bit streams are not comprised of the same sequence of bits.)

5. Since the stream from the source to the AVR is comprised of entirely different bits than the stream from the AVR to the display, then it is not possible that the AVR is just passing bits through. Rather, it must be creating a fresh stream of bits in the link from itself to the display.

CONCLUSIONs:

A. Provided that the bits in the signal arriving in the TMDS stream at the AVR can be decoded successfully to 0s and 1s, then the AVR should be entirely capable of generating a perfect TMDS signal out to the display.

B. Any signal loss in the link from the source to the AVR is, therefore, of no consequence to TMDS portion of the link from the source to the display UNLESS the signal loss (or skew, etc.) is enough to prevent the AVR from parsing that signal. If the AVR can parse the signal, the output of that parsing is a perfect stream of 0s and 1s. And, that perfect stream of 0s and 1s is what is fed as input into the HDMI transmitter that creates the stream going out to the display.

C. The AVR, itself, should not be a source of signal loss, as would be the case if it were simply passing along the signal as do baluns and other devices that are not, in fact, producing a new stream.


Now, I am not asserting that I am 100% certain this is all true. However, given all of the information available to me, it certainly seems to be so.

If anyone sees where this argument takes a wrong turn, I would very much appreciate if they could point to the specific (numbered) point and describe exactly how that is the case.

Thanks,