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RE: Will it support HD audio over HDMI?
By omnicronx on 4/24/2008 1:28:51 AM , Rating: 2
Read this part in the hdmi spec.
7.1 Relationship with IEC 60958/IEC 61937

It all has to do with the process they call 'Audio Sample Clock Capture and Regeneration'

Audio data being carried across the HDMI link, which is driven by a TMDS clock running at a rate corresponding to the video pixel rate, does not retain the original audio sample clock. The task of recreating this clock at the Sink is called Audio Clock Regeneration.

I took me a few minutes to actually wrap my head around it, so I know how confusing it sounds.
Whenever transmitting a valid audio stream, HDMI Sources shall always include valid and correct information in Channel Status bits 24 through 27. For L-PCM audio, these bits shall indicate the audio sample frequency. For compressed audio formats, these bits shall indicate the IEC 60958 frame rate. An HDMI audio stream shall only indicate values shown in Table 7-4. Note that the allowed values do not include the IEC 60958-specified “Sample frequency not indicated” value.
(you need to see the table)

Simply put the audio stream is sent down as part of the video stream, but they are able to change the audio sample clock speed but in the end both bitstream and lpcm are sent down in similar ways. It simply comes down to the fact that HDMI 1.2 devices do not support IEC 60958 formats and HDMI 1.3 does.

Whether or not this is because the new formats were not finalized in time, or some other reason is up in the air, I doubt anyone except for the guys at HDMI consortium, and Dolby/DTS know for sure.

By omnicronx on 4/24/2008 1:46:56 AM , Rating: 2
*support IEC 61937 formats and HDMI 1.3 does.*
I am still not convinced the TMDS bandwidth increase is actually needed for bitstream, although for deep colour, xvYCC and other 1.3 features it is probably required. (and don't get me started on deep colour, which is useless unless you have an expensive 1080p sony camcorder or you are waiting for the next iteration of consoles, as both the BD and ATSC spec only support colour depths up to 8bit, and thats never going to change)

