Bitstream audio support over HDMI now standard on Radeon 5xxx...finally!
By Mathieu CARBONNEAUX
It appears that the new ATI Series 5xxx cards allow audio transmission over HDMI in bitstream format… meaning they can transmit the audio from a Blu-ray or DVD without decoding it, passing it through as-is via the HDMI connector.
The advantage is that the decoding is no longer done by the PC’s CPU, but is left to the TV or HDMI Audio/Video amplifier.
http://www.homemedia.fr/actualites/5369-PowerColor-Radeon-HD-5750-SCS3-fanless.html
http://www.homemedia.fr/actualites/5414-Bitstream-avec-les-HD-5000-patch-PowerDVD-9.html
http://www.homemedia.fr/actualites/4312-LPCM-7.1-et-bitstream-HDMI.html
http://www.anandtech.com/video/showdoc.aspx?i=3411&p=1
http://www.homemedia.fr/actualites/5264-Bistream-audio-HD-HDMI-Clarkdale.html