Using HDMI Audio/Video On Linux

The last time we looked in-depth at HDMI support on Linux was last December when talking about HDMI with the ATI Catalyst Linux driver. Since then there has been improvements in a number of drivers for different hardware. In this article we have a brief overview on the status of HDMI support in the Intel, NVIDIA, and ATI Linux drivers.

For the testing done in this article we were using Ubuntu 8.10 with the Linux 2.6.27 kernel and the default ALSA 1.0.17 and later on we had built ALSA 1.0.18a. Earlier this year ALSA had also picked up R700 HDMI audio support, which means both Radeon HD 2000/3000 and Radeon HD 4000 owners can use the audio processor found on their graphics card under Linux. Though in a few configurations we tested, the audio would not work properly. The HDMI display we used was a Toshiba Regza 32RV530U 32" LCD HDTV.

The Catalyst 8.11 driver had no problems reading the TV's EDID data and properly setting its mode to the native 1080p resolution, but the audio once again was not working. The HDA ATI HDMI audio adapter was detected, but when trying to make that the default audio device and adjusting its volume, there was no audio being outputted. We had tried different ATI R600 and R700 graphics cards and it was to no avail.

A few months back an open-source developer had reverse-engineered the HDMI audio support in the Catalyst Linux driver in order to write an HDMI audio patch for RadeonHD, Novell's official open-source ATI driver for the R500 GPUs and later. At the end of October the master branch of this driver picked up the RadeonHD HDMI audio support. This support is enabled by default on supported ASICs, but can be toggled through the xorg.conf.