| Audio Support in IGT |
| ==================== |
| |
| This document provides information and instructions about audio support in IGT. |
| |
| Introduction |
| ------------ |
| |
| The audio test is aimed at testing the audio features of display connectors, |
| such as HDMI. |
| |
| Test setup |
| ---------- |
| |
| The setup required for the audio test consists of using an HDMI-VGA adapter with |
| an audio-out 3.5 mm jack to extract the audio from the HDMI interface. |
| The audio-out jack is connected back to the device-under-test's line-in. |
| |
| Depending on the behavior of the adapter, it may be necessary to connect a |
| ghost VGA dongle to it (in order to emulate a connected display) to enable the |
| audio output. There are guides available detailing how to build these. |
| |
| When executed, the test will automatically send the test audio signal to all |
| ALSA audio HDMI outputs and record from the standard ALSA capture device. |
| |
| Configuration |
| ------------- |
| |
| In order to deploy the test, ALSA controls have to be configured to set the |
| ALSA capture source to line-in. On Intel x86 systems, this can be achieved |
| with the following calls to the amixer utility: |
| # amixer sset Line 31 on |
| # amixer sset "Input Source" Line |
| |
| It is then useful to store the ALSA state permanently with the alsactl utility: |
| # alsactl store |
| |
| These settings can be restored with the alsactl utility: |
| # alsactl restore |
| |
| It is desirable to ensure that the alsa-restore and alsa-state systemd services |
| are enabled to do this job automatically, especially in the case of an |
| automated testing system: |
| # systemctl enable alsa-restore |
| # systemctl enable alsa-state |