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diff --git a/docs/audio.txt b/docs/audio.txt new file mode 100644 index 00000000..158ad5d1 --- /dev/null +++ b/docs/audio.txt @@ -0,0 +1,45 @@ +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 |