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Sound<br />
Sound does not work with an HDMI monitor<br />
This is caused by some computer monitors which select DVI mode even if an HDMI<br />
cable is connected. This fix may be necessary even if other HDMI devices work perfectly<br />
on the same monitor (or TV)!<br />
Edit the configuration file - see the instructions at R-Pi_ConfigurationFile.<br />
Add the following line to the configuration file:<br />
hdmi_drive=2<br />
This will force it to select HDMI mode.<br />
More reasons why sound does not work with an HDMI monitor<br />
With an HDMI connection it might be possible to hear:<br />
./hello_audio.bin 1<br />
but not:<br />
aplay /usr/share/sounds/alsa/Front_Center.wav<br />
Firstly, it seems that some HD TVs mute audible sound output when there is no digital<br />
input, and slowly fade the sound up and down at the start and end of digital input. This<br />
means that short duration sounds will not be heard. A work around is to play longer<br />
duration wav files.<br />
Secondly, it seems that some HD TVs mute audible sound output when there is only one<br />
channel of digital input. So, as the file Front_Center.wav is mono, it might not be heard.<br />
ALSA aplay uses the file information header to configure its digital output. And the aplay<br />
-c 2 option does not over-ride the settings aplay picks up from the file information header.<br />
So, if your HD TV doesn't accept just one channel of digital input, you cannot use aplay<br />
to hear a mono wav file. However, with the command speaker-test, the -c2 option does<br />
work, and sets 2 channels in the digital stream. So speaker-test can be used to hear the file<br />
Front_Center.wav in either the left or right speaker using the -s option 1 or 2. For<br />
example
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