5

I wanted to use my Raspberry Pi with a very old video projector which was not capable of processing audio signals. So I bought an HDMI-audio-extractor (Ligawo 6518725 HDMI Extractor), as the PWM analog audio output had poor quality.

This set-up did not really work from the beginning, because there was no audio output. I was checking all the hdmi_drive=2, hdmi_force_hotplug=1, hdmi_ignore_edid, etc. options in /boot/config.txt. Which didn't help, because the Raspberry Pi did not understand that it should send audio, although the final video signal sink was a "dumb" DVI display.

  • You may want to post the solution as an answer, Q&A style! – JVarhol Feb 2 '14 at 21:00
3

What finally helped was the following:

  • I dumped the EDID-file with tvservice -d edid_dump.bin
  • I edited this file with LIGHTWARE-EDID-editor (part of a demo suite).
  • What I actually needed to change was little: In the CEA part of the file, I needed to specify that the device was HDMI-compliant (HDMI/HDMI options), and under CEA/Audio data, I needed to add LPCM ("linear pulse code modulation" with two channels, and all quality levels, as the hdmi extractor has two channels only).
  • I then saved the file, renamed it to edid.dat and uploaded it to /boot/ (i.e. /flash/ if you are using openELEC) and added hdmi_edid_file=1 to the config.txt. Saved, rebooted, now it worked!
  • "What I actually needed to change was little: In the CEA part of the file, I needed to specify that the device was HDMI-compliant (HDMI/HDMI options), and under CEA/Audio data, I needed to add LPCM ("linear pulse code modulation" with two channels, and all quality levels, as the hdmi extractor has two channels only)." Would it be possible to let us know which Bytes you changed at which address? (I know this thread is old, but still keep my hopes high, to get an answer) – user79155 Jan 10 '18 at 10:05

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