EDID Overrides

[stewartm]

Have been trying to sort out surround sound on my setup that includes a Humax Fox T2 HDR. The short version is that some usefull custom firmware additions would be to allow the EDID info to be ignored or even reprogrammed to allow 5.1 surround to be sent by hdmi even if the sink device reports it is 2.0 channel only. The EDID-RW package could be used.

Long version. I have the following:
Room 1:
Humax Fox T2 HDR
LG 32LG5020 TV
LGHB957TZ Bluray Surround Amp
PS3
Chromecast
Cablesson 4x2 HDMI Matrix
Room2:
Vidoelogic Digitheatre DTS
Benq HDMI Monitor

Setup in theory for this was to be that CC, PS3 and Humax were all to be plugged into the matrix. This would allow them to be shared in both rooms, with the optical audio out of the matrix driving the Videologic DTS speakers, no need for surround on this output at present. The Bluray plaer has 2 HDMI in so would report 5.1 channel sound available to all the devices. The inputs are very unreliable at handshaking though with the switch and can take 10-15 min of turning things on and off before they will work, even starting the Netflix app on the PS3 can then knock it off again though.

I gave up and re-structured the cabling, with the matrix going straight to the LG tv and the Bluray now added as another input on the matrix. The optical out of the tv is into one optical in of the Bluray and the optical out of the Humax, which is set to output surround sound, is in the other optical in of the Bluray.

All is working to a degree, but could be better.

As the TV reports it is a 2 channel device, thats all it will get, even though it will happily passthrough 5.1 if it gets it. The PS3 allows the HDMI formats to be overridden from auto and manualy selected. Thats fine, however, when using the Humax, although the sound does work seamlessly on the TV it will only output 2 channel sound to the TV, which is why it has the optical connected to allow it to be changed to use the optical output from the Humax instead giving 5.1. A bit of a pain.

If it was possible to override the EDID setup info and set the HDMI output formats as required, like the PS3, no switching would be required. Better for me, but probably overkill, would be an on Humax version on EDID-RW to actualy write the change back to the TVs eeprom so that it reports the formats available with the connected surround system. Was starting to try and scrounge up an HDMI enabled laptop when I suddenly thought the Humax box (and the LG Bluray and the TV itself) are HDMI enabled linux boxes.

Is it possible?

 

[Black Hole]

No. We have no access to the HDMI hardware.

 

[stewartm]

Thanks that was what I suspected.

 

[Black Hole]

when using the Humax, although the sound does work seamlessly on the TV it will only output 2 channel sound to the TV, which is why it has the optical connected to allow it to be changed to use the optical output from the Humax instead giving 5.1. A bit of a pain.

I don't understand this bit. With Menu >> Settings >> Preferences >> Audio >> Digital Audio Output = Multi-channel (rather than Stereo), the Humax should output 5.1 over the HDMI as well as the optical (when the broadcast includes it).

 

[grahamlthompson]

I don't understand this bit. With Menu >> Settings >> Preferences >> Audio >> Digital Audio Output = Multi-channel (rather than Stereo), the Humax should output 5.1 over the HDMI as well as the optical (when the broadcast includes it).

Part of the HDCP handshake is for the destination device to report what audio it supports (EDID data). If the TV reports stereo only then 5.1 is not transmitted by HDMI. S/Pdif is dumb. Not sure what happens on S/Pdif when hdmi is forced down to 2.0.

There is no issue of course when HDMI connects to an AV amp other than when the audio is passed on via HDMI to a TV.

There are devices that can be set to falsely report that a TV supports 5.1.

http://aldoussystems.blogspot.co.uk/2010/07/why-edid-management-in-hdmi-is-so.html

http://www.rakuten.co.uk/shop/thecableplace/product/32103/?sku=32103&sclid=a_pla_uk

 

[stewartm]

Yep, thats the problem and partial workaround in one. Setting multichannel gives multichannel audio out on S/Pdif independant from the hdmi, which serves surround depending on the capeabilities reported by the edid handshake. As the tv reports it is 2.0 channel thats all it gets and is available to passthrough. Using the PS3 to effectively ignore the edid data and send 5.1 regardless (not hd audio as it is not supported on S/Pdif) confirmd the tv will pass it through to optical if it gets it.

PC workarounds patch inf files can be used to override the edid data for a monitor and thought that this may be outside the actual hdmi hardware settings on the hummy. It seems to be a similar idea to the audio settings on the PS3.

Also as well as the devices in the last post, some tv/monitors can be re-programmed over hdmi with patched edid data. edid-rw is a linux python script to read and re-write the edid data on the port itself. It is designed to fix corrupted ports, however, see no reason to not use it to give a least one of the 3 hdmi ports 5.1 surround or at least report it so that it gets passed through to S/Pdif.

Anyway mostly off the topic of this board. Just wondered about getting the hummy to ignore or even re-flash edid data.

 

[Black Hole]

Very interesting nonetheless.