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MilesP
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No TV PIcture

Had an unusual one today. On switching on the TV (a month old LG 4K one, connected via HDMI to TIVO V6), there was no TV picture on any channel, nor on any recorded programs. The sound was OK and the menu screens were showing on the TV. This seemed to imply that sound and audio was getting from V6 to TV. Spoke to Virgin Media and the technician suggested trying another HDMI cable. Before doing this, I simply unplugged and re-plugged the HDMI on the TV. Lo and behold the TV images came back and all was OK again.

Neither myself nor the technician could offer an explanation for this. Anyone in the community got an explanation?

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sidsewell
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Re: No TV PIcture

This has happened to me 3 times now, first 2 times I switched off the TV at the mains and back on again. Then I tried re-plugging the HDMI cable and that worked too.

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MilesP
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Re: No TV PIcture

I have done a bit of research on this and it may be to do with HDCP - High-bandwidth Digital Content Protection. This was a protocol introduced by Sony to protect digital content from Piracy amongst other things. If the protected content is being transmitted and the device does not support HDCP, the picture and or sound may be blocked and you get a blank screen. There has to be a handshake between the communicating devices to establish that both can deal with HDCP. It appears that sometimes if devices are powered up or brought out of sleep in the wrong order the handshake is missed. Obviously this is a bug in the design/software/firmware etc. Both my Tivo and TV are left on standby and what I do now is to always wake the TV up first. It is now waiting for content through the HDMI cable. Then I wake up the Tivo, which is the content provider. This then instigates the HDCP handshake.

I am not saying this is definitely the cause of the problem, but since I have been waking the TV up first, the problem has not re-occurred. It is still a nuisance though and needs a proper solution.

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frank_gm
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Re: No TV PIcture

This issue has been around for years although I have never suffered from it myself and I always ensure that the TV is available prior to the Tivo/V6 waking up.

I don't see this as a bug but the HDCP protocol working as designed. The Tivo/V6 sends a message out to the TV and waits for a response. If the TV does not respond within a certain, narrow, window then it assumes that there is no valid connection. If the TV is switched on first then it will be available to respond whereas if it is switched on second then it is likely that it will not be able to respond in time.

The whole point of the HDCP protocol is to ensure that the output device supports HDCP and, if there is no response within the time window defined in the protocol, then the protocol must assume that it is not a valid output device.

Nice to be able to post again, after their mistake (removed by the Censorship team).
¡No Pasarán!

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sidsewell
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Message 2 of 11
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Re: No TV PIcture

This has happened to me 3 times now, first 2 times I switched off the TV at the mains and back on again. Then I tried re-plugging the HDMI cable and that worked too.

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MilesP
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Message 3 of 11
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Re: No TV PIcture

I have done a bit of research on this and it may be to do with HDCP - High-bandwidth Digital Content Protection. This was a protocol introduced by Sony to protect digital content from Piracy amongst other things. If the protected content is being transmitted and the device does not support HDCP, the picture and or sound may be blocked and you get a blank screen. There has to be a handshake between the communicating devices to establish that both can deal with HDCP. It appears that sometimes if devices are powered up or brought out of sleep in the wrong order the handshake is missed. Obviously this is a bug in the design/software/firmware etc. Both my Tivo and TV are left on standby and what I do now is to always wake the TV up first. It is now waiting for content through the HDMI cable. Then I wake up the Tivo, which is the content provider. This then instigates the HDCP handshake.

I am not saying this is definitely the cause of the problem, but since I have been waking the TV up first, the problem has not re-occurred. It is still a nuisance though and needs a proper solution.

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johnmcl98
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Re: No TV PIcture

Many thanks - been tearin my air out trying to get an answer from virgin to an identical problem - resolved in 30 seconds

 

johnmcl98

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frank_gm
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Message 5 of 11
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Re: No TV PIcture

This issue has been around for years although I have never suffered from it myself and I always ensure that the TV is available prior to the Tivo/V6 waking up.

I don't see this as a bug but the HDCP protocol working as designed. The Tivo/V6 sends a message out to the TV and waits for a response. If the TV does not respond within a certain, narrow, window then it assumes that there is no valid connection. If the TV is switched on first then it will be available to respond whereas if it is switched on second then it is likely that it will not be able to respond in time.

The whole point of the HDCP protocol is to ensure that the output device supports HDCP and, if there is no response within the time window defined in the protocol, then the protocol must assume that it is not a valid output device.

Nice to be able to post again, after their mistake (removed by the Censorship team).
¡No Pasarán!
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LittleMick73
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Message 6 of 11
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Re: No TV PIcture

Of course otherwise the signal has nowhere to go
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MilesP
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Message 7 of 11
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Re: No TV PIcture

All true, but I think that when the TV or other device is switched on, the TiVo should be able to recognise this and resend the HDCP handshake. There are many wires in the HDMI cable and probably one of them does recognise when a device is attached. Actually when the TV screen is blank and you unplug and re-plug the HDMI cable, that also fixes the problem, so TIVO must know when there is a switched on device on the end of the cable.
Don't know enough about HDMI cables to verify if this is the case, but probably a software fix could solve the problem once and for all so it does not matter which order the devices are switched on.
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Steve67
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Message 8 of 11
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Re: No TV PIcture

switching the hdmi in and out used to work for me but my v6 has now crashed and reboot that many times this quick fix doesn't work and im left with sound and no picture along with all the other faults,,,, no iplayer, vevo or youtube pictures only sound... 

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MilesP
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Re: No TV PIcture

Have you tried making sure your TV is switched on and awake before waking up the Tivo?
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Steve67
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Re: No TV PIcture

Yes... I have tried everything
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