TVP5158 video data after disconnect of input

You can set the bluescreen register to control the data value when input is disconnected.

BR,
Eason

Eason,

Thanks, I understand that if blue frame feature is enabled TVP5158 will continue to give blue frames.

What I do want to know is that in case, if the blue feature is not enabled (i.e. default mode of operation) will TVP5158 insert EAV on the line after disconnect or it will continue to give 0s on 8-bit digital video port after disconnect?

Regards,

Shareef

My understanding is , when some channels has no video detected, it should not change the superframe format.
I am not aware of the 8bit value, but what I find in the datasheet is there is a VDET bit which is always enabled in line-mux mode that will indicate the capture driver that there is video not detect, thus you can fill in the data buffer with any value you want.

Eason,

The capture is in pixel multiplexed mode, let us assume the following data for a single channel say Channel-1 (not considering the other channels for ease of representation)
In normal operation, video data will be: EAV -> Blanking -> SAV -> Active Video data -> EAV and so on...
After disconnect in between active video data with blue frame feature disabled, how will the data be (1) or (2) below:
(1) EAV -> Blanking -> SAV -> Active Video data...(disconnect say at 500th pixel)...-> 0s->0s->0s.....(until new video lock is found)
(2) EAV -> Blanking -> SAV -> Active Video data...(disconnect say at 500th pixel)...-> EAV (inserted by TVP)

Regards,
Shareef

It is impossible to maintain a valid timing sequence so either the blanking or the active video region will change in length in order to re-align (there is no memory in the decoder).

The line format will remain valid though, and valid SAV/EAV codes will be sent for each line.

I can't recall whether the vertical alignment is configurable or not, but as I say either the blanking period will be reduced/extended or the active video region will be reduced/extended to synchronize with the incoming video (or free wheel when disconnected).

Reconnecting video will again cause a disruption in the vertical timing.

The data sequence itself will be a valid data stream though (i.e. if in 656 mode then only valid 656 line sequences will be sent)

It may be necessary for your back end processor to ensure that it can correctly align with short or long active video regions (and ignore extra lines if the field is large, and re-start if the field is short).

BR,
Steve

Hi Steve,

Thanks for your reply. I believe when you said "The line format will remain valid though, and valid SAV/EAV codes will be sent for each line."  You were talking about TVP with blue screen feature enabled. (with free wheeling)

I would be interested to know the behavior in the case of blue screen disabled mode. Please see my earlier post in which I have given two options (1) and (2) for the possible outputs from TVP and let me know which one is correct.

Thanks.

Shareef.

 

This is regardless of blue screen. All blue screen does is change the active data. It does not affect the control sequences.

BR,

Steve