Scopes Over HDMI

[djkarn105]

I had an interesting conversation with another DP the other day. I was talking about how I find the exposure mode on an EVF more helpful for exposing than a waveform because I can see exactly the part of the image that is in a given exposure area. He replied that he didn't trust an exposure indicator that was coming out of the camera display out. Which got me thinking: can I trust the output from HDMI or SDI as far as signal goes?

 

[j1clark@ucsd.edu]

I had an interesting conversation with another DP the other day. I was talking about how I find the exposure mode on an EVF more helpful for exposing than a waveform because I can see exactly the part of the image that is in a given exposure area. He replied that he didn't trust an exposure indicator that was coming out of the camera display out. Which got me thinking: can I trust the output from HDMI or SDI as far as signal goes?

I would presume that a signal output via HDMI with the manufacturer's 'intention' that that signal be digitized for recording... would be 'clean' and conforming to use with 'scopes'... I wonder about the HDMI output from DSLR's which was intended for 'live monitoring' of the video with no particular care for the signal other than human visual 'indication'.

I would presume SDI output would be suitable for recording and 'scope' monitoring.

 

[Shooter]

I absolutely trust the signals out of an HD SDI port as regards external recording, external image monitoring and external wavefom monitoring.

We are always in a HD-SDI chain and even if the last is a monitor with a built in WFM..I use that and trust it

Never had any any issue ....and also not sure what else would be used instead of SDI.

I dont use HDMI for anything so cant comment on that.

 

[djkarn105]

I absolutely trust the signals out of an HD SDI port as regards external recording, external image monitoring and external wavefom monitoring.

We are always in a HD-SDI chain and even if the last is a monitor with a built in WFM..I use that and trust it

Never had any any issue ....and also not sure what else would be used instead of SDI.

I dont use HDMI for anything so cant comment on that.

Sort of what I figured given HD SDI is a standard designed for broadcast workflow applications and HDMI is not. I would still love to hear from a technical perspective whether or not the signal out of HD SDI is the same as what's in camera.

 

[Gary Huff]

The HDMI out of my C100 recording into a Ninja-2 is incredibly close to the internal AVCHD, outside of the differences in compression and 4:2:2.

 

[Shooter]

Sort of what I figured given HD SDI is a standard designed for broadcast workflow applications and HDMI is not. I would still love to hear from a technical perspective whether or not the signal out of HD SDI is the same as what's in camera.

Well I cant give you a technical perspective ( data) but I can say that bars and images produced on my camera (AF102) are identical in every waveform in my chain .

Camera WFM, HD Monitor WFM, NLE WFM, Da Vinci WFM, Other NLE WFM, Flame WFM.

I dual record from my camera to a Samurai as well via HD0sdi connection. The identical files produce identical waveforms within the same chain as well.

These are test you can easily do your self of course.

Camera generated bars and shooting color / gray scale charts are best for a controlled test.