Blackmagic Forum

Hi,

I'm trying to record at 25fps while sending out a 50i signal. I thought I could do so, by using the "off-speed" recording function, where you can set the framerate being recorded. I switched this to 25 whilst the camera is set to 50fps (otherwise no interlaced signal).

The need for this is: we are recording talking heads very often. So there is no need for high framerates which only waste space on the card. We could of course record in 50i but since most of our productions end up online I like a progressive image being recorded.

The above trick works somehow, but you still get a 50fps ProRes file (didn't try DNxHD, yet) which makes it a bit akward in an editing system to work with (since the video plays at the wrong speed).

Am I missing something?

Knut

Off speed recording is used to set a “project” frame rate, like 25fps, while setting the shutter to 50fps, but you are still going to record the video at 50fps, and in playback on a NLE, project rate will be set to 25fps, and the play back will be in slowmo. There is no way to record at 25fps whilst streaming 1080i50 signal, as the camera needs to be set to 1080/50-60 fps to get an interlaced output.

Your only option would be to use a up/down/cross converter to take the 1080p25 signal and convert it to 1080i50 to get the required interlaced live streaming/switching signal.
Cheers