The ARRI ALEXA Mini LF camera is supported for SDI video in Shogun Live.
The following topics provide information about setup and calibration. Read them in conjunction with the ARRI ALEXA Mini LF Manual (PDF download from arri.com).
Use of the rolling shutter
The ARRI ALEXA Mini LF camera has a roller shutter sensor. In general, we don't recommend the use of cameras with rolling shutter sensors. However, the acceptability depends on the speed of the readout from the sensor. A good test is whether the calibrator detects wands during a normal fast wand wave. If it does, this indicates that the rolling shutter time is fast and the amount of distortion is unlikely to be problematic except for very fast movement.
If you are forced to use a deliberately slow wand wave to enable the calibrator to detect wands, it is likely the rolling shutter effect will be problematic in normal use.
Satisfactory results were obtained with a normal, fast wand wave with this camera.
Sync and timecode
The ARRI ALEXA Mini LF camera takes a separate timecode and sync/genlock connection. It can also extract reference sync from the timecode signal, but we do not recommend this mode of operation. As with all SDI video cameras, both sync/genlock (SYNC IN) and timecode (TC) are required for the camera to be calibrated in Shogun Live. The sync/genlock and timecode signal can come from a sync and timecode generator (SPG), such as the Evertz 5601MSC, or Courtyard CY440 or CY460.
Set up the required timecode
The timecode cable is used to carry an LTC signal from the sync and timecode generator. At the camera end, a 5-pin lemo connector plugs into the port on the camera labeled TC, and at the other end is either BNC or XLR, depending on the type of device being used. Plug it into an LTC output on the timecode generator, which is usually labeled LTC or Timecode.
As usual when using timecode, set the timecode generator to provide LTC at a rate equal to, or exactly half the video frame rate desired, as LTC rates only go up to 30 Hz.
To set up the camera for timecode:
- Navigate to HOME > TC > Options > Run Mode and ensure that the value is set to Free Run.
In this mode, the timecode continues to count up, even when not recording on the camera, which is the behavior required by Shogun Live.
- Navigate to HOME > TC > Options > Mode and ensure that the value is set to Regen.
In this mode, the timecode does not sync to the input once, but keeps in track with it, except when the camera is recording. If the timecode generator is also providing sync/genlock and the standards are set correctly on both outputs, there should be no discontinuities in the timecode received.
- As an additional check that the settings are correct, navigate to HOME > TC > Options > Regen Source and ensure that LTC in is displayed.
The camera displays TC in white when it has a timecode. The timecode itself is also shown on the camera's display.
When the timecode is set up correctly, it is displayed in Shogun Live below the Vicon system timecode. In this example, it is listed as DeckLink C1, referencing the SDI capture card in use.
Set up the required genlock
The genlock cable is a BNC-to-BNC cable that is used to carry genlock from the timecode generator.
- On the camera, plug the cable into the connector labeled SYNC IN.
- Ensure the cable is connected to a tri-sync output on the timecode generator, and set the video standard to that required for the camera.
- Navigate to MENU > System > Sensor > Genlock Sync and set the value to SYNC IN.
Check that the GEN message changes to orange when the cable is removed. It is important to do this to verify that the genlock input is being used, rather than the camera obtaining sync from timecode, which we don't recommend.
Check timecode and genlock
When timecode and genlock are being received, on the display TC in white and GEN in black are displayed, as shown here:
When there is a problem with timecode or genlock, the ARRI ALEXA Mini LF camera shows TC or GEN in amber respectively.
|Genlock / Sync In working|
Genlock / Sync In disconnected or not working
|Timecode disconnected or not working|
Shogun Live does not visually indicate whether the camera is getting a genlock signal, so it is particularly important to check this on the camera itself.
Set the required video standard
The ARRI ALEXA Mini LF camera supports 1.5 G and 3 G video standards on the outputs labeled SDI 1 and SDI 2. It supports only 6 G video standards on its SDI 2 output.
Connect the SDI 2 output to the Shogun Live PC. If SDI connections to other devices are required, use a distribution amplifier. Distribution amplifiers should not introduce a significant delay to the signal, but we recommend that you set up all of the cabling before calibrating, rather than plugging and unplugging cables after calibration.
The camera doesn't have a direct video standard setting. The video frame rate is determined in the Project settings. The transport format on the SDI output is set in the Monitoring settings.
To change the video standard:
- Navigate to HOME > FPS and use the jog wheel to choose the desired frame rate.
- Navigate to MENU > Monitoring > SDI > SDI 2: Clone SDI and ensure that the checkbox is cleared.
- Navigate to MENU > Monitoring > SDI > SDI 2 Format and set it to the desired video transport format. For example, to enable 2160 p (4K) output, change SDI 2 Format to 422 6G UHD.