BMPCC 4k HDMI trigger record

I have been trying to get my new Sound Devices MixPre-3 to have recording triggered from the BMPCC4K but can't get it to work properly. The camera manual states:
"Blackmagic Pocket Cinema Camera 4K automatically sends a signal via the HDMI output that
will trigger recording when connected to equipment that supports the trigger record feature,
such as Blackmagic Video Assist..."
The MixPre-3 has a record setting 'Rec Trigger: HDMI flag', which should enable automatic start and stop recording from a compatible HDMI source. However what happens is that the MixPre-3 starts recording as soon as starts getting timecode from the camera via the HDMI cable ( the camera continuously sends timecode whether recording or not). I then have to stop recording on the MixPre-3, but subsequently starting record on the camera does not trigger record on the MixPre-3.

Has anyone Record Triggering to work on a MixPre or other recorders?

Are you Are sure, you do not have a Record Trigger TC (time code) set, instead of Flag Record Trigger?
This feature works on my Micro camera with a PixE recorder.
Cheers

There no menu options on the Pocket 4K to control record triggering as far as I can see and the MixPre I have set up as recommended by Sound Devices, with 'TC Mode : HDMI TC in' and 'Record -> Rec Trigger : HDMI flag'. I have tried various combinations to no avail.

[Kristian Lam]

Hi,

The Pocket Cinema Camera 4K outputs an HDMI record trigger as well as timecode via the HDMI output. On most of the recorders. Most of the recorders we have encountered are able to use either a running timecode or the record trigger to start/stop recording.

Perhaps there is a setting in your recorder to ignore the timecode?

In my experience, most recorders offer different trigger signals (like Red, Panasonic etc.) to choose from. Unfortunately, these are not standardized, but normally I found one to work with BM.

Hi,

The Pocket Cinema Camera 4K outputs an HDMI record trigger as well as timecode via the HDMI output. On most of the recorders. Most of the recorders we have encountered are able to use either a running timecode or the record trigger to start/stop recording.

Perhaps there is a setting in your recorder to ignore the timecode?

Hi Kristian,
If I ignore the timecode (TC Mode : Off) then I don't get timecode and camera will still not trigger record.
The list of cameras (https://www.sounddevices.com/supported-cameras) known to work with the MixPre-3 include several Sony cameras and the Panasonic GH4/GH5, so I guess the BMPCC4K needs to be sending the same HDMI Flags those other cameras are sending.
I have send a query to Sound Devices about this issue too.

Got a response back from Sound Devices. The relevant bits of are:
"...Record triggers are dependent upon camera manufacturers and each manufacturer has different ways they enable them and also send them down the line. Most have proprietary ways of sending a record trigger/command and they have to provide that information to us and some never let us know so we can utilize it.

Unfortunately, we do not have a Blackmagic Pocket Cinema Camera 4K to test with."

So it would be great if Blackmagic could liaise with Sound Devices to get trigger record working.

[Kristian Lam]

Hi John,

If you could put me in touch with whomever you were in contact with at Sound Devices, I'm happy to have a chat with them. Just PM me if they are OK with you giving me their contact details.

Hi John,

If you could put me in touch with whomever you were in contact with at Sound Devices, I'm happy to have a chat with them. Just PM me if they are OK with you giving me their contact details.

Thanks, I've asked them who best to talk to.

Good work, John. Hopefully SD keeps you in the loop as I’m not eager to invest in a MixPre-3/6 until after this is resolved. That should really help things move along.


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I've passed on some contact details, so hopefully support can be added in some future Firmware update. I imagine it would be too late to get into the first update though.

About to take possession of a BMPCC 4k, I was thinking of adding yet another audio recorder to my stable for compact external audio recording synced by timecode to P4k clips. I'm thinking this would be very useful for those projects where I shoot sporadically throughout a day, such as on vacation for fun projects: I've long wanted to avoid having to hit record on cam and audio recorder or, worse, forgetting to do the latter in the heat of the moment.

Wouldn't it be great to record external audio triggered by the cam so that, at day's end, I would only have to sync the same number and length of external audio and cam video clips in a click because they're all stamped with timecode? I thought the SD MixPre 3 was the answer, delighted that it seems to be the only audio recorder (I've found) that accepts camera record triggers AND timecode over HDMI.

But then, this thread... I'm hoping that BMD and SD can nut out the record trigger for both devices to work in harmony. I don't think I'd hesitate to buy a MixPre 3 if that happened.

I’m hoping this gets sorted soon, too. It would be incredible if BMD could work with SD and other manufacturers like Zhiyun to ensure compatibility. That’s one thing DSLR manufacturers seem to do.

Not sure whether the firmware needs changing from the BMPCC4K side, SD side or both, but the first firmware update for the camera is taking so long that maybe we will see trigger record working when it finally gets released.

Following. Will get the MixPre-3 once it is compatible with the BMPCC4k.

Just a minor update. HDMI flag record trigger still does not work with with BMPCC4K 6.2 firmware with the MixPre3 version 3.02 firmware.

Another important thing to note if your wanting to use the camera timecode on the audio recorder is to set the MixPre Record->Rec Trigger = Timecode rather than HDMI flag. Otherwise the MixPre timestamps the recording with a timecode starting at 0 rather than the cameras timecode.

[Kristian Lam]

My last email trying to them to get clarification as to what protocol they support was unanswered. I'll try again.

Any updates on this? I have the MixPre-3 and my Pocket4k arrives tomorrow.

I guess I can do a passthrough straight to the camera, but it would be nice to have the backup recorded on the field recorder too.