Dfort, this is great! Hack or not, we now have Silent Pictures MLV video recording, on the EOS M and triggered by the audio. Here is a summary of what I found so far:
Camera: EOS M
ML build: magiclantern-Meloware-hack.2017Feb25.EOSM202
Canon Menu setup:
Image Quality – RAW
Image Review – Hold
Power Saving: (LCD auto off: 1 min), (Camera auto off: Disable)
ML modules enabled: mlv_rec, silent
ML features setup: Silent Picture (Full-res, MLV), Audio Remote Shot: ON (level 10)
External trigger is a audio loop, connected into the camera's microphone jack. There is a 200 ms 1000Hz burst followed by 7.8 sec of silence.
About 1 second after the tone burst, the display announces the first messages produced by the exposure. This message only appears for an instant and is therefore unreadable. The captured imaged then draws (which is probably what eliminates the initial message). At about 3.8 seconds, the summary data flashes on screen, which contains the over all frame count and total SD memory use. This is also where the message about using a long “half shutter” appears.
Of the two message events, the last one is most important. I monitor the LCD with a webcam along with a second webcam which continuously views the equipment (in case something unexpected happens). I watch these two displays from another room, while watching television or doing other work. The last status message tells me when the chip is getting full and needs to be exchanged. If the system runs beyond the memory capacity, I lose part of the film and need to waste time recovering.
The system exposure interval is hand adjusted on my own controller and it is set (by eye) to occur just after the appearance of the “long half shutter” message. This interval is generally around 6 seconds, depending on the write speed of the SD memory. The “long half shutter” message is my visual clue that the camera is ready for another exposure (too bad there is no “camera ready” signal to tap into).
With this build, the camera is unable to cycle again until the appearance of the “Audio Release On” message, which occurs about 7.8 seconds after the start of the tone burst.
Show Stopper! The LCD powersaver remains active and stops the recording after it times out. It cannot be disabled in the main menu and effectively needs to be. A 64 GB SD card takes over three hours to fill and 128 GB obviously more. In order to be practical, the system needs to run unattended for these kinds of times.
The exposure cycle time for this build is 8 seconds. This is two seconds slower than I currently have with the 650D and a remote shutter. Every second counts when you need to copy 30,000 frames for a 12 minute film. With this build, the “long half shutter” message occurs 4 seconds before the “Audio Release On” message. I am presuming the current frame is saved once the “long half shutter” message appears, so waiting another 4 seconds before you can take another exposure may be a big waste of precious time. Please investigate how fast the camera may be made to recover. I am hoping this can be twice as fast without too much trouble.
The final message, containing the “long half shutter”, frame count, and used memory are important to see in order to know when the system needs servicing. Can this be made to linger long enough to clearly read? The captured image and initial message are of little importance as compared to this last message.
This build runs reliably, otherwise! I am grateful for ML's support and interest. I hope to publicize the value of your project. Your work makes possible professional quality digital archiving of museum collections, on a budget affordable to most of us. Aside from movie transfer, high volume copying of fragile books, ledgers, and other documents (too fragile for the flatbed scanner), will now be possible.
I hope this application is an unexpected and welcome surprise to your group!
Museum of Our Industrial Heritagehttp://industrialhistory.org