Hello 100D users,
I would like to report my first impressions on the new SD-interface overclocking (OC) module called sd_uhs.mo which allows a substantial speed boost and will probably make it possible to record continuous 14-bit losslessly compressed RAW video at 2520x1080 resolution with sound at 24 fps. I tested a build provided to me by Danne with the above module included but I am not sure if he doesn't mind posting it here since, as I understand, there is some risk for data loss when using it. That is why, if someone wants to test it, I would suggest that they ask Danne for that build.
Here is what I did:
1) Install the build and activate all desired modules, including the sd_uhs.mo;
2) While in Photo mode, go to the Debug menu and activate the SD-card overclocking feature. Overclocking makes sense only if your SD card provides write speeds substantially higher than the native 100D interface write speed of about 40 MB/s. I tested with two cards indicating 62 and 57 MB/s write speeds with a fast USB 3.0 card reader.
3) With OC activated, the screen goes dark and the camera performs a pretty long (1 to 2 min.) test to find out the optimum OC parameters of your card. During the test the red LED blinks periodically. When the tests completes, the LED stops blinking and upon pressing the Play button, a message appears, saying the test is complete.
4) Now you can run a 1 minute benchmark test and see at what actual OC read and write speeds your 100D communicates with your SD card.
5) DO NOT TURN the camera OFF !!! It will forget the settings determined in the above test and you will have to run it again!
6) Now you can set your resolution to 2520x1080 in the RAW-video menu, record some clips and see how long they become.
RESULTS:
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I tested with two cards providing 62 and 57 MB/s card reader write speeds. The ML benchmark test indicated actual OC write speeds of 52 and 47 MB/s with these two cards which resulted in 350 to 600 recorded frames with the faster card and 250 to 350 frames with the slower one at 2520x1080 resolution and 24 fps. The large record time variation is due to the different compression ratio that the camera uses at 14-bit lossless dependent on the brightness of the scene. Without OC, the camera records just about 80 to 140 frames before it stops. As you see, overclocking provides substantially longer record times at the maximum camera MLV video resolution.
Overall impression:
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After playing with the above two cards for several hours, I found the camera to be very stable. I never got a corrupt frame or another glitch. Also, all the recorded clips on the camera stayed untouched, no matter how many times I turned the camera off and on again and ran the OC test. I am very pleased with this amazing new feature and will definitely continue using it. The only annoying thing is that the OC settings get lost every time when the camera is turned off or the card needs to be replaced. Danne said that it is possible to skip the OC test by reprogramming the sd_uhs.mo for every card used but I am not sure how this will work since SD cards do not always perform at the same read/write speeds. Some also need to warm up before reaching maximum speed. In fact, I experienced such inconsistent speed behavior with the faster card mentioned above.
Conclusion:
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Our developers have again provided a wonderful new feature to us that seems to work great with the 100D making this amazing little camera even more powerful. Danne reported 55 MB/s write speeds with a very fast (95 MB/s SanDisk Extreme pro SD card - is this correct, Danne?). I will probably purchase this card hoping that it will provide continuous recording at the highest recording resolution.
Suggestion for improvement:
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It would be very helpful if the OC module is modified in such manner that the OC test is performed just once for the card that ML is installed on and the optimum OC parameters are stored automatically and permanently as a configuration setting. This setting should then be applied automatically every time the camera is turned on and never forgotten when camera is turned off.
Acknowledgement:
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I extend my most sincere gratitude to all developers involved with this remarkable new development and hope, they will continue improving Magic Lantern.
