Interest in open-source capture software for Sumix M73

[Rob Scott]

Is there any interest out there in using the Sumix SMX-M73 camera for low-budget filmmaking? I have an opportunity to get one of these cameras fairly inexpensively, and I'm trying to decide if it's worth the money and time to add support to the open-source capture software I am developing.

If anyone out there has an M73 and would be interested in beta-testing the software, please let me know. Replying to this post is fine, of course.

Thanks!
Rob

[Sam Jankis]

I'm interested... a DIY Silicon Imaging setup?

The website indicates that it shoots at 12fps and 27fps (and more), but no mention of 24fps. Also, there is no mention of lens mounts.

[Rob Scott]

Originally Posted by Sam Jankis

I'm interested... a DIY Silicon Imaging setup?

Yes, but not the "real" cinema-quality SI-1920. The SI-1300 and SI-3300 are industrial cameras and have some drawbacks when it comes to cinema. But they are a good deal cheaper than the "real thing."

The website indicates that it shoots at 12fps and 27fps (and more), but no mention of 24fps.

Yeah, those specs are for the machine vision people, not for cinema. It does support 24 fps, but I have not yet determined how precisely.

Also, there is no mention of lens mounts.

It's C-mount, which means you can use Bolex lenses on it.

The software currently supports the SI-1300, but as the initial post mentions, I am also looking at the Sumix camera, which is less capable, but even less expensive as well.

Thanks for your interest! Let me know if you want more details.

[John Wyatt]

Rob -- I'm trying to make a short film with the Sumix M73 as a feasibility exercise. I'm going to start a thread here about it when I have a bit more experience with the camera to report with some credibility. Since I'm no programmer I'm using the supplied software for RAM-recording uncompressed Bayer video to a laptop. Would welcome the opportunity though to use other software options with this camera; happy to be a beta tester.

Sam -- I'm experimenting with different 16:9 frame sizes at the moment, all at 25 fps. You have the freedom to enter your own fps speed (asuming the computer can handle the frame size you set for the fps speed you want). RE: C-mount lenses -- I started a thread here (many pages back now) titled "Call for C-mount lens info". Many of these lenses (Angenieux, Schneider, etc) were used on 16mm movie cameras in the 1960's and 70's and certainly good enough for our purposes today. Because C-mount had been taken up by and continues to be used by the scientifc/industrial/security camera people, you can also get new lenses and 35mm SLR adaptors (to use lenses you may already own), though be warned the field of view will be fairly telephoto even with say a 28mm SLR lens. Also, some security camera lenses are not good enough for high resolution video.

John.

[Rob Scott]

Originally Posted by John Wyatt

Rob -- I'm trying to make a short film with the Sumix M73 as a feasibility exercise ... Would welcome the opportunity though to use other software options with this camera; happy to be a beta tester.

That sounds interesting, John. I'll try to get my hands on an M73 and I'll keep you posted.

[Sam Jankis]

25fps is close enough (NLEs can handle it). I'm assuming you'll post footage/grabs when you can.

How hard would it be to add on-board audio? That's the one thing that I don't like about the SI camera. Even though I also record to DAT, it's much more convenient in post.

[Rob Scott]

Originally Posted by Sam Jankis

How hard would it be to add on-board audio?

Good question. I know there is some open-source code out there to do this (Audacity comes to mind), but I've never written code to do that, so I have no idea how hard it would be. I expect it wouldn't be that hard. (Famous last words!)

Actually, "on board" in this case means using the PC's sound card. The configuration of one of these DIY cameras is a PC (desktop or laptop) connected via cable (CameraLink or USB) to a "box" camera. So there is no microphone as part of the camera box itself, unless you made a custom case for it.

BTW, the price difference between these two DIY systems is pretty large -- the SI1300 plus 64-bit frame grabber is probably around $3000, whereas the M73 is $800. There are additional pluses and minuses involved as well, if you're interested. I should probably write this up in the ObscuraCam wiki.

Edit: Fixed a typo.

[John Wyatt]

Rob -- I'm a bit busy at the moment but I'll read your wiki stuff to get up to speed on what you've done with the SI camera.

Sam -- "25fps is close enough" -- sorry, I didn't explain it very well: you can set 24 fps if you want to. I'm in a PAL country and since there's little chance of a film-out for my short film I decided to shoot 25 fps, but there are many options. The two main issues being frame size versus fps speed to stay within the datarate (this is a USB 2.0 camera); bigger frame = slower fps speed. "I'm assuming you'll post footage/grabs when you can" -- yeh, things are a bit mad at the moment at work (and I'm trying to find time to experiemnt with this project), but I'm hoping to get a simple website up along with some notes on my experiences and sample frames; will keep the discussion on threads here in Alt Imaging.

RE: sound with mute cameras -- my current tests involve using a DV camcorder to shoot alongside the M73. I import the DV footage and export a wav sound file, to sync up with a low res Quicktime movie copy of the M73 clips for off-line editing. Perhaps there's a better way, though it's nice having 16-bit stereo sound using something I already own.

[Rob Scott]

Originally Posted by Sam Jankis

How hard would it be to add on-board audio?

Looks like it should be pretty simple. I dug around in Audacity and found that it uses the Portable Audio library.

Originally Posted by John Wyatt

I'll read your wiki stuff to get up to speed...

I'm afraid the wiki is pretty slim and badly organized, John. (For one thing, it's hard to work with -- I'm not impressed with the DotNetNuke wiki.)

The two main issues being frame size versus fps speed to stay within the datarate...

The other issue, of course, is the rolling shutter. It seems to me that the best compromise with the M73 is to "bin" it both horizontally and vertically, resulting in a resolution of 1024x576 (16:9) or 1024x768 (4:3) at ~48 fps. By then skipping alternate frames, you get 24 fps, 1/48 second exposure and much reduced rolling shutter artifacts.

Downsides:

• it's only a "nearly-high-def" camera
• 8 bit depth

Upsides:

• 4:4:4
• define your own 10-to-8-bit LUT
• maximum use of sensor area

[John Wyatt]

Rob -- I looked at the your wiki pages. Was wondering if the Bayer recording is a still image sequence or a single video file? The M73 is a 10-bit camera which uses 8-bit for Bayer video; would your software be able to utilise the native 10-bit depth of the camera?
John.

[Rob Scott]

Originally Posted by John Wyatt

Rob -- I looked at the your wiki pages. Was wondering if the Bayer recording is a still image sequence or a single video file?

It is a "video" file, but it basically stores a sequence of bayer still frames in a single file. It's a format called IHD that Rob Lohman and I worked up -- basically a simple and efficient "digital negative" format.

The M73 is a 10-bit camera which uses 8-bit for Bayer video; would your software be able to utilise the native 10-bit depth of the camera?
John.

Yes, it supports 8-bit, 10-bit and 12-bit depths (though I haven't had the h/w to test 12 bits). It will be configurable to use whatever combination of frame rate, frame format (binning/windowing) and bit depth that you wish to use.

[John Wyatt]

Rob -- thanks for replying so quickly. If you can recode your app for the Sumix then it would dramatically increase the flexibility of this affordable camera. I wondered if your file format was a still sequence because the Wiki mentioned DNG as one of the output options (which I believe is a still image format?). This is interesting to me since I was planing on having my ultimate output to be a tif sequence with a seperate WAV sound file (to take to a facilities house and be layed back to HD tape).

I have 2GB of RAM in my laptop which was bought for RAM recording, so I guess I could set quite a high figure for accumulating frames in the RAM buffer? This might ensure no dropped frames (even for larger frame sizes) despite the laptop HDD only being a 5,400 rpm SATA drive.

[Rob Scott]

Originally Posted by John Wyatt

Rob -- thanks for replying so quickly.

You're welcome!

I wondered if your file format was a still sequence because the Wiki mentioned DNG as one of the output options (which I believe is a still image format?).

The "capture" app writes only to IHD. I am working on a separate command-line-only "transcoding/processing" app called ObscuraConvert, which currently bayer-filters and generates a series of 16-bit TIFFs from the IHD file. I am hoping to be able to output a series of DNG files in case someone would prefer to bayer-filter the images in a different application.

I have 2GB of RAM in my laptop which was bought for RAM recording, so I guess I could set quite a high figure for accumulating frames in the RAM buffer?

Yes, absolutely. You can configure it to pre-allocate as much memory as you like; it will accumulate the frames in RAM and write them out to disk as fast as possible. If the hard drive is slow, this should still allow for more recording time than RAM alone.

[Rob Scott]

Just a quick update -- I have ordered the Sumix M73 and will begin adding support as soon as I receive it. In the meantime I have been refactoring the code significantly and have made the following improvements to ObscuraCap:

• Migrating UI to wxWidgets to improve portability.
• Rewrote several sections in assembly/MMX/SSE
• Added support for 3 lossless compression libraries -- miniLZO, libLZF and QuickZ.
• Added some unit tests using CxxTest
• Migrating threads to zthread library to improve portability.
• Beginning to add audio record support using portaudio and libsndfile libraries.

All the code is in the SourceForge project, but it's a bit broken because the migrations are not complete yet.

[John Wyatt]

Rob -- big effort. It's good to know you're out there, working it! I'm still doing my tests to get a feel for the camera (going to write it up for a little website).