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Eric, might i suggest watching the clip thats Titled something like "guitar chair". its me sitting in a chair during a full bright sunny day. the one with the shovel i set the exposure too high, and that day was overcast anyway. But the one with me sitting in the chair you can actually see the sky is a deep darkish blue, deeper blue than what my eye actually made out of the sky that day. anyway, i filmed it with the iris set like that, and was able to record myself with perfect exposure. meaning the camera was able to record the subject in perfect balance with the sky. something i didnt think was possible until i saw it could handle it. check that out and let me know what you think.
and Konst, for all the info, please visit wiki.elphel.com and ww3.elphel.com basically, you control everything about the camera through your laptop or pc. to do outdoor stuff, you'll need to power your laptop (either AC or battery power) and you need to power a little box with either AC or some type of batter that work. this little power box has 2 ethernet plugs. one to go to the computer and one to go to the camera. the power supply allows you to use reallly really long etherent cables without losing performance. And the CD you get with the camera, and you can also download as an ISO and burn yourself is the program you work with. you pop it into your PC, reboot your system, and it will load its own Knoppix OS. all the neccesary software is on their to stream and record. Since the Knoppix is using Virtual Memory you wont want to record with that. youll need an external harddrive to store all your shots. basically thats it. controls look like this for the camera: http://wiki.elphel.com/index.php?tit...ol_panel_1.jpg |
yeah, that clip of you in the chair is very well exposed. if you could post something like that in raw format that i could mess with, i would appreciate it.. if possible, next time you're shooting, could you try underexposing alot.. something where everything is just really dark. that's the real test. thanks ;)
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With that mjpeg compression, underexposing might not be a good thing for image manipulation later.
Is there any way around this compression? Has elphel developed any other options in that area besides mjpeg? I like most of what I'm seeing, but the compression seems pretty heavy. |
Jef, what compression artifacts can you see? do you mean the image looks soft, or do you see jpeg squares (like the grid looking thing)
If you see there are image squares, it is because i have been recording files with 70-75% quality on the jpeg compression to save space mostly. i can record all the way to 99% quality, which is really overkill, basically no visiable sqaures should be seen. but i can try some at 90 or 95 to see if that solves any image square issues. but i cannot even see that big of a deal at 70 %. thanks, let me know what you see. |
Don't get me wrong, the images look nice, and I am NO expert. I love the real 24p with proper motion blur, lack of sharpening, and general flexibilty (and low cost) of the camera.
The artifacts I'm talking about are not very visible in normal viewing, but are brought out when manipulating the image in post. Desaturate a clip and you'll see them (blockiness in solid or dark areas, compression "fuzz" around the edges of moving objects, etc). I'm not enough of an expert to know if upping the mjpeg quality to 100% will change any of this. Depending on how one wants to use their footage, this may not be an issue at all. Minimal adjustment of images in post probably wouldn't be a problem, but I tend to push things... Perhaps I'm being overly picky. Compression is just one of those things that gets to me. :/ |
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Isn't it better to keep some things appart... of course there may be more potential in the Elphel camera, but to me it's a bit strange to talk about a compressed HD camera, and start talking about how to make it uncompressed.
The benefits of compression and the quality it seems to deliver (especially in the Theora codec) is pretty high. My camera was shipped about a week ago, so I guess it'll arrive early next week. I have my wax adapter ready, so I'm very curious. |
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OK, I understand, so your saying that USB2 will work at less than 100Mb/s on your camera. the idea of having an external sound box, like M-Audio and EMU/creative is very helpful. Something that nobody has answered, is the maximum data-rate of the compressed stream the camera can send over Ethernet for VP3 and for Mpeg. From this we can calculate minimum compression achievable for any resolution, as compression heavily effects quality of image. I know people think Mpeg is good, but for cinema even 100Mb/s Mpeg is not high grade for 4:2:2 1920*1080 frame (though it is not bad at 720p, and lossless bayer could fit in 100Mb/s, not quiet 1080). Once the image is blown up for the field of view used in cinema then compression artifacts could be ten times more evident then on a computer monitor. So, VP3 performance is the maker for this application I think. So, with Mpeg there is a strong advantage over the HVX200 DVCPROHD prosumer camera at 720p, and the same at the cut down 1080 resolution of the HVX200, but the compression ratio goes upto around 8:1 for 1920*1080 8 bit, which isn't too bad considering the quality of mpeg2 HDTV transmissions. But, if people want to use 3Mp sensor instead of 1.3Mp they have to consider this. But so far people experiment and play. The Micron 1.3Mp we experimented with a year or so ago had problems with blooming etc, which the 3Mp solved with a new circuit structure. Do any of the newer Microns 1.3Mp sensors solve these problems? (1.3Mp sensors, with larger sensor pads, are an important consideration, because of larger well capacity and lower noise, giving larger latitude and sensitivity.) Anyway, this on camera Axis ETRAX100LX processor, would it be fast enough to stream/control the current compressed stream to a Ethernet/USB caddy? Thanks Wayne. |
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That will change as I'm planing an upgrade to newer CPU (FX) that is both faster and has hardware checksum calculation. That camera will also have somewhat bigger FPGA and twice memory (64MB system, 64MB video, 32MB system flash) - it will likely have faster USB, but it will still be host, not device. Current Ogg Theora implementation is not really good for general filming - it was intended for fixed-view network camera applications, so only two types of frames - INTRA (key) and INTER_NOMV (inter, no motion vectors). It gives a lot of extra volume savings only if the background is not moving. Motion vectors will wait for the next bigger FPGA :-) The precise bandwidth for current Ogg Theora depends on multiple factors, I would say about 1-2 MB/sec is usually enough. Quote:
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On the other hand - each new of their sensors so far was better than the previous one, so 3MPix with binning is better than 1.3, and 5MPix with binning will have approximately the same resolution as 1.3MPix one. Quote:
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Have you considered raising the data rate (GigE or USB2) and implementing Bayer based Lossless compression routines in the FPGA? Quote:
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So what I meant was that with full speed (like 1280x1024x30fps) I need 1-2MB (megabytes)/s fro "good" quality, when most background stays the same. There are ways to decrease it even more. With the camera moving, current implementation will give very little advantage over plain motion JPEG - I do not have real measurements, but would estimate it as under 50% difference Quote:
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As for the "grade for phones" - this technology really benefits from higher volume and one of the best IC manufacturer (we all trust their memory, don't we?) Quote:
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how big is the image plane of this thing? I guess it's standardized somehow with C-mount?
Does it have fiber optical taper front of CCD? |
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As far as sound, there are many modules, USB2.0 as well. It should be able to control/sync external sound recording modules, or be good for minimum cinema sound 48Khz 2-8 channels, or stereo at 96Khz uncompressed. Quote:
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Bayer compression, yes good. If you can get the next camera upto 12.5-25MBytes/s with RAW bayer compression that would be really good for this market. We did find a number of lossless routines, some open source, I don't know about bayer, even visually lossless is good. But I think you are more oriented to purely security video and don't really need anything more than visually lossless 99% of the time, and most of the time only upto consumer grade video. Quote:
The Kodak CD's, are they better than the Micron, are they still available? Quote:
I still think that Micron is good for cheap cinema/doco camera, as it is as good/better than some prosumer HDV cameras. I would be surprised if it could match a mid end camera like the Sony XDCAM HD 1/2 inch though. Quote:
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Well Andrey, thanks for clearing these things up for me, I had been wondering about them for a while, I can stop now and wait to see the next camera and 5Mp sensor. I have had a little voice in me for a while telling me not to buy the present model, and now I understand why, it can process the framer rate but not the data rate I desire. Thanks Wayne. |
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ADCS quality: In particular lower on the Ibis5a, but also many chips, because of thermal noise consideration etc, and the quality of high end ADCs. There is more to silicon sensor quality (and ADC) then normal silicon circuits (on good ADC they go beyond silicon) just because a company is good in one does not mean they are good in another. But, seriously, I don't think Micron aims to make costly top quality sensors to put in mobile phones and security cameras, I think they might aim for cheap top quality mobile and security sensors instead. Kodak: Quote:
Ibis5a price: Quote:
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There has been talk of upcoming 5Ghz programmable gate array technology, is that any close to a commercial product? Quote:
Before I get to these techniques I will share another one that I had previous that it also turns out people are using in film restoration. Noise reduction, should improve existing performance, and the performance of lossless compression immensely. Most compression performance is lost in the last 2 bits of a image, because that contains the most noise. if you eliminate this noise you ramp of the compression that should be achievable at the same quality. Basically rather than just finding a pixel of noise and interpolating it out with the surrounding pixels, the pixel itself might still contain some information (in 3 chip, the other channels might contain the information) and the proceeding and succeeding frames contain information about the piece of image that should be in that pixel. By using this extra information you can restore the pixel with great accuracy, producing a cleaner image to compress. This would be a of great performance benefit to the techniques below. Thanks Wayne. |
Compression of Bayer:--------------------------------
While I wish to keep the most efficient ones for commercial reasons, I have also been talking about some, lesser, helpful ideas around here that might help. I will attempt to get back latter with links to previous discussions that outline it. But the basic idea is to store succeeding pixel values as the difference from proceeding ones, and to store the differential between succeeding frames. Now, all this data is compressed with run length encoding and the usual sorting/mnemonic representation compression techniques used in regular video compression, and in fax like compression techniques.
Now, the beauty is the next method to reduce the differential even more. We know that in an image luminance generally changes more often then chrominance, so colours are less variable pixel to pixel then luminance. This generally helps a debayer algorithm predict the other primaries for each pixel position. But with this scheme, what I propose is that the proceeding/surrounding pixels value be used to establish what the pixel should be, in that primary colour (using the previous/surrounding proportion of that colour present) as the base value for the differential, thus reducing the amount of data needed drastically. We also use the surrounding pixels to estimate an interpolate prediction to modify the base value. The whole basis is to use estimation/prediction (that does not have to be recorded as the decompression software makes the same prediction) to reduce the data size before finale compression, in a format hopefully more compressible by finale compression. There is a bit more sophisticated things that could be done then this, some of that commercial stuff I mentioned, but as you see, the work done would mostly be simple comparative circuits, plus the run lenght/mnemonic you already use. I'll just summarise, so I can remember, prediction based on previous pixel and interpolation of surrounding pixels, and previous proportion of that primary colour, modified for primary colour at the present pixel. Once the bayer is reconstructed, it is then debayered for display. Of course, the interpolation of surrounding pixels that have not yet been calculated, in decompression algorithm would enquire some fancy maths, but a simpler effective form of it can be done without interpolation of unprocessed pixels. I think I have posted somewhere a 3chip version of this scheme as well. This is just one of the several different areas of high performance compression technique I would like to use. It is also one of the most expendable, and potentially one of the least effective in compression performance. Thanks Wayne. |
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image plane = 6.55mm*4.92mm registration distance = 17.52mm FO taper = no am i right? |
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http://s03.picshome.com/d29/staircasesuppress.jpg |
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I do not even know how this is possible, But i was able to stream
1600 x 896 frame size @ 24fps. (16:9 aspect ratio, note: 900 had to 896) and 1920 x 816 @ 24fps (2.35:1 aspect ratio) This is unreal ! but i checked everything in the avi file on a timescale and made sure there are 24 frames for every second of footage and there is! it is true 24 at 1600 x 896 and 1920 x 816 the only thing i see that is the only downside of using more of the sensor is that the electronic rolling shutter artifact is more noticable.(at 1280 by 720, your only using a small portion of the sensor, so the electronic rolling shutter can sweep through unoticed. but even at 1600 x 896 the rolling shutter isnt too bad. but for 1920 x 816 you see the impact alot because of the widescreen. but for shots without quick whips , or shaky handheld footage. the rolling shutter can't be too bad. I am just amazed that the camera can actually stream these sizes at these speeds. i find it unbeleivable. is there a reason why this is possible Andrey? thanks |
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BTW - I've just made some FPGA mods to provide exact (to 1 usec) timestamp for each frame (measures at the start of the first line in each frame) - just need to add software to deliver this info through the stream. Quote:
The new 5MPix 96MHz will need an upgrade in the camera to keep up with the maximal frame rate (pixel rate can be 96MHz even with 333), it can also benefit from 12 (vs.10) bits - model 323 camera that uses older 313 boards receives 14 bit data. |
one more question, Andrey. Do You have any experiencies using non-C-mount lens with such camera? In other words is it possible to use there FO taper front of ccd to get larger image plane. Wich would be very helpful to use there 35mm photolens in full functionality.
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Did I say something wrong?:
Speed: So, are you saying that the Ogg codec can do 70Mbit per second (and 9MB/s) that definitely helps? Kodak sensor: ..will it do a 720p or 1080p frame at 25fps? There has been talk of upcoming 5Ghz programmable gate array technology, is that any close to a commercial product? The bayer differential compressing algorithm concept? Thanks Wayne. |
i apologize for nit picking here, but, is the MT9T001 the only micron's sensor that does global shutter? So why do you have rolling shutter ussues at widescreen rez then?
And, honestly, all the footage placed in this thread is either overburn or noisy due to low light. Is it camera, or shooter or setup difficulties? In this form, it slightly misses main reason of sample footage - to show the device in its best. to go a bit conceptual... i think from point of this forum, there are 2 features absolutely nesessary to make a good industrial camera head usable for digital filmmaking. First is direct recording of quality stream to harddrive and second is a way to monitor the picture on a device attached to the camera. As far as i understand, the present camera is a kind of sbc with fpga, so ideally it should be sbc with vga-out and ide/sata, where fpga doing debayer and resize function for preview. But it is different concept (from network camera) and camera board redisign. Not good. And even that ideal system, would require 2 person team to operate. 1 to control the camera settings via laptop and 1 to actually point and shoot. To eliminate this problem there must be all in one place: lense, head, recorder and screen. Why not attach a compact capable laptop to the head then, like a Tablet PC? And a battery bank. But in general, how could you summarize the reasons to use such a camera in real life shooting. Except very special areas, like permanent multicam video system in small music club, where it is probably excelent option to take already, and a toy for filmmaker wannabe who loves cameras more than above mentioned fimmaking? Iam not offending anybody here, of course, except myself :). |
Konstantin,
I have covered most of these points a few times. even with Andrey by email in times past. And yes I have noted what you said, but I was being kind not to point it out, because it does not prove how much it can do (and sensor and compression has a lot to do with it). What I have been discussing here is ways to maximise performance to get it upto quality output, and defining what the limits are. Including a practical bayer scheme. The problem is that it is a security camera (not industrial)so it is made for good security quality, and limited. A little extra quality and we can get to at least pro video quality. The Kodak sensor might deliver a lot better performance, but I note that Micron has extended latitude features now (there MT9V032 wide vga security chip pdf shows 32K lux and 2 lux test charts in the same shot. So there is hope for this to turn up on the HD chips. Computer: If you want a small platform, then car-PCs (about the size of a DVD drive) Origami and UMD, small cheap Tablet PC's, are worth looking at. There might be one out there with higher res screen and microphone input/s. Have fun with it, we need your sort of thinking around here. Thanks Wayne. |
Yes, you are correct that none of the test footage was performed under ideal condintions. and also, i recently found the zoom on the lens i am using has to be turned just a nudge away from 13.5mm to actually be at true infinity focus, where everything is in focus. i think the reason being is that, i can go past 13.5mm to macro function, and i was too close to macro. and note my lens is at f1.8 with it open.
Can i ask if you have seen all the footage posted on the link? there is one shot called guitar chair. and i wouldnt call that blown out. i had some focus issues perhaps on it, but nothing much else. and of course we can say there are improvements to be made, but that can always be said. What Andrey has here is a high definition network camera that he probally didnt plan to be used for this purpose. And he has made a great camera capable of beautful picture. and i applaud him for that. He has been very generous and helpful in making this project go foward. I will have to try a little harder to get shots out that can please you a little better. And its not a bad thing, it keeps me on my toes, which is good. I am going to shoot some stuff right now infact. ill see what i can do. thanks |
Yes... but please don't make this forum into a commercial discussion thing. We are discussing the first attempts of using a security camera for film making.
Forrest is sharing his experiments here, he's not selling a camera or something. Please share every footage, good and bad. I haven't received my camera yet, but they say it should arrive in a few days. |
Yes, thank you Oscar. We should discuss and show what the camera is capable of, not "what the camera should be capable of in a perfect world"
Thats what this thread is about, to show progress of using this as a film camera. And here is some more footage i shot this morning. The setup was this: Bright Sunny morning. The subject is under the shade of the tree in my backyard, the sky in the background was basically white to my eyes, with a little blue tint, but it was very bright. I tried my best to show that the camera can get a subject in the shade, while still preserving the colors of a bright background such as the sky. here is the file: http://www.savefile.com/files.php?fid=2614781 It as at full 1600 x 896 resolution but i convereted it to wmv for space. Slower computers (like mine) might have a bit of trouble playing back the high bit rate of the video. if anyone has this problem, and wants to see a lower rez version. let me know. |
well, i should apologize for being extra critical, the "chair" file is correctly exposed, and overall visually pleasent. But, there was one problem that become apparent in last the file, with girl. It is luck of crispness. May I consider that the lense you are using is not even an industrial purpose megapixel lense? You wrote in initial post that it was some combination of 35mm model with wideangle adaptor. It may be not adequate.
I had no intention to start a commercial discussion. But i think even being a thing in itself, the project like this still requires some perspective view. What is it good for and what is the goal? The only reason to use such a modular system in real shooting process is execptional video quality. Lets say noticebly better than present prosumer hdv. An interesting task. |
that last clip is very nice. the footage you're shooting reminds me alot of clips that a board member by the name of OBIN was shooting a year ago with a similar camera, possibly the same chip?
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Konstantin, you do not need to apologize at all. Your comments were very helpful in the for the fact that i must continue to better the progress and quality.
The lens i am using now is an f1.8 zoom lens that is c-mount. It is a correct type of lens, but prehaps its glass isnt good enough for the the cameras resoultion. That might be the case. I just finished ordering a 25mm c-mount prime lens. with f1.4. With this lens, i am going to build the 35mm adapter onto the camera with this lens to serve as the relay lens. I will post footage with that f1.4 to see how it handles the resolution also. thank you. And thank you Eric. I can't remember what chip Obin used, but the process that were going is quite similar. The chip in this model camera is a 3MPix Micron MT9T001 1/2" CMOS. |
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I hope it will soon be easier to troubleshoot - each frame will have a precise timestamp |
Oh wow, i didnt check that one. let me see if that has happened to some more recent footage i did. Thanks Andrey
EDIT: well it seems that things got a bit weird when i convereted to .wmv The original footage coverted to avi from ogm via VirtualDub shows full 24 fps. 24 frames for every 1 second of footage. for some reason, the wmv version doesnt want to play right, also the wmv in windows media player states 29 sec duration. perhaps when it says 32 sec in mplayer it is not playing it right? i dont know. |
I also think at 1600 by 896, i am really maxing it out. it seems on certain footage, it will do 24fps fine, but when i have footage in motion and pans, i lose frames. i think i need to scale down the resolution. 1600 by 896 is not really needed anyways. could this also cause the excess electronic rolling shutter artifact? the fact that i am trying to grab more frames than possible at that resolution. thanks
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I think it will be easier to locate problems with frame timestamping. Only what you can try right now - set low quality and see if it helps (eliminates frame drop). You see, the FPGA compressor can now process all the data from the sensor at any quality settings without drops - this frame rate is calculated and reported in web interface (of cause there might be bugs and with some settings the calculation of the frame rate can be wrong). But the sending of the compressed data out requires CPU activity and higher bandwidth needs more CPU power, so it can limit the frame rate. If reduced quality helps - that is probably the case. Did you use autoexposure? It also uses CPU and can steal some of it from the streamer - especially if the illumination of the scene really changes (when you move the camera). |
I think the main problem is my CPU speed. im only at 1.5 Ghz right now. I will buy a 2.8 Ghz processer soon.,and that should help alot. because its when i go for better quality compression that it usually drops. thanks Andrey
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Oh ok. I see now. thanks andrey
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