DVRs vor capturing analog thermal video - your experiences. - Page 1
Forum section: electronics / general

author: Vipitis
author_rank: Frequent Contributor
timestamp: October 29, 2019, 08:05:09 am
content: Just a quick and dirty thread to get some experiences from you. There are many different digital video recorders that take any analog input and record it into a digital format. Cheap USB capture cards, portable and battery powered all in one 'pocket grabber's, CCTV tester monitors, fpv drone racing DVR. I just wanted to know specific devices you have used with thermal cameras. The bug issue I am seeing is that most DVRs compress into mpeg and some h264, both compression algorithms work great when colorspace can be compressed, but AGC in thermal cameras usually fills up the complete range. This makes it a naturally bad match.any other setups to capture the analog signal gladly welcomed.

author: Ultrapurple
author_rank: Super Contributor
timestamp: October 29, 2019, 09:36:16 am
content: I've used a variety of means to capture video. Best success was with an 'Easycap'-type USB device and VLC - at least, once you figure out all the settings to make the darn thing work. You can set the capture to match the actual video standard, rather than (say) converting 25fps to 30fps.My experience with all-in-one battery powered DVR with screen things has not been great. The only one I tried had fairly high compression, rescaled to 800x600 and burned-in a date stamp that defaulted to 1938! (Click image for more info).(That image was originally posted as a comparison between cameras but it serves to illustrate the burned-in time).I'll post a photo of the device if I can find it. From what I recall it ran from a Nokia phone battery but required more drive current than most cheap knock-off batteries could manage.I've also tried using an HDMI-based 'game recorder' device that sits between an HDMI source and the monitor, outputting captured video over USB to a PC and/or recording to a micro SD card. I didn't use it much because the user interface was a bit weird - one button, if you press it when the LED is blue it does something different from when the LED is green, or red, and something entirely different again if you long-press on a change of colours. That way lies madness.I have also done a lot of playing around with standards converters and suchlike to try and make things talk to each other. I believe I have enough converter toys that I can take an analogue 30Hz NTSC signal, convert it to 25Hz PAL, then convert it to HDMI, then back to PAL and, just possibly, back to NTSC again. Whether there'd be anything left of the image is a moot point.

author: Bill W
author_rank: Super Contributor
timestamp: October 29, 2019, 03:29:23 pm
content: Tried several, but with very mixed results.Hauppauge cards good, but you are attached to a desktop !Hauppauge USB-Live2 are good.Real original EzCap are OK, but not the knock off ones.Bill

author: Ultrapurple
author_rank: Super Contributor
timestamp: October 31, 2019, 01:56:24 pm
content: I have also tried one of the blue aluminium-cased mini DVR units likeeBay auction: #392441125172which are inexpensive (about GBP15 and up). They use a micro SD card up to about 32GB and have various configurable functions; they pass video straight through so you can connect it between the source and monitor. The nice thing is that they record reasonably decent quality in a standard file format, unlike some things like dashcams that use very peculiar file types and/or require their own special .exe player.Mine worked OK for a while but then the video output failed. I think it is probably something simple; when I get a free moment I'll see what it looks like on a squigglyscope; I think the fault is probably something simple because it has all the hallmarks of something like a leaky output coupling capacitor.And hey - I've finally figured out how to resize big external images to the size I want them; the trick is{img width=150}hppt://image.url/here.jpg{/img}...but of course you use square brackets and the proper image address - which probably doesn't start with hppt://. The 150 is the size (in pixels I think). 30 is too small, 100 works OK, 150 gives the size you see on this page.Took me absolutely ages to find that particular magic incantation. Most of the online help files don't.

author: Vipitis
author_rank: Frequent Contributor
timestamp: October 31, 2019, 03:55:51 pm
content: there is likely a tiny circuit inside. FPV drones gave the market a need for shrinking these in size and weight. Since the whole camera runs on 5V anyway splitting that out for 3 different devices will be easily done, also gives me more room for a monitor and I could perhaps get away with a monochrome screen for it.if you know he embedding magic, let me know if you found a way to stop YouTube/Vimeo from autoembedding. This is ruining my posts about the music videos.

author: ArsenioDev
author_rank: Frequent Contributor
timestamp: October 31, 2019, 04:03:33 pm
content: FYI, I've use a cheap composite-HDMI converter dumping into an Elgato first gen to FANTASTIC success. The cam link should also work pretty good

author: Ultrapurple
author_rank: Super Contributor
timestamp: November 03, 2019, 10:59:12 am
content: My experience of cheap analogue to HDMI converters has been pretty good, too. I'm not sure I'd call it "fantastic" but these little boxes of tricks certainly provide a handy way to convert between connectors and standards.

author: KnuckleheadFlow
author_rank: Newbie
timestamp: November 20, 2019, 02:35:50 pm
content: I was looking at drone FPV DVRs (specifically the Runcam Mini, HMDVR-S and Eachine ProDVR). However, it seems like all analogue SD DVRs record 25/30 Hz, whereas my TIC outputs 50. Of course the HD ones can record 60 Hz, but I'm guessing that's because it's already digital and it's too much of a hassle to make something that can digitizeanddeinterlace.Has anyone seen a small DVR board that that does?At least the Runcam Mini is only like $20 so it's not as if I have to pay a lot on top of making do with half the framerate

author: Ultrapurple
author_rank: Super Contributor
timestamp: November 20, 2019, 03:07:08 pm
content: If your camera's output is viewable on a standard monitor (=TV) then a drone type recorder will work fine.By and large, 384x288 cameras are natively 25Hz and 320x240 cameras are natively 30Hz (it's all to do with the number of lines in the analogue TV picture - 50Hz '625' line TV has 576 active lines, split intotwo interlaced fieldsof 288 lines each). So a "25fps" analogue video signal actually contains 50 fields per second. There is no contradiction in describing a 25fps video signal as 50Hz, or 30fps as 60Hz.Note that it's important not to confuse the video standard with the frame rate of the camera. I have a 320x240 15fps camera that puts out 60 field per second (30 frames per second) NTSC video, which it achieves by simply repeating every 320x240 image four times. Likewise, <9Hz cameras repeat frames to give 25 or 30Hz (50/60 field) video.

author: Vipitis
author_rank: Frequent Contributor
timestamp: November 20, 2019, 07:50:08 pm
content: the main issue I have with these FPV DVR boards is that they all record in mpeg compression - which is troublesome with AGC. The mentioned RunCam Mini DVR Board is cheap and does offer VGA or NTSC/PAL, however I couldn't see any good information on compression and bitrates used. For me it is vital to have no compression at all in the final product. and I am seen reports about dropped frames on the cheap FPV DVR boards.

author: KnuckleheadFlow
author_rank: Newbie
timestamp: November 20, 2019, 08:12:35 pm
content: Wow yeah, of course. De-interlacing two fields would "halve" the frame rate of the two.Although the video it displays is 50 Hz (the manual lists "screen update rate: 50 Hz", it definitely looks that smooth), of course it won't output that. The resolution's not even right.It had an optional pistol grip that contained an optional DVR and optional transmitter (maybe ISG themselves repurposed a drone DVR lol). I doubt I'll ever find it by itself for a decent price. I did some poking around on the connector it uses and quickly found the video output, ground and what appears to be video ground (with the camera on, there's continuity between the video ground and ground but not when off) pins. Borrowing a pic from Fraser's thread about this bad boy:Once I have the DVR thing sorted out, I'll get some pogo pins and try to 3D print a grip.Quote from: Vipitis on November 20, 2019, 07:50:08 pmIt's a good thing you mentioned that, I checked and it's got 8 Mbps.I think for the same price the Eachine ProDVR is a better option. MJPEG 16-25 Mbps. Not sure how that stacks up ultimately, but seeing as how it's only $20 and I'm not using this TIC for anything serious or professional maybe it's as Dave says, good enough for Australia.

author: Fraser
author_rank: Super Contributor
timestamp: November 20, 2019, 08:35:08 pm
content: Knuckleheadflow,Regarding the ISG camera.....The set of four gold contacts are dedicated to connecting to the battery bay for charging the battery pack in a vehicle docking mount. The battery contains a temperature sensor and a battery “Positive” routing relay that switches between supplying the camera and taking a charge from an external charger.The other row of gold pins are the I/O port for the DVR hand grip. Video and video ground are taken from there.The other connections go to the ISG Control PCB and are likely involved in setting up the DVR from the cameras menu system.Fraser

author: Vipitis
author_rank: Frequent Contributor
timestamp: November 21, 2019, 01:25:37 pm
content: I found something called theImmersionRC PowerPlay FVP. It is a very new product a but claims to use h264(x264) in 60fps to record in PAL and NTSC resolution up to 15Mbit/s. It also works as a battery case with built in monitor. It's also available in a drone store close to me so I might check this out, it claims to solve 3 problems I am having and is reasonable cheap.

author: Ultrapurple
author_rank: Super Contributor
timestamp: November 21, 2019, 01:46:14 pm
content: Has anyone tried using security CCTV-type recorders for LWIR? I have a four-channel one somewhere that takes analogue in (CVBS/AHD, IIRC) and seems to make a half-decent job of recording, but I can't remember what the bitrate is. I suspect it's adjustable. The downside is that it's not designed for portability, as it's housed in a metal box about A4 size and runs from 12V.I notice there are 'naked' security DVRs (ie unboxed) on eBay and elsewhere, with varying numbers of channels, that just need a power supply and hard disk to make a very functional device. An old laptop (SATA) HDD is ideal (back up first if you need to, as it'll trash the data) and size isn't that important unless you're planning to makeverylong recordings. A four channel board like this is about GBP16 and they usually come with the necessary basic cables (but, as always, check the description).If you're clever it might even be possible to get into the 'works' of something like this and tweak the bitrate to something other than the default. I've no idea whether there's a command line interface lurking somewhere - or how to access it - but I'd bet a dollar to a dead dog that most of the systems are built on some flavour of Linux.(Please don't take me up on that wager - I have already got all the dead dogs I need: none).