I've noticed a lot on here have telemetry on their car videos. Was just wondering if this was a later add on to the original video or if it's an all in one camera system. I currently use the mk1 GoPro hero 3 black and I'm just about to buy another. My intentions were to film a 3D lap of donington when I visit so I was wondering if I could add telemetry as well.
I use Race Render to add in the telemetry to gopro footage. You can acquire the telemetry with various phone apps or a proper data logger. http://racerender.com/Products/index.html
You wiill have to add it to both streams and you may run into glitches, ive not dealt with 3d but have had to transcode a plethora of video types. The major issue is that gopro is an AVC format, this is also known as a LONG GOP ( group of picture) format. This means that not every frame of video is complete. This might pose problems, so consider converting your streams to a full "I" frame format before attempting it, such as motion jpeg or mpeg2 or dvcpro. These are full "I" frame formats and you also need to ensure your frame rates match, 25 is preferred in PAL countries. Be prepared for a hige intermediate file, in the order of 100mbits per second plus and transcode the vision back to an AVC format when its all done. Good luck, looking forward to seeing the results.
I add mine after, also using Race Render. I know Nige does the same. Obviously you need the data for the overlay, and you have to sync it up.
Do you know if its a video stream or data that is addedl with 3d, he has 2 video streams so he might want to add it to each before rendering out the 3d Ps.. oh ok so its data and he must add it to each camera before making the 3d Pps.. the term clapper comes from the visual moment the claoper closes. So clap your hands in front of the cameras to get an exact frame of reference
It's not the sound that needs synching, but the data. Unfortunately clapping doesn't register on the data logger.
I mean for the video, its not the sound, but when the hand touches. Clapper, you know that chalkboard thingy, the say... "Take one" its called a clapper, historically because audio was recorded separately. Well in this case he needs one to line up the data to the two same frames in both streams on the 3d video. With me? Otherwise the telemetry will look a mess on the two strwams if they are out of synch Btw, how do you synch data? Rpm at the start of the session? What is the point of reference?
Telemetry time shifting, data logging and sampling rates While on the subject, i notice a lot that telemetry lags or shifts... i get why...this might get a few hits on google too A FEW POINTS TO ASK What is the sampling rat3 of telemetry and how accurate is it.? Does the rendering software offer interpolation betweeen a variety of frame rates? Can you camera shoot in integers of the telemetry data? Does the redo ndering software support NTSC and how doea it cope with 29.97 frames per second? Do the data loggers offer options for sampling rates? NTSC is evil, its origins are for television broadcast and its not an integer because every few minutew they would pass data in the gaps.be ause you cant display .003 of a frame right, so they crept the timeline qnd did a duplicate frame, probably setting off thousands of epileptic fits too. Pal is a much more humane format, it used fly poop as they called it, those dots at the top of a frame to transfer data like timecodes. Nowadays, with digital imaging, the encoders create a separate timecode channel in the file. Most professional cameras have it. If you dont own a copy of mediainfo and you produce digital vision of any kind, go and get it, its esssntial. With telemetry, i would never use ntsc, its 29.97 or 59.94, mad huh! Id stick to Pal either 25 frames per second, or for fast moving, 50 fps. Dont shoot 30 frames per second in newer ntsc just because you get 5 more than 25, it makes sharing vision difficult. UNLESS... the data fro telemetry only divides into it... eg, if sample time is 12 samples per second, then you should shoot 60 fps. If you have the option, you could shoot 24 fps, but thats old school film and again you make it difficult to share vision. So that the telemtry matches the frame, its valid to duplicate, but you cant cut a frame in half if you know what I mean. Also avoid interlaced modes as again, you will have one frame at a diffeent point in time to telemetry, and you can get zig zags if you use the wrong field order, its a nightmare, dont go there unless you know you need it and those days are long gone. So what are the sampling rates for telemetry?
Ah, gotcha, it's for the two videos for the OP. I misunderstood. It's a completely manual process. Listen for RPM change, and adjust the data stream until it matches. Ish.
10hz for 30fps 20hz for 60fps The best option 50 for 50fps 100hz for 100fps overkill So I assume on a gopro to keep things manageable, shootong 1280x720 @50fps/hz is the go!
you do it manually, 2 streams at a time. Have them side by side, you can move one frame by frame until they sync. A bit of a faff, but I look for when the car starts moving, passes under a shadow of a bridge or an other similar fixed point. Gearchanges are done by first synching the videos then looking at the Throttle vs incar video. Look when I change gear and line that up with the throttle lift and re application. GPS Speed is done when leaving the pits and fine tuned to the loss of acceleration when changing gear. I can do it fairly quickly now, still a manual process, as it will always have to be. Then render a short clip and it`s surprising how obvious even the tiniest out of sync setting is when watching it back. I have some videos that are like that but I can`t change them now. My ECU sampling rate is very low, but the compilation software interpolates as well as it can and this smooths the sweep of the gauges. You`ll see on some clips, it looks like I don`t even lift for gearchanges on the Throttle trace, but you can clearly hear me do so, that`s just me `beating` the ECU data logging frequency.
Nige when you are using two streams, one is rear view correct? Or do you use 3d as well? Craig needs telemetry on both streams not picture in picture.synch., best option for him is to use wifi remote to trigger both cqms at the same time to limit the timeline frame offset. If these were prrofessional cams you would use timecodes and synch the timecodes on the two cameras first. Then you care less because the time code is not a run time, its real world time. I was the camera tech for a film and tv production company. Was a great experience.. loved setting up shoots and servicing cameras. Off topic... Oh and btw, i saw a post on google plus that claimed the fastest golf time around the nurburgring was 7:49... Perhaps one day you might shop the pinderwagen to bathurst for a classic run ... that would be an amazing track for you.
Here's an old one. PIP and telemetry. Sync is a bit off on the PIP. You just point Race Render at the source files, it figures out the timing and format differences. I used t do it all manually and create an animation from the log data that I would overlay on the video but race render makes it real easy. Race Technology DL1 hooked into a DTA ecu, sundry other sensors. [video=youtube;fZ5TXoxuNaM]https://www.youtube.com/watch?v=fZ5TXoxuNaM[/video]
