Autocross Video Setup

[Jamie]

You can see that the GPS data is VERY laggy. I need to switch the speed input to OBD, that should be very accurate.

You're using the phone's GPS, rather than an external receiver?

[Loren]

You can see that the GPS data is VERY laggy. I need to switch the speed input to OBD, that should be very accurate.

You're using the phone's GPS, rather than an external receiver?

Not ready to dump another $80-100 on an external GPS just yet. So, yes.

[Jamie]

You can see that the GPS data is VERY laggy. I need to switch the speed input to OBD, that should be very accurate.

You're using the phone's GPS, rather than an external receiver?

Not ready to dump another $80-100 on an external GPS just yet. So, yes.

I was using my phone back when I was posting telemetry on my videos...found the same thing -- 5Hz sample rate just isn't enough to keep up, so the speed and the lateral accel lag terribly. Speed you can take from OBD, but calculating Gs will require the external GPS. At some point, you'll find that useful for looking at braking and cornering technique.

[Carracer]

An external GPS is worth its weight in gold for me. I don't think the OBD speed channel will be accurate enough as it won't factor wheel hop. The main thing I look at is minimum speed in a corner and exit speed, a 2 mph difference can make a huge difference at the end of the lap.

[Loren]

It's taken me over 20 years of autocross to even bother doing video. I'll get more serious about data collection eventually. Maybe.

[Loren]

Spent more money last night. After spending way too much time exploring other options trying to save a buck, I bought a RAM suction cup phone mount. That will allow me to put the phone wherever I want in the car to either get a course view while the external camera is getting something interesting. Or, to get a driver view when the external camera is getting a course view. I like the RAM mount option because it is extensible. If I can't get enough reach, or I need another axis of adjustment or whatever, I can get RAM parts and make it happen. I can even get the RAM GoPro adapter and use this mount for the external camera.

If you're keeping up... total investment so far:
4k WiFi camera - $52
Cheap GoPro Suction Cup Mount - $8
360-degree swivel mount - $7
32 GB SD card - $25
RaceChrono software - $18
RAM Suction Cup Phone Mount - $31

My "$35 camera" is now up to $141. But, I now have a dual-camera setup that's fairly versatile. Unless I want/need to play with more mounting options, I should be done spending money for a while. And then there's the external GPS...

[Rpwolf]

I finally got a camera, a gopro hero 4 silver (it took way to long to figure out all the versions) that came with some mounts/ accessories, SD card, and a gopro suction cup mount (dare I saw how much I paid?). so now to follow in your footsteps....

any recommend brand for obd2 dongle? how do you manage to sync the throttle and speed to the video?

btw, if you guys are looking a gopro camera, I would look for any version of the 3+ or pay a little more for a 4. they usually come with accessories and such.

[Loren]

any recommend brand for obd2 dongle?

The generic ones seem to work just fine. The OBDII standard dates back to 1996, and it's not very "demanding" by today's standards.

I had a basic one that I used for 1.5 years before it died. Didn't like the fact that it stayed on all the time, so when I replaced it, I looked for one with a power switch. This One has been serving me well for 2 years now.

how do you manage to sync the throttle and speed to the video?

It's all done in the software. If you're taking video and data from the same app, they're probably going to be automatically synched together. It's when you bring in external video that you have to manually synch it. If you're using RaceChrono, you do it on your phone in that app. If you're using TrackAddict, you have to use RaceRender on your PC to do it.

The synch process is pretty easy. Get the video and data loaded in whatever app you're using, and they're going to give you some kind of visual data graph and the video on the same screen. You pick a data point in the data stream, and you play the video and stop at that point. Push whatever button you need to synch it up.

I've found the easiest way to synch data for me is to synch on the 2nd gear shift. You can look at throttle position or RPM in the data, and if your video shows your shifter hand, you can key on movement... if not, you can key on sound.

If you've got an accurate speed input, you could just key on vehicle movement at the start. As soon as you see the car start moving, you should see an immediate change in speed.

Yet another way to do it... your app will always let you record a video from your phone. Even if you're not USING that video, try to point the camera where you can see something... any kind of car movement. Then, when you load your external video, you can just visually synch the videos. When video A shows movement, video B should show movement. And the data stream is already synched to video A, so that takes care of that.

However you do it, you just need something you can pick up on the video, either motion or sound, that you can clearly find in the data stream and synchronize to.

If you're using RaceChrono, I can give you some more specific instructions. (and you might need them because the documentation and tutorials available for that app are lacking)

[Loren]

Thoughts from the first autocross:

The wifi on the camera works pretty well when the camera is IN the car. Put it outside of the car where there's some METAL between the camera and the phone and it absolutely will not connect! That was frustrating.

You can get close to the camera, connect wifi, and definietly use it to see your camera angles (without having to try to look at the tiny display on the camera). So, that's good. But, as far as starting and stopping it... I think I'm going to get out the wrist-strap remote with the start/stop button and see what kind of range that thing has. (it may not be any better, but at least it's easier to use than waiting for the phone app to connect to wifi and all that)

I was experimenting with 1080p and 60 fps with some of my video. I'm wondering if there's something buggy going on there. It seems like the audio may not be synched correctly, and the audio is curiously variable in volume, and when you play the video, it doesn't seem to play at the right speed. (it's not "half speed" or "double speed", just "off") When I tried to synch that video with the 30 fps video from my phone, they were clearly not finishing at the same time. I even thought I had the wrong video at first, but no... it was the correct video.

So, I need to try again with 1080p and 30 fps, which is the same as the camera phone. Maybe that will synch better?

I got some interesting, but not terribly usable, video putting the camera on the front bumper, dangled precariously close to the ground, and out where it was exposed to getting hit by a cone. My mount rig was a little too bouncy for that. But, you could definitely see tire contact patches and suspension movement. Nifty. Might try playing with the "handlebar" mount on a swaybar or something like that, and use fewer coupling points in the rig for better stability. Could get some fun shots that way.

The rear quarter-window driver-view video was pretty good. But, that's the one I shot at 60 fps and couldn't work with.

I was actually very pleased with the video I got from my phone on the RAM suction cup mount on the windshield. Video wasn't too bouncy, audio was good. I guess "simple" is sometimes best.

Philip showed me some of the cool things you can do with RaceChrono as far as reviewing data. But, I haven't mastered it yet. And, I screwed up and left the phone recording data (not video) for a LOOOOONG time without having defined what the "course" was, so I ended up with like 15 minutes of data that made it very hard to work with. I messed around and accidentally deleted the session data, so I can't play with it any more, even if I wanted to. (and I did want to)

I also dug out my old LG phone and charged it. It does 1080p video, and can run RaceChrono, as well. I could (should) set that up on the RAM mount and just leave it in the car during autocross so that I'm not constantly having to fidget with my actual phone.

Once I master the software, I can do things (even without looking at the video) like Philip is doing... looking at course segments, comparing between runs to see which method was faster, etc.

[jbrannon7]

It seems like the audio may not be synched correctly

I have had that problem with several cameras, It seems to depend on the video editor you used. Never made and sense to me but one camera will only work with total media extreme and another camera only works with Pinnacle Studio. Even though both files claim to be the same MP4 or AVI format.

[jbrannon7]

In the Past forum Loren posted about RaceChrono data, I will provide some here.

First is here is the file exported from my phone as an email attachment saved on my PC.


Here is the file opened as a txt file with notepad.


And here is the file opened with Excel

[Loren]

It gets better than that, Joe. Philip was showing me, in Race Chrono, how you can display your race "course" trace over a map, and define not just start/finish, but also sectors, and look at those sector times for each run right there on the phone. Lots of ways to analyze the data without even exporting it off of the phone or bothering to look at a video.

Philip thinks in ones and zeros.

[jbrannon7]

It gets better than that, Joe. Philip was showing me, in Race Chrono, how you can display your race "course" trace over a map, and define not just start/finish, but also sectors, and look at those sector times for each run right there on the phone. Lots of ways to analyze the data without even exporting it off of the phone or bothering to look at a video.

Philip thinks in ones and zeros.

Yes, I have done that. I thought you were interested in PC stuff.

[Loren]

The only real reason I'd need RaceChrono data on my PC would be to import into RaceRender. While I'm not a fan of RaceRender's big ol' logo on my screen, I do like the flexibility it offers in editing/configuring video. You can do A LOT more with video there than you can with RaceChrono on the phone.

For simplicity, so far nothing beats RaceChrono + your built-in phone camera.

[jbrannon7]

The only real reason I'd need RaceChrono data on my PC would be to import into RaceRender. While I'm not a fan of RaceRender's big ol' logo on my screen, I do like the flexibility it offers in editing/configuring video. You can do A LOT more with video there than you can with RaceChrono on the phone.

For simplicity, so far nothing beats RaceChrono + your built-in phone camera.

I am old and like a big monitor instead of a tiny phone screen. Also with the data on your PC you can clip the parts you don't want, it is easy to see when you step on the gas at the start. if you wanted to mess with some one you could also change the values.

[Jamie]

Philip was showing me, in Race Chrono, how you can display your race "course" trace over a map, and define not just start/finish, but also sectors, and look at those sector times for each run right there on the phone. Lots of ways to analyze the data without even exporting it off of the phone or bothering to look at a video.

For local events, who can find the time to paw through the data and format it between runs?

[jbrannon7]

Philip was showing me, in Race Chrono, how you can display your race "course" trace over a map, and define not just start/finish, but also sectors, and look at those sector times for each run right there on the phone. Lots of ways to analyze the data without even exporting it off of the phone or bothering to look at a video.

For local events, who can find the time to paw through the data and format it between runs?

Especially the Dec 2 event where you had a run every 60-90 seconds.

[Loren]

For local events, who can find the time to paw through the data and format it between runs?

Certainly not me. But, Philip makes it look easy.

I think if you do things right, it's not THAT bad. But, it takes being familiar with the software AND being dedicated to doing things right.

That would mean taking your phone with you on a course walk to get an accurate course map, then tagging it with proper start/finish and any segments that you wanted to monitor. From there, having a look at your run data and comparing runs should be pretty easy.

I haven't personally figured out how to do it yet. But, I've seen Philip do it. (and he doesn't even do the "course walk map" thing, I just think that would give you a very accurate map)

[Carracer]

I don't take video with RaceChrono, just GPS. I actually don't really know how video works in the app.

At the start of the course walk I set the GPS input to internal so I just need my phone. I create a new session and a new "track". Give them some names. I walk to the middle of the timing lights and add a "start" point. Takes about a minute thirty.

If I know the run group will be small I will set up my sectors as I walk. Basically when I find a good spot for one I grab the phone and click add sector.

Hot tip! Too many sectors will make for inaccurate "theoretical" times. Set them up so overshooting a corner won't have you sliding past the end of a sector giving you a great best sector but killing the next one. I normally have 3 or 4 total. I sometimes add 5 or 6 if the course is more complex.

When I get to the finish at the end of my walk I add the finish point and change the GPS input back to the external one. This really don't add any time to the course walk.

At the start of the run group I turn on the GPS, it the "start" button on the app and pull into grid. I put my phone in the back pocket behind the passenger seat.

After the first run I'll check the phone and make sure it's working. This is when I would toss some sectors on the map if I didn't do them on the course walk.

Next run I'll check sector times. See where I improved over my first run. It's color coded so a quick glance will do. I'll try and remember what worked on the 2 runs and put it all together.

After the 3rd or 4th run I look at my theoretical/optimal time. What would all my best sectors get me. On a good day I it will be about +0.5 or less than my actual best time. On a bad day it I'll be about +1.000 off. When I first got the GPS I was frequently +1.5 or more. I feel it taught me how to be constant and recognize a run that feels "fast" from one that was actually fast.

[Loren]