Nightcap (a short ride on an Optibike OB1 by Optibiker)

The bike is an Optibike OB1 with a Rohloff Speedhub. The video was shot by the YouTube user Optibiker, and marked up with my software.

Data feed recorded with a Garmin Edge 500. Future videos will have power data from an iBike power meter; stay tuned!

The software overlay is done on Linux using Inkscape to edit the SVG, Genshi as the templating language, librsvg to render, and gstreamer for the video management. Folks with the talent and inclination to build better templates -- please get in touch.

Category:

Sports

Tags:

• optibike
• garmin
• outdoor
• Austrailia
• cycling
• ebike

[drsquirrel0]

Hi mate.

I've been working on a way to do overlays and that kind of stuff (based on subtitle overlay)... but my biggest problem specially when it comes to making it easy for other people to do this is... How do you sync your video with your gps stream? (other than manually). Not everyone has a video timestamp (even if that is accurate).

Someone (Forgot his YouTube name) did a HUD with graphical direction bearing and various other stuff.

[charlesatdyfisdotnet]

By the way -- the way I *want* to do the video sync is by having each video start with a shot of the running Garmin, then provide a tool to let the user advance frame-by-frame until a seconds transition on the Garmin's time display is seen and enter the time displayed. That seems to me like the best approach -- but the videos I've gotten so far haven't had a good enough view of the Garmin's display to be readable for that purpose; will need to coordinate a little more.

[inclined2ride]

Great job - graphic overlay is much easier to read than the "transparent dial" types I have seen. I am keen to do similar for a road bike training HD dvd and look forward to your input on the recent email.

Next step from here is to develop a device that can translate gradient into resistance for an indoor trainer like a Kurt Kinetic and have the footage advance based on user power input.

[charlesdyfis]

Easier to see, yes, but also less accurate; the thing I like about finding an individual frame where the second counter changes on the Garmin's display is the level of precision.

I haven't given thought to split video input -- but as GStreamer (the video handling library I'm using) supports splicing together inputs easily, it shouldn't be much trouble if I ever find the need.

[drsquirrel0]

If you step through, seeing yourself pressing the start button on the video is more likely than as you say, seeing the time display.

Have you considered handling split video? (Some cameras split the videos into 30 minute segments etc).

[charlesatdyfisdotnet]

There are a few things I need to do before publishing -- checking up on the licenses of all the libraries I'm using, writing some documentation... frankly, the library dependency list is long enough I'm almost tempted when I finally distribute this to publish a virtual appliance. Anyhow, I'll post here when that happens.

[drsquirrel0]

I was looknig for the beep manually and looking at the timecode to offset, but automatically trying to find it might be interesting.

Just hope it doesn't get confused with autopause and stuff like that.

I tried to do other things like tapping the camera/mic when I press the Start button, the other option I thought about was starting the record and gps at the same time.

Is this programme you are working on available for anyone else to try?

[charlesatdyfisdotnet]

Yar; we've turned off the "Smart" mode. In the modern version of the software, we spline-fit the first derivative of the distance values for interpolation and smoothing... but when you see the iBike and Garmin numbers side-by-side, it's night and day.

Detecting the beep is a cute idea. I might have to try that.

[drsquirrel0]

I try using the beep from pressing Start on my unit, since that can be seen in the audio waveform.

gpx from a garmin unit works better if the edge isn't on smart mode so it records every second (although you can calculate the points between in smart mode easily, as they are assumed to be the same regarding direction speed and hr).

It's sad that the TCX format doesn't even save the speed from the cadence sensor (it just leaves it so we have to calculate it from the GPS distance over time).

[charlesatdyfisdotnet]

BTW, we're working on more graphical outputs as well; just takes some cleverness in building the SVG. :)

[charlesatdyfisdotnet]

The current version supports using not only the GPS but also an iBike (power output, wind speed, more exact elevation and grade numbers, and a much more accurate speed value than the Garmin's).

I have some code which tries to determine the offset between the two via a least-squared-error mechanism, but I'm not happy with it; the Garmin feed is noisy enough that even the clearly correct timing isn't always the global minima -- so in practice I graph the two and find the offset by hand.