A year has passed since we had a Gumstix Overo based video recorder onboard an amateur rocket and it is time to resume working on it. This time I will continue towards the original goal, namely live radio transmission of video encoded using the built-in DSP.
Back in August 2010 I ran a brief experiment using GstInputSelector to switch between various video sources. You may have noticed that it was using Theora encoder while most of my other DVB experiments used H.264 encoder in MPEG-TS container. The reason for this was that I could not make x264enc work in the pipeline used for the video switcher.
Oct 3, 2010 – Danish Space Challenge (DSC) held a Rocket Festival at Borris Sønderland, Denmark, where five rockets built by German and Danish students were launched together with one of DSC’s own rockets. For the first time, the DSC rocket was flying an Arduino Duemilanove based flight computer which was responsible for releasing the parachute. This worked well. The payload in the rocket consisted of the digital video recorder built by yours truly, based on the Gumstix Overo Fire embedded Linux computer that I have been blogging about during the last few weeks, see here. Continue reading “Successful flight and a crash landing”
Wednesday evening the Logitech Webcam Pro 9000 UVC camera and the Gumstix Overo Fire based video recorder have been integrated into the rocket. I will not have access to them before the launch day on Sunday. Shown below is the camera and video recorder integrated into the rocket.
Wednesday, the Gumstix Overo Fire-based video recorder was finally assembled and wired as it would go on the rocket.
I have been quite busy since the last update trying various options for recording MJPG video using a Logitech QuickCam Pro 9000 and the Gumstix Overo Fire embedded computer. The good news is that there has been significant progress reported in the following sections.
With only two weeks left until the flight opportunity it was time to make status and try to assess how much I can finish until the launch.
An email on the gst-devel mailing list last week pointed me to a rather interesting example in the gst-python repository: switch.py – shows how to use the GstInputSelector element in a Python script to select between different input streams. When I looked at the example I thought right away that it would be cool to use it to switch between different cameras in my simple DVB setup that uses Gstreamer and GNU Radio.
This weekend I have been playing with a full duplex transceiver version of the simple DVB setup that allows to use only one computer and one USRP as a transmitter and receiver. By using separate daughterboards I can use one side to transmit and the other side to receive. Using two sets and two frequencies the transceiver can be used for two-way video conferencing over the air 🙂
I have experienced an unexpected spin-off while fooling around with GStreamer and my Logitech QuickCam Vision Pro 9000 webcam: A simple and easy way to autonomously capture and render time-lapse videos.
One of the advantages of webcams compared to other digital still and video cameras is that it can be controlled from a computer and the captured frames are transfered from the camera to the computer in real-time using the USB interface. This is pretty much the definition of a webcam and this feature is indeed very convenient for capturing time-lapse videos. Unfortunately, the image quality of webcams has not been anywhere near good enough to make nice looking time-lapse videos but this has changed over the last few years and is continuously improving. The results presented in this article are captured using my Logitech QuickCam Vision Pro 9000 – one of the greatest UVC cameras out there.