Multimedia Sample Preparation
Scenario
Capture videos on the road and display related information.
Hardware
- DV Cam video
- GPS
- Laptop for GPS recording and/or DV cam direct capture
Software
- HyperTerminal (Windows software to capture GPS text streams)
- GPS USB interface Serial Emulator should be pre-installed. Download DeLorme Serial Emulation Driver for USB Earthmate® GPS and Earthmate® GPS LT-20 Receiver. This drive will create a number of virtual serial ports. Choose a port supporting the NMEA (National Marine Electronics Association) data format. After a port is opened and you see the GPS data streams, then select Transfer->Capture Text to save every source stream into a text file.
- Serial port configuration: 4800 BPS, 8 Data bits, No parity, 1 stop bit
- Microsoft MovieMaker and VirtualDub for video encoding
- VirtualDub for video compression
Experiment
- 01/15/2007 16:07:40 PM
- Saved to: (POVISERVER, E:\research\media\)
- Duration: 09:33 seconds
- Frame rate: 29 frames/sec
Data formats
Sample GPS data
$GPRMC,210710,A,3400.225,N,08403.651,W,0.0,0.0,150107,1.6,W*79
$GPGGA,210710,3400.225,N,08403.651,W,1,12,8.000,332.8,M,,,,*08
$GPGSA,A,3,00,00,00,00,00,00,00,00,00,00,00,00,0.000,8.000,0.000*3A
$GPGSV,3,1,12,10,85,351,43,06,31,314,39,29,26,161,00,07,23,315,37*70
$GPGSV,3,2,12,26,15,171,00,02,51,053,00,24,61,338,39,04,16,081,00*75
$GPGSV,3,3,12,13,05,033,00,12,30,227,42,30,31,266,33,134,00,000,00*49
$GPRMC,210711,A,3400.225,N,08403.651,W,0.1,0.0,150107,1.6,W*79
$GPGGA,210711,3400.225,N,08403.651,W,1,12,8.000,333.6,M,,,,*06
$GPGSA,A,3,00,00,00,00,00,00,00,00,00,00,00,00,0.000,8.000,0.000*3A
$GPGSV,3,1,12,10,85,351,43,06,31,314,38,29,26,161,00,07,23,315,38*7E
$GPGSV,3,2,12,26,15,171,00,02,51,053,00,24,61,338,39,04,16,081,00*75
$GPGSV,3,3,12,13,05,033,00,12,30,227,42,30,31,266,33,134,00,000,00*49
Please refer the NMEA data format specification to understand above sample data. Basically, this data is sampled every second. A simple formula to convert the longitude and latitude is below:
- ex) $GPRMC,210711,A,3400.225,N,08403.651,W: This data is capture at 21:07:11 at 3400.224N and 08403.651W. 3400.224N means 34 degree and 00.224 minutes. To convert into the decimal degree for use with Google earth or else (ex. 34.0037333, -84.0609000 Google Map). Then set left two characters(ex. 34) as a degree and all remainder (.0037333) as minutes. After apply the equation degree + (minutes)/60. In case of latitude, left three characters are degree. See attached the Excel file for details.
