This example shows how to use the go4vl API to create a simple program that captures several video frames, from an attached input (camera) device, and save them to files.
Firstly, the source code opens a device, devName, with a hard-coded pixel format (MPEG) and size. If the device does not support
the specified format, the open operation will fail, returning an error.
func main() {
devName := "/dev/video0"
// open device
device, err := device.Open(
devName,
device.WithPixFormat(
v4l2.PixFormat{PixelFormat: v4l2.PixelFmtMPEG, Width: 640, Height: 480},
),
)
...
}Next, the source code calls the device.Start method to start the input (capture) process.
func main() {
...
// start stream
ctx, stop := context.WithCancel(context.TODO())
if err := device.Start(ctx); err != nil {
log.Fatalf("failed to start stream: %s", err)
}
...
}Once the device starts, the code sets up a loop to capture incoming video frame buffers from the input device and save each frame to a local file.
func main() {
...
for frame := range device.GetOutput() {
fileName := fmt.Sprintf("capture_%d.jpg", count)
file, err := os.Create(fileName)
...
if _, err := file.Write(frame); err != nil {
log.Printf("failed to write file %s: %s", fileName, err)
continue
}
if err := file.Close(); err != nil {
log.Printf("failed to close file %s: %s", fileName, err)
}
}
}See the full source code here.