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This commit is contained in:
Alex Eidt 2021-12-28 22:11:25 -08:00
parent 1afe1bbfe5
commit 1062e2f4f8
4 changed files with 92 additions and 70 deletions
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35
camera.go
View file

@ -11,17 +11,19 @@ import (
)
type Camera struct {
name string
width int
height int
depth int
fps float64
codec string
framebuffer []byte
pipe *io.ReadCloser
cmd *exec.Cmd
name string // Camera device name.
width int // Camera frame width.
height int // Camera frame height.
depth int // Camera frame depth.
fps float64 // Camera frame rate.
codec string // Camera codec.
framebuffer []byte // Raw frame data.
pipe *io.ReadCloser // Stdout pipe for ffmpeg process streaming webcam.
cmd *exec.Cmd // ffmpeg command.
}
// Returns the webcam device name.
// On windows, ffmpeg output from the -list_devices command is parsed to find the device name.
func getDevicesWindows() []string {
// Run command to get list of devices.
cmd := exec.Command(
@ -53,6 +55,7 @@ func getDevicesWindows() []string {
return devices
}
// Get camera meta data such as width, height, fps and codec.
func getCameraData(device string, camera *Camera) {
// Run command to get camera data.
// Webcam will turn on and then off in quick succession.
@ -62,12 +65,13 @@ func getCameraData(device string, camera *Camera) {
"-f", webcam(),
"-i", device,
)
// The command will fail since we do not give a file to write to, therefore
// it will write the meta data to Stderr.
pipe, err := cmd.StderrPipe()
if err != nil {
panic(err)
}
// Start the command.
if err := cmd.Start(); err != nil {
panic(err)
}
@ -81,12 +85,13 @@ func getCameraData(device string, camera *Camera) {
break
}
}
// Wait for the command to finish.
cmd.Wait()
parseWebcamData(buffer[:total], camera)
}
// Creates a new camera struct that can read from the device with the given stream index.
func NewCamera(stream int) *Camera {
// Check if ffmpeg is installed on the users machine.
checkExists("ffmpeg")
@ -117,6 +122,8 @@ func NewCamera(stream int) *Camera {
return &camera
}
// Once the user calls Read() for the first time on a Camera struct,
// the ffmpeg command which is used to read the camera device is started.
func initCamera(camera *Camera) {
// If user exits with Ctrl+C, stop ffmpeg process.
camera.cleanup()
@ -146,6 +153,7 @@ func initCamera(camera *Camera) {
camera.framebuffer = make([]byte, camera.width*camera.height*camera.depth)
}
// Reads the next frame from the webcam and stores in the framebuffer.
func (camera *Camera) Read() bool {
// If cmd is nil, video reading has not been initialized.
if camera.cmd == nil {
@ -159,6 +167,7 @@ func (camera *Camera) Read() bool {
return true
}
// Closes the pipe and stops the ffmpeg process.
func (camera *Camera) Close() {
if camera.pipe != nil {
(*camera.pipe).Close()
@ -169,7 +178,7 @@ func (camera *Camera) Close() {
}
// Stops the "cmd" process running when the user presses Ctrl+C.
// https://stackoverflow.com/questions/11268943/is-it-possible-to-capture-a-ctrlc-signal-and-run-a-cleanup-function-in-a-defe
// https://stackoverflow.com/questions/11268943/is-it-possible-to-capture-a-ctrlc-signal-and-run-a-cleanup-function-in-a-defe.
func (camera *Camera) cleanup() {
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)

12
utils.go
View file

@ -11,7 +11,7 @@ import (
)
// Returns true if file exists, false otherwise.
// https://stackoverflow.com/questions/12518876/how-to-check-if-a-file-exists-in-go
// https://stackoverflow.com/questions/12518876/how-to-check-if-a-file-exists-in-go.
func exists(filename string) bool {
_, err := os.Stat(filename)
if err == nil {
@ -105,7 +105,7 @@ func parseDevices(buffer []byte) []string {
alt string
}
// Parses ffmpeg output to get device names. Windows only.
// Uses parsing approach from https://github.com/imageio/imageio/blob/master/imageio/plugins/ffmpeg.py#L681
// Uses parsing approach from https://github.com/imageio/imageio/blob/master/imageio/plugins/ffmpeg.py#L681.
pairs := []Pair{}
// Find all device names surrounded by quotes. E.g "Windows Camera Front"
@ -125,7 +125,7 @@ func parseDevices(buffer []byte) []string {
}
devices := []string{}
// If two devices have the same name, use the alternate name of the later device as its name
// If two devices have the same name, use the alternate name of the later device as its name.
for _, pair := range pairs {
if contains(devices, pair.name) {
devices = append(devices, pair.alt)
@ -155,7 +155,7 @@ func parseWebcamData(buffer []byte, camera *Camera) {
index++
}
bufferstr = bufferstr[index:]
// Dimensions. widthxheight
// Dimensions. widthxheight.
regex := regexp.MustCompile("\\d{2,}x\\d{2,}")
match := regex.FindString(bufferstr)
if len(match) > 0 {
@ -163,7 +163,7 @@ func parseWebcamData(buffer []byte, camera *Camera) {
camera.width = int(parse(split[0]))
camera.height = int(parse(split[1]))
}
// FPS
// FPS.
regex = regexp.MustCompile("\\d+(.\\d+)? fps")
match = regex.FindString(bufferstr)
if len(match) > 0 {
@ -173,7 +173,7 @@ func parseWebcamData(buffer []byte, camera *Camera) {
}
camera.fps = parse(match)
}
// Codec
// Codec.
regex = regexp.MustCompile("Video: .+,")
match = regex.FindString(bufferstr)
if len(match) > 0 {

43
video.go
View file

@ -9,21 +9,23 @@ import (
)
type Video struct {
filename string
width int
height int
depth int
bitrate int
frames int
duration float64
fps float64
codec string
pix_fmt string
framebuffer []byte
pipe *io.ReadCloser
cmd *exec.Cmd
filename string // Video Filename.
width int // Width of frames.
height int // Height of frames.
depth int // Depth of frames.
bitrate int // Bitrate for video encoding.
frames int // Total number of frames.
duration float64 // Duration of video in seconds.
fps float64 // Frames per second.
codec string // Codec used for video encoding.
pix_fmt string // Pixel format video is stored in.
framebuffer []byte // Raw frame data.
pipe *io.ReadCloser // Stdout pipe for ffmpeg process.
cmd *exec.Cmd // ffmpeg command.
}
// Creates a new Video struct.
// Uses ffprobe to get video information and fills in the Video struct with this data.
func NewVideo(filename string) *Video {
if !exists(filename) {
panic("File: " + filename + " does not exist")
@ -59,7 +61,7 @@ func NewVideo(filename string) *Video {
break
}
}
// Wait for ffprobe command to complete.
if err := cmd.Wait(); err != nil {
panic(err)
}
@ -68,10 +70,12 @@ func NewVideo(filename string) *Video {
return video
}
func initVideoStream(video *Video) {
// Once the user calls Read() for the first time on a Video struct,
// the ffmpeg command which is used to read the video is started.
func initVideo(video *Video) {
// If user exits with Ctrl+C, stop ffmpeg process.
video.cleanup()
// ffmpeg command to pipe video data to stdout in 8-bit RGB format.
cmd := exec.Command(
"ffmpeg",
"-i", video.filename,
@ -93,10 +97,12 @@ func initVideoStream(video *Video) {
video.framebuffer = make([]byte, video.width*video.height*video.depth)
}
// Reads the next frame from the video and stores in the framebuffer.
// If thelast frame has been read, returns false, otherwise true.
func (video *Video) Read() bool {
// If cmd is nil, video reading has not been initialized.
if video.cmd == nil {
initVideoStream(video)
initVideo(video)
}
total := 0
for total < video.width*video.height*video.depth {
@ -110,6 +116,7 @@ func (video *Video) Read() bool {
return true
}
// Closes the pipe and stops the ffmpeg process.
func (video *Video) Close() {
if video.pipe != nil {
(*video.pipe).Close()
@ -120,7 +127,7 @@ func (video *Video) Close() {
}
// Stops the "cmd" process running when the user presses Ctrl+C.
// https://stackoverflow.com/questions/11268943/is-it-possible-to-capture-a-ctrlc-signal-and-run-a-cleanup-function-in-a-defe
// https://stackoverflow.com/questions/11268943/is-it-possible-to-capture-a-ctrlc-signal-and-run-a-cleanup-function-in-a-defe.
func (video *Video) cleanup() {
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)

72
videowriter.go
View file

@ -11,30 +11,32 @@ import (
)
type VideoWriter struct {
filename string
width int
height int
bitrate int
loop int // For GIFs. -1=no loop, 0=loop forever, >0=loop n times
delay int // Delay for Final Frame of GIFs.
macro int
fps float64
quality float64
codec string
pipe *io.WriteCloser
cmd *exec.Cmd
filename string // Output filename.
width int // Frame width.
height int // Frame height.
bitrate int // Output video bitrate.
loop int // Number of times for GIF to loop.
delay int // Delay of final frame of GIF. Default -1 (same delay as previous frame).
macro int // Macroblock size for determining how to resize frames for codecs.
fps float64 // Frames per second for output video. Default 25.
quality float64 // Used if bitrate not given. Default 0.5.
codec string // Codec to encode video with. Default libx264.
pipe *io.WriteCloser // Stdout pipe of ffmpeg process.
cmd *exec.Cmd // ffmpeg command.
}
// Optional parameters for VideoWriter.
type Options struct {
bitrate int
loop int
delay int
macro int
fps float64
quality float64
codec string
bitrate int // Bitrate.
loop int // For GIFs only. -1=no loop, 0=infinite loop, >0=number of loops.
delay int // Delay for final frame of GIFs.
macro int // Macroblock size for determining how to resize frames for codecs.
fps float64 // Frames per second for output video.
quality float64 // If bitrate not given, use quality instead. Must be between 0 and 1. 0:best, 1:worst.
codec string // Codec for video.
}
// Creates a new VideoWriter struct with default values from the Options struct.
func NewVideoWriter(filename string, width, height int, options *Options) *VideoWriter {
// Check if ffmpeg is installed on the users machine.
checkExists("ffmpeg")
@ -45,12 +47,12 @@ func NewVideoWriter(filename string, width, height int, options *Options) *Video
writer.height = height
// Default Parameter options logic from:
// https://github.com/imageio/imageio-ffmpeg/blob/master/imageio_ffmpeg/_io.py#L268
// https://github.com/imageio/imageio-ffmpeg/blob/master/imageio_ffmpeg/_io.py#L268.
// GIF settings
writer.loop = options.loop // Default to infinite loop
writer.loop = options.loop // Default to infinite loop.
if options.delay == 0 {
writer.delay = -1 // Default to frame delay of previous frame
writer.delay = -1 // Default to frame delay of previous frame.
} else {
writer.delay = options.delay
}
@ -87,26 +89,28 @@ func NewVideoWriter(filename string, width, height int, options *Options) *Video
return &writer
}
// Once the user calls Write() for the first time on a VideoWriter struct,
// the ffmpeg command which is used to write to the video file is started.
func initVideoWriter(writer *VideoWriter) {
// If user exits with Ctrl+C, stop ffmpeg process.
writer.cleanup()
// ffmpeg command to write to video file. Takes in bytes from Stdin and encodes them.
command := []string{
"-y", // overwrite output file if it exists
"-y", // overwrite output file if it exists.
"-loglevel", "quiet",
"-f", "rawvideo",
"-vcodec", "rawvideo",
"-s", fmt.Sprintf("%dx%d", writer.width, writer.height), // frame w x h
"-s", fmt.Sprintf("%dx%d", writer.width, writer.height), // frame w x h.
"-pix_fmt", "rgb24",
"-r", fmt.Sprintf("%.02f", writer.fps), // frames per second
"-i", "-", // The input comes from stdin
"-an", // Tells ffmpeg not to expect any audio
"-r", fmt.Sprintf("%.02f", writer.fps), // frames per second.
"-i", "-", // The input comes from stdin.
"-an", // Tells ffmpeg not to expect any audio.
"-vcodec", writer.codec,
"-pix_fmt", "yuv420p", // Output is 8-bit RGB, no alpha
"-pix_fmt", "yuv420p", // Output is 8-bit RGB, no alpha.
}
// Code from the imageio-ffmpeg project.
// https://github.com/imageio/imageio-ffmpeg/blob/master/imageio_ffmpeg/_io.py#L399
// https://github.com/imageio/imageio-ffmpeg/blob/master/imageio_ffmpeg/_io.py#L399.
// If bitrate not given, use a default.
if writer.bitrate == 0 {
if writer.codec == "libx264" {
@ -119,7 +123,7 @@ func initVideoWriter(writer *VideoWriter) {
} else {
command = append(command, "-b:v", fmt.Sprintf("%d", writer.bitrate))
}
// For GIFs, add looping and delay parameters.
if strings.HasSuffix(strings.ToLower(writer.filename), ".gif") {
command = append(
command,
@ -129,7 +133,7 @@ func initVideoWriter(writer *VideoWriter) {
}
// Code from the imageio-ffmpeg project:
// https://github.com/imageio/imageio-ffmpeg/blob/master/imageio_ffmpeg/_io.py#L415
// https://github.com/imageio/imageio-ffmpeg/blob/master/imageio_ffmpeg/_io.py#L415.
// Resizes the video frames to a size that works with most codecs.
if writer.macro > 1 {
if writer.width%writer.macro > 0 || writer.height%writer.macro > 0 {
@ -162,6 +166,7 @@ func initVideoWriter(writer *VideoWriter) {
}
}
// Writes the given frame to the video file.
func (writer *VideoWriter) Write(frame []byte) {
// If cmd is nil, video writing has not been set up.
if writer.cmd == nil {
@ -178,6 +183,7 @@ func (writer *VideoWriter) Write(frame []byte) {
}
}
// Closes the pipe and stops the ffmpeg process.
func (writer *VideoWriter) Close() {
if writer.pipe != nil {
(*writer.pipe).Close()
@ -188,7 +194,7 @@ func (writer *VideoWriter) Close() {
}
// Stops the "cmd" process running when the user presses Ctrl+C.
// https://stackoverflow.com/questions/11268943/is-it-possible-to-capture-a-ctrlc-signal-and-run-a-cleanup-function-in-a-defe
// https://stackoverflow.com/questions/11268943/is-it-possible-to-capture-a-ctrlc-signal-and-run-a-cleanup-function-in-a-defe.
func (writer *VideoWriter) cleanup() {
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)