rgb to rgba

Author: AlexEidt

README.md

@@ -2,7 +2,7 @@
 
 A simple Video I/O library written in Go. This library relies on [FFmpeg](https://www.ffmpeg.org/), and [FFProbe](https://www.ffmpeg.org/) which must be downloaded before usage and added to the system path.
 
-All frames are encoded and decoded in 8-bit RGB format.
+All frames are encoded and decoded in 8-bit RGBA format.
 
 For Audio I/O using FFmpeg, see the [`aio`](https://github.com/AlexEidt/aio) project.
 
@@ -16,7 +16,7 @@ go get github.com/AlexEidt/Vidio
 
 The `Video` struct stores data about a video file you give it. The code below shows an example of sequentially reading the frames of the given video.
 
-Calling the `Read()` function will fill in the `Video` struct `framebuffer` with the next frame data as 8-bit RGB data, stored in a flattened byte array in row-major order where each pixel is represented by three consecutive bytes representing the R, G and B component of that pixel.
+Calling the `Read()` function will fill in the `Video` struct `framebuffer` with the next frame data as 8-bit RGBA data, stored in a flattened byte array in row-major order where each pixel is represented by four consecutive bytes representing the R, G, B and A components of that pixel. Note that the A (alpha) component will always be 255.
 
 ```go
 vidio.NewVideo(filename string) (*vidio.Video, error)
@@ -81,7 +81,6 @@ Macro() int
 FPS() float64
 Quality() float64
 Codec() string
-Format() string
 
 Write(frame []byte) error
 Close()
@@ -96,7 +95,6 @@ type Options struct {
 	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.
-	Format     string  // Pixel Format for video. Default "rgb24".
 	StreamFile string  // File path for extra stream data.
 }
 ```

camera.go

@@ -90,7 +90,7 @@ func NewCamera(stream int) (*Camera, error) {
 		return nil, fmt.Errorf("unsupported OS: %s", runtime.GOOS)
 	}
 
-	camera := &Camera{name: device, depth: 3}
+	camera := &Camera{name: device, depth: 4}
 	if err := camera.getCameraData(device); err != nil {
 		return nil, err
 	}
@@ -205,7 +205,7 @@ func (camera *Camera) init() error {
 		"-f", webcamDeviceName,
 		"-i", camera.name,
 		"-f", "image2pipe",
-		"-pix_fmt", "rgb24",
+		"-pix_fmt", "rgba",
 		"-vcodec", "rawvideo",
 		"-",
 	)

imageio.go

@@ -11,7 +11,7 @@ import (
 	"image/png"
 )
 
-// Reads an image from a file. Currently only supports png and jpeg.
+// Reads an image into an rgba byte buffer from a file. Currently only supports png and jpeg.
 func Read(filename string, buffer ...[]byte) (int, int, []byte, error) {
 	f, err := os.Open(filename)
 	if err != nil {
@@ -25,7 +25,7 @@ func Read(filename string, buffer ...[]byte) (int, int, []byte, error) {
 	}
 
 	bounds := image.Bounds().Max
-	size := bounds.X * bounds.Y * 3
+	size := bounds.X * bounds.Y * 4
 
 	var data []byte
 	if len(buffer) > 0 {
@@ -45,13 +45,14 @@ func Read(filename string, buffer ...[]byte) (int, int, []byte, error) {
 			data[index+0] = byte(r)
 			data[index+1] = byte(g)
 			data[index+2] = byte(b)
-			index += 3
+			data[index+3] = 255
+			index += 4
 		}
 	}
 	return bounds.X, bounds.Y, data, nil
 }
 
-// Writes an image to a file. Currently only supports png and jpeg.
+// Writes a rgba byte buffer to a file. Currently only supports png and jpeg.
 func Write(filename string, width, height int, buffer []byte) error {
 	f, err := os.Create(filename)
 	if err != nil {
@@ -63,9 +64,9 @@ func Write(filename string, width, height int, buffer []byte) error {
 	index := 0
 	for h := 0; h < height; h++ {
 		for w := 0; w < width; w++ {
-			r, g, b := buffer[index], buffer[index+1], buffer[index+2]
+			r, g, b := buffer[index+0], buffer[index+1], buffer[index+2]
 			image.Set(w, h, color.RGBA{r, g, b, 255})
-			index += 3
+			index += 4
 		}
 	}
 

video.go

@@ -143,7 +143,7 @@ func NewVideoStreams(filename string) ([]*Video, error) {
 	for i, data := range videoData {
 		video := &Video{
 			filename:   filename,
-			depth:      3,
+			depth:      4,
 			stream:     i,
 			hasstreams: hasstream,
 			metadata:   data,
@@ -190,13 +190,13 @@ func (video *Video) addVideoData(data map[string]string) {
 func (video *Video) init() error {
 	// If user exits with Ctrl+C, stop ffmpeg process.
 	video.cleanup()
-	// ffmpeg command to pipe video data to stdout in 8-bit RGB format.
+	// ffmpeg command to pipe video data to stdout in 8-bit RGBA format.
 	cmd := exec.Command(
 		"ffmpeg",
 		"-i", video.filename,
 		"-f", "image2pipe",
 		"-loglevel", "quiet",
-		"-pix_fmt", "rgb24",
+		"-pix_fmt", "rgba",
 		"-vcodec", "rawvideo",
 		"-map", fmt.Sprintf("0:v:%d", video.stream),
 		"-",

videowriter.go

@@ -23,7 +23,6 @@ type VideoWriter struct {
 	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.
-	format     string          // Output format. Default rgb24.
 	pipe       *io.WriteCloser // Stdout pipe of ffmpeg process.
 	cmd        *exec.Cmd       // ffmpeg command.
 }
@@ -37,7 +36,6 @@ type Options struct {
 	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.
-	Format     string  // Pixel Format for video. Default "rgb24".
 	StreamFile string  // File path for extra stream data.
 }
 
@@ -86,10 +84,6 @@ func (writer *VideoWriter) Codec() string {
 	return writer.codec
 }
 
-func (writer *VideoWriter) Format() string {
-	return writer.format
-}
-
 // Creates a new VideoWriter struct with default values from the Options struct.
 func NewVideoWriter(filename string, width, height int, options *Options) (*VideoWriter, error) {
 	// Check if ffmpeg is installed on the users machine.
@@ -149,12 +143,6 @@ func NewVideoWriter(filename string, width, height int, options *Options) (*Vide
 		writer.codec = options.Codec
 	}
 
-	if options.Format == "" {
-		writer.format = "rgb24"
-	} else {
-		writer.format = options.Format
-	}
-
 	if options.StreamFile != "" {
 		if !exists(options.StreamFile) {
 			return nil, fmt.Errorf("file %s does not exist", options.StreamFile)
@@ -177,7 +165,7 @@ func (writer *VideoWriter) init() error {
 		"-f", "rawvideo",
 		"-vcodec", "rawvideo",
 		"-s", fmt.Sprintf("%dx%d", writer.width, writer.height), // frame w x h.
-		"-pix_fmt", writer.format,
+		"-pix_fmt", "rgba",
 		"-r", fmt.Sprintf("%.02f", writer.fps), // frames per second.
 		"-i", "-", // The input comes from stdin.
 	}
@@ -206,7 +194,7 @@ func (writer *VideoWriter) init() error {
 	command = append(
 		command,
 		"-vcodec", writer.codec,
-		"-pix_fmt", "yuv420p", // Output is 8-bit RGB, no alpha.
+		"-pix_fmt", "yuv420p", // Output is 8-bit RGB, ignore alpha.
 	)
 
 	// Code from the imageio-ffmpeg project.
@@ -246,6 +234,8 @@ func (writer *VideoWriter) init() error {
 			if writer.height%writer.macro > 0 {
 				height += writer.macro - (writer.height % writer.macro)
 			}
+			writer.width = width
+			writer.height = height
 			command = append(
 				command,
 				"-vf", fmt.Sprintf("scale=%d:%d", width, height),

vidio_test.go

@@ -39,7 +39,7 @@ func TestVideoMetaData(t *testing.T) {
 	assertEquals(video.filename, "test/koala.mp4")
 	assertEquals(video.width, 480)
 	assertEquals(video.height, 270)
-	assertEquals(video.depth, 3)
+	assertEquals(video.depth, 4)
 	assertEquals(video.bitrate, 170549)
 	assertEquals(video.frames, 101)
 	assertEquals(video.duration, 3.366667)
@@ -67,17 +67,23 @@ func TestVideoFrame(t *testing.T) {
 	defer video.Close()
 
 	video.Read()
-	// [203 222 134 203 222 134 203 222 134 203]
+	// [203 222 134 255 203 222 134 255 203 222 134 255 203]
 	assertEquals(video.framebuffer[0], uint8(203))
 	assertEquals(video.framebuffer[1], uint8(222))
 	assertEquals(video.framebuffer[2], uint8(134))
-	assertEquals(video.framebuffer[3], uint8(203))
-	assertEquals(video.framebuffer[4], uint8(222))
-	assertEquals(video.framebuffer[5], uint8(134))
-	assertEquals(video.framebuffer[6], uint8(203))
-	assertEquals(video.framebuffer[7], uint8(222))
-	assertEquals(video.framebuffer[8], uint8(134))
-	assertEquals(video.framebuffer[9], uint8(203))
+	assertEquals(video.framebuffer[3], uint8(255))
+
+	assertEquals(video.framebuffer[4], uint8(203))
+	assertEquals(video.framebuffer[5], uint8(222))
+	assertEquals(video.framebuffer[6], uint8(134))
+	assertEquals(video.framebuffer[7], uint8(255))
+
+	assertEquals(video.framebuffer[8], uint8(203))
+	assertEquals(video.framebuffer[9], uint8(222))
+	assertEquals(video.framebuffer[10], uint8(134))
+	assertEquals(video.framebuffer[11], uint8(255))
+
+	assertEquals(video.framebuffer[12], uint8(203))
 
 	fmt.Println("Video Frame Test Passed")
 }
@@ -90,8 +96,8 @@ func TestVideoWriting(t *testing.T) {
 		}
 		options := Options{
 			FPS:     video.FPS(),
-			Bitrate: video.Bitrate(),
 			Codec:   video.Codec(),
+			Bitrate: video.Bitrate(),
 		}
 		if video.HasStreams() {
 			options.StreamFile = video.FileName()
@@ -101,12 +107,11 @@ func TestVideoWriting(t *testing.T) {
 		if err != nil {
 			panic(err)
 		}
+
 		for video.Read() {
-			err := writer.Write(video.FrameBuffer())
-			if err != nil {
-				panic(err)
-			}
+			writer.Write(video.FrameBuffer())
 		}
+
 		writer.Close()
 
 		os.Remove(output)
@@ -134,14 +139,6 @@ func TestCameraIO(t *testing.T) {
 	count := 0
 	for webcam.Read() {
 		frame := webcam.FrameBuffer()
-		for i := 0; i < len(frame); i += 3 {
-			rgb := frame[i : i+3]
-			r, g, b := int(rgb[0]), int(rgb[1]), int(rgb[2])
-			gray := uint8((3*r + 4*g + b) / 8)
-			frame[i] = gray
-			frame[i+1] = gray
-			frame[i+2] = gray
-		}
 		err := writer.Write(frame)
 		if err != nil {
 			panic(err)
@@ -250,18 +247,24 @@ func TestImageRead(t *testing.T) {
 
 	assertEquals(w, 200)
 	assertEquals(h, 133)
-	assertEquals(len(img), 200*133*3)
-	// [255 221 189 255 221 189 255 222 186 255]
+	assertEquals(len(img), 200*133*4)
+	// [255 221 189 255 255 221 189 255 255 222 186 255 255]
 	assertEquals(img[0], uint8(255))
 	assertEquals(img[1], uint8(221))
 	assertEquals(img[2], uint8(189))
 	assertEquals(img[3], uint8(255))
-	assertEquals(img[4], uint8(221))
-	assertEquals(img[5], uint8(189))
-	assertEquals(img[6], uint8(255))
-	assertEquals(img[7], uint8(222))
-	assertEquals(img[8], uint8(186))
-	assertEquals(img[9], uint8(255))
+
+	assertEquals(img[4], uint8(255))
+	assertEquals(img[5], uint8(221))
+	assertEquals(img[6], uint8(189))
+	assertEquals(img[7], uint8(255))
+
+	assertEquals(img[8], uint8(255))
+	assertEquals(img[9], uint8(222))
+	assertEquals(img[10], uint8(186))
+	assertEquals(img[11], uint8(255))
+
+	assertEquals(img[12], uint8(255))
 
 	fmt.Println("Image Reading Test Passed")
 }