GetVideoFrame() buffer param added
This commit is contained in:
Krzysztofz01
parent
1813715282
commit
957b8dc191
2 changed files with 60 additions and 46 deletions
82
frame.go
82
frame.go
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@ -3,7 +3,6 @@ package vidio
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import (
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"errors"
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"fmt"
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"image"
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"io"
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"os"
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"os/exec"
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@ -13,28 +12,40 @@ import (
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"syscall"
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)
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// Return the N-th frame of the video specified by the filename as a pointer to a RGBA image. The frames are indexed from 0.
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func GetVideoFrame(filename string, n int) (*image.RGBA, error) {
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// Return the N-th frame of the video specified by the filename in the RGBA format and stored it to the provided frame buffer. The frames are indexed from 0.
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func GetVideoFrame(filename string, n int, frameBuffer []byte) error {
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if !exists(filename) {
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return nil, fmt.Errorf("vidio: video file %s does not exist", filename)
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return fmt.Errorf("vidio: video file %s does not exist", filename)
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}
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if err := installed("ffmpeg"); err != nil {
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return nil, err
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return err
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}
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if err := installed("ffprobe"); err != nil {
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return nil, err
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return err
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}
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frameBufferSize, framesCount, err := probeVideo(filename)
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if err != nil {
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return err
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}
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if n >= framesCount {
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return errors.New("vidio: provided frame index is not in frame count range")
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}
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if frameBuffer == nil {
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frameBuffer = make([]byte, frameBufferSize)
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} else {
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if len(frameBuffer) < frameBufferSize {
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return errors.New("vidio: provided frame buffer size is smaller than the frame size")
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}
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}
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selectExpression, err := buildSelectExpression(n)
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if err != nil {
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return nil, fmt.Errorf("vidio: failed to parse the specified frame index: %w", err)
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}
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imageRect, stream, err := probeVideo(filename)
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if err != nil {
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return nil, err
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return fmt.Errorf("vidio: failed to parse the specified frame index: %w", err)
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}
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cmd := exec.Command(
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@ -44,7 +55,7 @@ func GetVideoFrame(filename string, n int) (*image.RGBA, error) {
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"-loglevel", "quiet",
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"-pix_fmt", "rgba",
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"-vcodec", "rawvideo",
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"-map", fmt.Sprintf("0:v:%d", stream),
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"-map", "0:v:0",
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"-vf", selectExpression,
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"-vsync", "0",
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"-",
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@ -52,11 +63,11 @@ func GetVideoFrame(filename string, n int) (*image.RGBA, error) {
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stdoutPipe, err := cmd.StdoutPipe()
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if err != nil {
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return nil, fmt.Errorf("vidio: failed to access the ffmpeg stdout pipe: %w", err)
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return fmt.Errorf("vidio: failed to access the ffmpeg stdout pipe: %w", err)
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}
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if err := cmd.Start(); err != nil {
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return nil, fmt.Errorf("vidio: failed to start the ffmpeg cmd: %w", err)
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return fmt.Errorf("vidio: failed to start the ffmpeg cmd: %w", err)
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}
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interruptChan := make(chan os.Signal, 1)
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@ -72,59 +83,70 @@ func GetVideoFrame(filename string, n int) (*image.RGBA, error) {
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os.Exit(1)
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}()
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imageBuffer := image.NewRGBA(imageRect)
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if _, err := io.ReadFull(stdoutPipe, imageBuffer.Pix); err != nil {
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return nil, fmt.Errorf("vidio: failed to read the ffmpeg cmd result to the image buffer: %w", err)
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if _, err := io.ReadFull(stdoutPipe, frameBuffer); err != nil {
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return fmt.Errorf("vidio: failed to read the ffmpeg cmd result to the image buffer: %w", err)
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}
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if err := stdoutPipe.Close(); err != nil {
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return nil, fmt.Errorf("vidio: failed to close the ffmpeg stdout pipe: %w", err)
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return fmt.Errorf("vidio: failed to close the ffmpeg stdout pipe: %w", err)
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}
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if err := cmd.Wait(); err != nil {
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return nil, fmt.Errorf("vidio: failed to free resources after the ffmpeg cmd: %w", err)
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return fmt.Errorf("vidio: failed to free resources after the ffmpeg cmd: %w", err)
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}
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return imageBuffer, nil
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return nil
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}
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// Helper function used to extract the target frame size and stream index
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func probeVideo(filename string) (image.Rectangle, int, error) {
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// Helper function used to extract the target frame buffer size and frames count
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func probeVideo(filename string) (int, int, error) {
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videoData, err := ffprobe(filename, "v")
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if err != nil {
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return image.Rectangle{}, 0, fmt.Errorf("vidio: no video data found in %s: %w", filename, err)
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return 0, 0, fmt.Errorf("vidio: no video data found in %s: %w", filename, err)
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}
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if len(videoData) == 0 {
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return image.Rectangle{}, 0, fmt.Errorf("vidio: no video streams found in %s", filename)
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return 0, 0, fmt.Errorf("vidio: no video streams found in %s", filename)
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}
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var (
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width int = 0
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height int = 0
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frames int = 0
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)
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if widthStr, ok := videoData[0]["width"]; !ok {
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return image.Rectangle{}, 0, errors.New("vidio: failed to access the image width")
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return 0, 0, errors.New("vidio: failed to access the image width")
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} else {
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if widthParsed, err := strconv.Atoi(widthStr); err != nil {
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return image.Rectangle{}, 0, fmt.Errorf("vidio: failed to parse the image width: %w", err)
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return 0, 0, fmt.Errorf("vidio: failed to parse the image width: %w", err)
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} else {
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width = widthParsed
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}
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}
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if heightStr, ok := videoData[0]["height"]; !ok {
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return image.Rectangle{}, 0, errors.New("vidio: failed to access the image height")
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return 0, 0, errors.New("vidio: failed to access the image height")
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} else {
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if heightParsed, err := strconv.Atoi(heightStr); err != nil {
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return image.Rectangle{}, 0, fmt.Errorf("vidio: failed to parse the image height: %w", err)
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return 0, 0, fmt.Errorf("vidio: failed to parse the image height: %w", err)
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} else {
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height = heightParsed
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}
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}
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return image.Rect(0, 0, width, height), 0, nil
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if framesStr, ok := videoData[0]["nb_frames"]; !ok {
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return 0, 0, errors.New("vidio: failed to access the frames count")
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} else {
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if framesParsed, err := strconv.Atoi(framesStr); err != nil {
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return 0, 0, fmt.Errorf("vidio: failed to parse the frames count: %w", err)
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} else {
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frames = framesParsed
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}
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}
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frameBufferSize := width * height * 4
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return frameBufferSize, frames, nil
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}
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// Error representing a strings.Builder failure in the buildSelectExpression func.
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@ -1,6 +1,7 @@
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package vidio
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import (
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"image"
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"image/png"
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"os"
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"testing"
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@ -8,12 +9,9 @@ import (
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func TestGetFrameShouldReturnErrorOnInvalidFilePath(t *testing.T) {
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path := "test/koala-video-not-present.mp4"
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img := image.NewRGBA(image.Rect(0, 0, 480, 270))
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frame, err := GetVideoFrame(path, 2)
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if frame != nil {
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t.Errorf("Frame was expected to be nil")
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}
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err := GetVideoFrame(path, 2, img.Pix)
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if err == nil {
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t.Error("Error was expected to not be nil")
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@ -22,13 +20,10 @@ func TestGetFrameShouldReturnErrorOnInvalidFilePath(t *testing.T) {
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func TestGetFrameShouldReturnErrorOnOutOfRangeFrame(t *testing.T) {
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path := "test/koala.mp4"
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img := image.NewRGBA(image.Rect(0, 0, 480, 270))
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framesCount := 101
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frame, err := GetVideoFrame(path, framesCount+1)
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if frame != nil {
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t.Error("Frames was expected to be nil")
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}
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err := GetVideoFrame(path, framesCount+1, img.Pix)
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if err == nil {
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t.Error("Error was expected to not be nil")
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@ -37,17 +32,14 @@ func TestGetFrameShouldReturnErrorOnOutOfRangeFrame(t *testing.T) {
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func TestGetFrameShouldReturnCorrectFrame(t *testing.T) {
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path := "test/koala.mp4"
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img := image.NewRGBA(image.Rect(0, 0, 480, 270))
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expectedFrameFile, _ := os.Open("test/koala-frame5.png")
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defer expectedFrameFile.Close()
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expectedFrame, _ := png.Decode(expectedFrameFile)
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actualFrame, err := GetVideoFrame(path, 5)
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if actualFrame == nil {
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t.Error("Frame was expected to not be nil")
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}
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err := GetVideoFrame(path, 5, img.Pix)
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if err != nil {
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t.Error("Error was expected to be nil")
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@ -56,7 +48,7 @@ func TestGetFrameShouldReturnCorrectFrame(t *testing.T) {
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for xIndex := 0; xIndex < expectedFrame.Bounds().Dx(); xIndex += 1 {
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for yIndex := 0; yIndex < expectedFrame.Bounds().Dy(); yIndex += 1 {
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eR, eG, eB, eA := expectedFrame.At(xIndex, yIndex).RGBA()
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aR, aG, aB, aA := actualFrame.At(xIndex, yIndex).RGBA()
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aR, aG, aB, aA := img.At(xIndex, yIndex).RGBA()
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if eR != aR || eG != aG || eB != aB || eA != aA {
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t.Error("The expected and actual frames were expected to be equal")
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