add example reading frame with ss

examples/example_test.go

@@ -30,6 +30,18 @@ func TestExampleReadFrameAsJpeg(t *testing.T) {
 	}
 }
 
+func TestExampleReadTimePositionAsJpeg(t *testing.T) {
+	reader := ExampleReadTimePositionAsJpeg("./sample_data/in1.mp4", 4)
+	img, err := imaging.Decode(reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = imaging.Save(img, "./sample_data/out2.jpeg")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestExampleShowProgress(t *testing.T) {
 	ExampleShowProgress("./sample_data/in1.mp4", "./sample_data/out2.mp4")
 }

examples/readTimePositionAsJpeg.go

@@ -0,0 +1,21 @@
+package examples
+
+import (
+	"bytes"
+	"io"
+	"os"
+
+	ffmpeg "github.com/u2takey/ffmpeg-go"
+)
+
+func ExampleReadTimePositionAsJpeg(inFileName string, seconds int) io.Reader {
+	buf := bytes.NewBuffer(nil)
+	err := ffmpeg.Input(inFileName, ffmpeg.KwArgs{"ss": seconds}).
+		Output("pipe:", ffmpeg.KwArgs{"vframes": 1, "format": "image2", "vcodec": "mjpeg"}).
+		WithOutput(buf, os.Stdout).
+		Run()
+	if err != nil {
+		panic(err)
+	}
+	return buf
+}