add example

example/example.go

@@ -10,9 +10,7 @@ import (
 
 func DemuxExample() {
 	file, _ := os.Open("test.mp4")
-	demuxer := &mp4.Demuxer{
-		R: file,
-	}
+	demuxer := &mp4.Demuxer{R: file}
 	demuxer.ReadHeader()
 
 	fmt.Println("Total tracks: ", len(demuxer.Tracks))
@@ -57,7 +55,35 @@ func DemuxExample() {
 	fmt.Print(hex.Dump(sample))
 }
 
-func main() {
-	DemuxExample()
+func MuxExample() {
+	infile, _ := os.Open("test.mp4")
+	outfile, _ := os.Create("test.out.mp4")
+
+	demuxer := &mp4.Demuxer{R: infile}
+	demuxer.ReadHeader()
+
+	muxer := &mp4.Muxer{W: outfile}
+	muxer.AddH264Track()
+	muxer.TrackH264.SetH264PPS(demuxer.TrackH264.GetH264PPS())
+	muxer.TrackH264.SetH264SPS(demuxer.TrackH264.GetH264SPS())
+	muxer.TrackH264.SetTimeScale(demuxer.TrackH264.TimeScale())
+
+	muxer.WriteHeader()
+	for {
+		pts, dts, isKeyFrame, data, err := demuxer.TrackH264.ReadSample()
+		if err != nil {
+			break
+		}
+		fmt.Println("sample #", dts, pts)
+		muxer.TrackH264.WriteSample(pts, dts, isKeyFrame, data)
+	}
+
+	muxer.WriteTrailer()
+	outfile.Close()
+}
+
+func main() {
+	//DemuxExample()
+	MuxExample()
 }