add example

examples/open_probe_file/main.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+	"github.com/nareix/joy4/av"
+	"github.com/nareix/joy4/av/avutil"
+	"github.com/nareix/joy4/format"
+)
+
+func init() {
+	format.RegisterAll()
+}
+
+func main() {
+	file, _ := avutil.Open("projectindex.flv")
+
+	streams, _ := file.Streams()
+	for _, stream := range streams {
+		if stream.Type().IsAudio() {
+			astream := stream.(av.AudioCodecData)
+			fmt.Println(astream.Type(), astream.SampleRate(), astream.SampleFormat(), astream.ChannelLayout())
+		} else if stream.Type().IsVideo() {
+			vstream := stream.(av.VideoCodecData)
+			fmt.Println(vstream.Type(), vstream.Width(), vstream.Height())
+		}
+	}
+
+	for i := 0; i < 10; i++ {
+		var pkt av.Packet
+		var err error
+		if pkt, err = file.ReadPacket(); err != nil {
+			break
+		}
+		fmt.Println("pkt", i, streams[pkt.Idx].Type(), "len", len(pkt.Data), "keyframe", pkt.IsKeyFrame)
+	}
+
+	file.Close()
+}
+