Initial work on downsampling

The http connection is being closed before sending all data. May have something to do with the Range header

stream/downsampling.go

@@ -0,0 +1,47 @@
+package stream
+
+import (
+	"github.com/astaxie/beego"
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+func Stream(path string, bitRate int, maxBitRate int, w io.Writer) error {
+	if maxBitRate > 0 && bitRate > maxBitRate {
+		cmdLine, args := createDownsamplingCommand(path, maxBitRate)
+		cmd := exec.Command(cmdLine, args...)
+		beego.Debug("Executing cmd:", cmdLine, args)
+
+		cmd.Stdout = w
+		cmd.Stderr = os.Stderr
+		err := cmd.Run()
+		if err != nil {
+			beego.Error("Error executing", cmdLine, ":", err)
+		}
+		return err
+	} else {
+		f, err := os.Open(path)
+		if err != nil {
+			beego.Error("Error opening file", path, ":", err)
+			return err
+		}
+		_, err = io.Copy(w, f)
+		return err
+	}
+}
+
+func createDownsamplingCommand(path string, maxBitRate int) (string, []string) {
+	cmd := beego.AppConfig.String("downsampleCommand")
+
+	split := strings.Split(cmd, " ")
+	for i, s := range split {
+		s = strings.Replace(s, "%s", path, -1)
+		s = strings.Replace(s, "%b", strconv.Itoa(maxBitRate), -1)
+		split[i] = s
+	}
+
+	return split[0], split[1:len(split)]
+}