Fix mjpeg source for Foscam G2 camera #1258

pkg/mpjpeg/multipart.go

@@ -18,17 +18,23 @@ func Next(rd *bufio.Reader) (http.Header, []byte, error) {
 			return nil, nil, err
 		}
 
-		if strings.HasPrefix(s, "--") {
-			break
-		}
-
 		if s == "\r\n" {
 			continue
 		}
 
+		if !strings.HasPrefix(s, "--") {
 			return nil, nil, errors.New("multipart: wrong boundary: " + s)
 		}
 
+		// Foscam G2 has a awful implementation of MJPEG
+		// https://github.com/AlexxIT/go2rtc/issues/1258
+		if b, _ := rd.Peek(2); string(b) == "--" {
+			continue
+		}
+
+		break
+	}
+
 	tp := textproto.NewReader(rd)
 	header, err := tp.ReadMIMEHeader()
 	if err != nil {
@@ -50,7 +56,5 @@ func Next(rd *bufio.Reader) (http.Header, []byte, error) {
 		return nil, nil, err
 	}
 
-	_, _ = rd.Discard(2) // skip "\r\n"
-
 	return http.Header(header), buf, nil
 }