Write streamer header from ScreenEncoder

The screen encoder is responsible for writing data to the video
streamer.

server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java

@@ -64,6 +64,9 @@ public class ScreenEncoder implements Device.RotationListener {
         MediaFormat format = createFormat(videoMimeType, bitRate, maxFps, codecOptions);
         IBinder display = createDisplay();
         device.setRotationListener(this);
+
+        streamer.writeHeader();
+
         boolean alive;
         try {
             do {

server/src/main/java/com/genymobile/scrcpy/Server.java

@@ -104,10 +104,7 @@ public final class Server {
 
             try {
                 // synchronous
-                VideoStreamer videoStreamer = new VideoStreamer(connection.getVideoFd(), options.getSendFrameMeta());
-                if (options.getSendCodecId()) {
-                    videoStreamer.writeHeader(codec.getId());
-                }
+                VideoStreamer videoStreamer = new VideoStreamer(connection.getVideoFd(), codec, options.getSendCodecId(), options.getSendFrameMeta());
                 screenEncoder.streamScreen(device, videoStreamer);
             } catch (IOException e) {
                 // Broken pipe is expected on close, because the socket is closed by the client

server/src/main/java/com/genymobile/scrcpy/VideoStreamer.java

@@ -12,20 +12,26 @@ public final class VideoStreamer {
     private static final long PACKET_FLAG_KEY_FRAME = 1L << 62;
 
     private final FileDescriptor fd;
+    private final VideoCodec codec;
+    private final boolean sendCodecId;
     private final boolean sendFrameMeta;
 
     private final ByteBuffer headerBuffer = ByteBuffer.allocate(12);
 
-    public VideoStreamer(FileDescriptor fd, boolean sendFrameMeta) {
+    public VideoStreamer(FileDescriptor fd, VideoCodec codec, boolean sendCodecId, boolean sendFrameMeta) {
         this.fd = fd;
+        this.codec = codec;
+        this.sendCodecId = sendCodecId;
         this.sendFrameMeta = sendFrameMeta;
     }
 
-    public void writeHeader(int codecId) throws IOException {
-        ByteBuffer buffer = ByteBuffer.allocate(4);
-        buffer.putInt(codecId);
-        buffer.flip();
-        IO.writeFully(fd, buffer);
+    public void writeHeader() throws IOException {
+        if (sendCodecId) {
+            ByteBuffer buffer = ByteBuffer.allocate(4);
+            buffer.putInt(codec.getId());
+            buffer.flip();
+            IO.writeFully(fd, buffer);
+        }
     }
 
     public void writePacket(ByteBuffer codecBuffer, MediaCodec.BufferInfo bufferInfo) throws IOException {