content: /*
   * Copyright 2021 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.google.android.exoplayer2.source.rtsp;
  
  import com.google.android.exoplayer2.source.rtsp.RtspMessageChannel.InterleavedBinaryDataListener;
  import com.google.android.exoplayer2.util.Clock;
  import com.google.android.exoplayer2.util.HandlerWrapper;
  import com.google.android.exoplayer2.util.Util;
  import com.google.common.collect.ImmutableList;
  
  /** Transmits media RTP packets periodically. */
  /* package */ final class RtpPacketTransmitter {
  
    private static final byte[] END_OF_STREAM = new byte[0];
  
    private final ImmutableList<String> packets;
    private final HandlerWrapper transmissionHandler;
    private final long transmissionIntervalMs;
  
    private RtspMessageChannel.InterleavedBinaryDataListener binaryDataListener;
    private int packetIndex;
    private volatile boolean isTransmitting;
  
    /**
     * Creates a new instance.
     *
     * @param rtpPacketStreamDump The {@link RtpPacketStreamDump} to provide RTP packets.
     * @param clock The {@link Clock} to use.
     */
    public RtpPacketTransmitter(RtpPacketStreamDump rtpPacketStreamDump, Clock clock) {
      this.packets = ImmutableList.copyOf(rtpPacketStreamDump.packets);
      this.transmissionHandler =
          clock.createHandler(Util.getCurrentOrMainLooper(), /* callback= */ null);
      this.transmissionIntervalMs = rtpPacketStreamDump.transmissionIntervalMs;
    }
  
    /**
     * Starts transmitting binary data to the {@link InterleavedBinaryDataListener}.
     *
     * <p>Calling this method after starting the transmission has no effect.
     */
    public void startTransmitting(InterleavedBinaryDataListener binaryDataListener) {
      if (isTransmitting) {
        return;
      }
  
      this.binaryDataListener = binaryDataListener;
      packetIndex = 0;
      isTransmitting = true;
      transmissionHandler.post(this::transmitNextPacket);
    }
  
    /** Stops transmitting, if transmitting has started. */
    private void stopTransmitting() {
      if (!isTransmitting) {
        return;
      }
  
      signalEndOfStream();
      transmissionHandler.removeCallbacksAndMessages(/* token= */ null);
      isTransmitting = false;
    }
  
    private void transmitNextPacket() {
      if (packetIndex == packets.size()) {
        stopTransmitting();
        return;
      }
  
      byte[] data = Util.getBytesFromHexString(packets.get(packetIndex++));
      binaryDataListener.onInterleavedBinaryDataReceived(data);
      transmissionHandler.postDelayed(this::transmitNextPacket, transmissionIntervalMs);
    }
  
    private void signalEndOfStream() {
      binaryDataListener.onInterleavedBinaryDataReceived(END_OF_STREAM);
    }
  }
  