Add support for RTSP VP8

Added VP8 RTP packet reader and added support for VP8 playback
through RTSP.

Change-Id: Ie22ab79a234f61681cf95886a6ed8104a742f056

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/RtpPayloadFormat.java

@@ -40,6 +40,7 @@ public final class RtpPayloadFormat {
   private static final String RTP_MEDIA_MPEG4_GENERIC = "MPEG4-GENERIC";
   private static final String RTP_MEDIA_H264 = "H264";
   private static final String RTP_MEDIA_H265 = "H265";
+  private static final String RTP_MEDIA_VP8 = "VP8";
 
   /** Returns whether the format of a {@link MediaDescription} is supported. */
   public static boolean isFormatSupported(MediaDescription mediaDescription) {
@@ -48,6 +49,7 @@ public final class RtpPayloadFormat {
       case RTP_MEDIA_H264:
       case RTP_MEDIA_H265:
       case RTP_MEDIA_MPEG4_GENERIC:
+      case RTP_MEDIA_VP8:
         return true;
       default:
         return false;
@@ -71,6 +73,8 @@ public final class RtpPayloadFormat {
         return MimeTypes.VIDEO_H265;
       case RTP_MEDIA_MPEG4_GENERIC:
         return MimeTypes.AUDIO_AAC;
+      case RTP_MEDIA_VP8:
+        return MimeTypes.VIDEO_VP8;
       default:
         throw new IllegalArgumentException(mediaType);
     }

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/RtspMediaTrack.java

@@ -56,6 +56,10 @@ import com.google.common.collect.ImmutableMap;
 
   private static final String GENERIC_CONTROL_ATTR = "*";
 
+  /** Default width and height for VP8. */
+  private static final int DEFAULT_VP8_WIDTH = 320;
+  private static final int DEFAULT_VP8_HEIGHT = 240;
+
   /** The track's associated {@link RtpPayloadFormat}. */
   public final RtpPayloadFormat payloadFormat;
   /** The track's URI. */
@@ -129,6 +133,10 @@ import com.google.common.collect.ImmutableMap;
         checkArgument(!fmtpParameters.isEmpty());
         processH265FmtpAttribute(formatBuilder, fmtpParameters);
         break;
+      case MimeTypes.VIDEO_VP8:
+        // VP8 does not require a FMTP attribute. So Setting default width and height.
+        formatBuilder.setWidth(DEFAULT_VP8_WIDTH).setHeight(DEFAULT_VP8_HEIGHT);
+        break;
       case MimeTypes.AUDIO_AC3:
         // AC3 does not require a FMTP attribute. Fall through.
       default:

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/reader/DefaultRtpPayloadReaderFactory.java

@@ -40,6 +40,8 @@ import androidx.media3.exoplayer.rtsp.RtpPayloadFormat;
         return new RtpH264Reader(payloadFormat);
       case MimeTypes.VIDEO_H265:
         return new RtpH265Reader(payloadFormat);
+      case MimeTypes.VIDEO_VP8:
+        return new RtpVP8Reader(payloadFormat);
       default:
         // No supported reader, returning null.
     }

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/reader/RtpVP8Reader.java

@@ -0,0 +1,220 @@
+/*
+ * Copyright 2022 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 androidx.media3.exoplayer.rtsp.reader;
+
+import static androidx.media3.common.util.Assertions.checkStateNotNull;
+import static androidx.media3.common.util.Util.castNonNull;
+
+import androidx.media3.common.C;
+import androidx.media3.common.Format;
+import androidx.media3.common.ParserException;
+import androidx.media3.common.util.Log;
+import androidx.media3.common.util.ParsableByteArray;
+import androidx.media3.common.util.Util;
+import androidx.media3.exoplayer.rtsp.RtpPacket;
+import androidx.media3.exoplayer.rtsp.RtpPayloadFormat;
+import androidx.media3.extractor.ExtractorOutput;
+import androidx.media3.extractor.TrackOutput;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+/**
+ * Parses a VP8 byte stream carried on RTP packets, and extracts VP8 individual video frames as
+ * defined in RFC7741.
+ */
+/* package */ final class RtpVP8Reader implements RtpPayloadReader {
+  private static final String TAG = "RtpVP8Reader";
+
+  private static final long MEDIA_CLOCK_FREQUENCY = 90_000;
+
+  private final RtpPayloadFormat payloadFormat;
+
+  private @MonotonicNonNull TrackOutput trackOutput;
+  @C.BufferFlags private int bufferFlags;
+
+  private long firstReceivedTimestamp;
+  private int previousSequenceNumber;
+  /** The combined size of a sample that is fragmented into multiple RTP packets. */
+  private int fragmentedSampleSizeBytes;
+  private long startTimeOffsetUs;
+  private boolean gotFirstPacketOfVP8Frame;
+  private boolean isKeyFrame;
+  private boolean isOutputFormatSet;
+
+  /** Creates an instance. */
+  public RtpVP8Reader(RtpPayloadFormat payloadFormat) {
+    this.payloadFormat = payloadFormat;
+    firstReceivedTimestamp = C.TIME_UNSET;
+    previousSequenceNumber = C.INDEX_UNSET;
+    fragmentedSampleSizeBytes = 0;
+    gotFirstPacketOfVP8Frame = false;
+    isKeyFrame = false;
+    isOutputFormatSet = false;
+  }
+
+  @Override
+  public void createTracks(ExtractorOutput extractorOutput, int trackId) {
+    trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_VIDEO);
+    castNonNull(trackOutput).format(payloadFormat.format);
+  }
+
+  @Override
+  public void onReceivingFirstPacket(long timestamp, int sequenceNumber) {}
+
+  @Override
+  public void consume(ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker)
+      throws ParserException {
+    checkStateNotNull(trackOutput);
+
+    if (parseVP8Descriptor(data, sequenceNumber)) {
+      //  VP8 Payload Header, RFC7741 Section 4.3
+      //  0 1 2 3 4 5 6 7
+      //  +-+-+-+-+-+-+-+-+
+      //  |Size0|H| VER |P|
+      //  +-+-+-+-+-+-+-+-+
+      // P: Inverse key frame flag.
+      if (fragmentedSampleSizeBytes == 0 && gotFirstPacketOfVP8Frame) {
+        isKeyFrame = (data.peekUnsignedByte() & 0x01) == 0;
+      }
+      if (!isOutputFormatSet) {
+        // Parsing frame data to get width and height, RFC6386 Section 9.1
+        int currPosition = data.getPosition();
+        data.setPosition(currPosition + 6);
+        int width = data.readLittleEndianUnsignedShort() & 0x3fff;
+        int height = data.readLittleEndianUnsignedShort() & 0x3fff;
+        data.setPosition(currPosition);
+
+        if (width != payloadFormat.format.width || height != payloadFormat.format.height) {
+          Format.Builder formatBuilder = new Format.Builder();
+          if (payloadFormat.format.bitrate > 0) {
+            formatBuilder.setAverageBitrate(payloadFormat.format.bitrate);
+          }
+          formatBuilder.setSampleMimeType(payloadFormat.format.sampleMimeType);
+          formatBuilder.setWidth(width).setHeight(height);
+          trackOutput.format(formatBuilder.build());
+        }
+        isOutputFormatSet = true;
+      }
+
+      int fragmentSize = data.bytesLeft();
+      // Write the video sample
+      trackOutput.sampleData(data, fragmentSize);
+      fragmentedSampleSizeBytes += fragmentSize;
+
+      if (rtpMarker) {
+        if (firstReceivedTimestamp == C.TIME_UNSET) {
+          firstReceivedTimestamp = timestamp;
+        }
+        bufferFlags = isKeyFrame ? C.BUFFER_FLAG_KEY_FRAME : 0;
+        long timeUs = toSampleUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp);
+        trackOutput.sampleMetadata(
+            timeUs,
+            bufferFlags,
+            fragmentedSampleSizeBytes,
+            /* offset= */ 0,
+            /* encryptionData= */ null);
+        fragmentedSampleSizeBytes = 0;
+        gotFirstPacketOfVP8Frame = false;
+      }
+      previousSequenceNumber = sequenceNumber;
+    }
+  }
+
+  @Override
+  public void seek(long nextRtpTimestamp, long timeUs) {
+    firstReceivedTimestamp = nextRtpTimestamp;
+    fragmentedSampleSizeBytes = 0;
+    startTimeOffsetUs = timeUs;
+  }
+
+  // Internal methods.
+  private boolean parseVP8Descriptor(ParsableByteArray payload, int packetSequenceNumber) {
+    // VP8 Payload Descriptor, RFC7741 Section 4.2
+    //       0 1 2 3 4 5 6 7
+    //       +-+-+-+-+-+-+-+-+
+    //       |X|R|N|S|R| PID | (REQUIRED)
+    //       +-+-+-+-+-+-+-+-+
+    //  X:   |I|L|T|K| RSV   | (OPTIONAL)
+    //       +-+-+-+-+-+-+-+-+
+    //  I:   |M| PictureID   | (OPTIONAL)
+    //       +-+-+-+-+-+-+-+-+
+    //  L:   |   TL0PICIDX   | (OPTIONAL)
+    //       +-+-+-+-+-+-+-+-+
+    //  T/K: |TID|Y| KEYIDX  | (OPTIONAL)
+    //       +-+-+-+-+-+-+-+-+
+
+    int header = payload.readUnsignedByte();
+    if (!gotFirstPacketOfVP8Frame) {
+      // For start of VP8 partition S=1 and PID=0 as per RFC7741 Section 4.2
+      if ((header & 0x17) != 0x10) {
+        Log.w(
+            TAG,
+            Util.formatInvariant(
+                "first payload octet of the RTP packet is not the beginning of a new VP8 "
+                    + "partition, Dropping current packet"));
+        return false;
+      }
+      gotFirstPacketOfVP8Frame = true;
+    } else {
+      // Check that this packet is in the sequence of the previous packet.
+      int expectedSequenceNumber = RtpPacket.getNextSequenceNumber(previousSequenceNumber);
+      if (packetSequenceNumber != expectedSequenceNumber) {
+        Log.w(
+            TAG,
+            Util.formatInvariant(
+                "Received RTP packet with unexpected sequence number. Expected: %d; received: %d."
+                    + " Dropping packet.",
+                expectedSequenceNumber, packetSequenceNumber));
+        return false;
+      }
+    }
+
+    // Check if optional X header is present
+    if ((header & 0x80) != 0) {
+      int xHeader = payload.readUnsignedByte();
+
+      // Check if optional I header present
+      if ((xHeader & 0x80) != 0) {
+        int iHeader = payload.readUnsignedByte();
+        if ((iHeader & 0x80) != 0) {
+          payload.skipBytes(1);
+          Log.i(TAG, "15 bits PictureID");
+        } else {
+          Log.i(TAG, "7 bits PictureID");
+        }
+      }
+
+      // Check if optional L header present
+      if ((xHeader & 0x40) != 0) {
+        payload.skipBytes(1);
+      }
+
+      // Check if optional T or K header(s) present
+      if ((xHeader & 0x20) != 0 || (xHeader & 0x10) != 0) {
+        payload.skipBytes(1);
+      }
+    }
+    return true;
+  }
+
+  private static long toSampleUs(
+      long startTimeOffsetUs, long rtpTimestamp, long firstReceivedRtpTimestamp) {
+    return startTimeOffsetUs
+        + Util.scaleLargeTimestamp(
+            (rtpTimestamp - firstReceivedRtpTimestamp),
+            /* multiplier= */ C.MICROS_PER_SECOND,
+            /* divisor= */ MEDIA_CLOCK_FREQUENCY);
+  }
+}