Add support for RTSP PCM/WAV and G711/WAV

Added PCM RTP packet reader and added support for PCM 8 bit,
16 bit, ALAW and MULAW playback through RTSP.

Change-Id: If0a187b55faa89850a159e17eae28358d6634799

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

@@ -16,6 +16,7 @@
 package androidx.media3.exoplayer.rtsp;
 
 import androidx.annotation.Nullable;
+import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
 import androidx.media3.common.util.UnstableApi;
@@ -40,6 +41,10 @@ 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_PCM_L8 = "L8";
+  private static final String RTP_MEDIA_PCM_L16 = "L16";
+  private static final String RTP_MEDIA_PCMA = "PCMA";
+  private static final String RTP_MEDIA_PCMU = "PCMU";
 
   /** Returns whether the format of a {@link MediaDescription} is supported. */
   public static boolean isFormatSupported(MediaDescription mediaDescription) {
@@ -48,6 +53,10 @@ public final class RtpPayloadFormat {
       case RTP_MEDIA_H264:
       case RTP_MEDIA_H265:
       case RTP_MEDIA_MPEG4_GENERIC:
+      case RTP_MEDIA_PCM_L8:
+      case RTP_MEDIA_PCM_L16:
+      case RTP_MEDIA_PCMA:
+      case RTP_MEDIA_PCMU:
         return true;
       default:
         return false;
@@ -71,6 +80,33 @@ public final class RtpPayloadFormat {
         return MimeTypes.VIDEO_H265;
       case RTP_MEDIA_MPEG4_GENERIC:
         return MimeTypes.AUDIO_AAC;
+      case RTP_MEDIA_PCM_L8:
+      case RTP_MEDIA_PCM_L16:
+        return MimeTypes.AUDIO_RAW;
+      case RTP_MEDIA_PCMA:
+        return MimeTypes.AUDIO_ALAW;
+      case RTP_MEDIA_PCMU:
+        return MimeTypes.AUDIO_MLAW;
+      default:
+        throw new IllegalArgumentException(mediaType);
+    }
+  }
+
+  /**
+   * Gets the PCM Encoding type for RAW track that is associated with the RTP media type.
+   *
+   * <p>For instance, RTP media type "L8" maps to {@link C.PcmEncoding#ENCODING_PCM_8BIT}.
+   *
+   * @throws IllegalArgumentException When the media type is not supported/recognized.
+   */
+  public static int getPCMEncodingFromRtpMediaType(String mediaType) {
+    switch (mediaType) {
+      case RTP_MEDIA_PCM_L8:
+        // Refer to RFC3551#section-4.5.10
+        return C.ENCODING_PCM_8BIT;
+      case RTP_MEDIA_PCM_L16:
+        // Refer to RFC3551#section-4.5.11
+        return C.ENCODING_PCM_16BIT_BIG_ENDIAN;
       default:
         throw new IllegalArgumentException(mediaType);
     }

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

@@ -20,6 +20,7 @@ import static androidx.media3.common.util.Assertions.checkNotNull;
 import static androidx.media3.common.util.Util.castNonNull;
 import static androidx.media3.exoplayer.rtsp.MediaDescription.MEDIA_TYPE_AUDIO;
 import static androidx.media3.exoplayer.rtsp.RtpPayloadFormat.getMimeTypeFromRtpMediaType;
+import static androidx.media3.exoplayer.rtsp.RtpPayloadFormat.getPCMEncodingFromRtpMediaType;
 import static androidx.media3.exoplayer.rtsp.SessionDescription.ATTR_CONTROL;
 import static androidx.media3.extractor.NalUnitUtil.NAL_START_CODE;
 
@@ -129,8 +130,15 @@ import com.google.common.collect.ImmutableMap;
         checkArgument(!fmtpParameters.isEmpty());
         processH265FmtpAttribute(formatBuilder, fmtpParameters);
         break;
+      case MimeTypes.AUDIO_RAW:
+        int pcmEncoding =
+            getPCMEncodingFromRtpMediaType(mediaDescription.rtpMapAttribute.mediaEncoding);
+        formatBuilder.setPcmEncoding(pcmEncoding);
+        break;
       case MimeTypes.AUDIO_AC3:
-        // AC3 does not require a FMTP attribute. Fall through.
+      case MimeTypes.AUDIO_ALAW:
+      case MimeTypes.AUDIO_MLAW:
+        // Does not require a FMTP attribute. Fall through.
       default:
         // Do nothing.
     }

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

@@ -40,6 +40,10 @@ import androidx.media3.exoplayer.rtsp.RtpPayloadFormat;
         return new RtpH264Reader(payloadFormat);
       case MimeTypes.VIDEO_H265:
         return new RtpH265Reader(payloadFormat);
+      case MimeTypes.AUDIO_RAW:
+      case MimeTypes.AUDIO_ALAW:
+      case MimeTypes.AUDIO_MLAW:
+        return new RtpPCMReader(payloadFormat);
       default:
         // No supported reader, returning null.
     }

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

@@ -0,0 +1,89 @@
+/*
+ * 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.checkState;
+
+import androidx.media3.common.C;
+import androidx.media3.common.util.ParsableByteArray;
+import androidx.media3.common.util.Util;
+import androidx.media3.exoplayer.rtsp.RtpPayloadFormat;
+import androidx.media3.extractor.ExtractorOutput;
+import androidx.media3.extractor.TrackOutput;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+/**
+ * Parses byte stream carried on RTP packets, and extracts PCM frames. Refer to RFC3551 for more
+ * details.
+ */
+/* package */ public final class RtpPCMReader implements RtpPayloadReader {
+
+  private final RtpPayloadFormat payloadFormat;
+  private @MonotonicNonNull TrackOutput trackOutput;
+  private long firstReceivedTimestamp;
+  private long startTimeOffsetUs;
+
+  public RtpPCMReader(RtpPayloadFormat payloadFormat) {
+    this.payloadFormat = payloadFormat;
+    firstReceivedTimestamp = C.TIME_UNSET;
+  }
+
+  @Override
+  public void createTracks(ExtractorOutput extractorOutput, int trackId) {
+    trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_AUDIO);
+    trackOutput.format(payloadFormat.format);
+  }
+
+  @Override
+  public void onReceivingFirstPacket(long timestamp, int sequenceNumber) {
+    checkState(firstReceivedTimestamp == C.TIME_UNSET);
+    firstReceivedTimestamp = timestamp;
+  }
+
+  @Override
+  public void consume(
+      ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker) {
+    long sampleTimeUs =
+        toSampleUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp, payloadFormat.clockRate);
+    int size = data.bytesLeft();
+    trackOutput.sampleData(data, size);
+    trackOutput
+        .sampleMetadata(
+            /* timeUs= */ sampleTimeUs,
+            /* flags= */ C.BUFFER_FLAG_KEY_FRAME,
+            /* size= */ size,
+            /* offset= */ 0,
+            /* cryptoData= */ null);
+  }
+
+  @Override
+  public void seek(long nextRtpTimestamp, long timeUs) {
+    firstReceivedTimestamp = nextRtpTimestamp;
+    startTimeOffsetUs = timeUs;
+  }
+
+  /**
+   * Returns the correct sample time from RTP timestamp, accounting for the given sampling rate.
+   */
+  private static long toSampleUs(
+      long startTimeOffsetUs, long rtpTimestamp, long firstReceivedRtpTimestamp, int sampleRate) {
+    return startTimeOffsetUs
+        + Util.scaleLargeTimestamp(
+        rtpTimestamp - firstReceivedRtpTimestamp,
+        /* multiplier= */ C.MICROS_PER_SECOND,
+        /* divisor= */ sampleRate);
+  }
+}