Merge pull request #46 from ittiam-systems:rtp_amr

PiperOrigin-RevId: 437274290

RELEASENOTES.md

@@ -38,6 +38,9 @@
 *   RTSP:
     *   Add RTP reader for HEVC
         ([#36](https://github.com/androidx/media/pull/36)).
+    *   Add RTP reader for AMR. Currently only mono-channel, non-interleaved 
+        AMR streams are supported. Compound AMR RTP payload is not supported.
+        ([#46](https://github.com/androidx/media/pull/46))
 *   Remove deprecated symbols:
     *   Remove `Player.Listener.onTracksChanged`. Use
         `Player.Listener.onTracksInfoChanged` instead.

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

@@ -37,6 +37,8 @@ import java.util.Map;
 public final class RtpPayloadFormat {
 
   private static final String RTP_MEDIA_AC3 = "AC3";
+  private static final String RTP_MEDIA_AMR = "AMR";
+  private static final String RTP_MEDIA_AMR_WB = "AMR-WB";
   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";
@@ -45,6 +47,8 @@ public final class RtpPayloadFormat {
   public static boolean isFormatSupported(MediaDescription mediaDescription) {
     switch (Ascii.toUpperCase(mediaDescription.rtpMapAttribute.mediaEncoding)) {
       case RTP_MEDIA_AC3:
+      case RTP_MEDIA_AMR:
+      case RTP_MEDIA_AMR_WB:
       case RTP_MEDIA_H264:
       case RTP_MEDIA_H265:
       case RTP_MEDIA_MPEG4_GENERIC:
@@ -65,6 +69,10 @@ public final class RtpPayloadFormat {
     switch (Ascii.toUpperCase(mediaType)) {
       case RTP_MEDIA_AC3:
         return MimeTypes.AUDIO_AC3;
+      case RTP_MEDIA_AMR:
+        return MimeTypes.AUDIO_AMR_NB;
+      case RTP_MEDIA_AMR_WB:
+        return MimeTypes.AUDIO_AMR_WB;
       case RTP_MEDIA_H264:
         return MimeTypes.VIDEO_H264;
       case RTP_MEDIA_H265:

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

@@ -48,6 +48,8 @@ import com.google.common.collect.ImmutableMap;
   private static final String PARAMETER_H265_SPROP_PPS = "sprop-pps";
   private static final String PARAMETER_H265_SPROP_VPS = "sprop-vps";
   private static final String PARAMETER_H265_SPROP_MAX_DON_DIFF = "sprop-max-don-diff";
+  private static final String PARAMETER_AMR_OCTET_ALIGN = "octet-align";
+  private static final String PARAMETER_AMR_INTERLEAVING = "interleaving";
 
   /** Prefix for the RFC6381 codecs string for AAC formats. */
   private static final String AAC_CODECS_PREFIX = "mp4a.40.";
@@ -121,6 +123,19 @@ import com.google.common.collect.ImmutableMap;
         checkArgument(!fmtpParameters.isEmpty());
         processAacFmtpAttribute(formatBuilder, fmtpParameters, channelCount, clockRate);
         break;
+      case MimeTypes.AUDIO_AMR_NB:
+      case MimeTypes.AUDIO_AMR_WB:
+        checkArgument(channelCount == 1, "Multi channel AMR is not currently supported.");
+        checkArgument(
+            !fmtpParameters.isEmpty(),
+            "fmtp parameters must include " + PARAMETER_AMR_OCTET_ALIGN + ".");
+        checkArgument(
+            fmtpParameters.containsKey(PARAMETER_AMR_OCTET_ALIGN),
+            "Only octet aligned mode is currently supported.");
+        checkArgument(
+            !fmtpParameters.containsKey(PARAMETER_AMR_INTERLEAVING),
+            "Interleaving mode is not currently supported.");
+        break;
       case MimeTypes.VIDEO_H264:
         checkArgument(!fmtpParameters.isEmpty());
         processH264FmtpAttribute(formatBuilder, fmtpParameters);

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

@@ -36,6 +36,9 @@ import androidx.media3.exoplayer.rtsp.RtpPayloadFormat;
         return new RtpAc3Reader(payloadFormat);
       case MimeTypes.AUDIO_AAC:
         return new RtpAacReader(payloadFormat);
+      case MimeTypes.AUDIO_AMR_NB:
+      case MimeTypes.AUDIO_AMR_WB:
+        return new RtpAmrReader(payloadFormat);
       case MimeTypes.VIDEO_H264:
         return new RtpH264Reader(payloadFormat);
       case MimeTypes.VIDEO_H265:

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

+/*
+ * 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.checkArgument;
+import static androidx.media3.common.util.Assertions.checkNotNull;
+import static androidx.media3.common.util.Assertions.checkStateNotNull;
+
+import androidx.media3.common.C;
+import androidx.media3.common.MimeTypes;
+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 an AMR byte stream carried on RTP packets and extracts individual samples. Interleaving
+ * mode is not supported. Refer to RFC4867 for more details.
+ */
+/* package */ final class RtpAmrReader implements RtpPayloadReader {
+  private static final String TAG = "RtpAmrReader";
+  /**
+   * The frame size in bytes, including header (1 byte), for each of the 16 frame types for AMR-NB
+   * (narrow band). AMR-NB supports eight narrow band speech encoding modes with bit rates between
+   * 4.75 and 12.2 kbps defined in RFC4867 Section 3.1. Refer to table 1a in 3GPP TS 26.101 for the
+   * mapping definition.
+   */
+  private static final int[] AMR_NB_FRAME_TYPE_INDEX_TO_FRAME_SIZE = {
+    13, // 4.75kbps
+    14, // 5.15kbps
+    16, // 5.90kbps
+    18, // 6.70kbps PDC-EFR
+    20, // 7.40kbps TDMA-EFR
+    21, // 7.95kbps
+    27, // 10.2kbps
+    32, // 12.2kbps GSM-EFR
+    6, // AMR SID
+    7, // GSM-EFR SID
+    6, // TDMA-EFR SID
+    6, // PDC-EFR SID
+    1, // Future use
+    1, // Future use
+    1, // Future use
+    1 // No data
+  };
+
+  /**
+   * The frame size in bytes, including header (1 byte), for each of the 16 frame types for AMR-WB
+   * (wide band). AMR-WB supports nine wide band speech encoding modes with bit rates between 6.6 to
+   * 23.85 kbps defined in RFC4867 Section 3.2. Refer to table 1a in 3GPP TS 26.201. for the mapping
+   * definition.
+   */
+  private static final int[] AMR_WB_FRAME_TYPE_INDEX_TO_FRAME_SIZE = {
+    18, // 6.60kbps
+    24, // 8.85kbps
+    33, // 12.65kbps
+    37, // 14.25kbps
+    41, // 15.85kbps
+    47, // 18.25kbps
+    51, // 19.85kbps
+    59, // 23.05kbps
+    61, // 23.85kbps
+    6, // AMR-WB SID
+    1, // Future use
+    1, // Future use
+    1, // Future use
+    1, // Future use
+    1, // speech lost
+    1 // No data
+  };
+
+  private final RtpPayloadFormat payloadFormat;
+  private final boolean isWideBand;
+  private final int sampleRate;
+
+  private @MonotonicNonNull TrackOutput trackOutput;
+  private long firstReceivedTimestamp;
+  private long startTimeOffsetUs;
+  private int previousSequenceNumber;
+
+  public RtpAmrReader(RtpPayloadFormat payloadFormat) {
+    this.payloadFormat = payloadFormat;
+    this.isWideBand =
+        MimeTypes.AUDIO_AMR_WB.equals(checkNotNull(payloadFormat.format.sampleMimeType));
+    this.sampleRate = payloadFormat.clockRate;
+    this.firstReceivedTimestamp = C.TIME_UNSET;
+    this.previousSequenceNumber = C.INDEX_UNSET;
+    // Start time offset must be 0 before the first seek.
+    this.startTimeOffsetUs = 0;
+  }
+
+  // RtpPayloadReader implementation.
+
+  @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) {
+    this.firstReceivedTimestamp = timestamp;
+  }
+
+  @Override
+  public void consume(
+      ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker) {
+    checkStateNotNull(trackOutput);
+    // Check that this packet is in the sequence of the previous packet.
+    if (previousSequenceNumber != C.INDEX_UNSET) {
+      int expectedSequenceNumber = RtpPacket.getNextSequenceNumber(previousSequenceNumber);
+      if (sequenceNumber != expectedSequenceNumber) {
+        Log.w(
+            TAG,
+            Util.formatInvariant(
+                "Received RTP packet with unexpected sequence number. Expected: %d; received: %d.",
+                expectedSequenceNumber, sequenceNumber));
+      }
+    }
+    //
+    // AMR as RTP payload (RFC4867 Section 4.2).
+    //
+    // +----------------+-------------------+----------------
+    // | payload header | table of contents | speech data ...
+    // +----------------+-------------------+----------------
+    //
+    // Payload header (RFC4867 Section 4.4.1).
+    //
+    // The header won't contain ILL and ILP, as interleaving is not currently supported.
+    // +-+-+-+-+-+-+-+- - - - - - - -
+    // | CMR |R|R|R|R| ILL  |  ILP  |
+    // +-+-+-+-+-+-+-+- - - - - - - -
+    //
+    // Skip CMR and reserved bits.
+    data.skipBytes(1);
+    // Loop over sampleSize to send multiple frames along with appropriate timestamp when compound
+    // payload support is added.
+    int frameType = (data.peekUnsignedByte() >> 3) & 0x0f;
+    int frameSize = getFrameSize(frameType, isWideBand);
+    int sampleSize = data.bytesLeft();
+    checkArgument(sampleSize == frameSize, "compound payload not supported currently");
+    trackOutput.sampleData(data, sampleSize);
+    long sampleTimeUs =
+        toSampleTimeUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp, sampleRate);
+    trackOutput.sampleMetadata(
+        sampleTimeUs, C.BUFFER_FLAG_KEY_FRAME, sampleSize, /* offset= */ 0, /* cryptoData= */ null);
+
+    previousSequenceNumber = sequenceNumber;
+  }
+
+  @Override
+  public void seek(long nextRtpTimestamp, long timeUs) {
+    firstReceivedTimestamp = nextRtpTimestamp;
+    startTimeOffsetUs = timeUs;
+  }
+
+  // Internal methods.
+
+  public static int getFrameSize(int frameType, boolean isWideBand) {
+    checkArgument(
+        // Valid frame types are defined in RFC4867 Section 4.3.1.
+        (frameType >= 0 && frameType <= 8) || frameType == 15,
+        "Illegal AMR " + (isWideBand ? "WB" : "NB") + " frame type " + frameType);
+
+    return isWideBand
+        ? AMR_WB_FRAME_TYPE_INDEX_TO_FRAME_SIZE[frameType]
+        : AMR_NB_FRAME_TYPE_INDEX_TO_FRAME_SIZE[frameType];
+  }
+
+  /** Returns the correct sample time from RTP timestamp, accounting for the AMR sampling rate. */
+  private static long toSampleTimeUs(
+      long startTimeOffsetUs, long rtpTimestamp, long firstReceivedRtpTimestamp, int sampleRate) {
+    return startTimeOffsetUs
+        + Util.scaleLargeTimestamp(
+            rtpTimestamp - firstReceivedRtpTimestamp,
+            /* multiplier= */ C.MICROS_PER_SECOND,
+            /* divisor= */ sampleRate);
+  }
+}