| /* |
| * Copyright (C) 2010 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 android.net.rtp; |
| |
| import java.util.Arrays; |
| |
| /** |
| * This class defines a collection of audio codecs to be used with |
| * {@link AudioStream}s. Their parameters are designed to be exchanged using |
| * Session Description Protocol (SDP). Most of the values listed here can be |
| * found in RFC 3551, while others are described in separated standards. |
| * |
| * <p>Few simple configurations are defined as public static instances for the |
| * convenience of direct uses. More complicated ones could be obtained using |
| * {@link #getCodec(int, String, String)}. For example, one can use the |
| * following snippet to create a mode-1-only AMR codec.</p> |
| * <pre> |
| * AudioCodec codec = AudioCodec.getCodec(100, "AMR/8000", "mode-set=1"); |
| * </pre> |
| * |
| * @see AudioStream |
| */ |
| public class AudioCodec { |
| /** |
| * The RTP payload type of the encoding. |
| */ |
| public final int type; |
| |
| /** |
| * The encoding parameters to be used in the corresponding SDP attribute. |
| */ |
| public final String rtpmap; |
| |
| /** |
| * The format parameters to be used in the corresponding SDP attribute. |
| */ |
| public final String fmtp; |
| |
| /** |
| * G.711 u-law audio codec. |
| */ |
| public static final AudioCodec PCMU = new AudioCodec(0, "PCMU/8000", null); |
| |
| /** |
| * G.711 a-law audio codec. |
| */ |
| public static final AudioCodec PCMA = new AudioCodec(8, "PCMA/8000", null); |
| |
| /** |
| * GSM Full-Rate audio codec, also known as GSM-FR, GSM 06.10, GSM, or |
| * simply FR. |
| */ |
| public static final AudioCodec GSM = new AudioCodec(3, "GSM/8000", null); |
| |
| /** |
| * GSM Enhanced Full-Rate audio codec, also known as GSM-EFR, GSM 06.60, or |
| * simply EFR. |
| */ |
| public static final AudioCodec GSM_EFR = new AudioCodec(96, "GSM-EFR/8000", null); |
| |
| /** |
| * Adaptive Multi-Rate narrowband audio codec, also known as AMR or AMR-NB. |
| * Currently CRC, robust sorting, and interleaving are not supported. See |
| * more details about these features in RFC 4867. |
| */ |
| public static final AudioCodec AMR = new AudioCodec(97, "AMR/8000", null); |
| |
| private static final AudioCodec[] sCodecs = {GSM_EFR, AMR, GSM, PCMU, PCMA}; |
| |
| private AudioCodec(int type, String rtpmap, String fmtp) { |
| this.type = type; |
| this.rtpmap = rtpmap; |
| this.fmtp = fmtp; |
| } |
| |
| /** |
| * Returns system supported audio codecs. |
| */ |
| public static AudioCodec[] getCodecs() { |
| return Arrays.copyOf(sCodecs, sCodecs.length); |
| } |
| |
| /** |
| * Creates an AudioCodec according to the given configuration. |
| * |
| * @param type The payload type of the encoding defined in RTP/AVP. |
| * @param rtpmap The encoding parameters specified in the corresponding SDP |
| * attribute, or null if it is not available. |
| * @param fmtp The format parameters specified in the corresponding SDP |
| * attribute, or null if it is not available. |
| * @return The configured AudioCodec or {@code null} if it is not supported. |
| */ |
| public static AudioCodec getCodec(int type, String rtpmap, String fmtp) { |
| if (type < 0 || type > 127) { |
| return null; |
| } |
| |
| AudioCodec hint = null; |
| if (rtpmap != null) { |
| String clue = rtpmap.trim().toUpperCase(); |
| for (AudioCodec codec : sCodecs) { |
| if (clue.startsWith(codec.rtpmap)) { |
| String channels = clue.substring(codec.rtpmap.length()); |
| if (channels.length() == 0 || channels.equals("/1")) { |
| hint = codec; |
| } |
| break; |
| } |
| } |
| } else if (type < 96) { |
| for (AudioCodec codec : sCodecs) { |
| if (type == codec.type) { |
| hint = codec; |
| rtpmap = codec.rtpmap; |
| break; |
| } |
| } |
| } |
| |
| if (hint == null) { |
| return null; |
| } |
| if (hint == AMR && fmtp != null) { |
| String clue = fmtp.toLowerCase(); |
| if (clue.contains("crc=1") || clue.contains("robust-sorting=1") || |
| clue.contains("interleaving=")) { |
| return null; |
| } |
| } |
| return new AudioCodec(type, rtpmap, fmtp); |
| } |
| } |