Set preferred video codec

Signed-off-by: Mario Danic <mario@lovelyhq.com>

app/src/main/java/com/nextcloud/talk/activities/CallActivity.java

@@ -61,6 +61,7 @@ import com.nextcloud.talk.events.SessionDescriptionSendEvent;
 import com.nextcloud.talk.persistence.entities.UserEntity;
 import com.nextcloud.talk.webrtc.MagicAudioManager;
 import com.nextcloud.talk.webrtc.MagicPeerConnectionWrapper;
+import com.nextcloud.talk.webrtc.MagicWebRTCUtils;
 
 import org.apache.commons.lang3.StringEscapeUtils;
 import org.greenrobot.eventbus.EventBus;
@@ -502,11 +503,17 @@ public class CallActivity extends AppCompatActivity {
                     switch (type) {
                         case "offer":
                         case "answer":
-                            Log.d("MARIO GOT ",  type + " " + ncSignalingMessage.getFrom());
                             magicPeerConnectionWrapper.setNick(ncSignalingMessage.getPayload().getNick());
+                            String sessionDescriptionStringWithPreferredCodec = MagicWebRTCUtils.preferCodec
+                                    (ncSignalingMessage.getPayload().getSdp(),
+                                    "VP8", false);
+
+                            SessionDescription sessionDescriptionWithPreferredCodec = new SessionDescription(
+                                    SessionDescription.Type.fromCanonicalForm(type),
+                                    sessionDescriptionStringWithPreferredCodec);
+
                             magicPeerConnectionWrapper.getPeerConnection().setRemoteDescription(magicPeerConnectionWrapper
-                                    .getMagicSdpObserver(), new SessionDescription(SessionDescription.Type.fromCanonicalForm(type),
-                                    ncSignalingMessage.getPayload().getSdp()));
+                                    .getMagicSdpObserver(), sessionDescriptionWithPreferredCodec);
                             break;
                         case "candidate":
                             NCIceCandidate ncIceCandidate = ncSignalingMessage.getPayload().getIceCandidate();

app/src/main/java/com/nextcloud/talk/webrtc/MagicPeerConnectionWrapper.java

@@ -16,6 +16,7 @@
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
  */
 
 package com.nextcloud.talk.webrtc;
@@ -272,9 +273,17 @@ public class MagicPeerConnectionWrapper {
 
         @Override
         public void onCreateSuccess(SessionDescription sessionDescription) {
-            EventBus.getDefault().post(new SessionDescriptionSendEvent(sessionDescription, sessionId,
+            String sessionDescriptionStringWithPreferredCodec = MagicWebRTCUtils.preferCodec
+                    (sessionDescription.description,
+                            "VP8", false);
+
+            SessionDescription sessionDescriptionWithPreferredCodec = new SessionDescription(
+                    sessionDescription.type,
+                    sessionDescriptionStringWithPreferredCodec);
+
+            EventBus.getDefault().post(new SessionDescriptionSendEvent(sessionDescriptionWithPreferredCodec, sessionId,
                     sessionDescription.type.canonicalForm().toLowerCase(), null));
-            peerConnection.setLocalDescription(magicSdpObserver, sessionDescription);
+            peerConnection.setLocalDescription(magicSdpObserver, sessionDescriptionWithPreferredCodec);
         }
 
         @Override
@@ -290,4 +299,5 @@ public class MagicPeerConnectionWrapper {
             }
         }
     }
+
 }

app/src/main/java/com/nextcloud/talk/webrtc/MagicWebRTCUtils.java

@@ -0,0 +1,125 @@
+/*
+ * Nextcloud Talk application
+ *
+ * @author Mario Danic
+ * Copyright (C) 2017 Mario Danic <mario@lovelyhq.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Original code:
+ *
+ *
+ * Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package com.nextcloud.talk.webrtc;
+
+import android.util.Log;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class MagicWebRTCUtils {
+    private static final String TAG = "MagicWebRTCUtils";
+
+    public static String preferCodec(String sdpDescription, String codec, boolean isAudio) {
+        final String[] lines = sdpDescription.split("\r\n");
+        final int mLineIndex = findMediaDescriptionLine(isAudio, lines);
+        if (mLineIndex == -1) {
+            Log.w(TAG, "No mediaDescription line, so can't prefer " + codec);
+            return sdpDescription;
+        }
+        // A list with all the payload types with name |codec|. The payload types are integers in the
+        // range 96-127, but they are stored as strings here.
+        final List<String> codecPayloadTypes = new ArrayList<String>();
+        // a=rtpmap:<payload type> <encoding name>/<clock rate> [/<encoding parameters>]
+        final Pattern codecPattern = Pattern.compile("^a=rtpmap:(\\d+) " + codec + "(/\\d+)+[\r]?$");
+        for (int i = 0; i < lines.length; ++i) {
+            Matcher codecMatcher = codecPattern.matcher(lines[i]);
+            if (codecMatcher.matches()) {
+                codecPayloadTypes.add(codecMatcher.group(1));
+            }
+        }
+        if (codecPayloadTypes.isEmpty()) {
+            Log.w(TAG, "No payload types with name " + codec);
+            return sdpDescription;
+        }
+
+        final String newMLine = movePayloadTypesToFront(codecPayloadTypes, lines[mLineIndex]);
+        if (newMLine == null) {
+            return sdpDescription;
+        }
+        Log.d(TAG, "Change media description from: " + lines[mLineIndex] + " to " + newMLine);
+        lines[mLineIndex] = newMLine;
+        return joinString(Arrays.asList(lines), "\r\n", true /* delimiterAtEnd */);
+    }
+
+    /** Returns the line number containing "m=audio|video", or -1 if no such line exists. */
+    private static int findMediaDescriptionLine(boolean isAudio, String[] sdpLines) {
+        final String mediaDescription = isAudio ? "m=audio " : "m=video ";
+        for (int i = 0; i < sdpLines.length; ++i) {
+            if (sdpLines[i].startsWith(mediaDescription)) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    private static String movePayloadTypesToFront(List<String> preferredPayloadTypes, String mLine) {
+        // The format of the media description line should be: m=<media> <port> <proto> <fmt> ...
+        final List<String> origLineParts = Arrays.asList(mLine.split(" "));
+        if (origLineParts.size() <= 3) {
+            Log.e(TAG, "Wrong SDP media description format: " + mLine);
+            return null;
+        }
+        final List<String> header = origLineParts.subList(0, 3);
+        final List<String> unpreferredPayloadTypes =
+                new ArrayList<String>(origLineParts.subList(3, origLineParts.size()));
+        unpreferredPayloadTypes.removeAll(preferredPayloadTypes);
+        // Reconstruct the line with |preferredPayloadTypes| moved to the beginning of the payload
+        // types.
+        final List<String> newLineParts = new ArrayList<String>();
+        newLineParts.addAll(header);
+        newLineParts.addAll(preferredPayloadTypes);
+        newLineParts.addAll(unpreferredPayloadTypes);
+        return joinString(newLineParts, " ", false /* delimiterAtEnd */);
+    }
+
+    private static String joinString(
+            Iterable<? extends CharSequence> s, String delimiter, boolean delimiterAtEnd) {
+        Iterator<? extends CharSequence> iter = s.iterator();
+        if (!iter.hasNext()) {
+            return "";
+        }
+        StringBuilder buffer = new StringBuilder(iter.next());
+        while (iter.hasNext()) {
+            buffer.append(delimiter).append(iter.next());
+        }
+        if (delimiterAtEnd) {
+            buffer.append(delimiter);
+        }
+        return buffer.toString();
+    }
+
+}