From ccf8b5667049a9e3165a80635071bd3bcd0a38ae Mon Sep 17 00:00:00 2001
From: "fischman@webrtc.org"
 <fischman@webrtc.org@4adac7df-926f-26a2-2b94-8c16560cd09d>
Date: Tue, 3 Sep 2013 19:02:11 +0000
Subject: [PATCH] AppRTCDemo(android): prefer ISAC for audio codec.

R=wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2126004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4666 4adac7df-926f-26a2-2b94-8c16560cd09d
---
 .../appspot/apprtc/AppRTCDemoActivity.java    | 59 ++++++++++++++++++-
 1 file changed, 56 insertions(+), 3 deletions(-)

diff --git a/talk/examples/android/src/org/appspot/apprtc/AppRTCDemoActivity.java b/talk/examples/android/src/org/appspot/apprtc/AppRTCDemoActivity.java
index 936cb2bd7..7c673d813 100644
--- a/talk/examples/android/src/org/appspot/apprtc/AppRTCDemoActivity.java
+++ b/talk/examples/android/src/org/appspot/apprtc/AppRTCDemoActivity.java
@@ -62,6 +62,8 @@ import org.webrtc.VideoTrack;
 import java.util.EnumSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Main Activity of the AppRTCDemo Android app demonstrating interoperability
@@ -289,6 +291,55 @@ public class AppRTCDemoActivity extends Activity
     }
   }
 
+  // Mangle SDP to prefer ISAC/16000 over any other audio codec.
+  private String preferISAC(String sdpDescription) {
+    String[] lines = sdpDescription.split("\n");
+    int mLineIndex = -1;
+    String isac16kRtpMap = null;
+    Pattern isac16kPattern =
+        Pattern.compile("^a=rtpmap:(\\d+) ISAC/16000[\r]?$");
+    for (int i = 0;
+         (i < lines.length) && (mLineIndex == -1 || isac16kRtpMap == null);
+         ++i) {
+      if (lines[i].startsWith("m=audio ")) {
+        mLineIndex = i;
+        continue;
+      }
+      Matcher isac16kMatcher = isac16kPattern.matcher(lines[i]);
+      if (isac16kMatcher.matches()) {
+        isac16kRtpMap = isac16kMatcher.group(1);
+        continue;
+      }
+    }
+    if (mLineIndex == -1) {
+      Log.d(TAG, "No m=audio line, so can't prefer iSAC");
+      return sdpDescription;
+    }
+    if (isac16kRtpMap == null) {
+      Log.d(TAG, "No ISAC/16000 line, so can't prefer iSAC");
+      return sdpDescription;
+    }
+    String[] origMLineParts = lines[mLineIndex].split(" ");
+    StringBuilder newMLine = new StringBuilder();
+    int origPartIndex = 0;
+    // Format is: m=<media> <port> <proto> <fmt> ...
+    newMLine.append(origMLineParts[origPartIndex++]).append(" ");
+    newMLine.append(origMLineParts[origPartIndex++]).append(" ");
+    newMLine.append(origMLineParts[origPartIndex++]).append(" ");
+    newMLine.append(isac16kRtpMap).append(" ");
+    for (; origPartIndex < origMLineParts.length; ++origPartIndex) {
+      if (!origMLineParts[origPartIndex].equals(isac16kRtpMap)) {
+        newMLine.append(origMLineParts[origPartIndex]).append(" ");
+      }
+    }
+    lines[mLineIndex] = newMLine.toString();
+    StringBuilder newSdpDescription = new StringBuilder();
+    for (String line : lines) {
+      newSdpDescription.append(line).append("\n");
+    }
+    return newSdpDescription.toString();
+  }
+
   // Implementation detail: observe ICE & stream changes and react accordingly.
   private class PCObserver implements PeerConnection.Observer {
     @Override public void onIceCandidate(final IceCandidate candidate){
@@ -360,10 +411,12 @@ public class AppRTCDemoActivity extends Activity
   // Implementation detail: handle offer creation/signaling and answer setting,
   // as well as adding remote ICE candidates once the answer SDP is set.
   private class SDPObserver implements SdpObserver {
-    @Override public void onCreateSuccess(final SessionDescription sdp) {
+    @Override public void onCreateSuccess(final SessionDescription origSdp) {
       runOnUiThread(new Runnable() {
           public void run() {
-            logAndToast("Sending " + sdp.type);
+            logAndToast("Sending " + origSdp.type);
+            SessionDescription sdp = new SessionDescription(
+                origSdp.type, preferISAC(origSdp.description));
             JSONObject json = new JSONObject();
             jsonPut(json, "type", sdp.type.canonicalForm());
             jsonPut(json, "sdp", sdp.description);
@@ -449,7 +502,7 @@ public class AppRTCDemoActivity extends Activity
         } else if (type.equals("answer") || type.equals("offer")) {
           SessionDescription sdp = new SessionDescription(
               SessionDescription.Type.fromCanonicalForm(type),
-              (String) json.get("sdp"));
+              preferISAC((String) json.get("sdp")));
           pc.setRemoteDescription(sdpObserver, sdp);
         } else if (type.equals("bye")) {
           logAndToast("Remote end hung up; dropping PeerConnection");