diff --git a/include/media/stagefright/foundation/ABitReader.h b/include/media/stagefright/foundation/ABitReader.h
index 5135211..5510b12 100644
--- a/include/media/stagefright/foundation/ABitReader.h
+++ b/include/media/stagefright/foundation/ABitReader.h
@@ -31,6 +31,8 @@
     uint32_t getBits(size_t n);
     void skipBits(size_t n);
 
+    void putBits(uint32_t x, size_t n);
+
     size_t numBitsLeft() const;
 
     const uint8_t *data() const;
@@ -43,7 +45,6 @@
     size_t mNumBitsLeft;
 
     void fillReservoir();
-    void putBits(uint32_t x, size_t n);
 
     DISALLOW_EVIL_CONSTRUCTORS(ABitReader);
 };
diff --git a/media/libstagefright/foundation/ABitReader.cpp b/media/libstagefright/foundation/ABitReader.cpp
index 24c8df8..f07dd4f 100644
--- a/media/libstagefright/foundation/ABitReader.cpp
+++ b/media/libstagefright/foundation/ABitReader.cpp
@@ -90,9 +90,7 @@
 }
 
 const uint8_t *ABitReader::data() const {
-    CHECK_EQ(mNumBitsLeft % 8, 0u);
-
-    return mData - mNumBitsLeft / 8;
+    return mData - (mNumBitsLeft + 7) / 8;
 }
 
 }  // namespace android
diff --git a/media/libstagefright/rtsp/AMPEG4AudioAssembler.cpp b/media/libstagefright/rtsp/AMPEG4AudioAssembler.cpp
index 8bfe285..11d9c22 100644
--- a/media/libstagefright/rtsp/AMPEG4AudioAssembler.cpp
+++ b/media/libstagefright/rtsp/AMPEG4AudioAssembler.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+//#define LOG_NDEBUG 0
+#define LOG_TAG "AMPEG4AudioAssembler"
+
 #include "AMPEG4AudioAssembler.h"
 
 #include "ARTPSource.h"
@@ -139,7 +142,10 @@
     return OK;
 }
 
-static status_t parseAudioSpecificConfig(ABitReader *bits) {
+static status_t parseAudioSpecificConfig(ABitReader *bits, sp<ABuffer> *asc) {
+    const uint8_t *dataStart = bits->data();
+    size_t totalNumBits = bits->numBitsLeft();
+
     unsigned audioObjectType;
     CHECK_EQ(parseAudioObjectType(bits, &audioObjectType), (status_t)OK);
 
@@ -185,13 +191,13 @@
         }
     }
 
-#if 0
-    // This is not supported here as the upper layers did not explicitly
-    // signal the length of AudioSpecificConfig.
-
     if (extensionAudioObjectType != 5 && bits->numBitsLeft() >= 16) {
+        size_t numBitsLeftAtStart = bits->numBitsLeft();
+
         unsigned syncExtensionType = bits->getBits(11);
         if (syncExtensionType == 0x2b7) {
+            LOGI("found syncExtension");
+
             CHECK_EQ(parseAudioObjectType(bits, &extensionAudioObjectType),
                      (status_t)OK);
 
@@ -203,9 +209,45 @@
                     /* unsigned extensionSamplingFrequency = */bits->getBits(24);
                 }
             }
+
+            size_t numBitsInExtension =
+                numBitsLeftAtStart - bits->numBitsLeft();
+
+            if (numBitsInExtension & 7) {
+                // Apparently an extension is always considered an even
+                // multiple of 8 bits long.
+
+                LOGI("Skipping %d bits after sync extension",
+                     8 - (numBitsInExtension & 7));
+
+                bits->skipBits(8 - (numBitsInExtension & 7));
+            }
+        } else {
+            bits->putBits(syncExtensionType, 11);
         }
     }
-#endif
+
+    if (asc != NULL) {
+        size_t bitpos = totalNumBits & 7;
+
+        ABitReader bs(dataStart, (totalNumBits + 7) / 8);
+
+        totalNumBits -= bits->numBitsLeft();
+
+        size_t numBytes = (totalNumBits + 7) / 8;
+
+        *asc = new ABuffer(numBytes);
+
+        if (bitpos & 7) {
+            bs.skipBits(8 - (bitpos & 7));
+        }
+
+        uint8_t *dstPtr = (*asc)->data();
+        while (numBytes > 0) {
+            *dstPtr++ = bs.getBits(8);
+            --numBytes;
+        }
+    }
 
     return OK;
 }
@@ -214,6 +256,7 @@
         ABitReader *bits,
         unsigned *numSubFrames,
         unsigned *frameLengthType,
+        ssize_t *fixedFrameLength,
         bool *otherDataPresent,
         unsigned *otherDataLenBits) {
     unsigned audioMuxVersion = bits->getBits(1);
@@ -242,12 +285,14 @@
 
     if (audioMuxVersion == 0) {
         // AudioSpecificConfig
-        CHECK_EQ(parseAudioSpecificConfig(bits), (status_t)OK);
+        CHECK_EQ(parseAudioSpecificConfig(bits, NULL /* asc */), (status_t)OK);
     } else {
         TRESPASS();  // XXX to be implemented
     }
 
     *frameLengthType = bits->getBits(3);
+    *fixedFrameLength = -1;
+
     switch (*frameLengthType) {
         case 0:
         {
@@ -260,7 +305,14 @@
 
         case 1:
         {
-            /* unsigned frameLength = */bits->getBits(9);
+            *fixedFrameLength = bits->getBits(9);
+            break;
+        }
+
+        case 2:
+        {
+            // reserved
+            TRESPASS();
             break;
         }
 
@@ -338,9 +390,21 @@
                 break;
             }
 
-            default:
-                TRESPASS();  // XXX to be implemented
+            case 2:
+            {
+                // reserved
+
+                TRESPASS();
                 break;
+            }
+
+            default:
+            {
+                CHECK_GE(mFixedFrameLength, 0);
+
+                payloadLength = mFixedFrameLength;
+                break;
+            }
         }
 
         CHECK_LE(offset + payloadLength, buffer->size());
@@ -393,6 +457,7 @@
     ABitReader bits(config->data(), config->size());
     status_t err = parseStreamMuxConfig(
             &bits, &mNumSubFrames, &mFrameLengthType,
+            &mFixedFrameLength,
             &mOtherDataPresent, &mOtherDataLenBits);
 
     CHECK_EQ(err, (status_t)NO_ERROR);
diff --git a/media/libstagefright/rtsp/AMPEG4AudioAssembler.h b/media/libstagefright/rtsp/AMPEG4AudioAssembler.h
index 9cef94c..1361cd2 100644
--- a/media/libstagefright/rtsp/AMPEG4AudioAssembler.h
+++ b/media/libstagefright/rtsp/AMPEG4AudioAssembler.h
@@ -46,6 +46,7 @@
     bool mMuxConfigPresent;
     unsigned mNumSubFrames;
     unsigned mFrameLengthType;
+    ssize_t mFixedFrameLength;
     bool mOtherDataPresent;
     unsigned mOtherDataLenBits;