RTP: support payloads with larger packetization interval.

RFC 3551 section 4.2 said that a receiver should accept packets
representing between 0 and 200ms of audio data. Now we add the
ability to decode multiple frames in a payload as long as the
jitter buffer is not full. This change covers G711, GSM, and
GSM-EFR. AMR will be added later.

Bug: 3029736
Change-Id: Ifd194596766d14f02177925c58432cd620e44dd7

1 files changed, 12 insertions, 8 deletions

diff --git a/voip/jni/rtp/AmrCodec.cpp b/voip/jni/rtp/AmrCodec.cpp
index 84c7166..e2d820e 100644
--- a/voip/jni/rtp/AmrCodec.cpp
+++ b/voip/jni/rtp/AmrCodec.cpp
@@ -52,7 +52,7 @@ public:
 
     int set(int sampleRate, const char *fmtp);
     int encode(void *payload, int16_t *samples);
-    int decode(int16_t *samples, void *payload, int length);
+    int decode(int16_t *samples, int count, void *payload, int length);
 
 private:
     void *mEncoder;
@@ -128,7 +128,7 @@ int AmrCodec::encode(void *payload, int16_t *samples)
     return length;
 }
 
-int AmrCodec::decode(int16_t *samples, void *payload, int length)
+int AmrCodec::decode(int16_t *samples, int count, void *payload, int length)
 {
     unsigned char *bytes = (unsigned char *)payload;
     Frame_Type_3GPP type;
@@ -213,7 +213,7 @@ public:
     }
 
     int encode(void *payload, int16_t *samples);
-    int decode(int16_t *samples, void *payload, int length);
+    int decode(int16_t *samples, int count, void *payload, int length);
 
 private:
     void *mEncoder;
@@ -239,20 +239,24 @@ int GsmEfrCodec::encode(void *payload, int16_t *samples)
     return -1;
 }
 
-int GsmEfrCodec::decode(int16_t *samples, void *payload, int length)
+int GsmEfrCodec::decode(int16_t *samples, int count, void *payload, int length)
 {
     unsigned char *bytes = (unsigned char *)payload;
-    if (length == 31 && (bytes[0] >> 4) == 0x0C) {
+    int n = 0;
+    while (n + 160 <= count && length >= 31 && (bytes[0] >> 4) == 0x0C) {
         for (int i = 0; i < 30; ++i) {
             bytes[i] = (bytes[i] << 4) | (bytes[i + 1] >> 4);
         }
         bytes[30] <<= 4;
 
-        if (AMRDecode(mDecoder, AMR_122, bytes, samples, MIME_IETF) == 31) {
-            return 160;
+        if (AMRDecode(mDecoder, AMR_122, bytes, &samples[n], MIME_IETF) != 31) {
+            break;
         }
+        n += 160;
+        length -= 31;
+        bytes += 31;
     }
-    return -1;
+    return n;
 }
 
 } // namespace