Make Python ByteVector can be used more efficiently (#4588)

Author: wxiaoguang

.gitignore

@@ -49,6 +49,7 @@ pjsip-apps/src/pjsua/ios-swift/Libraries/
 pjsip-apps/src/pjsua2/ios-swift-pjsua2/Libraries/
 
 # SWIG Java/Android stuff
+.gradle
 pjsip-apps/src/swig/java/android/app/src/main/java/org/pjsip/pjsua2/*.java
 pjsip-apps/src/swig/java/android/app/src/main/java/org/pjsip/PjCamera*.java
 pjsip-apps/src/swig/java/android/app/src/main/jniLibs/
@@ -60,12 +61,14 @@ pjsip-apps/src/swig/csharp/sample/SimplePjsua2CS/obj
 pjsip-apps/src/swig/csharp/sample/SimplePjsua2CS/*.user
 
 # SWIG Python stuff
+__pycache__
 pjsip-apps/src/swig/python/build/
+pjsip-apps/src/swig/python/dist/
 pjsip-apps/src/swig/python/pjsua2.py
 pjsip-apps/src/swig/python/pjsua2_wrap.*
+pjsip-apps/src/swig/python/pjsua2.egg-info
 
 # unit tests files
-tests/pjsua/**/__pycache__/
 tests/pjsua/*.pyc
 tests/pjsua/scripts-*/*.pyc
 tests/pjsua/*.log

pjsip-apps/src/swig/pjsua2.i

@@ -40,6 +40,35 @@ using namespace pj;
       //Py_Exit(1);
     }
   }
+
+  %extend std::vector<unsigned char> {
+    void assign_from_bytes(PyObject* obj) {
+      Py_buffer view;
+      if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) != 0) {
+        SWIG_Python_RaiseOrModifyTypeError("expected a bytes-like object (bytes, bytearray, memoryview)");
+        return;
+      }
+      $self->assign((unsigned char*)view.buf, (unsigned char*)view.buf + view.len);
+      PyBuffer_Release(&view);
+    }
+    void copy_to_bytearray(PyObject* obj) {
+      // Not using return value here, because in SWIG, using return value will cause one more copy
+      Py_buffer view;
+      if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) != 0) {
+        SWIG_Python_RaiseOrModifyTypeError("expected a writable bytes-like object (bytearray, memoryview)");
+        return;
+      }
+      if (view.len < (Py_ssize_t)$self->size()) {
+        PyBuffer_Release(&view);
+        SWIG_Python_RaiseOrModifyTypeError("bytearray too small");
+        return;
+      }
+      if ($self->size() > 0) {
+        memcpy(view.buf, $self->data(), $self->size());
+      }
+      PyBuffer_Release(&view);
+    }
+  }
 #endif
 
 #ifdef SWIGCSHARP

pjsip-apps/src/swig/python/test.py

@@ -50,6 +50,20 @@ def ua_data_test():
         write(s  + "\r\n")
     write("\r\n")
 
+    #
+    # ByteVector
+    # Assign bytes/bytearray/memoryview to a ByteVector
+    # Copy the content of a ByteVector to a bytearray/memoryview
+    #
+    bv = pj.ByteVector()
+    bv.assign_from_bytes(bytearray([1, 2, 3]))
+    assert bv.size() == 3
+    assert bv[0] == 1 and bv[1] == 2 and bv[2] == 3
+
+    ba = memoryview(bytearray(5))
+    bv.copy_to_bytearray(ba[1:])
+    assert ba == b'\x00\x01\x02\x03\x00'
+
 #
 # Exception test
 #
@@ -78,39 +92,45 @@ def write(self, entry):
         write("This is Python:" + entry.msg + "\r\n")
 
 class AMP(pj.AudioMediaPort):
-    frames = deque()
+    buffers = deque()
 
     def onFrameRequested(self, frame):
-        if len(self.frames):
-            # Get a frame from the queue and pass it to PJSIP
-            frame_ = self.frames.popleft()
+        if len(self.buffers):
+            # Get a buffer from the queue
+            buffer_out = self.buffers.popleft()
+            # Copy the buffer to PJSIP's frame
             frame.type = pj.PJMEDIA_TYPE_AUDIO
-            frame.buf = frame_
+            frame.buf.assign_from_bytes(buffer_out)
 
     def onFrameReceived(self, frame):
-        frame_ = pj.ByteVector()
-        for i in range(frame.buf.size()):
+        # Get the incoming audio buffer from PJSIP's frame
+        buffer_in = bytearray(frame.buf.size())
+        frame.buf.copy_to_bytearray(buffer_in)
+        # Prepare an output buffer
+        buffer_out = bytearray(len(buffer_in))
+
+        # Now you can process these byte arrays directly, e.g. use numpy
+        for i in range(len(buffer_in)):
             if (i % 2 == 1):
                 # Convert it to signed 16-bit integer
-                x = frame.buf[i] << 8 | frame.buf[i-1]
+                x = buffer_in[i] << 8 | buffer_in[i-1]
                 x = struct.unpack('<h', struct.pack('<H', x))[0]
 
                 # Amplify the signal by 50% and clip it
                 x = int(x * 1.5)
-                if (x > 32767):
+                if x > 32767:
                     x = 32767
-                else:
-                    if (x < -32768):
-                        x = -32768
+                elif x < -32768:
+                    x = -32768
 
                 # Convert it to unsigned 16-bit integer
                 x = struct.unpack('<H', struct.pack('<h', x))[0]
 
-                # Put it back in the vector in little endian order
-                frame_.append(x & 0xff)
-                frame_.append((x & 0xff00) >> 8)
+                # Put it in the output buffer in little endian order
+                buffer_out[i-1] = (x & 0xff)
+                buffer_out[i] = (x & 0xff00) >> 8
 
-        self.frames.append(frame_)
+        self.buffers.append(buffer_out)
 
 #
 # Testing log writer callback