handle empty converter chain

csdr/chain/__init__.py

@@ -11,6 +11,9 @@ class Chain:
         for i in range(1, len(self.workers)):
             self._connect(self.workers[i - 1], self.workers[i])
 
+    def empty(self):
+        return not self.workers
+
     def _connect(self, w1, w2):
         writer = Buffer(w1.getOutputFormat())
         w1.setWriter(writer)
@@ -73,7 +76,7 @@ class Chain:
                 error = e
 
         if error is not None:
-            raise e
+            raise error
 
     def append(self, newWorker):
         previousWorker = None
@@ -90,6 +93,21 @@ class Chain:
         if self.writer is not None:
             newWorker.setWriter(self.writer)
 
+    def insert(self, newWorker):
+        nextWorker = None
+        if self.workers:
+            nextWorker = self.workers[0]
+
+        self.workers.insert(0, newWorker)
+
+        if nextWorker:
+            self._connect(newWorker, nextWorker)
+        elif self.writer is not None:
+            newWorker.setWriter(self.writer)
+
+        if self.reader is not None:
+            newWorker.setReader(self.reader)
+
     def remove(self, index):
         removedWorker = self.workers[index]
         self.workers.remove(removedWorker)

csdr/chain/clientaudio.py

@@ -21,7 +21,10 @@ class ClientAudioChain(Chain):
         self.format = format
         self.inputRate = inputRate
         self.clientRate = clientRate
-        workers = [self._buildConverter()]
+        workers = []
+        converter = self._buildConverter()
+        if not converter.empty():
+            workers += [converter]
         if compression == "adpcm":
             workers += [AdpcmEncoder(sync=True)]
         super().__init__(workers)
@@ -29,23 +32,35 @@ class ClientAudioChain(Chain):
     def _buildConverter(self):
         return Converter(self.format, self.inputRate, self.clientRate)
 
+    def _updateConverter(self):
+        converter = self._buildConverter()
+        index = self.indexOf(lambda x: isinstance(x, Converter))
+        if converter.empty():
+            if index >= 0:
+                self.remove(index)
+        else:
+            if index >= 0:
+                self.replace(index, converter)
+            else:
+                self.insert(converter)
+
     def setFormat(self, format: Format) -> None:
         if format == self.format:
             return
         self.format = format
-        self.replace(0, self._buildConverter())
+        self._updateConverter()
 
     def setInputRate(self, inputRate: int) -> None:
         if inputRate == self.inputRate:
             return
         self.inputRate = inputRate
-        self.replace(0, self._buildConverter())
+        self._updateConverter()
 
     def setClientRate(self, clientRate: int) -> None:
         if clientRate == self.clientRate:
             return
         self.clientRate = clientRate
-        self.replace(0, self._buildConverter())
+        self._updateConverter()
 
     def setAudioCompression(self, compression: str) -> None:
         index = self.indexOf(lambda x: isinstance(x, AdpcmEncoder))