Fix encoding g722 format

test/torchaudio_unittest/io/stream_writer_test.py

@@ -389,6 +389,22 @@ def test_audio_num_frames_lossy(self, ext, num_channels, sample_rate):
             return
         self.assertEqual(saved.shape, data.shape)
 
+    def test_g722_sample_rate(self):
+        """Encoding G.722 properly converts sample rate to 16k"""
+        filename = "test.g722"
+        sample_rate = 41000
+        data = get_sinusoid(sample_rate=sample_rate, n_channels=1, channels_first=False)
+
+        # write data
+        dst = self.get_temp_path(filename)
+        w = StreamWriter(dst, format="g722")
+        w.add_audio_stream(sample_rate=sample_rate, num_channels=1)
+        with w.open():
+            w.write_audio_chunk(0, data)
+
+        r = StreamReader(src=self.get_temp_path(filename))
+        self.assertEqual(r.get_src_stream_info(0).sample_rate, 16000)
+
     def test_preserve_fps(self):
         """Decimal point frame rate is properly saved
 

torchaudio/csrc/ffmpeg/stream_writer/encode_process.cpp

@@ -273,6 +273,20 @@ int get_enc_sr(
     int src_sample_rate,
     const c10::optional<int>& encoder_sample_rate,
     const AVCodec* codec) {
+  // G.722 only supports 16000 Hz, but it does not list the sample rate in
+  // supported_samplerates so we hard code it here.
+  if (codec->id == AV_CODEC_ID_ADPCM_G722) {
+    if (encoder_sample_rate) {
+      auto val = encoder_sample_rate.value();
+      TORCH_CHECK(
+          val == 16'000,
+          codec->name,
+          " does not support sample rate ",
+          val,
+          ". Supported values are; 16000.");
+    }
+    return 16'000;
+  }
   if (encoder_sample_rate) {
     const int& encoder_sr = encoder_sample_rate.value();
     TORCH_CHECK(