text: import fractions
  
  from aiortc.codecs import get_decoder, get_encoder
  from aiortc.codecs.opus import OpusDecoder, OpusEncoder
  from aiortc.jitterbuffer import JitterFrame
  from aiortc.rtcrtpparameters import RTCRtpCodecParameters
  
  from .codecs import CodecTestCase
  
  OPUS_CODEC = RTCRtpCodecParameters(
      mimeType="audio/opus", clockRate=48000, channels=2, payloadType=100
  )
  
  
  class OpusTest(CodecTestCase):
      def test_decoder(self):
          decoder = get_decoder(OPUS_CODEC)
          self.assertIsInstance(decoder, OpusDecoder)
  
          frames = decoder.decode(JitterFrame(data=b"\xfc\xff\xfe", timestamp=0))
          self.assertEqual(len(frames), 1)
          frame = frames[0]
          self.assertEqual(frame.format.name, "s16")
          self.assertEqual(frame.layout.name, "stereo")
          self.assertEqual(bytes(frame.planes[0]), b"\x00" * 4 * 960)
          self.assertEqual(frame.sample_rate, 48000)
          self.assertEqual(frame.pts, 0)
          self.assertEqual(frame.time_base, fractions.Fraction(1, 48000))
  
      def test_encoder_mono_8khz(self):
          encoder = get_encoder(OPUS_CODEC)
          self.assertIsInstance(encoder, OpusEncoder)
  
          frames = self.create_audio_frames(layout="mono", sample_rate=8000, count=2)
  
          # first frame
          payloads, timestamp = encoder.encode(frames[0])
          self.assertEqual(payloads, [b"\xfc\xff\xfe"])
          self.assertEqual(timestamp, 0)
  
          # second frame
          payloads, timestamp = encoder.encode(frames[1])
          self.assertEqual(timestamp, 960)
  
      def test_encoder_stereo_8khz(self):
          encoder = get_encoder(OPUS_CODEC)
          self.assertIsInstance(encoder, OpusEncoder)
  
          frames = self.create_audio_frames(layout="stereo", sample_rate=8000, count=2)
  
          # first frame
          payloads, timestamp = encoder.encode(frames[0])
          self.assertEqual(payloads, [b"\xfc\xff\xfe"])
          self.assertEqual(timestamp, 0)
  
          # second frame
          payloads, timestamp = encoder.encode(frames[1])
          self.assertEqual(timestamp, 960)
  
      def test_encoder_stereo_48khz(self):
          encoder = get_encoder(OPUS_CODEC)
          self.assertIsInstance(encoder, OpusEncoder)
  
          frames = self.create_audio_frames(layout="stereo", sample_rate=48000, count=2)
  
          # first frame
          payloads, timestamp = encoder.encode(frames[0])
          self.assertEqual(payloads, [b"\xfc\xff\xfe"])
          self.assertEqual(timestamp, 0)
  
          # second frame
          payloads, timestamp = encoder.encode(frames[1])
          self.assertEqual(timestamp, 960)
  
      def test_roundtrip(self):
          self.roundtrip_audio(
              OPUS_CODEC, output_layout="stereo", output_sample_rate=48000
          )
  
      def test_roundtrip_with_loss(self):
          self.roundtrip_audio(
              OPUS_CODEC, output_layout="stereo", output_sample_rate=48000, drop=[1]
          )
  