| /* | |
| * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. | |
| * | |
| * Use of this source code is governed by a BSD-style license | |
| * that can be found in the LICENSE file in the root of the source | |
| * tree. An additional intellectual property rights grant can be found | |
| * in the file PATENTS. All contributing project authors may | |
| * be found in the AUTHORS file in the root of the source tree. | |
| */ | |
| #include <memory> | |
| #include <string> | |
| #include "modules/audio_coding/codecs/opus/opus_inst.h" | |
| #include "modules/audio_coding/codecs/opus/opus_interface.h" | |
| #include "modules/audio_coding/neteq/tools/audio_loop.h" | |
| #include "rtc_base/checks.h" | |
| #include "rtc_base/numerics/safe_conversions.h" | |
| #include "test/gtest.h" | |
| #include "test/testsupport/file_utils.h" | |
| namespace webrtc { | |
| namespace { | |
| // Equivalent to SDP params | |
| // {{"channel_mapping", "0,1,2,3"}, {"coupled_streams", "2"}}. | |
| constexpr unsigned char kQuadChannelMapping[] = {0, 1, 2, 3}; | |
| constexpr int kQuadTotalStreams = 2; | |
| constexpr int kQuadCoupledStreams = 2; | |
| constexpr unsigned char kStereoChannelMapping[] = {0, 1}; | |
| constexpr int kStereoTotalStreams = 1; | |
| constexpr int kStereoCoupledStreams = 1; | |
| constexpr unsigned char kMonoChannelMapping[] = {0}; | |
| constexpr int kMonoTotalStreams = 1; | |
| constexpr int kMonoCoupledStreams = 0; | |
| void CreateSingleOrMultiStreamEncoder(WebRtcOpusEncInst** opus_encoder, | |
| int channels, | |
| int application, | |
| bool use_multistream, | |
| int encoder_sample_rate_hz) { | |
| EXPECT_TRUE(channels == 1 || channels == 2 || use_multistream); | |
| if (use_multistream) { | |
| EXPECT_EQ(encoder_sample_rate_hz, 48000); | |
| if (channels == 1) { | |
| EXPECT_EQ(0, WebRtcOpus_MultistreamEncoderCreate( | |
| opus_encoder, channels, application, kMonoTotalStreams, | |
| kMonoCoupledStreams, kMonoChannelMapping)); | |
| } else if (channels == 2) { | |
| EXPECT_EQ(0, WebRtcOpus_MultistreamEncoderCreate( | |
| opus_encoder, channels, application, kStereoTotalStreams, | |
| kStereoCoupledStreams, kStereoChannelMapping)); | |
| } else if (channels == 4) { | |
| EXPECT_EQ(0, WebRtcOpus_MultistreamEncoderCreate( | |
| opus_encoder, channels, application, kQuadTotalStreams, | |
| kQuadCoupledStreams, kQuadChannelMapping)); | |
| } else { | |
| EXPECT_TRUE(false) << channels; | |
| } | |
| } else { | |
| EXPECT_EQ(0, WebRtcOpus_EncoderCreate(opus_encoder, channels, application, | |
| encoder_sample_rate_hz)); | |
| } | |
| } | |
| void CreateSingleOrMultiStreamDecoder(WebRtcOpusDecInst** opus_decoder, | |
| int channels, | |
| bool use_multistream, | |
| int decoder_sample_rate_hz) { | |
| EXPECT_TRUE(channels == 1 || channels == 2 || use_multistream); | |
| if (use_multistream) { | |
| EXPECT_EQ(decoder_sample_rate_hz, 48000); | |
| if (channels == 1) { | |
| EXPECT_EQ(0, WebRtcOpus_MultistreamDecoderCreate( | |
| opus_decoder, channels, kMonoTotalStreams, | |
| kMonoCoupledStreams, kMonoChannelMapping)); | |
| } else if (channels == 2) { | |
| EXPECT_EQ(0, WebRtcOpus_MultistreamDecoderCreate( | |
| opus_decoder, channels, kStereoTotalStreams, | |
| kStereoCoupledStreams, kStereoChannelMapping)); | |
| } else if (channels == 4) { | |
| EXPECT_EQ(0, WebRtcOpus_MultistreamDecoderCreate( | |
| opus_decoder, channels, kQuadTotalStreams, | |
| kQuadCoupledStreams, kQuadChannelMapping)); | |
| } else { | |
| EXPECT_TRUE(false) << channels; | |
| } | |
| } else { | |
| EXPECT_EQ(0, WebRtcOpus_DecoderCreate(opus_decoder, channels, | |
| decoder_sample_rate_hz)); | |
| } | |
| } | |
| int SamplesPerChannel(int sample_rate_hz, int duration_ms) { | |
| const int samples_per_ms = rtc::CheckedDivExact(sample_rate_hz, 1000); | |
| return samples_per_ms * duration_ms; | |
| } | |
| using test::AudioLoop; | |
| using ::testing::Combine; | |
| using ::testing::TestWithParam; | |
| using ::testing::Values; | |
| // Maximum number of bytes in output bitstream. | |
| const size_t kMaxBytes = 2000; | |
| class OpusTest | |
| : public TestWithParam<::testing::tuple<size_t, int, bool, int, int>> { | |
| protected: | |
| OpusTest() = default; | |
| void TestDtxEffect(bool dtx, int block_length_ms); | |
| void TestCbrEffect(bool dtx, int block_length_ms); | |
| // Prepare `speech_data_` for encoding, read from a hard-coded file. | |
| // After preparation, `speech_data_.GetNextBlock()` returns a pointer to a | |
| // block of `block_length_ms` milliseconds. The data is looped every | |
| // `loop_length_ms` milliseconds. | |
| void PrepareSpeechData(int block_length_ms, int loop_length_ms); | |
| int EncodeDecode(WebRtcOpusEncInst* encoder, | |
| rtc::ArrayView<const int16_t> input_audio, | |
| WebRtcOpusDecInst* decoder, | |
| int16_t* output_audio, | |
| int16_t* audio_type); | |
| void SetMaxPlaybackRate(WebRtcOpusEncInst* encoder, | |
| opus_int32 expect, | |
| int32_t set); | |
| void CheckAudioBounded(const int16_t* audio, | |
| size_t samples, | |
| size_t channels, | |
| uint16_t bound) const; | |
| WebRtcOpusEncInst* opus_encoder_ = nullptr; | |
| WebRtcOpusDecInst* opus_decoder_ = nullptr; | |
| AudioLoop speech_data_; | |
| uint8_t bitstream_[kMaxBytes]; | |
| size_t encoded_bytes_ = 0; | |
| const size_t channels_{std::get<0>(GetParam())}; | |
| const int application_{std::get<1>(GetParam())}; | |
| const bool use_multistream_{std::get<2>(GetParam())}; | |
| const int encoder_sample_rate_hz_{std::get<3>(GetParam())}; | |
| const int decoder_sample_rate_hz_{std::get<4>(GetParam())}; | |
| }; | |
| } // namespace | |
| // Singlestream: Try all combinations. | |
| INSTANTIATE_TEST_SUITE_P(Singlestream, | |
| OpusTest, | |
| testing::Combine(testing::Values(1, 2), | |
| testing::Values(0, 1), | |
| testing::Values(false), | |
| testing::Values(16000, 48000), | |
| testing::Values(16000, 48000))); | |
| // Multistream: Some representative cases (only 48 kHz for now). | |
| INSTANTIATE_TEST_SUITE_P( | |
| Multistream, | |
| OpusTest, | |
| testing::Values(std::make_tuple(1, 0, true, 48000, 48000), | |
| std::make_tuple(2, 1, true, 48000, 48000), | |
| std::make_tuple(4, 0, true, 48000, 48000), | |
| std::make_tuple(4, 1, true, 48000, 48000))); | |
| void OpusTest::PrepareSpeechData(int block_length_ms, int loop_length_ms) { | |
| std::map<int, std::string> channel_to_basename = { | |
| {1, "audio_coding/testfile32kHz"}, | |
| {2, "audio_coding/teststereo32kHz"}, | |
| {4, "audio_coding/speech_4_channels_48k_one_second"}}; | |
| std::map<int, std::string> channel_to_suffix = { | |
| {1, "pcm"}, {2, "pcm"}, {4, "wav"}}; | |
| const std::string file_name = webrtc::test::ResourcePath( | |
| channel_to_basename[channels_], channel_to_suffix[channels_]); | |
| if (loop_length_ms < block_length_ms) { | |
| loop_length_ms = block_length_ms; | |
| } | |
| const int sample_rate_khz = | |
| rtc::CheckedDivExact(encoder_sample_rate_hz_, 1000); | |
| EXPECT_TRUE(speech_data_.Init(file_name, | |
| loop_length_ms * sample_rate_khz * channels_, | |
| block_length_ms * sample_rate_khz * channels_)); | |
| } | |
| void OpusTest::SetMaxPlaybackRate(WebRtcOpusEncInst* encoder, | |
| opus_int32 expect, | |
| int32_t set) { | |
| opus_int32 bandwidth; | |
| EXPECT_EQ(0, WebRtcOpus_SetMaxPlaybackRate(opus_encoder_, set)); | |
| EXPECT_EQ(0, WebRtcOpus_GetMaxPlaybackRate(opus_encoder_, &bandwidth)); | |
| EXPECT_EQ(expect, bandwidth); | |
| } | |
| void OpusTest::CheckAudioBounded(const int16_t* audio, | |
| size_t samples, | |
| size_t channels, | |
| uint16_t bound) const { | |
| for (size_t i = 0; i < samples; ++i) { | |
| for (size_t c = 0; c < channels; ++c) { | |
| ASSERT_GE(audio[i * channels + c], -bound); | |
| ASSERT_LE(audio[i * channels + c], bound); | |
| } | |
| } | |
| } | |
| int OpusTest::EncodeDecode(WebRtcOpusEncInst* encoder, | |
| rtc::ArrayView<const int16_t> input_audio, | |
| WebRtcOpusDecInst* decoder, | |
| int16_t* output_audio, | |
| int16_t* audio_type) { | |
| const int input_samples_per_channel = | |
| rtc::CheckedDivExact(input_audio.size(), channels_); | |
| int encoded_bytes_int = | |
| WebRtcOpus_Encode(encoder, input_audio.data(), input_samples_per_channel, | |
| kMaxBytes, bitstream_); | |
| EXPECT_GE(encoded_bytes_int, 0); | |
| encoded_bytes_ = static_cast<size_t>(encoded_bytes_int); | |
| if (encoded_bytes_ != 0) { | |
| int est_len = WebRtcOpus_DurationEst(decoder, bitstream_, encoded_bytes_); | |
| int act_len = WebRtcOpus_Decode(decoder, bitstream_, encoded_bytes_, | |
| output_audio, audio_type); | |
| EXPECT_EQ(est_len, act_len); | |
| return act_len; | |
| } else { | |
| int total_dtx_len = 0; | |
| const int output_samples_per_channel = input_samples_per_channel * | |
| decoder_sample_rate_hz_ / | |
| encoder_sample_rate_hz_; | |
| while (total_dtx_len < output_samples_per_channel) { | |
| int est_len = WebRtcOpus_DurationEst(decoder, NULL, 0); | |
| int act_len = WebRtcOpus_Decode(decoder, NULL, 0, | |
| &output_audio[total_dtx_len * channels_], | |
| audio_type); | |
| EXPECT_EQ(est_len, act_len); | |
| total_dtx_len += act_len; | |
| } | |
| return total_dtx_len; | |
| } | |
| } | |
| // Test if encoder/decoder can enter DTX mode properly and do not enter DTX when | |
| // they should not. This test is signal dependent. | |
| void OpusTest::TestDtxEffect(bool dtx, int block_length_ms) { | |
| PrepareSpeechData(block_length_ms, 2000); | |
| const size_t input_samples = | |
| rtc::CheckedDivExact(encoder_sample_rate_hz_, 1000) * block_length_ms; | |
| const size_t output_samples = | |
| rtc::CheckedDivExact(decoder_sample_rate_hz_, 1000) * block_length_ms; | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| // Set bitrate. | |
| EXPECT_EQ( | |
| 0, WebRtcOpus_SetBitRate(opus_encoder_, channels_ == 1 ? 32000 : 64000)); | |
| // Set input audio as silence. | |
| std::vector<int16_t> silence(input_samples * channels_, 0); | |
| // Setting DTX. | |
| EXPECT_EQ(0, dtx ? WebRtcOpus_EnableDtx(opus_encoder_) | |
| : WebRtcOpus_DisableDtx(opus_encoder_)); | |
| int16_t audio_type; | |
| int16_t* output_data_decode = new int16_t[output_samples * channels_]; | |
| for (int i = 0; i < 100; ++i) { | |
| EXPECT_EQ(output_samples, | |
| static_cast<size_t>(EncodeDecode( | |
| opus_encoder_, speech_data_.GetNextBlock(), opus_decoder_, | |
| output_data_decode, &audio_type))); | |
| // If not DTX, it should never enter DTX mode. If DTX, we do not care since | |
| // whether it enters DTX depends on the signal type. | |
| if (!dtx) { | |
| EXPECT_GT(encoded_bytes_, 1U); | |
| EXPECT_EQ(0, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(0, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(0, audio_type); // Speech. | |
| } | |
| } | |
| // We input some silent segments. In DTX mode, the encoder will stop sending. | |
| // However, DTX may happen after a while. | |
| for (int i = 0; i < 30; ++i) { | |
| EXPECT_EQ(output_samples, static_cast<size_t>(EncodeDecode( | |
| opus_encoder_, silence, opus_decoder_, | |
| output_data_decode, &audio_type))); | |
| if (!dtx) { | |
| EXPECT_GT(encoded_bytes_, 1U); | |
| EXPECT_EQ(0, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(0, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(0, audio_type); // Speech. | |
| } else if (encoded_bytes_ == 1) { | |
| EXPECT_EQ(1, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(1, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(2, audio_type); // Comfort noise. | |
| break; | |
| } | |
| } | |
| // When Opus is in DTX, it wakes up in a regular basis. It sends two packets, | |
| // one with an arbitrary size and the other of 1-byte, then stops sending for | |
| // a certain number of frames. | |
| // `max_dtx_frames` is the maximum number of frames Opus can stay in DTX. | |
| // TODO(kwiberg): Why does this number depend on the encoding sample rate? | |
| const int max_dtx_frames = | |
| (encoder_sample_rate_hz_ == 16000 ? 800 : 400) / block_length_ms + 1; | |
| // We run `kRunTimeMs` milliseconds of pure silence. | |
| const int kRunTimeMs = 4500; | |
| // We check that, after a `kCheckTimeMs` milliseconds (given that the CNG in | |
| // Opus needs time to adapt), the absolute values of DTX decoded signal are | |
| // bounded by `kOutputValueBound`. | |
| const int kCheckTimeMs = 4000; | |
| #if defined(OPUS_FIXED_POINT) | |
| // Fixed-point Opus generates a random (comfort) noise, which has a less | |
| // predictable value bound than its floating-point Opus. This value depends on | |
| // input signal, and the time window for checking the output values (between | |
| // `kCheckTimeMs` and `kRunTimeMs`). | |
| const uint16_t kOutputValueBound = 30; | |
| #else | |
| const uint16_t kOutputValueBound = 2; | |
| #endif | |
| int time = 0; | |
| while (time < kRunTimeMs) { | |
| // DTX mode is maintained for maximum `max_dtx_frames` frames. | |
| int i = 0; | |
| for (; i < max_dtx_frames; ++i) { | |
| time += block_length_ms; | |
| EXPECT_EQ(output_samples, static_cast<size_t>(EncodeDecode( | |
| opus_encoder_, silence, opus_decoder_, | |
| output_data_decode, &audio_type))); | |
| if (dtx) { | |
| if (encoded_bytes_ > 1) | |
| break; | |
| EXPECT_EQ(0U, encoded_bytes_) // Send 0 byte. | |
| << "Opus should have entered DTX mode."; | |
| EXPECT_EQ(1, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(1, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(2, audio_type); // Comfort noise. | |
| if (time >= kCheckTimeMs) { | |
| CheckAudioBounded(output_data_decode, output_samples, channels_, | |
| kOutputValueBound); | |
| } | |
| } else { | |
| EXPECT_GT(encoded_bytes_, 1U); | |
| EXPECT_EQ(0, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(0, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(0, audio_type); // Speech. | |
| } | |
| } | |
| if (dtx) { | |
| // With DTX, Opus must stop transmission for some time. | |
| EXPECT_GT(i, 1); | |
| } | |
| // We expect a normal payload. | |
| EXPECT_EQ(0, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(0, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(0, audio_type); // Speech. | |
| // Enters DTX again immediately. | |
| time += block_length_ms; | |
| EXPECT_EQ(output_samples, static_cast<size_t>(EncodeDecode( | |
| opus_encoder_, silence, opus_decoder_, | |
| output_data_decode, &audio_type))); | |
| if (dtx) { | |
| EXPECT_EQ(1U, encoded_bytes_); // Send 1 byte. | |
| EXPECT_EQ(1, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(1, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(2, audio_type); // Comfort noise. | |
| if (time >= kCheckTimeMs) { | |
| CheckAudioBounded(output_data_decode, output_samples, channels_, | |
| kOutputValueBound); | |
| } | |
| } else { | |
| EXPECT_GT(encoded_bytes_, 1U); | |
| EXPECT_EQ(0, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(0, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(0, audio_type); // Speech. | |
| } | |
| } | |
| silence[0] = 10000; | |
| if (dtx) { | |
| // Verify that encoder/decoder can jump out from DTX mode. | |
| EXPECT_EQ(output_samples, static_cast<size_t>(EncodeDecode( | |
| opus_encoder_, silence, opus_decoder_, | |
| output_data_decode, &audio_type))); | |
| EXPECT_GT(encoded_bytes_, 1U); | |
| EXPECT_EQ(0, opus_encoder_->in_dtx_mode); | |
| EXPECT_EQ(0, opus_decoder_->in_dtx_mode); | |
| EXPECT_EQ(0, audio_type); // Speech. | |
| } | |
| // Free memory. | |
| delete[] output_data_decode; | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| // Test if CBR does what we expect. | |
| void OpusTest::TestCbrEffect(bool cbr, int block_length_ms) { | |
| PrepareSpeechData(block_length_ms, 2000); | |
| const size_t output_samples = | |
| rtc::CheckedDivExact(decoder_sample_rate_hz_, 1000) * block_length_ms; | |
| int32_t max_pkt_size_diff = 0; | |
| int32_t prev_pkt_size = 0; | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| // Set bitrate. | |
| EXPECT_EQ( | |
| 0, WebRtcOpus_SetBitRate(opus_encoder_, channels_ == 1 ? 32000 : 64000)); | |
| // Setting CBR. | |
| EXPECT_EQ(0, cbr ? WebRtcOpus_EnableCbr(opus_encoder_) | |
| : WebRtcOpus_DisableCbr(opus_encoder_)); | |
| int16_t audio_type; | |
| std::vector<int16_t> audio_out(output_samples * channels_); | |
| for (int i = 0; i < 100; ++i) { | |
| EXPECT_EQ(output_samples, | |
| static_cast<size_t>( | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), | |
| opus_decoder_, audio_out.data(), &audio_type))); | |
| if (prev_pkt_size > 0) { | |
| int32_t diff = std::abs((int32_t)encoded_bytes_ - prev_pkt_size); | |
| max_pkt_size_diff = std::max(max_pkt_size_diff, diff); | |
| } | |
| prev_pkt_size = rtc::checked_cast<int32_t>(encoded_bytes_); | |
| } | |
| if (cbr) { | |
| EXPECT_EQ(max_pkt_size_diff, 0); | |
| } else { | |
| EXPECT_GT(max_pkt_size_diff, 0); | |
| } | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| // Test failing Create. | |
| TEST(OpusTest, OpusCreateFail) { | |
| WebRtcOpusEncInst* opus_encoder; | |
| WebRtcOpusDecInst* opus_decoder; | |
| // Test to see that an invalid pointer is caught. | |
| EXPECT_EQ(-1, WebRtcOpus_EncoderCreate(NULL, 1, 0, 48000)); | |
| // Invalid channel number. | |
| EXPECT_EQ(-1, WebRtcOpus_EncoderCreate(&opus_encoder, 257, 0, 48000)); | |
| // Invalid applciation mode. | |
| EXPECT_EQ(-1, WebRtcOpus_EncoderCreate(&opus_encoder, 1, 2, 48000)); | |
| // Invalid sample rate. | |
| EXPECT_EQ(-1, WebRtcOpus_EncoderCreate(&opus_encoder, 1, 0, 12345)); | |
| EXPECT_EQ(-1, WebRtcOpus_DecoderCreate(NULL, 1, 48000)); | |
| // Invalid channel number. | |
| EXPECT_EQ(-1, WebRtcOpus_DecoderCreate(&opus_decoder, 257, 48000)); | |
| // Invalid sample rate. | |
| EXPECT_EQ(-1, WebRtcOpus_DecoderCreate(&opus_decoder, 1, 12345)); | |
| } | |
| // Test failing Free. | |
| TEST(OpusTest, OpusFreeFail) { | |
| // Test to see that an invalid pointer is caught. | |
| EXPECT_EQ(-1, WebRtcOpus_EncoderFree(NULL)); | |
| EXPECT_EQ(-1, WebRtcOpus_DecoderFree(NULL)); | |
| } | |
| // Test normal Create and Free. | |
| TEST_P(OpusTest, OpusCreateFree) { | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| EXPECT_TRUE(opus_encoder_ != NULL); | |
| EXPECT_TRUE(opus_decoder_ != NULL); | |
| // Free encoder and decoder memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| #define ENCODER_CTL(inst, vargs) \ | |
| inst->encoder \ | |
| ? opus_encoder_ctl(inst->encoder, vargs) \ | |
| : opus_multistream_encoder_ctl(inst->multistream_encoder, vargs) | |
| TEST_P(OpusTest, OpusEncodeDecode) { | |
| PrepareSpeechData(20, 20); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| // Set bitrate. | |
| EXPECT_EQ( | |
| 0, WebRtcOpus_SetBitRate(opus_encoder_, channels_ == 1 ? 32000 : 64000)); | |
| // Check number of channels for decoder. | |
| EXPECT_EQ(channels_, WebRtcOpus_DecoderChannels(opus_decoder_)); | |
| // Check application mode. | |
| opus_int32 app; | |
| ENCODER_CTL(opus_encoder_, OPUS_GET_APPLICATION(&app)); | |
| EXPECT_EQ(application_ == 0 ? OPUS_APPLICATION_VOIP : OPUS_APPLICATION_AUDIO, | |
| app); | |
| // Encode & decode. | |
| int16_t audio_type; | |
| const int decode_samples_per_channel = | |
| SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/20); | |
| int16_t* output_data_decode = | |
| new int16_t[decode_samples_per_channel * channels_]; | |
| EXPECT_EQ(decode_samples_per_channel, | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), | |
| opus_decoder_, output_data_decode, &audio_type)); | |
| // Free memory. | |
| delete[] output_data_decode; | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| TEST_P(OpusTest, OpusSetBitRate) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_SetBitRate(opus_encoder_, 60000)); | |
| // Create encoder memory, try with different bitrates. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| EXPECT_EQ(0, WebRtcOpus_SetBitRate(opus_encoder_, 30000)); | |
| EXPECT_EQ(0, WebRtcOpus_SetBitRate(opus_encoder_, 60000)); | |
| EXPECT_EQ(0, WebRtcOpus_SetBitRate(opus_encoder_, 300000)); | |
| EXPECT_EQ(0, WebRtcOpus_SetBitRate(opus_encoder_, 600000)); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| TEST_P(OpusTest, OpusSetComplexity) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_SetComplexity(opus_encoder_, 9)); | |
| // Create encoder memory, try with different complexities. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| EXPECT_EQ(0, WebRtcOpus_SetComplexity(opus_encoder_, 0)); | |
| EXPECT_EQ(0, WebRtcOpus_SetComplexity(opus_encoder_, 10)); | |
| EXPECT_EQ(-1, WebRtcOpus_SetComplexity(opus_encoder_, 11)); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| TEST_P(OpusTest, OpusSetBandwidth) { | |
| if (channels_ > 2) { | |
| // TODO(webrtc:10217): investigate why multi-stream Opus reports | |
| // narrowband when it's configured with FULLBAND. | |
| return; | |
| } | |
| PrepareSpeechData(20, 20); | |
| int16_t audio_type; | |
| const int decode_samples_per_channel = | |
| SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/20); | |
| std::unique_ptr<int16_t[]> output_data_decode( | |
| new int16_t[decode_samples_per_channel * channels_]()); | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, | |
| WebRtcOpus_SetBandwidth(opus_encoder_, OPUS_BANDWIDTH_NARROWBAND)); | |
| EXPECT_EQ(-1, WebRtcOpus_GetBandwidth(opus_encoder_)); | |
| // Create encoder memory, try with different bandwidths. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| EXPECT_EQ(-1, WebRtcOpus_SetBandwidth(opus_encoder_, | |
| OPUS_BANDWIDTH_NARROWBAND - 1)); | |
| EXPECT_EQ(0, | |
| WebRtcOpus_SetBandwidth(opus_encoder_, OPUS_BANDWIDTH_NARROWBAND)); | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), opus_decoder_, | |
| output_data_decode.get(), &audio_type); | |
| EXPECT_EQ(OPUS_BANDWIDTH_NARROWBAND, WebRtcOpus_GetBandwidth(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_SetBandwidth(opus_encoder_, OPUS_BANDWIDTH_FULLBAND)); | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), opus_decoder_, | |
| output_data_decode.get(), &audio_type); | |
| EXPECT_EQ(encoder_sample_rate_hz_ == 16000 ? OPUS_BANDWIDTH_WIDEBAND | |
| : OPUS_BANDWIDTH_FULLBAND, | |
| WebRtcOpus_GetBandwidth(opus_encoder_)); | |
| EXPECT_EQ( | |
| -1, WebRtcOpus_SetBandwidth(opus_encoder_, OPUS_BANDWIDTH_FULLBAND + 1)); | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), opus_decoder_, | |
| output_data_decode.get(), &audio_type); | |
| EXPECT_EQ(encoder_sample_rate_hz_ == 16000 ? OPUS_BANDWIDTH_WIDEBAND | |
| : OPUS_BANDWIDTH_FULLBAND, | |
| WebRtcOpus_GetBandwidth(opus_encoder_)); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| TEST_P(OpusTest, OpusForceChannels) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_SetForceChannels(opus_encoder_, 1)); | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| ASSERT_NE(nullptr, opus_encoder_); | |
| if (channels_ >= 2) { | |
| EXPECT_EQ(-1, WebRtcOpus_SetForceChannels(opus_encoder_, 3)); | |
| EXPECT_EQ(0, WebRtcOpus_SetForceChannels(opus_encoder_, 2)); | |
| EXPECT_EQ(0, WebRtcOpus_SetForceChannels(opus_encoder_, 1)); | |
| EXPECT_EQ(0, WebRtcOpus_SetForceChannels(opus_encoder_, 0)); | |
| } else { | |
| EXPECT_EQ(-1, WebRtcOpus_SetForceChannels(opus_encoder_, 2)); | |
| EXPECT_EQ(0, WebRtcOpus_SetForceChannels(opus_encoder_, 1)); | |
| EXPECT_EQ(0, WebRtcOpus_SetForceChannels(opus_encoder_, 0)); | |
| } | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| // Encode and decode one frame, initialize the decoder and | |
| // decode once more. | |
| TEST_P(OpusTest, OpusDecodeInit) { | |
| PrepareSpeechData(20, 20); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| // Encode & decode. | |
| int16_t audio_type; | |
| const int decode_samples_per_channel = | |
| SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/20); | |
| int16_t* output_data_decode = | |
| new int16_t[decode_samples_per_channel * channels_]; | |
| EXPECT_EQ(decode_samples_per_channel, | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), | |
| opus_decoder_, output_data_decode, &audio_type)); | |
| WebRtcOpus_DecoderInit(opus_decoder_); | |
| EXPECT_EQ(decode_samples_per_channel, | |
| WebRtcOpus_Decode(opus_decoder_, bitstream_, encoded_bytes_, | |
| output_data_decode, &audio_type)); | |
| // Free memory. | |
| delete[] output_data_decode; | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| TEST_P(OpusTest, OpusEnableDisableFec) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_EnableFec(opus_encoder_)); | |
| EXPECT_EQ(-1, WebRtcOpus_DisableFec(opus_encoder_)); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| EXPECT_EQ(0, WebRtcOpus_EnableFec(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DisableFec(opus_encoder_)); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| TEST_P(OpusTest, OpusEnableDisableDtx) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_EnableDtx(opus_encoder_)); | |
| EXPECT_EQ(-1, WebRtcOpus_DisableDtx(opus_encoder_)); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| opus_int32 dtx; | |
| // DTX is off by default. | |
| ENCODER_CTL(opus_encoder_, OPUS_GET_DTX(&dtx)); | |
| EXPECT_EQ(0, dtx); | |
| // Test to enable DTX. | |
| EXPECT_EQ(0, WebRtcOpus_EnableDtx(opus_encoder_)); | |
| ENCODER_CTL(opus_encoder_, OPUS_GET_DTX(&dtx)); | |
| EXPECT_EQ(1, dtx); | |
| // Test to disable DTX. | |
| EXPECT_EQ(0, WebRtcOpus_DisableDtx(opus_encoder_)); | |
| ENCODER_CTL(opus_encoder_, OPUS_GET_DTX(&dtx)); | |
| EXPECT_EQ(0, dtx); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| TEST_P(OpusTest, OpusDtxOff) { | |
| TestDtxEffect(false, 10); | |
| TestDtxEffect(false, 20); | |
| TestDtxEffect(false, 40); | |
| } | |
| TEST_P(OpusTest, OpusDtxOn) { | |
| if (channels_ > 2) { | |
| // TODO(webrtc:10218): adapt the test to the sizes and order of multi-stream | |
| // DTX packets. | |
| return; | |
| } | |
| TestDtxEffect(true, 10); | |
| TestDtxEffect(true, 20); | |
| TestDtxEffect(true, 40); | |
| } | |
| TEST_P(OpusTest, OpusCbrOff) { | |
| TestCbrEffect(false, 10); | |
| TestCbrEffect(false, 20); | |
| TestCbrEffect(false, 40); | |
| } | |
| TEST_P(OpusTest, OpusCbrOn) { | |
| TestCbrEffect(true, 10); | |
| TestCbrEffect(true, 20); | |
| TestCbrEffect(true, 40); | |
| } | |
| TEST_P(OpusTest, OpusSetPacketLossRate) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_SetPacketLossRate(opus_encoder_, 50)); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| EXPECT_EQ(0, WebRtcOpus_SetPacketLossRate(opus_encoder_, 50)); | |
| EXPECT_EQ(-1, WebRtcOpus_SetPacketLossRate(opus_encoder_, -1)); | |
| EXPECT_EQ(-1, WebRtcOpus_SetPacketLossRate(opus_encoder_, 101)); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| TEST_P(OpusTest, OpusSetMaxPlaybackRate) { | |
| // Test without creating encoder memory. | |
| EXPECT_EQ(-1, WebRtcOpus_SetMaxPlaybackRate(opus_encoder_, 20000)); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_FULLBAND, 48000); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_FULLBAND, 24001); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_SUPERWIDEBAND, 24000); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_SUPERWIDEBAND, 16001); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_WIDEBAND, 16000); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_WIDEBAND, 12001); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_MEDIUMBAND, 12000); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_MEDIUMBAND, 8001); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_NARROWBAND, 8000); | |
| SetMaxPlaybackRate(opus_encoder_, OPUS_BANDWIDTH_NARROWBAND, 4000); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| } | |
| // Test PLC. | |
| TEST_P(OpusTest, OpusDecodePlc) { | |
| PrepareSpeechData(20, 20); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| // Set bitrate. | |
| EXPECT_EQ( | |
| 0, WebRtcOpus_SetBitRate(opus_encoder_, channels_ == 1 ? 32000 : 64000)); | |
| // Check number of channels for decoder. | |
| EXPECT_EQ(channels_, WebRtcOpus_DecoderChannels(opus_decoder_)); | |
| // Encode & decode. | |
| int16_t audio_type; | |
| const int decode_samples_per_channel = | |
| SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/20); | |
| int16_t* output_data_decode = | |
| new int16_t[decode_samples_per_channel * channels_]; | |
| EXPECT_EQ(decode_samples_per_channel, | |
| EncodeDecode(opus_encoder_, speech_data_.GetNextBlock(), | |
| opus_decoder_, output_data_decode, &audio_type)); | |
| // Call decoder PLC. | |
| constexpr int kPlcDurationMs = 10; | |
| const int plc_samples = decoder_sample_rate_hz_ * kPlcDurationMs / 1000; | |
| int16_t* plc_buffer = new int16_t[plc_samples * channels_]; | |
| EXPECT_EQ(plc_samples, | |
| WebRtcOpus_Decode(opus_decoder_, NULL, 0, plc_buffer, &audio_type)); | |
| // Free memory. | |
| delete[] plc_buffer; | |
| delete[] output_data_decode; | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| // Duration estimation. | |
| TEST_P(OpusTest, OpusDurationEstimation) { | |
| PrepareSpeechData(20, 20); | |
| // Create. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| // 10 ms. We use only first 10 ms of a 20 ms block. | |
| auto speech_block = speech_data_.GetNextBlock(); | |
| int encoded_bytes_int = WebRtcOpus_Encode( | |
| opus_encoder_, speech_block.data(), | |
| rtc::CheckedDivExact(speech_block.size(), 2 * channels_), kMaxBytes, | |
| bitstream_); | |
| EXPECT_GE(encoded_bytes_int, 0); | |
| EXPECT_EQ(SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/10), | |
| WebRtcOpus_DurationEst(opus_decoder_, bitstream_, | |
| static_cast<size_t>(encoded_bytes_int))); | |
| // 20 ms | |
| speech_block = speech_data_.GetNextBlock(); | |
| encoded_bytes_int = | |
| WebRtcOpus_Encode(opus_encoder_, speech_block.data(), | |
| rtc::CheckedDivExact(speech_block.size(), channels_), | |
| kMaxBytes, bitstream_); | |
| EXPECT_GE(encoded_bytes_int, 0); | |
| EXPECT_EQ(SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/20), | |
| WebRtcOpus_DurationEst(opus_decoder_, bitstream_, | |
| static_cast<size_t>(encoded_bytes_int))); | |
| // Free memory. | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| TEST_P(OpusTest, OpusDecodeRepacketized) { | |
| if (channels_ > 2) { | |
| // As per the Opus documentation | |
| // https://mf4.xiph.org/jenkins/view/opus/job/opus/ws/doc/html/group__opus__repacketizer.html#details, | |
| // multiple streams are not supported. | |
| return; | |
| } | |
| constexpr size_t kPackets = 6; | |
| PrepareSpeechData(20, 20 * kPackets); | |
| // Create encoder memory. | |
| CreateSingleOrMultiStreamEncoder(&opus_encoder_, channels_, application_, | |
| use_multistream_, encoder_sample_rate_hz_); | |
| ASSERT_NE(nullptr, opus_encoder_); | |
| CreateSingleOrMultiStreamDecoder(&opus_decoder_, channels_, use_multistream_, | |
| decoder_sample_rate_hz_); | |
| ASSERT_NE(nullptr, opus_decoder_); | |
| // Set bitrate. | |
| EXPECT_EQ( | |
| 0, WebRtcOpus_SetBitRate(opus_encoder_, channels_ == 1 ? 32000 : 64000)); | |
| // Check number of channels for decoder. | |
| EXPECT_EQ(channels_, WebRtcOpus_DecoderChannels(opus_decoder_)); | |
| // Encode & decode. | |
| int16_t audio_type; | |
| const int decode_samples_per_channel = | |
| SamplesPerChannel(decoder_sample_rate_hz_, /*ms=*/20); | |
| std::unique_ptr<int16_t[]> output_data_decode( | |
| new int16_t[kPackets * decode_samples_per_channel * channels_]); | |
| OpusRepacketizer* rp = opus_repacketizer_create(); | |
| size_t num_packets = 0; | |
| constexpr size_t kMaxCycles = 100; | |
| for (size_t idx = 0; idx < kMaxCycles; ++idx) { | |
| auto speech_block = speech_data_.GetNextBlock(); | |
| encoded_bytes_ = | |
| WebRtcOpus_Encode(opus_encoder_, speech_block.data(), | |
| rtc::CheckedDivExact(speech_block.size(), channels_), | |
| kMaxBytes, bitstream_); | |
| if (opus_repacketizer_cat(rp, bitstream_, | |
| rtc::checked_cast<opus_int32>(encoded_bytes_)) == | |
| OPUS_OK) { | |
| ++num_packets; | |
| if (num_packets == kPackets) { | |
| break; | |
| } | |
| } else { | |
| // Opus repacketizer cannot guarantee a success. We try again if it fails. | |
| opus_repacketizer_init(rp); | |
| num_packets = 0; | |
| } | |
| } | |
| EXPECT_EQ(kPackets, num_packets); | |
| encoded_bytes_ = opus_repacketizer_out(rp, bitstream_, kMaxBytes); | |
| EXPECT_EQ(decode_samples_per_channel * kPackets, | |
| static_cast<size_t>(WebRtcOpus_DurationEst( | |
| opus_decoder_, bitstream_, encoded_bytes_))); | |
| EXPECT_EQ(decode_samples_per_channel * kPackets, | |
| static_cast<size_t>( | |
| WebRtcOpus_Decode(opus_decoder_, bitstream_, encoded_bytes_, | |
| output_data_decode.get(), &audio_type))); | |
| // Free memory. | |
| opus_repacketizer_destroy(rp); | |
| EXPECT_EQ(0, WebRtcOpus_EncoderFree(opus_encoder_)); | |
| EXPECT_EQ(0, WebRtcOpus_DecoderFree(opus_decoder_)); | |
| } | |
| TEST(OpusVadTest, CeltUnknownStatus) { | |
| const uint8_t celt[] = {0x80}; | |
| EXPECT_EQ(WebRtcOpus_PacketHasVoiceActivity(celt, 1), -1); | |
| } | |
| TEST(OpusVadTest, Mono20msVadSet) { | |
| uint8_t silk20msMonoVad[] = {0x78, 0x80}; | |
| EXPECT_TRUE(WebRtcOpus_PacketHasVoiceActivity(silk20msMonoVad, 2)); | |
| } | |
| TEST(OpusVadTest, Mono20MsVadUnset) { | |
| uint8_t silk20msMonoSilence[] = {0x78, 0x00}; | |
| EXPECT_FALSE(WebRtcOpus_PacketHasVoiceActivity(silk20msMonoSilence, 2)); | |
| } | |
| TEST(OpusVadTest, Stereo20MsVadOnSideChannel) { | |
| uint8_t silk20msStereoVadSideChannel[] = {0x78 | 0x04, 0x20}; | |
| EXPECT_TRUE( | |
| WebRtcOpus_PacketHasVoiceActivity(silk20msStereoVadSideChannel, 2)); | |
| } | |
| TEST(OpusVadTest, TwoOpusMonoFramesVadOnSecond) { | |
| uint8_t twoMonoFrames[] = {0x78 | 0x1, 0x00, 0x80}; | |
| EXPECT_TRUE(WebRtcOpus_PacketHasVoiceActivity(twoMonoFrames, 3)); | |
| } | |
| } // namespace webrtc |