1 files changed, 98 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webcodecs/audio-encoder-codec-specific.https.any.js b/testing/web-platform/tests/webcodecs/audio-encoder-codec-specific.https.any.js
new file mode 100644
index 0000000000..28c75d2a60
--- /dev/null
+++ b/testing/web-platform/tests/webcodecs/audio-encoder-codec-specific.https.any.js
@@ -0,0 +1,98 @@
+// META: global=window
+// META: script=/webcodecs/utils.js
+
+function make_silent_audio_data(timestamp, channels, sampleRate, frames) {
+  let data = new Float32Array(frames*channels);
+
+  return new AudioData({
+    timestamp: timestamp,
+    data: data,
+    numberOfChannels: channels,
+    numberOfFrames: frames,
+    sampleRate: sampleRate,
+    format: "f32-planar",
+  });
+}
+
+// The Opus DTX flag (discontinuous transmission) reduces the encoding bitrate
+// for silence. This test ensures the DTX flag is working properly by encoding
+// almost 10s of silence and comparing the bitrate with and without the flag.
+promise_test(async t => {
+  let sample_rate = 48000;
+  let total_duration_s = 10;
+  let data_count = 100;
+  let normal_outputs = [];
+  let dtx_outputs = [];
+
+  let normal_encoder = new AudioEncoder({
+    error: e => {
+      assert_unreached('error: ' + e);
+    },
+    output: chunk => {
+      normal_outputs.push(chunk);
+    }
+  });
+
+  let dtx_encoder = new AudioEncoder({
+    error: e => {
+      assert_unreached('error: ' + e);
+    },
+    output: chunk => {
+      dtx_outputs.push(chunk);
+    }
+  });
+
+  let config = {
+    codec: 'opus',
+    sampleRate: sample_rate,
+    numberOfChannels: 2,
+    bitrate: 256000,  // 256kbit
+  };
+
+  let normal_config = {...config, opus: {usedtx: false}};
+  let dtx_config = {...config, opus: {usedtx: true}};
+
+  let normal_config_support = await AudioEncoder.isConfigSupported(normal_config);
+  assert_implements_optional(normal_config_support.supported, "Opus not supported");
+
+  let dtx_config_support = await AudioEncoder.isConfigSupported(dtx_config);
+  assert_implements_optional(dtx_config_support.supported, "Opus DTX not supported");
+
+  // Configure one encoder with and one without the DTX flag
+  normal_encoder.configure(normal_config);
+  dtx_encoder.configure(dtx_config);
+
+  let timestamp_us = 0;
+  let data_duration_s = total_duration_s / data_count;
+  let data_length = data_duration_s * config.sampleRate;
+  for (let i = 0; i < data_count; i++) {
+    let data;
+
+    if (i == 0 || i == (data_count - 1)) {
+      // Send real data for the first and last 100ms.
+      data = make_audio_data(
+          timestamp_us, config.numberOfChannels, config.sampleRate,
+          data_length);
+
+    } else {
+      // Send silence for the rest of the 10s.
+      data = make_silent_audio_data(
+          timestamp_us, config.numberOfChannels, config.sampleRate,
+          data_length);
+    }
+
+    normal_encoder.encode(data);
+    dtx_encoder.encode(data);
+    data.close();
+
+    timestamp_us += data_duration_s * 1_000_000;
+  }
+
+  await Promise.all([normal_encoder.flush(), dtx_encoder.flush()])
+
+  normal_encoder.close();
+  dtx_encoder.close();
+
+  // We expect a significant reduction in the number of packets, over ~10s of silence.
+  assert_less_than(dtx_outputs.length, (normal_outputs.length / 2));
+}, 'Test the Opus DTX flag works.');