LayoutTests/http/tests/webcodecs/audio-decoder-aac.html

<!DOCTYPE html>
<html>
<head>
    <script src="../../resources/testharness.js"></script>
    <script src="../../resources/testharnessreport.js"></script>
</head>
<body>
    <script>
// Data offsets for audio-aac.mp4
// - AudioSpecificConfig (description): offset 1757, size 25 bytes
// - First AAC sample: offset 44, size 28 bytes
// - Sample rate: 48000 Hz
// - Channels: 4 (quad)
// - First sample timestamp: 0 (in 48000 Hz time base)
// - Sample duration: 1024 samples

const descriptionOffset = 1757;
const descriptionSize = 25;
const sampleOffset = 44;
const sampleSize = 28;
const sampleRate = 48000;
const numberOfChannels = 4;
const sampleTimestamp = 0; // in 48000 Hz time base
const sampleDuration = 1024; // in samples

promise_test(async () => {
    const response = await fetch("./resources/audio-aac.mp4");
    const buffer = await response.arrayBuffer();

    let decodedFrames = [];
    let decodeError = null;

    const decoder = new AudioDecoder({
        output(frame) {
            decodedFrames.push({
                timestamp: frame.timestamp,
                duration: frame.duration,
                numberOfFrames: frame.numberOfFrames,
                numberOfChannels: frame.numberOfChannels,
                sampleRate: frame.sampleRate,
                format: frame.format
            });
            frame.close();
        },
        error(e) {
            decodeError = e;
        }
    });

    // Configure the decoder with AAC-LC codec and the AudioSpecificConfig from the MP4 file
    const description = new Uint8Array(buffer, descriptionOffset, descriptionSize);
    decoder.configure({
        codec: 'mp4a.40.2', // AAC-LC
        sampleRate: sampleRate,
        numberOfChannels: numberOfChannels,
        description: description
    });

    // Create an EncodedAudioChunk from the first AAC sample
    const sampleData = new Uint8Array(buffer, sampleOffset, sampleSize);
    // Convert timestamp from 48000 Hz time base to microseconds
    const timestampMicroseconds = Math.round((sampleTimestamp / sampleRate) * 1000000);
    const durationMicroseconds = Math.round((sampleDuration / sampleRate) * 1000000);

    const chunk = new EncodedAudioChunk({
        type: 'key',
        timestamp: timestampMicroseconds,
        duration: durationMicroseconds,
        data: sampleData
    });

    decoder.decode(chunk);
    await decoder.flush();

    assert_equals(decodeError, null, "No decode error should occur");
    assert_equals(decodedFrames.length, 1, "Should have decoded exactly one frame");

    const frame = decodedFrames[0];
    assert_equals(frame.numberOfChannels, numberOfChannels, "Decoded frame should have correct number of channels");
    assert_equals(frame.sampleRate, sampleRate, "Decoded frame should have correct sample rate");
    assert_equals(frame.numberOfFrames, sampleDuration, "Decoded frame should have correct number of samples");
    assert_equals(frame.timestamp, timestampMicroseconds, "Decoded frame should have correct timestamp");

    decoder.close();
}, "Decode first AAC sample from MP4 file with extended AudioSpecificConfig");
    </script>
</body>
</html>