libavjs-webcodecs-polyfill/samples/audio-decoder-opus/audio-decoder-opus.js

A WebCodecs polyfill (ponyfill, really), using libav.js

/*
 * This (un)license applies only to this sample code, and not to
 * libavjs-webcodecs-polyfill as a whole:
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or distribute
 * this software, either in source code form or as a compiled binary, for any
 * purpose, commercial or non-commercial, and by any means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors of
 * this software dedicate any and all copyright interest in the software to the
 * public domain. We make this dedication for the benefit of the public at
 * large and to the detriment of our heirs and successors. We intend this
 * dedication to be an overt act of relinquishment in perpetuity of all present
 * and future rights to this software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

importScripts("../worker-util.js");

(async function() {
    await LibAVWebCodecs.load();

    const [[stream], allPackets] =
        await sampleDemux("../sample1.opus", "opus");
    const packets = allPackets[stream.index];

    const init = {
        codec: "opus",
        sampleRate: 48000,
        numberOfChannels: 2
    };

    const a = await decodeAudio(
        init, packets, stream, LibAVWebCodecs.AudioDecoder,
        LibAVWebCodecs.EncodedAudioChunk);
    let b = null;
    if (typeof AudioDecoder !== "undefined") {
        try {
            b = await decodeAudio(
                init, packets, stream, AudioDecoder, EncodedAudioChunk);
        } catch (ex) {
            console.error(ex);
        }
    }

    postMessage({a, b});
})();