html5 – MediaSource API – 将多个视频追加/连接到一个缓冲区中

更新：

所以我能够通过使用offsetTimestamp属性(在附加每个视频后递增它)来使其工作.

我现在的问题：
1)为什么在将MediaSource.mode设置为序列时没有正确完成？

2)为什么我的MediaSource.duration总是“无限”而不是正确的持续时间？

我正在尝试使用MediaSource API附加多个视频文件并无缝播放,就好像它是1个视频一样.

我根据规范(DASH-MPEG)正确地对我的视频进行了转码,当单独播放时,它们工作正常.

但是,当我尝试追加多个时,我遇到的问题是段相互覆盖,持续时间不正确等等.即使所有内容似乎都按预期执行.

我已经尝试过使用offsetTimestamp,但根据文档设置MediaSource.mode到’sequence’应该自动处理这个.此外,出于某种原因,MediaSource.duration即使在追加一个片段之后也总是似乎是“无限”.

这是我的代码：

<script>
 function downloadData(url,cb) {
    console.log("Downloading " + url);

    var xhr = new XMLHttpRequest;
    xhr.open('get',url);
    xhr.responseType = 'arraybuffer';
    xhr.onload = function () {
        cb(new Uint8Array(xhr.response));
    };
    xhr.send();
}

if (MediaSource.isTypeSupported('video/mp4; codecs="avc1.64001E"')) {
    console.log("mp4 codec supported");
}

var videoSources = [
    "{% static 'mp4/ff_97.mp4' %}","{% static 'mp4/ff_98.mp4' %}","{% static 'mp4/ff_99.mp4' %}","{% static 'mp4/ff_118.mp4' %}"
]

var mediaSource = new MediaSource();


mediaSource.addEventListener('sourceopen',function(e) {


    var sourceBuffer = mediaSource.addSourceBuffer('video/mp4; codecs="avc1.64001E"');
    sourceBuffer.mode = 'sequence';

    console.log('SourceBuffer mode set to ' + sourceBuffer.mode);

    sourceBuffer.addEventListener('updateend',function(e) {
        console.log('Finished updating buffer');
        console.log('New duration is ' + String(mediaSource.duration));

        if (videoSources.length == 0) {
            mediaSource.endOfStream();
            video.currentTime = 0;
            video.play();
            return;
        }

        downloadData(videoSources.pop(),function(arrayBuffer) {
            console.log('Finished downloading buffer of size ' + String(arrayBuffer.length));
            console.log('Updating buffer');
            sourceBuffer.appendBuffer(arrayBuffer);
        });

        console.log('New duration: ' + String(mediaSource.duration));

    });

    downloadData(videoSources.pop(),function(arrayBuffer) {
        console.log('Finished downloading buffer of size ' + String(arrayBuffer.length));
        console.log('Updating buffer');
        sourceBuffer.appendBuffer(arrayBuffer);
    });



},false);

var video = document.querySelector('video');
video.src = window.URL.createObjectURL(mediaSource);

这是日志：

mp4 codec supported
(index):78 SourceBuffer mode set to sequence
(index):45 Downloading /static/mp4/ff_118.mp4
(index):103 Finished downloading buffer of size 89107
(index):104 Updating buffer
(index):81 Finished updating buffer
(index):82 New duration is Infinity
(index):45 Downloading /static/mp4/ff_99.mp4
(index):98 New duration: Infinity
(index):92 Finished downloading buffer of size 46651
(index):93 Updating buffer
(index):81 Finished updating buffer
(index):82 New duration is Infinity
(index):45 Downloading /static/mp4/ff_98.mp4
(index):98 New duration: Infinity
(index):92 Finished downloading buffer of size 79242
(index):93 Updating buffer
(index):81 Finished updating buffer
(index):82 New duration is Infinity
(index):45 Downloading /static/mp4/ff_97.mp4
(index):98 New duration: Infinity
(index):92 Finished downloading buffer of size 380070
(index):93 Updating buffer
(index):81 Finished updating buffer
(index):82 New duration is Infinity

解决方法

2) Why is my MediaSource.duration always “Infinity” and not the correct duration?

您需要调用MediaSource.endOfStream()以使MediaSource对象计算其SourceBuffer中段的实际持续时间.我看到你正在这样做,但看起来你在调用endOfStream()之前试图访问MediaSource.duration.我建议你阅读MSE规范中的end of stream algorithm,你会发现它会导致调用duration change algorithm.

如果你想要你的< video> element在调用MediaSource.endOfStream()之前报告持续时间,您实际上可以根据您自己对附加段的估计使用MediaSource.duration设置一个值.

1) Why isn’t this done properly when setting the MediaSource.mode to sequence?

据我所知,应该这样做.但是我自己更喜欢显式的timestampOffset方法,因为它在想要在缓冲区中远远追加段时提供了更大的灵活性(即,如果用户在当前缓冲区结束之前寻找方式,你将需要在差距之后开始加载附加).虽然我很欣赏在你的用例中寻求我不是一个要求.