重新排序短划线段列表中的细分

问题描述 投票：1回答：1

我有一个看起来像这样的实时破折号清单。

<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" id="" maxSegmentDuration="PT4S" minimumUpdatePeriod="PT595H" minBufferTime="PT2S" type="dynamic" availabilityStartTime="2016-11-20T17:00:54Z" publishTime="2016-11-20T17:00:54Z" profiles="urn:hbbtv:dash:profile:isoff-live:2012,urn:mpeg:dash:profile:isoff-live:2011" xsi:schemaLocation="urn:mpeg:dash:schema:mpd:2011 DASH-MPD.xsd" timeShiftBufferDepth="PT120S">
<ProgramInformation>
    <Title>Title</Title>
</ProgramInformation>
<Period start="PT0S" id="p1">
    <AdaptationSet mimeType="audio/mp4" lang="en" startWithSAP="1" contentType="audio" segmentAlignment="true">
        <Representation audioSamplingRate="48000" bandwidth="128000" id="128kb" codecs="mp4a.40.2">
            <AudioChannelConfiguration value="2" schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011"/>
            <SegmentTemplate duration="4" media="audio/128kbps/segment_$Number$.m4s" initialization="audio/128kbps/init.mp4" startNumber="0"/>
        </Representation>
    </AdaptationSet>
    <AdaptationSet mimeType="video/mp4" minWidth="426" contentType="video" maxWidth="1920" minHeight="240" segmentAlignment="true" startWithSAP="1" maxHeight="1080">
        <Representation frameRate="60000/1000" height="480" width="858" bandwidth="1200000" codecs="avc1.42c00d" id="1200kb">
            <SegmentTemplate duration="4" media="video/480p/segment_$Number$.m4s" initialization="video/480p/init.mp4" startNumber="0"/>
        </Representation>
        <!-- Some more representations -->
    </AdaptationSet>
</Period>

在流式传输时，所有段都保存到磁盘以在VIDeos中使用，并从流式会话中突出显示。我通过将狮子清单重新制作成静态清单来完成VOD解决方案。

我的问题是当我想要创建精彩片段时，我想重新排序片段并准确指定应下载和播放的片段。我尝试使用SegmentationList执行此操作。我创建的新清单看起来像这样：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

突出测试

<Period start="PT0S" duration="PT0H2M24.000S">
    <AdaptationSet mimeType="video/mp4" minWidth="426" contentType="video" maxWidth="1920" minHeight="240" segmentAlignment="true" startWithSAP="1" maxHeight="1080">
        <Representation frameRate="60000/1000" height="480" width="858" bandwidth="1200000" codecs="avc1.42c00d" id="1200kb">
            <SegmentList duration="61440" timescale="15360">
                <Initialization sourceURL="video/480p/init.mp4"/>
                <!--Highlight 1-->
                <SegmentURL media="video/480p/segment_9399.m4s"/>
                <SegmentURL media="video/480p/segment_9400.m4s"/>
                <!--Highlight 2-->
                <SegmentURL media="video/480p/segment_9351.m4s"/>
                <SegmentURL media="video/480p/segment_9352.m4s"/>
                <!--Highlight 3-->
                <SegmentURL media="video/480p/segment_9449.m4s"/>
                <SegmentURL media="video/480p/segment_9450.m4s"/>
            </SegmentList>
        </Representation>
    </AdaptationSet>
    <AdaptationSet mimeType="audio/mp4" lang="en" startWithSAP="1" contentType="audio" segmentAlignment="true">
        <Representation audioSamplingRate="48000" bandwidth="128000" id="128kb" codecs="mp4a.40.2">
            <AudioChannelConfiguration value="2" schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011"/>
            <SegmentList duration="192000" timescale="48000">
                <Initialization sourceURL="audio/128kbps/init.mp4"/>
                <!--Highlight 1-->
                <SegmentURL media="audio/128kbps/segment_9399.m4s"/>
                <SegmentURL media="audio/128kbps/segment_9400.m4s"/>
                <!--Highlight 2-->
                <SegmentURL media="audio/128kbps/segment_9351.m4s"/>
                <SegmentURL media="audio/128kbps/segment_9352.m4s"/>
                <SegmentURL media="audio/128kbps/segment_9357.m4s"/>
                <!--Highlight 3-->
                <SegmentURL media="audio/128kbps/segment_9449.m4s"/>
                <SegmentURL media="audio/128kbps/segment_9450.m4s"/>
            </SegmentList>
        </Representation>
    </AdaptationSet>
</Period>

我遇到这个解决方案的问题首先是计时器不从0开始，它从37596（9399 * 4）开始。我的第二个问题是当高亮1完成时它不会播放高亮2。相反，如果冻结好像已经到达视频的结尾。

我猜可以在init文件中指定如何播放段。

有没有办法通过只创建一个新的清单而不是创建一个新的init文件来做到这一点？

video-streaming streaming mpeg-dash
1个回答
1
投票

您不需要新的init文件。主要问题是媒体片段的时间戳。要解决初始时间的问题，您应该将presentationTimeOffset属性添加到Manifest，并显示您要播放的第一个段的开始时间。

第二个问题是，不连续性（在你的情况下，两个亮点之间的时间变化）应该通过将它们分成新的周期来处理，因为MPEG-DASH标准建议：

如果出现不连续，建议添加新的Period以重置@presentationTimeOffset的值。

这两件事可以组合如下（为了简单起见，我跳过音频AdaptationSets）。在这种情况下我使用了SegmentTimeline。

<MPD type="static" mediaPresentationDuration="PT0H2M24.000S" minBufferTime="PT4S" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:mpeg:dash:schema:mpd:2011" xsi:schemaLocation="urn:mpeg:dash:schema:mpd:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd" profiles="urn:mpeg:dash:profile:isoff-live:2011,urn:com:dashif:dash264">
    <Period start="PT0S" duration="PT8S">
        <!--Highlight 1-->
        <AdaptationSet mimeType="video/mp4" minWidth="426" contentType="video" maxWidth="1920" minHeight="240" segmentAlignment="true" startWithSAP="1" maxHeight="1080">
            <SegmentTemplate timescale="1" presentationTimeOffset="37596" startNumber="9399" initialization="video/480p/init.mp4" media="video/$RepresentationID$/segment_$Number$.m4s">
                <SegmentTimeline>
                    <S t="37596" d="4" r="1"/>
                </SegmentTimeline>
            </SegmentTemplate>
            <Representation frameRate="60000/1000" height="480" width="858" bandwidth="1200000" codecs="avc1.42c00d" id="480p" />
        </AdaptationSet>
    </Period>
    <Period duration="PT8S">
        <!--Highlight 2-->
        <AdaptationSet mimeType="video/mp4" minWidth="426" contentType="video" maxWidth="1920" minHeight="240" segmentAlignment="true" startWithSAP="1" maxHeight="1080">
            <SegmentTemplate timescale="1" presentationTimeOffset="37404" startNumber="9351" initialization="video/480p/init.mp4" media="video/$RepresentationID$/segment_$Number$.m4s">
                <SegmentTimeline>
                    <S t="37404" d="61440" r="1"/>
                </SegmentTimeline>
            </SegmentTemplate>
            <Representation frameRate="60000/1000" height="480" width="858" bandwidth="1200000" codecs="avc1.42c00d" id="480p" />
        </AdaptationSet>
    </Period>
    <Period duration="PT8S">
        <!--Highlight 3-->
        <AdaptationSet mimeType="video/mp4" minWidth="426" contentType="video" maxWidth="1920" minHeight="240" segmentAlignment="true" startWithSAP="1" maxHeight="1080">
            <SegmentTemplate timescale="1" presentationTimeOffset="37796" startNumber="9449" initialization="video/480p/init.mp4" media="video/$RepresentationID$/segment_$Number$.m4s">
                <SegmentTimeline>
                    <S t="37796" d="61440" r="1"/>
                </SegmentTimeline>
            </SegmentTemplate>
            <Representation frameRate="60000/1000" height="480" width="858" bandwidth="1200000" codecs="avc1.42c00d" id="480p" />
        </AdaptationSet>
    </Period>
</MPD>

当然，球员需要同时支持presentationTimeOffset和多个时期。我认为Bitmovin Player应该工作，不确定像dash.js这样的其他人。

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