php - 带有安全 S3 URL 的 MPEG-Dash

Question

我正在尝试使用 MPEG-Dash 设置视频服务器，其中视频内容托管在 S3 存储桶中。在本地托管(nginx 服务器)时它工作正常，但是当我更改 MPD 文件以指向 S3 存储桶时，它不起作用。

这是我正在做的:

--首先我将视频转换为多比特率 MP4

/usr/bin/ffmpeg -y -async 1 -vsync -1 -analyzeduration 999999999 -i <SOURCE> \
    -movflags faststart -keyint_min 30 -x264opts "keyint=30:min-keyint=30:no-scenecut" -g 30 -filter:v "scale=iw*min(320/iw\,180/ih):ih*min(320/iw\,180/ih), pad=320:180:(320-iw*min(320/iw\,180/ih))/2:(180-ih*min(320/iw\,180/ih))/2" -r:v 30 -s 320x180 -b:v 320k -c:v libx264 -pix_fmt yuv420p -profile:v baseline -level 3.0 -an "'.$base.'180p.mp4" \
    -movflags faststart -keyint_min 30 -x264opts "keyint=30:min-keyint=30:no-scenecut" -g 30 -filter:v "scale=iw*min(640/iw\,360/ih):ih*min(640/iw\,360/ih), pad=640:360:(640-iw*min(640/iw\,360/ih))/2:(360-ih*min(640/iw\,360/ih))/2" -r:v 30 -s 640x360 -b:v 640k -c:v libx264 -pix_fmt yuv420p -profile:v baseline -level 3.0 -an "'.$base.'360p.mp4" \
    -movflags faststart -keyint_min 30 -x264opts "keyint=30:min-keyint=30:no-scenecut" -g 30 -filter:v "scale=iw*min(1280/iw\,720/ih):ih*min(1280/iw\,720/ih), pad=1280:720:(1280-iw*min(1280/iw\,720/ih))/2:(720-ih*min(1280/iw\,720/ih))/2" -r:v 30 -s 1280x720 -b:v 1280k -c:v libx264 -pix_fmt yuv420p -profile:v baseline -level 3.1 -an "'.$base.'720p.mp4" \
    -c:v copy -c:a libfdk_aac -ac 2 -ar 48000 -b:a 96k "'.$base.'aacp.mp4"

--然后我用MP4Box来破

/usr/bin/MP4Box -dash 10000 -rap -profile dashavc264:onDemand -out "stream.mpd" \
    180p.mp4#video \
    360p.mp4#video \
    720p.mp4#video \
    aacp.mp4#audio

--这导致以下 MPD

<?xml version="1.0"?>
<!-- MPD file Generated with GPAC version 0.5.1-DEV-rev4065  on 2015-08-08T02:18:28Z-->
<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" minBufferTime="PT1.500000S" type="static" mediaPresentationDuration="PT0H1M56.11S" profiles="urn:mpeg:dash:profile:isoff-on-demand:2011, http://dashif.org/guildelines/dash264">
 <ProgramInformation moreInformationURL="http://gpac.sourceforge.net">
  <Title>/webdata/temp/10/dash/10.mpd generated by GPAC</Title>
 </ProgramInformation>

 <Period duration="PT0H1M56.11S">
  <AdaptationSet segmentAlignment="true" maxWidth="1280" maxHeight="720" maxFrameRate="30" par="16:9" lang="und">
   <Representation id="1" mimeType="video/mp4" codecs="avc1.42c01e" width="320" height="180" frameRate="30" sar="1:1" startWithSAP="1" bandwidth="349890">
    <BaseURL>180p_track1_dashinit.mp4</BaseURL>
    <SegmentBase indexRangeExact="true" indexRange="900-1075">
      <Initialization range="0-899"/>
    </SegmentBase>
   </Representation>
   <Representation id="2" mimeType="video/mp4" codecs="avc1.42c01e" width="640" height="360" frameRate="30" sar="1:1" startWithSAP="1" bandwidth="701122">
    <BaseURL>360p_track1_dashinit.mp4</BaseURL>
    <SegmentBase indexRangeExact="true" indexRange="900-1075">
      <Initialization range="0-899"/>
    </SegmentBase>
   </Representation>
   <Representation id="3" mimeType="video/mp4" codecs="avc1.42c01f" width="1280" height="720" frameRate="30" sar="1:1" startWithSAP="1" bandwidth="1401368">
    <BaseURL>720p_track1_dashinit.mp4</BaseURL>
    <SegmentBase indexRangeExact="true" indexRange="900-1075">
      <Initialization range="0-899"/>
    </SegmentBase>
   </Representation>
  </AdaptationSet>
  <AdaptationSet segmentAlignment="true" lang="und">
   <Representation id="4" mimeType="audio/mp4" codecs="mp4a.40.2" audioSamplingRate="48000" startWithSAP="1" bandwidth="97736">
    <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
    <BaseURL>aacp_track2_dashinit.mp4</BaseURL>
    <SegmentBase indexRangeExact="true" indexRange="837-1012">
      <Initialization range="0-836"/>
    </SegmentBase>
   </Representation>
  </AdaptationSet>
 </Period>
</MPD>

当我编辑 MPD 以具有动态 URLS 时:

--PHP源码--

<?php
    $temp = S3URL("<VIDEOBUCKET>","10/dash/180p_track1_dashinit.mp4","653");
    echo "<BaseURL>".str_replace("https://<VIDEOBUCKET>.s3.amazonaws.com/10/dash/","",$temp)."</BaseURL>".PHP_EOL;
?>

-- echo 数据--

<BaseURL>180p_track1_dashinit.mp4?AWSAccessKeyId=XXXXXXXXXX&Expires=XXXXXXXXXX&Signature=XXXXXXXXXX</BaseURL>

我在 MPD 文件中得到无效内容。我环顾四周并尝试将 BaseURL 移动到适应、表示和 XML 的其他节，但似乎没有任何效果。

正确的做法是什么？

Answer 1

我遇到了同样的问题。我遇到的问题是 S3 预签名 URL 具有需要为 XML 转义的字符。否则，您最终会得到无效的 XML。

我使用的是 C#，所以我必须使用 HttpUtility.HtmlEncode() 方法来确保我的安全链接不会使 XML 无效。