FFmpeg生成符合第三方系统要求的MPEG-DASH manifest命令调整求助

我正在折腾FFmpeg生成适配第三方播放系统的MPEG-DASH manifest文件，可目前的输出格式和系统要求的对不上，导致流没法正常播放。下面是我的尝试细节和遇到的问题，求各位帮忙看看怎么调整参数才能匹配上目标格式！

当前使用的FFmpeg命令 #

"$ffmpeg_path" \
-i "$input_file" \
-r 30000/1001 \
-vf "scale=3840:1080" \
-c:v libx265 \
-c:a aac -b:a 128k \
-ar 48000 \
-f dash \
-use_timeline 1 \
-use_template 1 \
-init_seg_name "init-stream\$RepresentationID\$.m4s" \
-media_seg_name "chunk-stream\$RepresentationID\$-\$Number%05d\$.m4s" \
-seg_duration 3 \
"$output_file"

当前命令生成的Manifest内容 #

<?xml version="1.0" encoding="utf-8"?>
<MPD xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:mpeg:dash:schema:mpd:2011"
xmlns:xlink="http://www.w3.org/1999/xlink"
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"
type="static"
mediaPresentationDuration="PT1M35.1S"
maxSegmentDuration="PT3.0S"
minBufferTime="PT16.8S">
<ProgramInformation>
</ProgramInformation>
<ServiceDescription id="0">
</ServiceDescription>
<Period id="0" start="PT0.0S">
<AdaptationSet id="0" contentType="video" startWithSAP="1" segmentAlignment="true" bitstreamSwitching="true" frameRate="30000/1001" maxWidth="3840" maxHeight="1080" par="32:9">
<Representation id="0" mimeType="video/mp4" codecs="hev1" bandwidth="2227590" width="3840" height="1080" sar="1:1">
<SegmentTemplate timescale="30000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startNumber="1">
<SegmentTimeline>
<S t="0" d="247247" />
<S d="250250" r="9" />
<S d="104104" />
</SegmentTimeline>
</SegmentTemplate>
</Representation>
</AdaptationSet>
<AdaptationSet id="1" contentType="audio" startWithSAP="1" segmentAlignment="true" bitstreamSwitching="true">
<Representation id="1" mimeType="audio/mp4" codecs="mp4a.40.2" bandwidth="128000" audioSamplingRate="48000">
<AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="1" />
<SegmentTemplate timescale="48000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startNumber="1">
<SegmentTimeline>
<S t="0" d="143360" />
<S d="144384" r="29" />
<S d="93120" />
</SegmentTimeline>
</SegmentTemplate>
</Representation>
</AdaptationSet>
</Period>
</MPD>

第三方系统要求的目标Manifest格式 #

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" mediaPresentationDuration="PT1M35.7S" minBufferTime="PT5.9S" xsi:schemaLocation="urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd">
<ProgramInformation />
<Period id="0" start="PT0.0S">
<AdaptationSet id="0" contentType="video" segmentAlignment="true" bitstreamSwitching="true">
<Representation id="0" bandwidth="12000000" width="3840" height="1080" frameRate="30000/1001" mimeType="video/mp4" codecs="hev1">
<SegmentTemplate media="chunk-stream$RepresentationID$-$Number%05d$.m4s" initialization="init-stream$RepresentationID$.m4s" startNumber="1" timescale="30000">
<SegmentTimeline>
<S t="0" d="89089" r="31" />
<S d="21021" />
</SegmentTimeline>
</SegmentTemplate>
</Representation>
</AdaptationSet>
<AdaptationSet id="1" contentType="audio" segmentAlignment="true" bitstreamSwitching="true">
<Representation id="1" bandwidth="1536000" audioSamplingRate="48000" mimeType="audio/mp4" codecs="mp4a.40.2">
<AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="16" />
<SegmentTemplate media="chunk-stream$RepresentationID$-$Number%05d$.m4s" initialization="init-stream$RepresentationID$.m4s" startNumber="1" timescale="48000">
<SegmentTimeline>
<S t="0" d="143360" />
<S d="142336" r="2" />
<S d="143360" />
<S d="142336" r="3" />
<S d="143360" />
<S d="142336" r="3" />
<S d="143360" />
<S d="142336" r="3" />
<S d="143360" />
<S d="142336" r="3" />
<S d="143360" />
<S d="142336" r="3" />
<S d="143360" />
<S d="142336" r="1" />
<S d="32768" />
</SegmentTimeline>
</SegmentTemplate>
</Representation>
</AdaptationSet>
</Period>
</MPD>

我观察到的主要差异点 #

• 带宽配置：当前视频带宽是FFmpeg自动计算的~2.2Mbps，目标要求固定12Mbps；音频当前128Kbps，目标是1536Kbps
• 音频通道配置：AudioChannelConfiguration的value当前是1，目标是16
• 分段时间线：视频和音频的SegmentTimeline结构差异极大——当前视频分段时长d值大、重复次数少，目标的d值更小且重复次数多；音频的分段结构也完全不同
• MPD属性：当前minBufferTime是16.8秒，目标是5.9秒；当前Manifest里有多余的ServiceDescription节点和带空内容的ProgramInformation，目标只有<ProgramInformation />
• AdaptationSet属性：当前的AdaptationSet带有startWithSAP="1"，目标Manifest里没有这个属性
• 媒体属性位置：当前视频的frameRate等属性在AdaptationSet节点，目标里这些属性在Representation节点

想请教下各位，怎么调整FFmpeg的参数来解决这些差异，让生成的Manifest完全匹配目标格式？尤其是带宽指定、音频通道value、分段时间线和那些节点/属性的调整，实在摸不准对应的参数。

备注：内容来源于stack exchange，提问作者Seth Haberman