问题描述
根据我们的经验，即使在下载大块时存在延迟，ExoPlayer 也不会使用较低的比特率，这会导致冻结和缓冲。然而带宽是 6 Mbit，因为 VBR 有时一个 2 秒块的大小从 1.5 兆字节到 15 兆字节不等。根据我们的经验，当比特率增加时，播放器仍会尝试使用相同的比特率而不是降低比特率来下载下一个块。是什么导致了这个问题。有没有办法或配置来解决这个问题？
private const val ADAPTIVE_MIN_DURATION_FOR_QUALITY_INCREASE_MS = 10000
private const val ADAPTIVE_MAX_DURATION_FOR_QUALITY_DECREASE_MS = 25000
private const val ADAPTIVE_MIN_DURATION_TO_RETAIN_AFTER_disCARD_MS = 25000
private const val ADAPTIVE_BANDWIDTH_FRACTION = 0.70f
private const val ADAPTIVE_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE = 0.75f
public static final int DEFAULT_MIN_BUFFER_MS = 50_000;
public static final int DEFAULT_MAX_BUFFER_MS = 50_000;
public static final int DEFAULT_BUFFER_FOR_PLAYBACK_MS = 2500;
public static final int DEFAULT_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS = 5000;
//MPD File
<?xml version="1.0" encoding="UTF-8"?>
<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:cenc="urn:mpeg:cenc:2013" xmlns:mspr="urn:microsoft:playready" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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="dynamic" minimumUpdatePeriod="PT500S" suggestedPresentationDelay="PT2S" availabilityStartTime="2020-09-09T00:10:16Z" publishTime="2021-01-23T17:28:55Z" minBufferTime="PT4.0S" timeShiftBufferDepth="PT86400.0S">
<Programinformation />
<Period id="0" start="PT0.0S">
<AdaptationSet id="0" contentType="video" segmentAlignment="true" bitstreamSwitching="true" maxFrameRate="50/1">
<Representation id="0" mimeType="video/mp4" codecs="avc1.4d4015" bandwidth="800000" width="480" height="270" frameRate="25/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" media="ExtAst1599610204_chunk_20200909T001000_$RepresentationID$_$Number$.m4v?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
<Representation id="1" mimeType="video/mp4" codecs="avc1.4d401e" bandwidth="1400000" width="704" height="396" frameRate="25/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
<Representation id="2" mimeType="video/mp4" codecs="avc1.4d401f" bandwidth="2000000" width="960" height="540" frameRate="25/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
<Representation id="3" mimeType="video/mp4" codecs="avc1.4d4020" bandwidth="3150000" width="1280" height="720" frameRate="50/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
<Representation id="4" mimeType="video/mp4" codecs="avc1.4d402a" bandwidth="6000000" width="1920" height="1080" frameRate="50/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
<Representation id="5" mimeType="video/mp4" codecs="avc1.4d400d" bandwidth="400000" width="416" height="234" frameRate="25/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
<Representation id="6" mimeType="video/mp4" codecs="avc1.4d400d" bandwidth="200000" width="416" height="234" frameRate="25/1">
<SegmentTemplate timescale="12800" duration="25600" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
</AdaptationSet>
<AdaptationSet id="1" contentType="audio" segmentAlignment="true" bitstreamSwitching="true" lang="tur">
<Representation id="8" mimeType="audio/mp4" codecs="mp4a.40.5" bandwidth="128000" audioSamplingRate="48000">
<AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2" />
<SegmentTemplate timescale="48000" duration="96000" initialization="ExtAst1599610204_init_$RepresentationID$.m4i?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" media="ExtAst1599610204_chunk_20200909T001000_$RepresentationID$_$Number$.m4a?hw_dash=1&servicetype=1&rrsip=izmottrrs.tvplus.com.tr:443&zoneoffset=0&devkbps=190-7000&accounttype=1&limitflux=-1&limitdur=-1&tenantId=9001&validdev=5499,5270&vqe=3&mount=1000001&targetdev=5387&pbf=2_2_2_2331729884" startNumber="1" />
</Representation>
</AdaptationSet>
</Period>
<UTCTiming schemeIdUri="urn:mpeg:dash:utc:http-iso:2014" value="https://time.akamai.com/?iso" />
</MPD>
解决方法
我为此做了一个解决方法。它主要工作。
protected boolean canSelectFormat(Format format,int trackBitrate,float playbackSpeed,long effectiveBitrate) {
if (lastBufferEvaluationMediaChunk != null && trackBitrate == lastBufferEvaluationMediaChunk.trackFormat.bitrate) {
long chunkDurationInSeconds = (lastBufferEvaluationMediaChunk.endTimeUs - lastBufferEvaluationMediaChunk.startTimeUs) / 1_000_000;
double chunkBitrate = lastBufferEvaluationMediaChunk.bytesLoaded() / chunkDurationInSeconds * 8.0;
double bitrateCoefficient = chunkBitrate / trackBitrate;
if (bitrateCoefficient > 1.0f) {
return Math.round(trackBitrate * playbackSpeed) * bitrateCoefficient <= effectiveBitrate;
}
}
return Math.round(trackBitrate * playbackSpeed) <= effectiveBitrate;
}