Server Version#: 1.20.3.3483
Web Player Version#: 4.45.0
Mac Player Version#: 1.21.0.1410-50a34597
I am using the Plex Web client on a Macbook Pro 2019 (i5). Even when I am on the same local network as my server, Plex Web is practically unusable. It takes anywhere between 30 sec to 5 minutes to buffer any point of the media.
My server is running on a linux box with an AMD Athlon II 645 with 6GB RAM. I have checked the transcoding speed on the server via verbose logging (https://support.plex.tv/articles/201575036-why-is-my-video-stream-buffering/) and the transcoder speed is always above 1. This means the client should have no problem buffering in a reasonable amount of time.
Interestingly, when I use the Plex Mac app (version 1.21.0.1410-50a34597), playback is instant. There is no buffering even when transcoding in 1080p. This tells me that the server is definitely fast enough at transcoding.
Why is Plex Web not able to buffer? My player machine’s ping to my server server is only about ~2ms, so I do not think my local network is the bottleneck.
Very likely, the web app requires transcoding on the server, while the proper desktop player can Direct Play the file as-is.
Your cpu is a really slow and old one, so I’d expect issues like this.
The Plex documentation says 1080p transcoding should work adequately on a CPU with a 2000 PassMark score. This CPU has a score of 2212.
You are probably right about how transcoding is differing from Direct Play, but I’m surprised the transcoder can’t keep up if the benchmark is as-expected and the verbose logging shows it as being fast enough.
The general rule of 2000 passmark points only applies to source video files with maximum of 10mbps in H.264 codec, and with primitive DTS core or AC3 audio and no activated subtitles.
Whether your example file falls into these boundaries, needs to be determined.
Please post the content of the Plex XML info of an affected movie.
<?xml version="1.0" encoding="UTF-8"?>
<MediaContainer size="1" allowSync="1" identifier="com.plexapp.plugins.library" librarySectionID="1" librarySectionTitle="Movies" librarySectionUUID="5e51b2f0-4ec4-4998-be98-f1f505cdde03" mediaTagPrefix="/system/bundle/media/flags/" mediaTagVersion="1603315428">
<Video ratingKey="2555" key="/library/metadata/2555" guid="com.plexapp.agents.imdb://tt3748528?lang=en" studio="Lucasfilm Ltd." type="movie" title="Rogue One: A Star Wars Story" librarySectionTitle="Movies" librarySectionID="1" librarySectionKey="/library/sections/1" contentRating="PG-13" summary="A rogue band of resistance fighters unite for a mission to steal the Death Star plans and bring a new hope to the galaxy." rating="8.4" audienceRating="8.6" viewOffset="2244000" viewCount="2" lastViewedAt="1603863000" year="2016" tagline="A Rebellion Built on Hope" thumb="/library/metadata/2555/thumb/1603862923" art="/library/metadata/2555/art/1603862923" duration="8037280" originallyAvailableAt="2016-12-14" addedAt="1603862899" updatedAt="1603862923" audienceRatingImage="rottentomatoes://image.rating.upright" chapterSource="media" hasPremiumExtras="1" hasPremiumPrimaryExtra="1" ratingImage="rottentomatoes://image.rating.ripe">
<Media id="4643" duration="8037280" bitrate="10516" width="1920" height="808" aspectRatio="2.35" audioChannels="6" audioCodec="dca" videoCodec="h264" videoResolution="1080" container="mkv" videoFrameRate="24p" audioProfile="dts" videoProfile="high">
<Part accessible="1" exists="1" id="4730" key="/library/parts/4730/1590702085/file.mkv" duration="8037280" file="" size="10565482757" audioProfile="dts" container="mkv" videoProfile="high">
<Stream id="11225" streamType="1" default="1" codec="h264" index="0" bitrate="8980" language="English" languageCode="eng" bitDepth="8" chromaLocation="left" chromaSubsampling="4:2:0" codedHeight="816" codedWidth="1920" frameRate="23.976" hasScalingMatrix="0" height="808" level="41" profile="high" refFrames="5" scanType="progressive" width="1920" displayTitle="1080p (H.264)" extendedDisplayTitle="1080p (H.264)"/>
<Stream id="11226" streamType="2" selected="1" default="1" codec="dca" index="1" channels="6" bitrate="1536" language="English" languageCode="eng" audioChannelLayout="5.1(side)" bitDepth="24" profile="dts" samplingRate="48000" displayTitle="English (DTS 5.1)" extendedDisplayTitle="English (DTS 5.1)"/>
</Part>
</Media>
</Video>
</MediaContainer>
Pasting relevant info from the xml here. It looks like my browser is using Direct Stream for video, but transcoding audio. The Plex for Mac app is using Direct Play for both.
I missing the results of the extended media analysis in there. The generic bandwidth value is just the averaged value which is primitively calculated by doing file size/run length.
But video files rarely have constant bitrates. So if the peaks of the video bandwidth differ significantly from the averaged value, there could be simply too little bandwidth available when streaming to the client.
Like I assumed: the file has actually much higher video bandwidth “peaks” than 10 mbps. requiredBandwidths="22200,18933,13373,10335,9856,9544,9174,9174"
When these bandwidth peaks occur for a longer time, the playback buffer might get depleted, because the cpu cannot top it up fast enough.
And let’s not forget the DTS audio, which needs to be transcoded to AAC for the web app. Because it doesn’t have the necessary codec support to decode DTS audio itself.
While transcoding audio has significantly lower cpu requirements than transcoding video, it is still not negligible – particularly if the cpu is already burdened to the max with video transcoding.
