Question about transcoding

General Discussions
1

Hi,

Sorry if this is in the wrong section, I wasn’t sure which was best.

I am currently in the process of moving my entire library to an online server due to it being a faster connection to share with family members.

I have a lot of 4K content that I previously streamed locally. These files were between 50-90GB a disk file… (full remux’s).

My connection is 80Mbps downstream so this isn’t good enough to watch these at full quality with Direct Play. Therefore I was wondering if I can set something so I still get a good 4K image but at a reduced quality that’s still way better than 1080P. The actual data transferred would need to be less than than the full amount or it would just buffer constantly

Is this possible or does transcoding still send the full amount of data?

I don’t really want to upload a load of lower quality 4K videos because I’ll have to do it all again when I get a faster connection which is able to download them at full quality (sometime within the next 12 months).

Thanks.

p.s. I have multiple WAN connections if something can be done to download it over 2 or 3 lines but I doubt that’s possible?

2

Check the bitrate of the 4K files. In Plex Web or Plex for Window/Mac, sort the library by bitrate. The bitrate shown in Plex is an average for the entire video, so some scenes will burst to a higher rate. Some of your movies may direct play over a 80 Mbps link.

Transcoding HDR video, of any resolution, in Plex is not a good idea. Plex transcodes all video to H.264 8-bit and does not map HDR to SDR. As a result, the video has washed out colors.

If any of your 4K material is non-HDR, H264/265 8-bit video, then you can have Plex transcode without color mapping problems. Transcoding 4K material is very compute intensive, so you will need the appropriate hardware.

There is no way to split a stream across multiple WAN connections.

One alternative would be to keep a local server in addition to the online server. You could keep a copy of your 4K media on the local server for local use only. Plex supports having multiple servers per account. You can pin the local 4K library to the home page on your local clients, along with the appropriate libraries from the online server.

3

Hi,

Thanks for the detailed reply.

I don’t want to go down the route of two servers and don’t like the sound of the washed out colours.

So it sounds like the best option would be to obtain a copy with a lower bitrate but still high quality?

I can stream around 50-60GB files but it’s borderline buffering so if I get something slightly less i shouldn’t be loosing much quality.

Does that sound okay?

4

I’m not sure that is possible for 4K HDR video. Many transcoding tools, such as Handbrake, do not preserve the HDR data in a video.

I’m sure there is a way to use FFMPEG to transcode 4K HDR to 1080P HDR. However, I haven’t seen any examples or any freeware/commercial tools that do such things.

File size is irrelevant. It is bit rate that matters. You can view the bitrate in Plex (sort library by bitrate). You can use Get Info to see the bitrate for individual video/audio tracks (see Investigate Media Information and Formats). You can also use tools such as MediaInfo.

That’s why I mentioned keeping a local server.

If you don’t have enough bandwidth to stream 4K material, then it will either buffer or transcode.

If it transcodes in Plex, you’ll lose any HDR data and have washed out colors.

If you can find the right tools, you can manually transcode your 4K media to a lower rate or size. However, transcoding 4K media is incredibly compute intensive, so expect long transcode times.

FYI, if you want to see washed out colors, just force a transcode while watching a 4K HDR video. It should be readily apparent that things look “off.”

5

Only the second option will give you meaningful information. And this one even only if you allow Plex server to perform the “extensive analysis”.
Everything else will only give you the average bandwidth, which can be off by a factor of 3 (and sometimes even more!).

Compare the values of bitrate="5879" and requiredBandwidths="20798,16927,8766,7384,6747,6501,6424,6424"
for the first stream (video) of this MKV file.

<Media id="1231750" duration="7150186" bitrate="11086" width="1920" height="1036" aspectRatio="1.85" audioChannels="7" audioCodec="dca-ma" videoCodec="h264" videoResolution="1080" container="mkv" videoFrameRate="24p" audioProfile="ma" videoProfile="high">
<Part accessible="1" exists="1" id="1234308" key="/library/parts/1234308/1594638307/file.mkv" duration="7150186" file="E:\Animation2\Das wandelnde Schloss (2004)\Das wandelnde Schloss (2004).mkv" size="9899886733" audioProfile="ma" container="mkv" deepAnalysisVersion="4" indexes="sd" requiredBandwidths="26945,23074,14562,13215,12482,11780,11634,11634" videoProfile="high">
<Stream id="2007132" streamType="1" default="1" codec="h264" index="0" bitrate="5879" language="日本語" languageCode="jpn" bitDepth="8" chromaLocation="left" chromaSubsampling="4:2:0" codedHeight="1040" codedWidth="1920" colorPrimaries="bt709" colorRange="tv" colorSpace="bt709" colorTrc="bt709" frameRate="23.976" hasScalingMatrix="0" height="1036" level="40" profile="high" refFrames="4" requiredBandwidths="20798,16927,8766,7384,6747,6501,6424,6424" scanType="progressive" width="1920" displayTitle="1080p (H.264)" extendedDisplayTitle="1080p (H.264)"/>
<Stream id="2007133" streamType="2" default="1" codec="dca" index="1" channels="7" bitrate="2488" language="Deutsch" languageCode="ger" audioChannelLayout="6.1" bitDepth="16" profile="ma" requiredBandwidths="2876,2715,2550,2496,2496,2496,2496,2496" samplingRate="48000" displayTitle="Deutsch (DTS-HD MA 6.1)" extendedDisplayTitle="Deutsch (DTS-HD MA 6.1)"/>
<Stream id="2007134" streamType="2" selected="1" codec="dca" index="2" channels="7" bitrate="2695" language="日本語" languageCode="jpn" audioChannelLayout="6.1" bitDepth="16" profile="ma" requiredBandwidths="3008,2854,2723,2707,2707,2707,2707,2707" samplingRate="48000" displayTitle="日本語 (DTS-HD MA 6.1)" extendedDisplayTitle="日本語 (DTS-HD MA 6.1)"/>
<Stream id="2007135" streamType="3" selected="1" default="1" codec="srt" index="3" bitrate="0" language="Deutsch" languageCode="ger" requiredBandwidths="1,1,1,1,1,1,1,1" title="full" displayTitle="Deutsch (SRT)" extendedDisplayTitle="full (Deutsch SRT)"/>
<Stream id="2007136" streamType="3" codec="pgs" index="4" bitrate="23" language="Deutsch" languageCode="ger" headerCompression="1" requiredBandwidths="50,50,50,50,50,50,50,50" title="full" displayTitle="Deutsch (PGS)" extendedDisplayTitle="full (Deutsch PGS)"/>
<Stream id="2007137" streamType="3" codec="srt" index="5" bitrate="0" language="English" languageCode="eng" requiredBandwidths="1,1,1,1,1,1,1,1" title="full" displayTitle="English (SRT)" extendedDisplayTitle="full (English SRT)"/>
</Part>
</Media>

There is more than one bandwidth value here, because the type of the client determines the practically required bandwidth too. Namely the size of the network receiving buffer memory.
The less RAM is available for this, the more often you can expect to see buffering occur unless there is plenty of bandwidth surplus.
The numbers mean the practically required download bandwidth for 5/10/25/50/75/100/250/500MB network buffer sizes.

(And this is just the video. In the case of Direct Play you must add the bandwidth of all remaining tracks on top, which is what you can see in the requiredBandwidths="26945,23074,14562,13215,12482,11780,11634,11634" for the overall file.)

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