AAC being transcoded to AAC5.1

Plex Players Streaming Devices
,
1

I have a some family members with different AV setups (but all using an ATV) who use my Plex server and I am trying to get content to be useable by most people without having to create multiple copies of the video files and reduce transcoding where possible.

(In the cases where video transcoding is needed, (4k content to a 1080 tv), it’s working pretty well since 64-bit Plex Server and Nvidia HW support for HDR tonemapping was introduced.)

All content is watched with SRT subtitles, either embedded in the video file, or using seperate SRT files. I have instructed the users to never use PGS subtitles (Some video files have these embedded as well) as I cannot seem to get this into a playable state.

Now I am troubleshooting(or trying to understand) an issue, where I have a 4K HDR video file with an AAC (6 channel) audio track and embedded SRT subtitles. Playing this file on a 1080 capable tv using the Plex app on atv results in the following:

image

I understand why it’s transcoding the video and as you can see, transcoding speed is not an issue. The video plays just fine. But I am curious as to why it’s also transcoding the audio, seeing as it’s already in AAC? And would subs not be transcoded if I’d have them stored in vtt format?

I realise this does not change much from a functional standpoint, but I’d like to avoid transcoding on audio (and subs) if it’s as easy as adding an additional audio track to the video files, and having a compatible format for the subs.

Perhaps my logic is wrong, and audio always needs to be transcoded when video is? Does the same count for subs then?

Thanks for enlightening me in advance :slight_smile:

2

There are different types of AAC. Possibly, converting from 1 to another. Would need to see your Plex logs to identify if this is the case.

3

I have gathered logs as outlined in the general post. Could you point me in the right direction?

I do see mention of the following in them, but I am unsure how it comes to this conclusion:

MDE: E6 - Universal Therapy: Audio Direct Streaming is disabled, so video's audio stream will be transcoded
MDE: Cannot direct stream audio stream due to profile or setting limitations

Thanks in advance for looking into it.

Plex Media Server Logs_2023-03-04_14-32-54.zip (2.4 MB)

4

It looks like the video is getting transcoded due to tone mapping and the bitrate is higher than what is set in the client. When video is transcoded we set it to a certain percentage of the quality setting. If the audio fits in what’s left over we include it as-is, if not then we have to transcode it to lower the bitrate a bit so it will fit. This is what’s going on. The video needs most of the bitrate so there isn’t enough to keep the audio intact. Can you post the xml info for that video so I can check the bitrates for the video and audio?

5

Ah, that’s already information I could not find anywhere.

Also, I completely understand why Video transcoding is taking place, so I am fine with that (And it’s working fine)

I believe the XML of the specific episode that I tested is as below:

<MediaContainer size="1" allowSync="1" identifier="com.plexapp.plugins.library" librarySectionID="2" librarySectionTitle="TV Shows" librarySectionUUID="7bf722eb-7c3a-4d74-a760-41852c99c276" mediaTagPrefix="/system/bundle/media/flags/" mediaTagVersion="1677685782">
<Video ratingKey="23779" key="/library/metadata/23779" parentRatingKey="23592" grandparentRatingKey="16588" guid="plex://episode/639df5558cd09102ee4af4ae" parentGuid="plex://season/6398da2acb590ccf68b787b1" grandparentGuid="plex://show/60844302404320002c149cc9" type="episode" title="Universal Therapy" grandparentKey="/library/metadata/16588" parentKey="/library/metadata/23592" librarySectionTitle="TV Shows" librarySectionID="2" librarySectionKey="/library/sections/2" grandparentTitle="How I Met Your Father" parentTitle="Season 2" contentRating="TV-14" summary="Sophie encounters an obstacle with a new beau. Ellen uses her new job insurance to see a therapist. Jesse gives Valentina a hand at work while Sid and Charlie try to sell terrible wine." index="6" parentIndex="2" audienceRating="5.3" year="2023" thumb="/library/metadata/23779/thumb/1678245984" art="/library/metadata/16588/art/1678246519" parentThumb="/library/metadata/23592/thumb/1674704653" grandparentThumb="/library/metadata/16588/thumb/1678246519" grandparentArt="/library/metadata/16588/art/1678246519" grandparentTheme="/library/metadata/16588/theme/1678246519" duration="1276437" originallyAvailableAt="2023-02-28" addedAt="1677569756" updatedAt="1678245984" audienceRatingImage="themoviedb://image.rating">
<Media id="77018" duration="1276437" bitrate="14024" width="3840" height="2160" aspectRatio="1.78" audioChannels="6" audioCodec="aac" videoCodec="hevc" videoResolution="4k" container="mkv" videoFrameRate="24p" audioProfile="lc" videoProfile="main 10">
<Part accessible="1" exists="1" id="80911" key="/library/parts/80911/1677560400/file.mkv" duration="1276437" file="D:\Series\How I Met Your Father\Season 02\How I Met Your Father - S02E06 - Universal Therapy WEBDL-2160p 5.1 x265 EAC3.mkv" size="2238935032" audioProfile="lc" container="mkv" deepAnalysisVersion="6" requiredBandwidths="18301,16065,14866,14637,14637,14637,14637,14637" videoProfile="main 10">
<Stream id="283863" streamType="1" default="1" codec="hevc" index="0" bitrate="13425" bitDepth="10" chromaLocation="left" chromaSubsampling="4:2:0" codedHeight="2160" codedWidth="3840" colorPrimaries="bt2020" colorRange="tv" colorSpace="bt2020nc" colorTrc="smpte2084" frameRate="23.976" height="2160" level="150" profile="main 10" refFrames="1" requiredBandwidths="17703,15467,14265,14045,14045,14045,14045,14045" width="3840" displayTitle="4K HDR10 (HEVC Main 10)" extendedDisplayTitle="4K HDR10 (HEVC Main 10)"> </Stream>
<Stream id="283864" streamType="2" selected="1" default="1" codec="aac" index="1" channels="6" bitrate="341" language="English" languageTag="en" languageCode="eng" audioChannelLayout="5.1" original="1" profile="lc" requiredBandwidths="341,341,341,341,341,341,341,341" samplingRate="48000" displayTitle="English (AAC 5.1)" extendedDisplayTitle="English (AAC 5.1)"> </Stream>
<Stream id="283888" streamType="2" default="1" codec="eac3" index="2" channels="6" bitrate="256" language="English" languageTag="en" languageCode="eng" audioChannelLayout="5.1(side)" original="1" requiredBandwidths="256,256,256,256,256,256,256,256" samplingRate="48000" displayTitle="English (EAC3 5.1)" extendedDisplayTitle="English (EAC3 5.1)"> </Stream>
<Stream id="283866" streamType="3" selected="1" default="1" codec="srt" index="3" bitrate="0" language="English" languageTag="en" languageCode="eng" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="English (SRT)" extendedDisplayTitle="English (SRT)"> </Stream>
<Stream id="283867" streamType="3" codec="srt" index="4" bitrate="0" language="English" languageTag="en" languageCode="eng" hearingImpaired="1" requiredBandwidths="1,1,1,1,1,1,1,1" title="SDH" displayTitle="English SDH (SRT)" extendedDisplayTitle="SDH (English SRT)"> </Stream>
<Stream id="283868" streamType="3" codec="srt" index="5" bitrate="0" language="Czech" languageTag="cs" languageCode="ces" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Czech (SRT)" extendedDisplayTitle="Czech (SRT)"> </Stream>
<Stream id="283869" streamType="3" codec="srt" index="6" bitrate="0" language="Danish" languageTag="da" languageCode="dan" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Danish (SRT)" extendedDisplayTitle="Danish (SRT)"> </Stream>
<Stream id="283870" streamType="3" codec="srt" index="7" bitrate="0" language="German" languageTag="de" languageCode="deu" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="German (SRT)" extendedDisplayTitle="German (SRT)"> </Stream>
<Stream id="283871" streamType="3" codec="srt" index="8" bitrate="0" language="Greek" languageTag="el" languageCode="ell" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Greek (SRT)" extendedDisplayTitle="Greek (SRT)"> </Stream>
<Stream id="283872" streamType="3" codec="srt" index="9" bitrate="0" language="Spanish" languageTag="es" languageCode="spa" requiredBandwidths="1,1,1,1,1,1,1,1" title="Spanish (Latin America)" displayTitle="Spanish (SRT)" extendedDisplayTitle="Spanish (Latin America) (Spanish SRT)"> </Stream>
<Stream id="283873" streamType="3" codec="srt" index="10" bitrate="0" language="Spanish" languageTag="es" languageCode="spa" requiredBandwidths="1,1,1,1,1,1,1,1" title="Spanish (Spain)" displayTitle="Spanish (SRT)" extendedDisplayTitle="Spanish (Spain) (Spanish SRT)"> </Stream>
<Stream id="283874" streamType="3" codec="srt" index="11" bitrate="0" language="Finnish" languageTag="fi" languageCode="fin" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Finnish (SRT)" extendedDisplayTitle="Finnish (SRT)"> </Stream>
<Stream id="283875" streamType="3" codec="srt" index="12" bitrate="0" language="French" languageTag="fr" languageCode="fra" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="French (SRT)" extendedDisplayTitle="French (SRT)"> </Stream>
<Stream id="283876" streamType="3" codec="srt" index="13" bitrate="0" language="Hungarian" languageTag="hu" languageCode="hun" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Hungarian (SRT)" extendedDisplayTitle="Hungarian (SRT)"> </Stream>
<Stream id="283877" streamType="3" codec="srt" index="14" bitrate="0" language="Italian" languageTag="it" languageCode="ita" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Italian (SRT)" extendedDisplayTitle="Italian (SRT)"> </Stream>
<Stream id="283878" streamType="3" codec="srt" index="15" bitrate="0" language="Japanese" languageTag="ja" languageCode="jpn" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Japanese (SRT)" extendedDisplayTitle="Japanese (SRT)"> </Stream>
<Stream id="283879" streamType="3" codec="srt" index="16" bitrate="0" language="Korean" languageTag="ko" languageCode="kor" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Korean (SRT)" extendedDisplayTitle="Korean (SRT)"> </Stream>
<Stream id="283880" streamType="3" codec="srt" index="17" bitrate="0" language="Dutch" languageTag="nl" languageCode="nld" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Dutch (SRT)" extendedDisplayTitle="Dutch (SRT)"> </Stream>
<Stream id="283881" streamType="3" codec="srt" index="18" bitrate="0" language="Norwegian" languageTag="no" languageCode="nor" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Norwegian (SRT)" extendedDisplayTitle="Norwegian (SRT)"> </Stream>
<Stream id="283882" streamType="3" codec="srt" index="19" bitrate="0" language="Polish" languageTag="pl" languageCode="pol" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Polish (SRT)" extendedDisplayTitle="Polish (SRT)"> </Stream>
<Stream id="283883" streamType="3" codec="srt" index="20" bitrate="0" language="Portuguese" languageTag="pt" languageCode="por" requiredBandwidths="1,1,1,1,1,1,1,1" title="Portuguese (Brazil)" displayTitle="Portuguese (SRT)" extendedDisplayTitle="Portuguese (Brazil) (Portuguese SRT)"> </Stream>
<Stream id="283884" streamType="3" codec="srt" index="21" bitrate="0" language="Portuguese" languageTag="pt" languageCode="por" requiredBandwidths="1,1,1,1,1,1,1,1" title="Portuguese (Portugal)" displayTitle="Portuguese (SRT)" extendedDisplayTitle="Portuguese (Portugal) (Portuguese SRT)"> </Stream>
<Stream id="283885" streamType="3" codec="srt" index="22" bitrate="0" language="Romanian" languageTag="ro" languageCode="ron" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Romanian (SRT)" extendedDisplayTitle="Romanian (SRT)"> </Stream>
<Stream id="283886" streamType="3" codec="srt" index="23" bitrate="0" language="Swedish" languageTag="sv" languageCode="swe" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Swedish (SRT)" extendedDisplayTitle="Swedish (SRT)"> </Stream>
<Stream id="283887" streamType="3" codec="srt" index="24" bitrate="0" language="Turkish" languageTag="tr" languageCode="tur" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Turkish (SRT)" extendedDisplayTitle="Turkish (SRT)"> </Stream>
<Stream id="283889" streamType="3" codec="srt" index="25" bitrate="0" language="Chinese" languageTag="zh" languageCode="zho" requiredBandwidths="1,1,1,1,1,1,1,1" displayTitle="Chinese (SRT)" extendedDisplayTitle="Chinese (SRT)"> </Stream>
</Part>
</Media>
<Director id="92099" filter="director=92099" tag="Michael J. Shea"/>
<Writer id="57428" filter="writer=57428" tag="Christopher Encell"/>
<Guid id="imdb://tt18257052"/>
<Guid id="tmdb://4107911"/>
<Guid id="tvdb://9505358"/>
<Rating image="themoviedb://image.rating" value="5.3" type="audience"/>
<Role id="18480" filter="actor=18480" tag="Josh Peck" tagKey="5d77682954f42c001f8c2e18" role="Drew" thumb="https://metadata-static.plex.tv/8/people/8b8e537c9424082ddf8a28a246482ec5.jpg"/>
<Role id="57231" filter="actor=57231" tag="Dan Bucatinsky" tagKey="5d776834961905001eb93ae3" role="Fred" thumb="https://metadata-static.plex.tv/people/5d776834961905001eb93ae3.jpg"/>
<Role id="18010" filter="actor=18010" tag="Rose Abdoo" tagKey="5d77682d8718ba001e3131aa" role="Dr. Dominguez" thumb="https://metadata-static.plex.tv/c/people/cca4a0b930206d7bf9043ca56b5363ff.jpg"/>
<Role id="91046" filter="actor=91046" tag="Valentina Garcia" tagKey="5d7768412ec6b5001f6bdfa0" role="Excited Woman" thumb="https://metadata-static.plex.tv/f/people/f43b7894bd555a5d9861b3380be350ab.jpg"/>
<Role id="91047" filter="actor=91047" tag="Janelle Gray" tagKey="63616a11b5672b38ed0f36fd" role="Olivia"/>
<Role id="92080" filter="actor=92080" tag="Judith Sheindlin" tagKey="5d77697b9ab54400214f2685" role="Judge Judy Sheindlin" thumb="https://metadata-static.plex.tv/a/people/a37fde45f4162dd71b81334a2741c4ad.jpg"/>
<Role id="14257" filter="actor=14257" tag="Victor Rasuk" tagKey="5d7768346f4521001ea9bd3b" role="Oscar" thumb="https://metadata-static.plex.tv/people/5d7768346f4521001ea9bd3b.jpg"/>
<Marker final="1" id="77120" type="credits" startTimeOffset="1240793" endTimeOffset="1276437">
<Attributes id="77120" version="4"/>
</Marker>
<Extras size="0"> </Extras>
<Related> </Related>
</Video>
</MediaContainer>

Also, what about the subs and them being transcoded to Webvtt? Is this due to the Audio being transcoded?

Thanks for looking into it :slight_smile:

6

Which Apple TV do you have?

7

For this test, an Apple TV 4K (2nd generation) was used.

What is the significance between ATV versions for this case?

Thanks!

8

Different devices have different support for codecs. Your device should be able to direct play that file. I don’t know why it’s trying to transcode. And for the audio, it’s actually increasing the bitrate. Not sure why it’s doing that either.

Can you replay this file and then get me the Apple TV log. It must be something with the client, not your server. The server is being told what to do by the client.

9

I have gathered a fresh set of logs, both server and client (atv) side.

Server:
Plex Media Server Logs_2023-03-08_22-47-37.zip (2.9 MB)

Client:
logging.zip (1.1 MB)

The test was performed at ~22.42 using the same file as before.

Thanks in advance for looking into this.

10

Your logs show the client is using the old player which doesn’t support that file. Please turn that off and try again.

The setting is called “Use Old Video Player”, turn that off.

11

That does indeed fix the issue. Sorry for not mentioning that before /facepalm. We have been using the old player to prevent audio sync issues we have been experiencing, and I kind of forgot about that…

The audio sync issues are a whole other matter which I hope to see improved upon in the future, so for now, this seems pretty much solved.

12

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