Hello,
I’ve recently moved my Media serving needs from a NAS + Infuse to Plex. Its working pretty damn great!
However, there is one nagging problem: no matter how I configure it, unless I disable ‘Automatically adjust quality’, Plex unnecessarily transcodes.
For example: I have a .mkv with a H264 video stream and a DTS 5.1 track inside, totalling about 19mbps. This plays fine on my Apple TV 4 or in my browser with Direct Stream (tested it multiple times!).
However, Plex feels the need to transcode this into a 25mbps+ stream…
Is there any way to leave automatic transcoding on but make it clear to Plex that, if the connection speed and device support it, no transcoding (especially transcoding that makes the file bigger) should happen?
you can’t… transcoding decision depends on the capabilities of the player. If I remember correctly, the Apple TV 4 doesn’t support DTS, so Plex will transcode the audio stream to AC3 instead.
without further details on your file it’s hard to tell why the increase from 19Mb/s to 25Mb/s
I know why its increasing from 19Mb/s to 25Mb/s: the x264 video stream is getting transcoded (to x264), I can see so right in the web interface of Plex (top bar when clicking ‘status’).
Again: I know my Apple TV and my browser can play the video stream as is, since I can select ‘original quality’.
But basically what I’m understanding is that the Automatic Transcode function isn’t intelligent enough to figure out the threshold where it is preferable to Direct Stream / Direct Play vs needing to to transcode because bandwidth is too low?
I mean, isn’t it logical that Plex should prefer sending a 19mbps file of higher quality (because not lossy -> lossy transcode) rather than a 25mbps file, especially since the transcoding is triggered by a function specifically meant to reduce connection strain…?
you being able to select “original quality” doesn’t mean the Apple TV can play the video without transcoding.
From Apple.com:
| Video Formats |
|
HEVC SDR up to 1080p, 30 fps, Main/Main 10 profile
H.264 video up to 1080p, 60 fps, High or Main Profile level 4.2 or lower
H.264 Baseline Profile level 3.0 or lower with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
MPEG-4 video up to 2.5 Mbps, 640 by 480 pixels, 30 fps, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats |
You’ll need to check your file’s media details (container, streams and their codecs/levels/bitrates) for an adequate evaluation.
If the video is e.g. h264 w/ a profile >4.2, Plex will transcode.
Other restrictions might apply if your file has subtitles not supported by Apple TV… in that case, Plex will mix the subtitle into the video stream (=transcoding it).
