iOS Client Forcing 4K VP9 MKV to Transcode Instead of Direct Play

Plex Players Mobile Devices
1

Server Version#: 1.41.5.9522
Player Version#: 2025.10.2

Hello Plex Support,

I’m having an issue where 4K VP9 MKV videos no longer direct play on my iPhone 14 Pro w/ iOS 18.3.2 since the most recent Plex for iOS update. These same files used to play directly without any problem. Now, the logs show the client explicitly requesting directPlay=0&directStream=0, and the server log indicates:

MDE: no direct play video profile exists for http/mkv/vp9
MDE: media must be transcoded in order to use the hls protocol
MDE: … Direct Play is disabled

When the server tries to transcode, it fails due to hardware decode errors like:

Cannot load libcuda.so.1
Could not dynamically load CUDA
Not enough CPU for conversion of this item

The transcoding failure is expected, the PMS is running on a Synology NAS that is not powerful enough to transcode, so I have disabled transcoding (Settings → Transcoder → Disable video stream transcoding).

I have logging enabled on the Plex Media Server. Below is a relevant snippet of the server logs:

DEBUG — Request: GET /video/:/transcode/universal/decision?directPlay=0&directStream=0 …
DEBUG — MDE: … no direct play video profile exists for http/mkv/vp9
DEBUG — MDE: media must be transcoded in order to use the hls protocol
DEBUG — Could not create hardware context for vp9
ERROR — [FFMPEG] - Cannot load libcuda.so.1
ERROR — [FFMPEG] - Could not dynamically load CUDA
DEBUG — Not enough CPU for conversion of this item.

Steps tried so far:

  1. Double-checked my Plex settings to ensure Direct Play was enabled.
  2. Confirmed that these same 4K VP9 MKV files used to direct play before the latest Plex iOS update.
  3. Verified network conditions are unchanged, and the server has adequate bandwidth.

Any help in restoring direct play for these files (or any work arounds I can do around VP9 in MKV) would be greatly appreciated. Please let me know if you need any additional information.

Thank you!

FYI - This is the media info of an example video that now fails to direct play:


Media

    Duration 37:30
    Bitrate 9862 kbps
    Width 3840
    Height 2160
    Aspect Ratio 1.78
    Video Resolution 4K
    Container MKV
    Video Frame Rate NTSC
    Audio Profile lc
    Video Profile profile 0


    Duration 37:30
    Size 2.59 GB
    Audio Profile lc
    Container MKV
    Video Profile profile 0


    Codec VP9
    Bitrate 9734 kbps
    Bit Depth 8
    Chroma Subsampling 4:2:0
    Coded Height 2160
    Coded Width 3840
    Color Primaries bt709
    Color Range tv
    Color Space bt709
    Color Trc bt709
    Frame Rate 29.973 fps
    Height 2160
    Profile profile 0
    Ref Frames 1
    Width 3840
    Display Title 4K (VP9)
    Extended Display Title 4K (VP9)

    Codec AAC
    Channels 2
    Bitrate 128 kbps
    Language English
    Language Tag en
    Audio Channel Layout stereo
    Profile lc
    Sampling Rate 44100 Hz
    Display Title English (AAC Stereo)
    Extended Display Title English (AAC Stereo)

    Codec SRT
    Language English
    Language Tag en
    Display Title English (SRT)
    Extended Display Title English (SRT)
2

FYI - I just tested using version 2025.11.1 and the issue described above is still present (i.e. 4K VP9 videos in MVKs are still requiring transcoding on my iPhone 14 Pro running iOS 18.3.2, while before they would direct play/stream)

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