The log files do not contain enough information. Please enable debug, but not verbose, level logging. See Reporting issues with Plex Media Server for details.
FYI, you can attach the log files directly to the thread. Drag the ZIP file into the message window and it will insert at the cursor location. There is a 30 MB size limit for attachments.
There are four possible issues:
- Server not strong enough to transcode video
- Video transcoding required due device limitations
- Video transcoding required due to Plex app limitations
- Video transcoding due to less than optimal video encoding
Without debug level logs it is difficult to tell which of the above is causing playback to fail (or if something else is the cause).
Try playing the video with subtitles turned off. If it plays, then the problem is subtitles forcing a video transcode and the server’s inability to transcode the video.
Server Limitations
The CPU in your server, an AMD Turion II Neo N54L, is not powerful enough to transcode video. The log files do not contain enough information to tell if hardware accelerated transcoding was attempted. If hardware accelerated transcoding is not available, and video transcoding is required, playback will fail.
Mobile Device Limitations
Edit: Re-reading your post, this is probably not the problem since the devices can play the video locally.
Unknown if your device can direct play 10-bit video. If it cannot, Plex will try to transcode the video. If the server cannot transcode the video, playback fails.
Plex App Limitations
The Plex Android & Android TV apps have limited support for ASS subtitles. Enabling ASS subtitles with default settings results in Plex Media Server transcoding the video. If your server is not capable of transcoding the video, playback will fail.
A workaround is to set Burn Subtitles = Only Image Formats in the Plex Android app. Formatting & style information is lost, but the video will not transcode just because ASS subtitles are enabled.
Plex Web and other Plex clients such as the Smart TV apps, also have poor ASS subtitle support, resulting in video transcoding when the subtitles are enabled.
Video Encoding
The video could be encoded better. If the device cannot direct play the video due to the way it is encoded, Plex Media Server will try to transcode the video. If the server is not strong enough, playback will fail.
16 reference frames will cause problems on some devices. The video should have no more than 5 reference frames.
Level 5 for 1280x720 is also not necessary. Level 3.2 is sufficient for 1280x720@30fps. As a reference, 1080p Blu-ray movies are Level 4.1. Most modern devices will play Level 5 H.264 video, but it helps compatibility to keep the level to only what is necessary. Increasing it does not increase the video quality. Additional info at Wikipedia: H.264 Info
Try re-encoding the video using Handbrake or similar software. When using Handbrake, do not leave the Encoder Profile or Encoder Level to Auto. The software tends to choose too high a level and insert too many reference frames when doing so.
Here’s a 15 second sample. It is High 10@3.2 with 4 reference frames.
Madan no Ou to Vanadis (15 sec).zip (1.8 MB)
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High 10@L5
Format settings : CABAC / 16 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 16 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 24 min 10 s
Bit rate : 2 842 kb/s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Handbrake settings used to generate the sample:
brb!
