I need help identifying when a file will be transcoded

[andres87]

Hello, I'm new to Jellyfin and not very tech savy. I inherited a very cheap NAS that can't transcode properly. Until I can afford to upgrade I've been using it as server for a Jellyfin WebOs client and it works great except when transcoding.

I know image based subtitles need transcoding, so I only allowed "text based" in the config and I make sure I add a external srt file for the content that I want to have subtitles.

The problem is some videos seem to need transcoding and I can't understand why. As I saw in another thread you can see the transcoding reason in the logs, it says "PlayMethod=Transcode, TranscodeReason=VideoCodecNotSupported, AudioCodecNotSupported"

This video needs transcoding:

Video
Title: 1080p H264 SDR
Codec: H264
AVC: No
Profile: High 10
Level: 50
Resolution: 1920x1080
Aspect ratio: 16:9
Interlaced: No
Framerate: 23.976025
Bitrate: 5142 kbps
Bit depth: 10 bit
Video range: SDR
Video range type: SDR
Pixel format: yuv420p10le
Ref frames: 1
NAL: 0

But this one doesn't need it:
Video
Title: 1080p - HEVC - SDR
Codec: HEVC
Profile: Main 10
Level: 120
Resolution: 1920x1080
Aspect ratio: 16:9
Interlaced: No
Framerate: 23.976042
Bitrate: 2742 kbps
Bit depth: 10 bit
Video range: SDR
Video range type: SDR
Colour space: bt709
Colour transfer: bt709
Colour primaries: bt709
Pixel format: yuv420p10le
Ref frames: 1

They look the same to me except for the codec but I own lots of H264 videos and they don't need transcoding.

The audio for the transcoding video is this:
Audio
Title: Japanese - AAC - Stereo - Default
Language: jpn
Codec: AAC
Profile: LC
Layout: stereo
Channels: 2 ch
Bitrate: 316 kbps
Sample rate: 48000 Hz
Default: Yes
Forced: No
External: No

The audio for the non-transcoding video is this:
Audio
Title: Surround - English - AAC - 5.1 - Default
Language: eng
Codec: AAC
Profile: LC
Layout: 5.1
Channels: 6 ch
Bitrate: 320 kbps
Sample rate: 48000 Hz
Default: Yes
Forced: No
External: No

Any idea of what the problem could be?

[toytown]

I would guess it's due to the client hardware not supporting H264 10Bit. The file that works is H265 10bit which has much more support in devices.

[TheDreadPirate]

I'm wondering if the video that is transcoding is doing so because the device doesn't support 10-bit H264. I've seen devices that support 10-bit HEVC but not 10-bit H264. The other possibility is the codec level, 50. I've seen devices support up to level 42 but not higher levels.

[andres87]

Oh so this is quite complicated. Unfortunately the only information I can find says it can play H264 and HEVC, but doesn't say anything at all about "bits".

I can confirm I've played lots of HEVC 1080p/4K SDR/HDR 10bit files without issue. I can't find in my library any other H264 10bit files to test, they're all 8bit.

I tried playing the H264 10bit file through DLNA and it says not supported, but HEVC 10bit files play nicely. So it looks like the codec and bits combination is indeed the issue. I learned something new today so I'll keep an eye out for the bits from now on.

Just to add more information if anyone is interested, this is the TV: https://www.lg.com/us/tvs/lg-oled65c3pua...#pdp_specs

Thanks for the help!

[TheDreadPirate]

You could use Handbrake or something to re-encode to something it can play without transcoding if transcoding is not possible/slow on your setup.