Transcoded downloads not playable on Android

[mavrik 1]

I'm observing a really annoying problem on my Lenovo Legion Tab 3 - Emby seems to be created transcoded downloads that cannot be played.

When trying to play, I just get a black screen with playback timer not running:

The behaviour seems a bit inconsistent - not all of the episodes are unplayable, but most of the episodes are. The files are also unplayable with other players - builtin device player, next player, etc.

Some observations:

1. The unplayable files seem to have video format set as 720p Dolby Vision. The playable episodes are only 720p.
2. When trying to play the files, a notification saying "playing Dolby Vision content" pops up.
3. I have both "Software Tone Mapping" and "Hardware Tone Mapping" enabled on the server side (Synology with Intel GPU) which should ensure that the downloads are transcoded to SDR.

This makes me think that the server is ignoring those settings and transcoding to DV HDR video tracks which the Emby app isn't capable of handling.

Versions:

Emby Server 4.8.11.0 on a Intel Celeron Synology NAS
Emby for Android 3.4.36

Question:

1. Is it possible to fix the client to play these videos correctly?
2. If not, how do I force the server transcodes to be SDR?

I'm attaching client log and transcode log for the files shown.

 

 

 

ffmpeg-transcode-d292dd51-8208-47f3-bfd9-27056e4f2a66_1.txt emby_android_1744932824162.txt

[Luke 42077]

HI, if it's a full transcode then there is no DV in the output.

Just for testing purposes, if you were to disable hardware transcoding in server transcoding settings, then try a new download, is that playable?

[mavrik 1]

This is a full transcode (it happens both for 4Mbit and 8Mbit profile - transcode log attached. Also happens for other shows.). I'll try a software transcode and attach a log.

[mavrik 1]

Same thing happens with software transcode - both versions attach a DoVi record to the output.

x264:

09:12:54.721 Press [q] to stop, [?] for help
09:12:55.054 [libx264 @ 0x16306c0] using SAR=1/1
09:12:55.054 [libx264 @ 0x16306c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2
09:12:55.057 [libx264 @ 0x16306c0] profile Main, level 3.1, 4:2:0, 8-bit
09:12:55.057 [libx264 @ 0x16306c0] 264 - core 163 r3060 5db6aa6 - H.264/MPEG-4 AVC codec - Copyleft 2003-2021 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x1:0 me=hex subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=4 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=144 keyint_min=73 scenecut=0 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=2976 vbv_bufsize=5952 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
09:12:55.057 Output #0, matroska, to '/var/packages/EmbyServer/var/sync/18/96/69dd2ce1-1f32-4bfa-9717-5d8dd9e58397.mkv':
09:12:55.057   Metadata:
09:12:55.057     encoder         : Lavf59.27.100
09:12:55.057   Stream #0:0: Video: h264 (H264 / 0x34363248), yuv420p(tv, bt709, progressive), 1280x536 [SAR 1:1 DAR 160:67], q=2-31, 23.98 fps, 1k tbn
09:12:55.057     Metadata:
09:12:55.057       encoder         : Lavc59.37.100 libx264
09:12:55.057     Side data:
09:12:55.057       cpb: bitrate max/min/avg: 2976000/0/0 buffer size: 5952000 vbv_delay: N/A
09:12:55.057       DOVI configuration record: version: 1.0, profile: 8, level: 6, rpu flag: 1, el flag: 0, bl flag: 1, compatibility id: 1

 

QuickSync:

15:12:58.471   Stream #0:0: Video: h264 (H264 / 0x34363248), qsv(bt2020nc/bt2020/bt709, progressive), 1280x536 [SAR 1:1 DAR 160:67], q=2-31, 2976 kb/s, 23.98 fps, 1k tbn
15:12:58.471     Metadata:
15:12:58.471       encoder         : Lavc59.37.100 h264_qsv
15:12:58.471     Side data:
15:12:58.471       cpb: bitrate max/min/avg: 2976000/0/2976000 buffer size: 5952000 vbv_delay: N/A
15:12:58.472       DOVI configuration record: version: 1.0, profile: 8, level: 6, rpu flag: 1, el flag: 0, bl flag: 1, compatibility id: 1

Despite tonemapping being enabled and (seemingly) active.

Attaching transcoding log for software version.

ffmpeg-transcode-69dd2ce1-1f32-4bfa-9717-5d8dd9e58397_1_sw.txt

[Luke 42077]

@mavrikare you still seeing this with the latest update to Emby for Android?

[mavrik 1]

Unfortunately yes - I've updated the server to latest beta and client from play store, then redownloaded the file.

The file still does not play (same symptoms - empty screen with player counter not advancing, device showing "Dolby Vision video playing" notification). Another observation - the file is not playable in any other player on device either, except for VLC (which I assume falls back to software decode).

The server still attached DoVi side data despite me having "Tone Mapping" enabled. This happens for both QuickSync and libx264 transcode. Selected quality is 4Mbps.
I compared this to Plex behavior and Plex transcodes file to non-HDR version when downloading.

Attaching both new server transcode logs and Android client playback logs.

ffmpeg-transcode-25037d23-09ae-4048-9da4-ac96c5602b82_1.txt emby_android_1750071191000.txt

Edited June 16, 2025 by mavrik

[Luke 42077]

OK we're looking into this. Thanks.