notalpha 0 Posted August 7, 2025 Posted August 7, 2025 (edited) Hello there! I have had issues with stutters and movies not starting (actually caused by movies waiting fully for the transcode to finish) when using hardware transcoding. So i decided to do some investigation. Setup Server CPU: Ryzen 5, 5600G GPU: Nvidia RTX 3060 (12GB) Drivers: 576.88 OS: Windows 11 Pro (24H2, 26100.4652) Emby: 4.8.11.0 Client Streamer (chromecasting to our chromecast): Server PC, (Chrome 138.0.7204.184) Device: Chromecast gen3 Receiver: JVC RX-5052 (AC3, does NOT support EAC3) Display: BenQ Projector (1080p, non-HDR) Investigation I tried 3 different videos with different formats. I change the HW encoder and decoder settings, and then play the video to see if it works. I have an active Emby Premier subscription. Video 1: 4K Dolby Vision HEVC, TRUEHD 7.1 Codecs Stream: MKV (79mbps) Video: 4K Dolby Vision HEVC Transcode (H264) Tone Mapping (Hable) Audio: TRUEHD 7.1 (Default) Transcode (AC3 384 kbps) Results BTW none of these use Hardware accelerated tone mapping!!!! Decoder Encoder Status Utilization Disabled Disabled Works (around 90% CPU) Disabled NVENC(Default) Waits until transcode is complete Disabled NVENC(Baseline) Stutters Disabled NVENC(Main) Waits until transcode is complete Disabled NVENC(High) Waits until transcode is complete HVDEC Disabled Stutters, but much more rarely. HVDEC NVENC(Default) Waits until transcode is complete HVDEC NVENC(Baseline) Stutters HVDEC NVENC(Main) Waits until transcode is complete HVDEC NVENC(High) Waits until transcode is complete DX11VA Disabled Works (around 30% CPU, 40% GPU) DX11VA* NVENC(Default) Waits until transcode is complete DX11VA* NVENC(Baseline) Stutters (Actually crashed once, not reproducable) DX11VA* NVENC(Main) Waits until transcode is complete DX11VA* NVENC(High) Waits until transcode is complete CUVID Disabled Works (around 40% CPU, 40% GPU) CUVID NVENC(Default) Waits until transcode is complete CUVID NVENC(Baseline) Stutters CUVID NVENC(Main) Waits until transcode is complete CUVID NVENC(High) Waits until transcode is complete * Strikethrough means that it does not get reported being used in the Now Playing view in Admin, which means that it probably got disabled for some reason. Video 2: 4K HDR 10 HEVC, DTS-HD MA 5.1 Codecs Stream: MKV (15mbps) Video: 4K HDR 10 HEVC Transcode (H264) Tone Mapping (Hable) Audio: DTS-HD MA 5.1(Default) Transcode (AC3 384 kbps) Results With HDR10 HEVC, we no longer have issues with it waiting for the entire transcoding to complete. But we just have stutters where we instead would have non-streaming with Dolby Vision. BTW none of these use Hardware accelerated tone mapping!!!! (again) Decoder Encoder Status Disabled Disabled Works Disabled NVENC(Default) Stutters DX11VA Disabled Works DX11VA* NVENC(Default) Stutters CUVID Disabled Works CUVID NVENC(Default) Stutters CUVID NVENC(Baseline) Stutters CUVID NVENC(Main) Stutters NVDEC Disabled Works NVDEC NVENC(Default) Stutters NVDEC NVENC(Baseline) Stutters NVDEC NVENC(Main) Stutters * Strikethrough means that it does not get reported being used in the Now Playing view in Admin, which means that it probably got disabled for some reason. Video 3: 4K HEVC, AAC 5.1 Codecs Stream: MKV (6mbps) Video: 4K HEVC Transcode (H264) Audio: AAC 5.1 (Default) Transcode (AC3 320 kbps) Results First time where we can get HW-encoding to sortof work. No HDR here. Decoder Encoder Status Disabled Disabled Works Disabled NVENC(Default) Works, stutters at start Disabled NVENC(Baseline) Works, stutters at start NVDEC Disabled Works NVDEC NVENC(Default) Stutters NVDEC NVENC(Baseline) Stutters CUVID Disabled Works CUVID NVENC(Default) Stutters CUVID NVENC(Baseline) Stutters DX11VA Disabled Works DX11VA* NVENC(Default) Works DX11VA* NVENC(Baseline) Works * Strikethrough means that it does not get reported being used in the Now Playing view in Admin, which means that it probably got disabled for some reason. all-logs.zip embyserver.txt Edited August 7, 2025 by notalpha Added log files, small typo
Abobader 3464 Posted August 7, 2025 Posted August 7, 2025 Hello notalpha, ** This is an auto reply ** Please wait for someone from staff support or our members to reply to you. It's recommended to provide more info, as it explain in this thread: Thank you. Emby Team
Neminem 1518 Posted August 7, 2025 Posted August 7, 2025 Have you enabled this ? In my experience the wording is wrong, it also includes GPU. Meaning it will transcode in bursts, instead of the whole file at once.
notalpha 0 Posted August 7, 2025 Author Posted August 7, 2025 No, throttling is not enabled. I could try with it on, but this is not a utilization problem as my GPU/CPU is never quite maxed (except if we don't use any HW-accel at all). It would be interesting to see if it fixes the streaming problem with the Dolby Vision video though.
Neminem 1518 Posted August 7, 2025 Posted August 7, 2025 (edited) Well I would strip out PGS subs they are really bad when streaming. Also you have Stream #0:39(hin) in total in that media file, remove the once you do not need. I only have official, English, in there as audio and all subs are also stripped. I get my subs as .srt files if I can't move the embedded into .srt ( Text based that all clients work with ). Further more you are using webui to stream, that huge file 79.307 bitrate. This is what i get out of this log ffmpeg-remux-a8506053-9b55-4a74-bdca-eaa7ba8ab26b_1.txt Edited August 7, 2025 by Neminem
notalpha 0 Posted August 7, 2025 Author Posted August 7, 2025 Oops. I accidentally included logs from when i accidentally started streaming in my browser, instead of the chromecast (all remux logs). --- About the browser, this is really interesting. Transcoding with HVDEC and HVENC (Default) works without issues (On firefox), and causes it to blink black every 5 seconds on Chrome. Note, it is transcoding to HLS on the browser, instead of MKV (chromecast). Firefox: Works without issues Stream MKV (79 mbps) -> HLS (119 mbps 84 fps) Converting to compatible container Recovering from playback error Video 4K Dolby Vision HEVC (HW) Main 10 153 79 mbps 23.976 fps -> Transcode (H264 119 mbps) (HW) -> Tone Mapping (Hable) Dropped Frames 0 Audio English TRUEHD 7.1 (Default) 48000 Hz -> Transcode (AAC 192 kbps) Chrome: Constantly freezes with a black screen, then resumes playing for 2 second. Repeat repeat. Stream MKV (79 mbps) -> HLS (119 mbps 286 fps) Converting audio to compatible codec Video 4K Dolby Vision HEVC (HW) Main 10 153 79 mbps 23.976 fps -> Direct Play Audio English TRUEHD 7.1 (Default) 48000 Hz -> Transcode (MP3 192 kbps)
Neminem 1518 Posted August 7, 2025 Posted August 7, 2025 Ok no worries I would guess Dev's need to answer. But I would try with a lower bit rate version of file or with a copy with out all the PGS subs in it. Just for the fun of it.
Fyn0X6F 2 Posted August 8, 2025 Posted August 8, 2025 17 hours ago, Luke said: Hi, we are looking into it. Thanks. Same issue for me when using a browser. It is fine through the apps but the browser blinks out and stalls every few seconds or just stops playing all together. I did some digging on my server and I noticed when it is playing through the browser ffmpeg is maxing out the HDD reads and that appears to be what is freezing it. When I play through the apps/theater the HDD stays around 3-4% which is normal. This started within the last week from what I can tell. Hope this helps.
Fyn0X6F 2 Posted August 8, 2025 Posted August 8, 2025 (edited) Just did another few tests and I can get it working in Firefox without stalling or stuttering and it does not max the HDD activity out but it is running 100% on the GPU (3090 FTW3 Ultra). Went back and tested it from the Theater app and GPU usage sits at 1-3% and HDD usage is 3-5%. Whatever it is doing to serve up the files to browsers is definitely off. Has the ffmpeg package been updated recently? Just guessing at this point, but that could be the root cause. Edited August 8, 2025 by Fyn0X6F
Luke 42077 Posted August 8, 2025 Posted August 8, 2025 5 hours ago, Fyn0X6F said: Has the ffmpeg package been updated recently? Just guessing at this point, but that could be the root cause. Hi, no, but we will be updating the ffmpeg build on the server beta channel in the near future, so stay tuned for that.
bandit8623 213 Posted August 9, 2025 Posted August 9, 2025 20 hours ago, Luke said: Hi, no, but we will be updating the ffmpeg build on the server beta channel in the near future, so stay tuned for that. https://www.phoronix.com/news/FFmpeg-Vulkan-AV1-Encoding 1
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