huge encoding lag on multipass set to quater resolution but not in full

B

bxq

New Member
HW: 13900KF + 5090 [596.21 driver]
OBS: version 32.1.21

issue: when setting the "Multipass Mode" to "Two Passes (Quater Resolution)" stream stutters/hitches and OBS reports +50% in "Skipped framed due to encoding lag" - basically stream has a very low fps displayed once every second or two

fix: changing "Multipass Mode" to "Two Passes (Full Resolution)" - so a bit unusual since Full is supposed to be more taxing on the GPU, works well also when set to "Single Pass" but i want to take advantage of "Two Passes"

is is some 'under the hood' magic that i don't understand or an issue with OBS or NVENC

background: streaming UHD to YouTube with AV1 in at 51000 Kbps, settings:
1777285924389.png
 
I see you're streaming 4k but why are you using the Split Encoder? I don't know what else you're encoding but Split Encoding is for 8k/60FPS or 4k/120FPS. There can only be (1) encode running when using Split Encoding so if you're encoding 4k/60FPS, disable Split Encoding.

Also, the correct Preset is P5, Multipass should be 2 Pass/qres or Disabled/1 Pass. I will also mention that B Frames are the absolute lowest quality Frame Type. 2 or 3 should be the max.....

developer.nvidia.com

Video Encoding at 8K60 with Split-Frame Encoding and NVIDIA Ada Lovelace Architecture | NVIDIA Technical Blog

Capturing video footage and playing games at 8K resolution with 60 frames per second (FPS) is now possible, thanks to advances in camera and display technologies. Major leading multimedia companies…
developer.nvidia.com developer.nvidia.com

NVIDIA Video Codec SDK 13.0 — Video Codec SDK Documentation

docs.nvidia.com docs.nvidia.com
 
  • Haha
Reactions: bxq
you might have missed my question, so again: those settings work perfectly fine for me when Mutlipass Mode is set to Single Pass or Two Passes (Full Resolution) with issue happening only on Two Passes (Quater Resolution) so setting "2 Pass/qres" is not a solution - "is it some 'under the hood' magic that i don't understand or an issue with OBS or NVENC"


also can you elaborate on the changes you've proposed?

1. Three-way split: have not had any issues with this, eg. visible seams or quality degradation, 5090 has 3 of encoders - why not use them all?
2. why "the correct Preset is P5" - again, P7 works fine and per description offers better quality at some 'speed' cost so why would i lower that setting, why P5 is "correct" and P7 is not with my spec?
3. Mutlipass Mode why "should be 2 Pass/qres or Disabled/1 Pass" if Two Passes (Full Resolution) works fine, it's the Quater Resolution that creates the "Skipped frames due to encoding lag"
4. B-Frames why 2-3 not 4 that seems to be optimal?
 
Not sure what you expect. You're not using NVENC as intended. Only (1) encoder is required for (1) 4k/60FPS encode. Split encoding has it's place & it's not what you're doing. If you add additional encodes, the GPU will automatically distribute the load evenly across the encoders. Up to (8) concurrent encodes on consumer GPU's.
 
rockbottom said:
Not sure what you expect. You're not using NVENC as intended. Only (1) encoder is required for (1) 4k/60FPS encode. Split encoding has it's place & it's not what you're doing. If you add additional encodes, the GPU will automatically distribute the load evenly across the encoders. Up to (8) concurrent encodes on consumer GPU's.
Click to expand...
the question was why "Two Passes (Quater Resolution)" causes +50% in "Skipped framed due to encoding lag" and "Two Passes (Full Resolution)" not - but I've already poked AI about it with all the data and it seems to be connected to "two different resolution buffers" that saturate the 'encoding process' even on 5090... maybe because i was using split on 3 or maybe even becuse i've added 7 b-frames
 
but since rtss / task manager reported video encoding on ~30% i thought i had headroom, apparently it's more complicated than basic metrics - will adjust the settings, thanks for chipping in
 
Disable RTSS before testing, see below.

If there's any lag remaining after the settings are corrected, post the log from the session.

Known Application Conflicts | OBS

OBS (Open Broadcaster Software) is free and open source software for video recording and live streaming. Stream to Twitch, YouTube and many other providers or record your own videos with high quality H264 / AAC encoding.
obsproject.com obsproject.com
 
so that's with three-way split
1777307965677.png


and that's with split disabled
1777308049542.png


i knew that i had it set this way for some reason but was not sure why, changed the b-frames to 4 tho
 
rockbottom said:
No lag now using the split encoder. Check
Click to expand...
huh?
as for log, nothing seems funky in there
20:46:33.233: CPU Name: 13th Gen Intel(R) Core(TM) i9-13900KF
20:46:33.233: CPU Speed: 2995MHz
20:46:33.233: Physical Cores: 24, Logical Cores: 32
20:46:33.233: Physical Memory: 65366MB Total, 51536MB Free
20:46:33.233: Windows Version: 10.0 Build 26220 (release: 25H2; revision: 8283; 64-bit)
20:46:33.233: Running as administrator: true
20:46:33.233: Windows 10/11 Gaming Features:
20:46:33.233: Game Bar: Off
20:46:33.233: Game DVR: Off
20:46:33.233: Game DVR Background Recording: Off
20:46:33.233: Game Mode: On
20:46:33.233: Sec. Software Status:
20:46:33.234: Microsoft Defender Antivirus: enabled (AV)
20:46:33.234: Windows Firewall: enabled (FW)
20:46:33.235: Current Date/Time: 2026-04-27, 20:46:33
20:46:33.235: Browser Hardware Acceleration: true
20:46:33.235: Hide OBS windows from screen capture: false
20:46:33.235: Qt Version: 6.8.3 (runtime), 6.8.3 (compiled)
20:46:33.235: Portable mode: false
20:46:33.648: OBS 32.1.2 (64-bit, windows)
20:46:33.648: ---------------------------------
20:46:33.723: ---------------------------------
20:46:33.723: audio settings reset:
20:46:33.723: samples per sec: 48000
20:46:33.723: speakers: 2
20:46:33.723: max buffering: 960 milliseconds
20:46:33.723: buffering type: dynamically increasing
20:46:33.724: ---------------------------------
20:46:33.724: Initializing D3D11...
20:46:33.724: Available Video Adapters:
20:46:33.732: Adapter 0: NVIDIA GeForce RTX 5090
20:46:33.732: Dedicated VRAM: 33750515712 (31.4 GiB)
20:46:33.732: Shared VRAM: 34270648320 (31.9 GiB)
20:46:33.732: PCI ID: 10de:2b85
20:46:33.732: HAGS Status: Enabled (Default: No, Driver status: Supported)
20:46:33.732: Driver Version: 32.0.15.9621
20:46:33.733: output 0:
20:46:33.733: name=LG TV SSCR2
20:46:33.733: pos={0, 0}
20:46:33.733: size={3840, 2160}
20:46:33.733: attached=true
20:46:33.733: refresh=60
20:46:33.733: bits_per_color=8
20:46:33.733: space=RGB_FULL_G22_NONE_P709
20:46:33.733: primaries=[r=(0.649292, 0.330595), g=(0.324212, 0.602424), b=(0.152391, 0.061202), wp=(0.312716, 0.329000)]
20:46:33.733: relative_gamut_area=[709=0.993512, P3=0.732388, 2020=0.525439]
20:46:33.733: sdr_white_nits=80
20:46:33.733: nit_range=[min=0.000000, max=80.000000, max_full_frame=80.000000]
20:46:33.733: dpi=168 (175%)
20:46:33.733: id=\\?\DISPLAY#GSM0001#5&250b84b9&0&UID4352#{e6f07b5f-ee97-4a90-b076-33f57bf4eaa7}
20:46:33.733: alt_id=\\.\DISPLAY1
20:46:33.733: Loading up D3D11 on adapter NVIDIA GeForce RTX 5090 (0)
20:46:33.819: D3D11 loaded successfully, feature level used: b000
20:46:33.819: DXGI increase maximum frame latency success
20:46:33.819: Hardware-Accelerated GPU Scheduling enabled on adapter!
20:46:33.820: D3D11 GPU priority setup success
20:46:33.869: ---------------------------------
20:46:33.869: video settings reset:
20:46:33.869: base resolution: 3840x2160
20:46:33.869: output resolution: 3840x2160
20:46:33.869: downscale filter: Bicubic
20:46:33.869: fps: 60/1
20:46:33.869: format: NV12
20:46:33.869: YUV mode: Rec. 709/Partial
20:46:33.870: NV12 texture support enabled
20:46:33.870: P010 texture support not available
20:46:33.870: Audio monitoring device:
20:46:33.870: name: Domyślne
20:46:33.870: id: default
20:46:33.872: ---------------------------------
20:46:33.874: No AJA devices found, skipping loading AJA UI plugin
20:46:33.874: Failed to initialize module 'aja-output-ui.dll'
20:46:33.875: No AJA devices found, skipping loading AJA plugin
20:46:33.875: Failed to initialize module 'aja.dll'
20:46:33.875: Skipping module '../../obs-plugins/64bit/chrome_elf.dll', not an OBS plugin
20:46:33.877: [CoreAudio encoder]: CoreAudio AAC encoder not installed on the system or couldn't be loaded
20:46:33.878: Failed to load 'en-US' text for module: 'decklink-captions.dll'
20:46:33.878: Failed to load 'en-US' text for module: 'decklink-output-ui.dll'
20:46:33.880: A DeckLink iterator could not be created. The DeckLink drivers may not be installed
20:46:33.880: Failed to initialize module 'decklink.dll'
20:46:33.897: [AMF] Unable to load 'amfrt64.dll', error code 126.
20:46:33.898: [AMF] AMF Test failed due to one or more errors.
20:46:33.898: Failed to initialize module 'enc-amf.dll'
20:46:33.902: [Python] Could not load library: C:/Users/brykk/AppData/Local/Microsoft/WindowsApps/
20:46:33.903: Skipping module '../../obs-plugins/64bit/libcef.dll', not an OBS plugin
20:46:33.903: Skipping module '../../obs-plugins/64bit/libEGL.dll', not an OBS plugin
20:46:33.903: Skipping module '../../obs-plugins/64bit/libGLESv2.dll', not an OBS plugin
20:46:33.905: [NVIDIA Audio Effects:] NVIDIA denoiser disabled, redistributable not found or could not be loaded.
20:46:33.906: Failed to get NVVideoEffects.dll version info size
20:46:33.907: [NVIDIA VIDEO FX]: FX disabled, redistributable not found or could not be loaded.
20:46:33.912: [obs-browser]: Version 2.26.8
20:46:33.912: [obs-browser]: CEF Version 127.0.6533.120 (runtime), 127.145.7+g2b7d20b+chromium-127.0.6533.120 (compiled)
20:46:34.027: [obs-nvenc] NVENC version: 12.2 (compiled) / 13.0 (driver), CUDA driver version: 13.20, AV1 supported: true
20:46:34.066: [obs-websocket] [obs_module_load] you can haz websockets (Version: 5.7.3 | RPC Version: 1)
20:46:34.066: [obs-websocket] [obs_module_load] Qt version (compile-time): 6.8.3 | Qt version (run-time): 6.8.3
20:46:34.066: [obs-websocket] [obs_module_load] Linked ASIO Version: 103200
20:46:34.069: [obs-websocket] [obs_module_load] Module loaded.
20:46:34.072: [vlc-video]: Couldn't find VLC installation, VLC video source disabled
20:46:34.078: ---------------------------------
20:46:34.078: Loaded Modules:
20:46:34.078: win-wasapi.dll
20:46:34.078: win-dshow.dll
20:46:34.078: win-capture.dll
20:46:34.078: vlc-video.dll
20:46:34.078: text-freetype2.dll
20:46:34.078: rtmp-services.dll
20:46:34.078: obs-x264.dll
20:46:34.078: obs-websocket.dll
20:46:34.078: obs-webrtc.dll
20:46:34.078: obs-vst.dll
20:46:34.078: obs-transitions.dll
20:46:34.078: obs-text.dll
20:46:34.078: obs-qsv11.dll
20:46:34.078: obs-outputs.dll
20:46:34.078: obs-nvenc.dll
20:46:34.078: obs-filters.dll
20:46:34.078: obs-ffmpeg.dll
20:46:34.078: obs-browser.dll
20:46:34.078: nv-filters.dll
20:46:34.078: logi_obs_plugin_x64.dll
20:46:34.078: image-source.dll
20:46:34.078: frontend-tools.dll
20:46:34.078: decklink-output-ui.dll
20:46:34.078: decklink-captions.dll
20:46:34.078: coreaudio-encoder.dll
20:46:34.078: ---------------------------------
20:46:34.086: ---------------------------------
20:46:34.086: Available Encoders:
20:46:34.086: Video Encoders:
20:46:34.086: - ffmpeg_svt_av1 (SVT-AV1)
20:46:34.086: - ffmpeg_aom_av1 (AOM AV1)
20:46:34.086: - obs_nvenc_h264_tex (NVIDIA NVENC H.264)
20:46:34.086: - obs_nvenc_hevc_tex (NVIDIA NVENC HEVC)
20:46:34.086: - obs_nvenc_av1_tex (NVIDIA NVENC AV1)
20:46:34.086: - obs_x264 (x264)
20:46:34.086: Audio Encoders:
20:46:34.086: - ffmpeg_aac (FFmpeg AAC)
20:46:34.086: - ffmpeg_opus (FFmpeg Opus)
20:46:34.086: - ffmpeg_pcm_s16le (FFmpeg PCM (16-bit))
20:46:34.086: - ffmpeg_pcm_s24le (FFmpeg PCM (24-bit))
20:46:34.086: - ffmpeg_pcm_f32le (FFmpeg PCM (32-bit float))
20:46:34.086: - ffmpeg_alac (FFmpeg ALAC (24-bit))
20:46:34.086: - ffmpeg_flac (FFmpeg FLAC (16-bit))
20:46:34.086: ==== Startup complete ===============================================
20:46:34.109: All scene data cleared
20:46:34.109: ------------------------------------------------
redacted
20:46:34.709: Switched to scene 'Scena'
20:46:34.709: ------------------------------------------------
20:46:34.709: Loaded scenes:
redacted
20:46:34.709: ------------------------------------------------
20:46:34.747: warning: deprecated pixel format used, make sure you did set range correctly
20:46:53.260: Uploading thumbnail file "D:/Screenshots/Screenshot (2142).jpg"...
20:46:58.904: User is ignoring service bitrate limits.
20:46:58.904: Service Recommendations:
20:46:58.904: video bitrate: 51000
20:46:58.904: audio bitrate: 160
20:46:58.924: [obs-nvenc: 'advanced_video_stream'] settings:
20:46:58.924: codec: AV1
20:46:58.924: rate_control: CBR
20:46:58.924: bitrate: 51000
20:46:58.924: keyint: 120
20:46:58.924: preset: p7
20:46:58.924: tuning: hq
20:46:58.924: multipass: fullres
20:46:58.924: profile: main
20:46:58.924: width: 3840
20:46:58.924: height: 2160
20:46:58.924: b-frames: 4
20:46:58.924: b-ref-mode: 1
20:46:58.924: lookahead: true (8 frames)
20:46:58.924: aq: true
20:46:58.924: split encode: 15
20:46:58.924:
20:46:58.995: ---------------------------------
20:46:58.995: [FFmpeg aac encoder: 'adv_stream_audio'] bitrate: 160, channels: 2, channel_layout: stereo, track: 1
20:46:58.995:
20:46:58.996: [rtmp stream: 'adv_stream'] Connecting to RTMP URL rtmps://b.rtmps.youtube.com:443/live2?backup=1...
20:46:59.033: [rtmp stream: 'adv_stream'] Interface: Killer E3100G 2.5 Gigabit Ethernet Controller (ethernet, 1000↓/1000↑ mbps)
20:46:59.691: [rtmp stream: 'adv_stream'] Connection to rtmps://b.rtmps.youtube.com:443/live2?backup=1 (172.217.171.172) successful
20:46:59.691: [rtmp stream: 'adv_stream'] Socket send buffer is 65536 bytes
20:46:59.696: ==== Streaming Start ===============================================
20:48:04.398: [rtmp stream: 'adv_stream'] User stopped the stream
20:48:04.398: [rtmp stream: 'adv_stream'] Socket send buffer is 4194304 bytes
20:48:04.398: Output 'adv_stream': stopping
20:48:04.398: Output 'adv_stream': Total frames output: 3501
20:48:04.398: Output 'adv_stream': Total drawn frames: 3924
20:48:04.398: [rtmp stream: 'adv_stream'] Freeing 1 remaining packets
20:48:04.398: Video stopped, number of skipped frames due to encoding lag: 3086/3524 (87.6%)
20:48:04.400: ==== Streaming Stop ================================================
20:48:04.786: warning: 2 frames left in the queue on closing
Click to expand...
 
Truncated log, there's no Scene information, it was redacted. For all I know, you have a house of cards in your Scene collection. Anyway, encodings settings are still wrong with lots of encoding lag. OBS isn't the issue, this is operator error.

20:48:04.398: Video stopped, number of skipped frames due to encoding lag: 3086/3524 (87.6%)
 
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