"Dropped Frames" in recording

Harpers Tate

New Member
Note: recording to PC SSD, not streaming.

I have a recorded video on another device. The recorded video is in 25/50hz ("PAL") full HD 1920x1080. And to avoid jerkiness, that is how I want to capture it. Either 50z or 25hz - full HD. The device on which it is stored is only partly functional; all it will do is play back via HDMI - with this recording as 25hz progressive (or video in SD - but I don't want that). I can't extract the file by other means.

I have an HDMI > USB external capture device which appears to work well enough. However I have a curious artefact with OBS:

I have set the capture frequency to full HD 25hz. What happens is that it will capture (and record) for a variable length of time (between a few and about 30 minutes) perfectly and then quite suddenly it will begin to repeatedly only capture alternate frames, duplicating each to keep the 25hz frequency.
In other words, watching the recording, frame by frame, I will see:
- when it's good a sequence like 1 2 3 4 5 6 7 8 9 10........
- when it suddenly misbehaves 1 1 3 3 5 5 7 7 9 9........ - duplicated alternate frames, so it plays back jerky.

If I do these things and only these things:
- rewind the video to a point before the instability began
- restart the OBS app
- recommence recording
then I will get another variable period before it fails again.

I do not think it is a glitch in the original recording, because the alternate frame capture will not begin again at the same point when recording is recommenced
I do not think it is an artefact of the capture card, because that does not need restarting to clear the problem. I only need to close and reopen OBS.
I do not think it's the encoding process, either, because I can also see the jerkiness in the OBS live preview window.

Machine is a fairly high spec laptop; i7, 16gb RAM, NVidia MX250, Win10 latest version. Processor (according to OBS) runs at 20-30% throughout.

Any help or suggestions gratefully received.

Log file for one such attempt; this one only lasted about 3 minutes before I observed a jerky live preview:

14:22:05.637: CPU Name: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
14:22:05.637: CPU Speed: 1992MHz
14:22:05.637: Physical Cores: 4, Logical Cores: 8
14:22:05.637: Physical Memory: 16198MB Total, 12806MB Free
14:22:05.637: Windows Version: 10.0 Build 19042 (release: 2009; revision: 630; 64-bit)
14:22:05.637: Running as administrator: true
14:22:05.637: Aero is Enabled (Aero is always on for windows 8 and above)
14:22:05.637: Windows 10 Gaming Features:
14:22:05.637: Game DVR: On
14:22:05.637: Hardware GPU Scheduler: On
14:22:05.639: Sec. Software Status:
14:22:05.640: Microsoft Defender Antivirus: enabled (AV)
14:22:05.640: Windows Firewall: enabled (FW)
14:22:05.641: Current Date/Time: 2020-11-14, 14:22:05
14:22:05.641: Browser Hardware Acceleration: true
14:22:05.641: Portable mode: false
14:22:06.196: OBS 26.0.2 (64-bit, windows)
14:22:06.196: ---------------------------------
14:22:06.196: ---------------------------------
14:22:06.196: audio settings reset:
14:22:06.196: samples per sec: 48000
14:22:06.196: speakers: 2
14:22:06.198: ---------------------------------
14:22:06.198: Initializing D3D11...
14:22:06.198: Available Video Adapters:
14:22:06.206: Adapter 0: NVIDIA GeForce MX250
14:22:06.206: Dedicated VRAM: 2080043008
14:22:06.206: Shared VRAM: 4197578752
14:22:06.206: PCI ID: 10de:1d52
14:22:06.206: Driver Version: 27.21.14.5730
14:22:06.206: output 0: pos={0, 0}, size={1920, 1080}, attached=true, refresh=60, name=
14:22:06.206: Adapter 1: Intel(R) UHD Graphics 620
14:22:06.206: Dedicated VRAM: 134217728
14:22:06.206: Shared VRAM: 4197578752
14:22:06.206: PCI ID: 8086:3ea0
14:22:06.207: Driver Version: 26.20.100.7870
14:22:06.211: Loading up D3D11 on adapter NVIDIA GeForce MX250 (0)
14:22:06.916: D3D11 loaded successfully, feature level used: b000
14:22:06.916: DXGI increase maximum frame latency success
14:22:06.916: D3D11 GPU priority setup success
14:22:07.277: ---------------------------------
14:22:07.277: video settings reset:
14:22:07.277: base resolution: 1920x1080
14:22:07.277: output resolution: 1920x1080
14:22:07.277: downscale filter: Bicubic
14:22:07.277: fps: 25/1
14:22:07.277: format: NV12
14:22:07.277: YUV mode: 709/Full
14:22:07.277: NV12 texture support enabled
14:22:07.279: Audio monitoring device:
14:22:07.279: name: Default
14:22:07.279: id: default
14:22:07.279: ---------------------------------
14:22:07.285: [CoreAudio encoder]: CoreAudio AAC encoder not installed on the system or couldn't be loaded
14:22:07.285: Failed to load 'en-US' text for module: 'decklink-ouput-ui.dll'
14:22:07.317: [AMF] Unable to load 'amfrt64.dll', error code 126.
14:22:07.319: [AMF] AMF Test failed due to one or more errors.
14:22:07.319: Failed to initialize module 'enc-amf.dll'
14:22:07.336: [obs-browser]: Version 2.8.7
14:22:07.369: VLC found, VLC video source enabled
14:22:07.377: A DeckLink iterator could not be created. The DeckLink drivers may not be installed
14:22:07.378: No blackmagic support
14:22:07.383: ---------------------------------
14:22:07.383: Loaded Modules:
14:22:07.383: win-wasapi.dll
14:22:07.383: win-mf.dll
14:22:07.383: win-dshow.dll
14:22:07.383: win-decklink.dll
14:22:07.383: win-capture.dll
14:22:07.383: vlc-video.dll
14:22:07.383: text-freetype2.dll
14:22:07.383: rtmp-services.dll
14:22:07.383: obs-x264.dll
14:22:07.383: obs-vst.dll
14:22:07.383: obs-transitions.dll
14:22:07.383: obs-text.dll
14:22:07.383: obs-qsv11.dll
14:22:07.383: obs-outputs.dll
14:22:07.383: obs-filters.dll
14:22:07.383: obs-ffmpeg.dll
14:22:07.383: obs-browser.dll
14:22:07.383: image-source.dll
14:22:07.383: frontend-tools.dll
14:22:07.383: enc-amf.dll
14:22:07.383: decklink-ouput-ui.dll
14:22:07.383: coreaudio-encoder.dll
14:22:07.383: ---------------------------------
14:22:07.383: ==== Startup complete ===============================================
14:22:07.389: All scene data cleared
14:22:07.389: ------------------------------------------------
14:22:07.435: WASAPI: Device 'Microphone (USB3.0 HD Audio Capture)' [48000 Hz] initialized
14:22:07.435: [Loaded global audio device]: 'Mic/Aux'
14:22:07.445: WASAPI: Device 'Microphone (USB3.0 HD Audio Capture)' [48000 Hz] initialized
14:22:07.463: adding 42 milliseconds of audio buffering, total audio buffering is now 42 milliseconds (source: Mic/Aux)
14:22:07.463:
14:22:07.571: Switched to scene 'Scene'
14:22:07.571: ------------------------------------------------
14:22:07.571: Loaded scenes:
14:22:07.571: - scene 'Scene':
14:22:07.571: - source: 'Video Capture Device' (dshow_input)
14:22:07.571: - source: 'Audio Input Capture' (wasapi_input_capture)
14:22:07.571: - monitoring: monitor and output
14:22:07.571: ------------------------------------------------
14:22:08.104: ---------------------------------
14:22:08.104: [DShow Device: 'Video Capture Device'] settings updated:
14:22:08.104: video device: USB3.0 HD Video Capture
14:22:08.104: video path: \\?\usb#vid_eba4&pid_7588&mi_02#6&31cbce1e&0&0002#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global
14:22:08.104: resolution: 1920x1080
14:22:08.104: flip: 0
14:22:08.104: fps: 60.00 (interval: 166666)
14:22:08.104: format: MJPEG
14:22:08.386: using video device audio: no
14:22:08.386: audio device: Microphone (USB3.0 HD Audio Capture)
14:22:08.386: sample rate: 0
14:22:08.386: channels: 0
14:22:08.386: audio type: DirectSound
14:22:14.781: ---------------------------------
14:22:14.781: [x264 encoder: 'recording_h264'] preset: veryfast
14:22:14.781: [x264 encoder: 'recording_h264'] profile: high
14:22:14.781: [x264 encoder: 'recording_h264'] settings:
14:22:14.781: rate_control: VBR
14:22:14.781: bitrate: 6000
14:22:14.781: buffer size: 0
14:22:14.781: crf: 7
14:22:14.781: fps_num: 25
14:22:14.781: fps_den: 1
14:22:14.781: width: 1920
14:22:14.781: height: 1080
14:22:14.781: keyint: 250
14:22:14.781:
14:22:14.781: [x264 encoder: 'recording_h264'] VBV maxrate specified, but no bufsize, ignored
14:22:14.781:
14:22:14.784: ---------------------------------
14:22:14.785: [FFmpeg aac encoder: 'Track1'] bitrate: 320, channels: 2, channel_layout: 3
14:22:14.785:
14:22:14.802: ==== Recording Start ===============================================
14:22:14.802: [ffmpeg muxer: 'adv_file_output'] Writing file 'C:/Users/NSSAS/Videos/2020-11-14 14-22-14.mp4'...
14:34:25.094: [ffmpeg muxer: 'adv_file_output'] Output of file 'C:/Users/NSSAS/Videos/2020-11-14 14-22-14.mp4' stopped
14:34:25.094: Output 'adv_file_output': stopping
14:34:25.094: Output 'adv_file_output': Total frames output: 18231
14:34:25.094: Output 'adv_file_output': Total drawn frames: 18257
14:34:25.095: ==== Recording Stop ================================================
14:34:25.134: warning: 2 frames left in the queue on closing
14:34:26.573: ==== Shutting down ==================================================
14:34:26.857: WASAPI: Device 'Microphone (USB3.0 HD Audio Capture)' Terminated
14:34:26.861: WASAPI: Device 'Microphone (USB3.0 HD Audio Capture)' Terminated
14:34:26.863: All scene data cleared
14:34:26.863: ------------------------------------------------
14:34:26.965: [Scripting] Total detached callbacks: 0
14:34:26.967: Freeing OBS context data
14:34:26.992: == Profiler Results =============================
14:34:26.992: run_program_init: 2146.52 ms
14:34:26.992: ┣OBSApp::AppInit: 15.518 ms
14:34:26.992: ┃ ┗OBSApp::InitLocale: 1.142 ms
14:34:26.992: ┗OBSApp::OBSInit: 2058.44 ms
14:34:26.992: ┣obs_startup: 3.738 ms
14:34:26.992: ┗OBSBasic::OBSInit: 1499.15 ms
14:34:26.992: ┣OBSBasic::InitBasicConfig: 0.318 ms
14:34:26.992: ┣OBSBasic::ResetAudio: 0.137 ms
14:34:26.992: ┣OBSBasic::ResetVideo: 1082.68 ms
14:34:26.992: ┣OBSBasic::InitOBSCallbacks: 0.007 ms
14:34:26.992: ┣OBSBasic::InitHotkeys: 0.057 ms
14:34:26.992: ┣obs_load_all_modules: 103.644 ms
14:34:26.992: ┃ ┣obs_init_module(coreaudio-encoder.dll): 1.757 ms
14:34:26.992: ┃ ┣obs_init_module(decklink-ouput-ui.dll): 0.527 ms
14:34:26.992: ┃ ┣obs_init_module(enc-amf.dll): 31.998 ms
14:34:26.992: ┃ ┣obs_init_module(frontend-tools.dll): 4.413 ms
14:34:26.992: ┃ ┣obs_init_module(image-source.dll): 0.006 ms
14:34:26.992: ┃ ┣obs_init_module(obs-browser.dll): 0.254 ms
14:34:26.992: ┃ ┣obs_init_module(obs-ffmpeg.dll): 0.288 ms
14:34:26.992: ┃ ┃ ┗nvenc_check: 0.279 ms
14:34:26.992: ┃ ┣obs_init_module(obs-filters.dll): 0.02 ms
14:34:26.992: ┃ ┣obs_init_module(obs-outputs.dll): 0.007 ms
14:34:26.992: ┃ ┣obs_init_module(obs-qsv11.dll): 6.704 ms
14:34:26.992: ┃ ┣obs_init_module(obs-text.dll): 0.216 ms
14:34:26.992: ┃ ┣obs_init_module(obs-transitions.dll): 0.01 ms
14:34:26.992: ┃ ┣obs_init_module(obs-vst.dll): 0.001 ms
14:34:26.992: ┃ ┣obs_init_module(obs-x264.dll): 0.002 ms
14:34:26.992: ┃ ┣obs_init_module(rtmp-services.dll): 1.107 ms
14:34:26.992: ┃ ┣obs_init_module(text-freetype2.dll): 0.074 ms
14:34:26.992: ┃ ┣obs_init_module(vlc-video.dll): 1.517 ms
14:34:26.992: ┃ ┣obs_init_module(win-capture.dll): 2.553 ms
14:34:26.992: ┃ ┣obs_init_module(win-decklink.dll): 4.386 ms
14:34:26.992: ┃ ┣obs_init_module(win-dshow.dll): 1.475 ms
14:34:26.992: ┃ ┣obs_init_module(win-mf.dll): 0 ms
14:34:26.992: ┃ ┣obs_init_module(win-wasapi.dll): 0.005 ms
14:34:26.992: ┃ ┗reset_win32_symbol_paths: 0.269 ms
14:34:26.992: ┣OBSBasic::ResetOutputs: 0.512 ms
14:34:26.992: ┣OBSBasic::CreateHotkeys: 0.056 ms
14:34:26.992: ┣OBSBasic::InitService: 2.026 ms
14:34:26.992: ┣OBSBasic::InitPrimitives: 0.111 ms
14:34:26.992: ┗OBSBasic::Load: 187.66 ms
14:34:26.992: obs_hotkey_thread(25 ms): min=0.002 ms, median=0.007 ms, max=0.469 ms, 99th percentile=0.14 ms, 100% below 25 ms
14:34:26.992: audio_thread(Audio): min=0 ms, median=0.538 ms, max=3.308 ms, 99th percentile=1.254 ms
14:34:26.992: ┗receive_audio: min=0.003 ms, median=0.473 ms, max=2.951 ms, 99th percentile=1 ms
14:34:26.992: ┣buffer_audio: min=0 ms, median=0.001 ms, max=0.13 ms, 99th percentile=0.002 ms
14:34:26.992: ┗do_encode: min=0.027 ms, median=0.468 ms, max=2.947 ms, 99th percentile=0.993 ms
14:34:26.992: ┗encode(Track1): min=0.023 ms, median=0.429 ms, max=2.933 ms, 99th percentile=0.905 ms
14:34:26.992: obs_graphics_thread(40 ms): min=0.071 ms, median=2.034 ms, max=129.578 ms, 99th percentile=3.73 ms, 99.9946% below 40 ms
14:34:26.992: ┣tick_sources: min=0.002 ms, median=0.008 ms, max=129.453 ms, 99th percentile=0.03 ms
14:34:26.992: ┣output_frame: min=0.045 ms, median=1.281 ms, max=7.573 ms, 99th percentile=2.759 ms
14:34:26.992: ┃ ┣gs_context(video->graphics): min=0.045 ms, median=0.797 ms, max=7.573 ms, 99th percentile=1.877 ms
14:34:26.992: ┃ ┃ ┣render_video: min=0.005 ms, median=0.571 ms, max=7.412 ms, 99th percentile=1.585 ms
14:34:26.992: ┃ ┃ ┃ ┣render_main_texture: min=0.003 ms, median=0.551 ms, max=7.409 ms, 99th percentile=1.547 ms
14:34:26.993: ┃ ┃ ┃ ┣render_convert_texture: min=0.006 ms, median=0.008 ms, max=0.147 ms, 99th percentile=0.033 ms
14:34:26.993: ┃ ┃ ┃ ┗stage_output_texture: min=0.002 ms, median=0.003 ms, max=0.223 ms, 99th percentile=0.022 ms
14:34:26.993: ┃ ┃ ┣gs_flush: min=0.037 ms, median=0.205 ms, max=0.693 ms, 99th percentile=0.391 ms
14:34:26.993: ┃ ┃ ┗download_frame: min=0 ms, median=0.002 ms, max=0.178 ms, 99th percentile=0.02 ms
14:34:26.993: ┃ ┗output_video_data: min=0.314 ms, median=0.46 ms, max=1.649 ms, 99th percentile=1.058 ms
14:34:26.993: ┗render_displays: min=0 ms, median=0.708 ms, max=21.32 ms, 99th percentile=1.218 ms
14:34:26.993: video_thread(video): min=1.234 ms, median=1.584 ms, max=11.543 ms, 99th percentile=2.629 ms
14:34:26.993: ┗receive_video: min=1.232 ms, median=1.582 ms, max=11.541 ms, 99th percentile=2.627 ms
14:34:26.993: ┗do_encode: min=1.231 ms, median=1.581 ms, max=11.539 ms, 99th percentile=2.625 ms
14:34:26.993: ┗encode(recording_h264): min=1.181 ms, median=1.488 ms, max=9.236 ms, 99th percentile=2.537 ms
14:34:26.993: =================================================
14:34:26.993: == Profiler Time Between Calls ==================
14:34:26.993: obs_hotkey_thread(25 ms): min=24.929 ms, median=25.924 ms, max=26.584 ms, 14.1399% within ±2% of 25 ms (0% lower, 85.8601% higher)
14:34:26.993: obs_graphics_thread(40 ms): min=30.416 ms, median=40 ms, max=129.585 ms, 99.9892% within ±2% of 40 ms (0.00540862% lower, 0.00540862% higher)
14:34:26.993: =================================================
14:34:27.068: Number of memory leaks: 0
 
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