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Created page with "When using video in your experiment, especially when presenting time-critical stimuli, special care should be taken to optimize the video and audio settings on multiple levels..."
When using video in your experiment, especially when presenting time-critical stimuli, special care should be taken to optimize the video and audio settings on multiple levels (hardware, OS, script), as many things can go wrong along the way.
This page outlines some best practices; however, we advise to always consult a TSG member if you plan to run a video experiment in the labs.
==Recording==
When recording video for stimulus material or as input for your experiment, please:
Use a high-quality camera, with settings appropriate for your application (e.g., frame rate, resolution).
Use a high-quality recorder or capture device, capable of recording at 1080p (1920×1080) and 60fps or higher.
Stabilize the camera and avoid automatic exposure, white balance, or focus during recording to prevent inconsistencies.
Record in a controlled environment with consistent lighting and minimal background distractions.
You can use the facecam for high quality video recording.
==Editing==
We recommend using DaVinci Resolve for editing and converting video files. DaVinci Resolve is a free, professional-grade editing program, available here: https://www.blackmagicdesign.com/products/davinciresolve
Alternatively, you can use Shotcut, a simple open-source editor, available here: https://shotcut.org/
===Video Settings===
We recommend using the following settings:
File format: .mp4 (H.264 codec(libx264))
Frame rate: 60 fps (frames per second)
Resolution: 1920×1080 (Full HD) or match your experiment's display settings
Bitrate: 10-20 Mbps for Full HD video
Constant Frame Rate (CFR): Always enforce a constant frame rate.
Example: -vsync cfr in ffmpeg.
The [[Lab Computer]] displays are typically set to 1920×1080 at 120Hz. We found that this is sufficient for most applications. There are possibilities to go higher.
==Windows Settings==
Windows 10 has a habit of automatically enabling '''video enhancements''' or unnecessary processing features, which can interfere with smooth playback. Therefore, please make sure these are disabled:
Open Settings → System → Display → Graphics Settings.
If available, disable "Hardware-accelerated GPU scheduling" for critical timing experiments.
For specific applications (e.g., PsychoPy), under "Graphics Performance Preference," set them to "High Performance" to ensure they use the dedicated GPU.
==Playback==
=== PsychoPy ===
This is an example of a Python script that plays a .mp4 video file with high time accuracy. <syntaxhighlight lang="python" line> from psychopy import visual, core, prefs prefs.hardware['videoLib'] = ['avbin', 'ffpyplayer'] # Choose based on installed libraries
Create a window
win = visual.Window(fullscr=True, monitor="testMonitor", units="pix")
Path to video file
video_file = "stimulus.mp4"
Load video
movie = visual.MovieStim3(win, video_file, size=(1920, 1080), flipVert=False, flipHoriz=False, loop=False)
Play video
while movie.status != visual.FINISHED: movie.draw() win.flip()
Close window
win.close() core.quit() </syntaxhighlight>
This page outlines some best practices; however, we advise to always consult a TSG member if you plan to run a video experiment in the labs.
==Recording==
When recording video for stimulus material or as input for your experiment, please:
Use a high-quality camera, with settings appropriate for your application (e.g., frame rate, resolution).
Use a high-quality recorder or capture device, capable of recording at 1080p (1920×1080) and 60fps or higher.
Stabilize the camera and avoid automatic exposure, white balance, or focus during recording to prevent inconsistencies.
Record in a controlled environment with consistent lighting and minimal background distractions.
You can use the facecam for high quality video recording.
==Editing==
We recommend using DaVinci Resolve for editing and converting video files. DaVinci Resolve is a free, professional-grade editing program, available here: https://www.blackmagicdesign.com/products/davinciresolve
Alternatively, you can use Shotcut, a simple open-source editor, available here: https://shotcut.org/
===Video Settings===
We recommend using the following settings:
File format: .mp4 (H.264 codec(libx264))
Frame rate: 60 fps (frames per second)
Resolution: 1920×1080 (Full HD) or match your experiment's display settings
Bitrate: 10-20 Mbps for Full HD video
Constant Frame Rate (CFR): Always enforce a constant frame rate.
Example: -vsync cfr in ffmpeg.
The [[Lab Computer]] displays are typically set to 1920×1080 at 120Hz. We found that this is sufficient for most applications. There are possibilities to go higher.
==Windows Settings==
Windows 10 has a habit of automatically enabling '''video enhancements''' or unnecessary processing features, which can interfere with smooth playback. Therefore, please make sure these are disabled:
Open Settings → System → Display → Graphics Settings.
If available, disable "Hardware-accelerated GPU scheduling" for critical timing experiments.
For specific applications (e.g., PsychoPy), under "Graphics Performance Preference," set them to "High Performance" to ensure they use the dedicated GPU.
==Playback==
=== PsychoPy ===
This is an example of a Python script that plays a .mp4 video file with high time accuracy. <syntaxhighlight lang="python" line> from psychopy import visual, core, prefs prefs.hardware['videoLib'] = ['avbin', 'ffpyplayer'] # Choose based on installed libraries
Create a window
win = visual.Window(fullscr=True, monitor="testMonitor", units="pix")
Path to video file
video_file = "stimulus.mp4"
Load video
movie = visual.MovieStim3(win, video_file, size=(1920, 1080), flipVert=False, flipHoriz=False, loop=False)
Play video
while movie.status != visual.FINISHED: movie.draw() win.flip()
Close window
win.close() core.quit() </syntaxhighlight>