P.dewater: /* Recommended FFmpeg Command */

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.

==Video playback==

=== Python ===
Example demonstrating how to play a video with audio:
<syntaxhighlight lang="python" line>
from psychopy import logging, prefs
prefs.hardware['audioLib'] = ['PTB']
prefs.hardware['audioLatencyMode'] = 2

from psychopy import visual, core, event
from psychopy.hardware import keyboard

# File paths for video and audio
video_file = "tick_rhythm_combined_30min.mp4"

win = visual.Window(size=(1024, 768), fullscr=False, color=(0, 0, 0))

video = visual.VlcMovieStim(
win, filename=video_file,
autoStart= False
)

kb = keyboard.Keyboard()

# Play the video
win.flip()
core.wait(3.0)
video.play()
video_start_time = core.getTime()

# Main loop for video playback
while video.status != visual.FINISHED:
# Draw the current video frame
video.draw()
win.flip()

keys = kb.getKeys(['q'], waitRelease=True)
if 'q' in keys:
break

win.close()
core.quit()
</syntaxhighlight>

Example demonstrating how to play a video with audio disconected:
<syntaxhighlight lang="python" line>
from psychopy import logging, prefs
from psychopy import visual, core, sound, event
import time

prefs.hardware['audioLib'] = ['PTB']
prefs.hardware['audioLatencyMode'] = 2

# File paths for video and audio
video_file = "tick_rhythm_30min.mp4"
audio_file = "tick_rhythm_30min.wav"

win = visual.Window(size=(1280, 720), fullscr=False, color=(0, 0, 0), units="pix")

video = visual.VlcMovieStim(
win, filename=video_file,
size=None, # Use the native video size
pos=[0, 0],
flipVert=False,
flipHoriz=False,
loop=False,
autoStart=False,
noAudio=True,
volume=100,
name='myMovie'
)

# Load the audio
audio = sound.Sound(audio_file, -1)

# Synchronize audio and video playback
win.flip()
time.sleep(5)

audio.play()
time.sleep(0.04)
video.play()
video_start_time = core.getTime()

while video.status != visual.FINISHED:
# Draw the current video frame
video.draw()
win.flip()

# Check for keypress to quit
if "q" in event.getKeys():
audio.stop()
break

# Close the PsychoPy window
win.close()
core.quit()

</syntaxhighlight>

Example demonstrating how to disconnect audio from video:
<syntaxhighlight lang="python" line>
import os
import subprocess

input_file = 'tick_rhythm_combined_1min.mp4'

directory = os.path.dirname(input_file)
base_name = os.path.splitext(os.path.basename(input_file))[0]

output_video = os.path.join(directory, f"{base_name}_video_only.mp4")
output_audio = os.path.join(directory, f"{base_name}_audio_only.wav")

subprocess.run(['ffmpeg', '-i', input_file, '-an', output_video])

subprocess.run(['ffmpeg', '-i', input_file, '-vn', '-acodec', 'pcm_s16le', '-ar', '44100', output_audio])

print(f"Video saved to: {output_video}")
print(f"Audio saved to: {output_audio}")
</syntaxhighlight>

Example demonstrating how to combine audio and video:
<syntaxhighlight lang="python" line>
import os
import subprocess

# --- Inputs
video_file = 'tick_rhythm_combined_1min_video_only.mp4' # Your video-only file
audio_file = 'mic_segment.wav' # Your trimmed audio
output_file = 'final_synced_output.mp4' # Output file name

# --- FFmpeg command to combine
subprocess.run([
'ffmpeg',
'-i', video_file,
'-i', audio_file,
'-c:v', 'copy', # Copy video stream as-is
'-c:a', 'aac', # Encode audio with AAC (widely compatible)
'-shortest', # Trim to the shortest stream (prevents overhang)
output_file
])

print(f"Synchronized video saved to: {output_file}")

</syntaxhighlight>

==Video encoding==
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.

===Video Settings===
We recommend using the following settings:
{| class="wikitable"
|-
!File format
|.mp4 (H.264 codec(libx264)) ik wil hier een link naar de dll?
|-
!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)
|enforce a constant frame rate
|-
|}

===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:

right click background → Display settings → 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.

=== Python ===
Example demonstrating how to record a video with a facecam:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10
# -*- coding: utf-8 -*-

import datetime
import cv2
import ctypes
import ffmpegcv

#set sleep to 1ms accuracy
winmm = ctypes.WinDLL('winmm')
winmm.timeBeginPeriod(1)

def configure_webcam(cam_id, width=1920, height=1080, fps=60):
cap = cv2.VideoCapture(cam_id, cv2.CAP_DSHOW)
if not cap.isOpened():
print(f"Error: Couldn't open webcam {cam_id}.")
return None

# Try to set each property
cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
cap.set(cv2.CAP_PROP_FPS, fps)

# Read back the values
actual_width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
actual_height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
actual_fps = cap.get(cv2.CAP_PROP_FPS)

print(f"Resolution set to: {actual_width}x{actual_height}")
print(f"FPS set to: {actual_fps}")

return cap

def getWebcamData():
global frame_width
global frame_height

print("opening webcam...")
camera = configure_webcam(1, frame_width, frame_height)
time_stamp = datetime.datetime.now().strftime('%Y-%m-%d %H-%M-%S')
file_name = time_stamp +'_output.avi'
video_writer = ffmpegcv.VideoWriter(file_name, 'h264', fps=freq)

while True:
grabbed = camera.grab()
if grabbed:
grabbed, frame = camera.retrieve()

video_writer.write(frame) # Write the video to the file system

frame = cv2.resize(frame, (int(frame_width/4),int(frame_height/4)))
cv2.imshow("Frame", frame) # show the frame to our screen

if cv2.waitKey(1) & 0xFF == ord('q'):
break

freq = 60
frame_width = 1920
frame_height = 1080

getWebcamData()

cv2.destroyAllWindows()
</syntaxhighlight>

==Audio encoding==
===Audio Settings===
We recommend using the following settings for audio:
{| class="wikitable"
|-
!Codec
|lossless or high-quality codecs
|-
!PCM (WAV)
|uncompressed
|-
!Sample Rate
|48 kHz
|-
|}

Set your audio for low-latency, high-accuracy playback with ffmpeg:
<pre>
ffmpeg -i input.wav -ar 48000 -ac 2 -sample_fmt s16 output_fixed.wav

Explanation:
-ar 48000 → Set sample rate to 48000 Hz (standard for ASIO/Windows audio, matches most soundcards)
-ac 2 → Set 2 channels (stereo)
-sample_fmt s16 → Use 16-bit signed integer samples

</pre>

===Windows Settings===
Windows 10 Settings to check
<pre>
sound → Playback → right-click → Properties → Advanced Tab:

- Set Default Format to 48000 Hz, 16 bit, Studio Quality.

- Disable sound enhancements.

- In the same properties window, go to Enhancements tab → Disable all enhancements.

- Exclusive Mode:

- In the same Advanced tab.

- Allow applications to take exclusive control of this device → CHECKED

- Give exclusive mode applications priority → CHECKED
</pre>

=== Python ===
Example demonstrating how to check and play your audio:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10

import psychopy
print(psychopy.__version__)
import sys
print(sys.version)

import keyboard
from psychopy import prefs
from psychopy import visual, core, event

from psychopy.sound import backend_ptb
# 0: No special settings (default, not optimized)
# 1: Try low-latency but allow some delay
# 2: Aggressive low-latency
# 3: Exclusive mode, lowest latency but may not work on all systems
backend_ptb.SoundPTB.latencyMode = 2

prefs.hardware['audioLib'] = ['PTB']
prefs.hardware['audioDriver'] = ['ASIO']
prefs.hardware['audioDevice'] = ['ASIO4ALL v2']
from psychopy import sound

# --- OS-level audio device sample rate ---
default_output = sd.query_devices(kind='output')
print("\nDefault output device info (OS level):")
print(f" Name: {default_output['name']}")
print(f" Default Sample Rate: {default_output['default_samplerate']} Hz")
print(f" Max Output Channels: {default_output['max_output_channels']}")

# Confirm the audio library and output settings
print(f"Using {sound.audioLib} for sound playback.")
print(f"Audio library options: {prefs.hardware['audioLib']}")
print(f"Audio driver: {prefs.hardware.get('audioDriver', 'Default')}")
print(f"Audio device: {prefs.hardware.get('audioDevice', 'Default')}")

audio_file = 'tick_rhythm_5min.wav'

print("Creating sound...")
wave_file = sound.Sound(audio_file)

print("Playing sound...")
wave_file.play()

while not keyboard.is_pressed('q'):
pass

# Clean up
print("Exiting...")
win.close()
core.quit()

</syntaxhighlight>

==FFmpeg==
===Synchronization===
Ensure the audio and video streams have consistent timestamps:

FFmpeg Options:

<pre>
-fflags +genpts: Generates accurate presentation timestamps (PTS) for the video.

-async 1: Synchronizes audio and video when they drift.

-map 0:v:0 and -map 0:a:0: Explicitly map video and audio streams to avoid accidental mismatches.
</pre>

=== Python ===
Example demonstrating how to use ffmpeg:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10
# -*- coding: utf-8 -*-
</syntaxhighlight>

===Recommended FFmpeg Command===
Here’s a command that encodes video and audio while maintaining high time accuracy:
<pre>
ffmpeg -i input.mp4 -c:v libx264 -preset slow -crf 18 -vsync cfr -g 30 -c:a pcm_s16le -ar 44100 -fflags +genpts -async 1 output.mp4
-c:v libx264: Encode video using H.264.
-preset slow: Optimize for quality and compression efficiency.
-crf 18: Adjusts quality (lower = better; range: 0–51).
-vsync cfr: Enforces constant frame rate.
-c:a pcm_s16le: Encodes audio in uncompressed WAV format.
-ar 48000: Sets audio sample rate to 48.0 kHz.
-fflags +genpts: Ensures accurate timestamps.
-async 1: Synchronizes audio and video streams.
</pre>

===Tips===
• Ensure Low Latency: If you're processing video/audio in real time, use low-latency settings (e.g., -tune zerolatency for H.264).
• Avoid Resampling: If possible, use the original frame rate and sample rate to avoid timing mismatches.
• Testing: Always test playback on different devices or players to confirm synchronization.

Alternatively, you can use Shotcut, a simple open-source editor, available here: https://shotcut.org/

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.

==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

==Playback==

=== PsychoPy ===
Example demonstrating how to play a video:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10
# -*- coding: utf-8 -*-

import time
import keyboard
from psychopy import visual
from psychopy import core

## Setup Section
win = visual.Window([720,720], fullscr=False, monitor="testMonitor", units='cm')

# append this stimulus to the list of prepared stimuli
vlc_movies = []
my_movies = ['YourMovie.mp4']#path to your movies from this directory

for movie in my_movies:
mov = visual.VlcMovieStim(win, movie,
size=600, # set as `None` to use the native video size
pos=[0, 0], # pos specifies the /center/ of the movie stim location
flipVert=False, # flip the video picture vertically
flipHoriz=False, # flip the video picture horizontally
loop=False, # replay the video when it reaches the end
autoStart=True) # start the video automatically when first drawn
vlc_movies.append(mov)

print("playing video....")
while not(keyboard.is_pressed('q')) and vlc_movies[0].status != visual.FINISHED:
vlc_movies[0].draw()
win.flip()
buffer_in = vlc_movies[0].frameIndex
print(vlc_movies[0].status)

print("Stop")

## Closing Section
core.quit()
</syntaxhighlight>

Video Playback

2025-04-28T14:38:07Z

P.dewater: /* Recommended FFmpeg Command */

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.

==Video playback==

=== Python ===
Example demonstrating how to play a video with audio:
<syntaxhighlight lang="python" line>
from psychopy import logging, prefs
prefs.hardware['audioLib'] = ['PTB']
prefs.hardware['audioLatencyMode'] = 2

from psychopy import visual, core, event
from psychopy.hardware import keyboard

# File paths for video and audio
video_file = "tick_rhythm_combined_30min.mp4"

win = visual.Window(size=(1024, 768), fullscr=False, color=(0, 0, 0))

video = visual.VlcMovieStim(
win, filename=video_file,
autoStart= False
)

kb = keyboard.Keyboard()

# Play the video
win.flip()
core.wait(3.0)
video.play()
video_start_time = core.getTime()

# Main loop for video playback
while video.status != visual.FINISHED:
# Draw the current video frame
video.draw()
win.flip()

keys = kb.getKeys(['q'], waitRelease=True)
if 'q' in keys:
break

win.close()
core.quit()
</syntaxhighlight>

Example demonstrating how to play a video with audio disconected:
<syntaxhighlight lang="python" line>
from psychopy import logging, prefs
from psychopy import visual, core, sound, event
import time

prefs.hardware['audioLib'] = ['PTB']
prefs.hardware['audioLatencyMode'] = 2

# File paths for video and audio
video_file = "tick_rhythm_30min.mp4"
audio_file = "tick_rhythm_30min.wav"

win = visual.Window(size=(1280, 720), fullscr=False, color=(0, 0, 0), units="pix")

video = visual.VlcMovieStim(
win, filename=video_file,
size=None, # Use the native video size
pos=[0, 0],
flipVert=False,
flipHoriz=False,
loop=False,
autoStart=False,
noAudio=True,
volume=100,
name='myMovie'
)

# Load the audio
audio = sound.Sound(audio_file, -1)

# Synchronize audio and video playback
win.flip()
time.sleep(5)

audio.play()
time.sleep(0.04)
video.play()
video_start_time = core.getTime()

while video.status != visual.FINISHED:
# Draw the current video frame
video.draw()
win.flip()

# Check for keypress to quit
if "q" in event.getKeys():
audio.stop()
break

# Close the PsychoPy window
win.close()
core.quit()

</syntaxhighlight>

Example demonstrating how to disconnect audio from video:
<syntaxhighlight lang="python" line>
import os
import subprocess

input_file = 'tick_rhythm_combined_1min.mp4'

directory = os.path.dirname(input_file)
base_name = os.path.splitext(os.path.basename(input_file))[0]

output_video = os.path.join(directory, f"{base_name}_video_only.mp4")
output_audio = os.path.join(directory, f"{base_name}_audio_only.wav")

subprocess.run(['ffmpeg', '-i', input_file, '-an', output_video])

subprocess.run(['ffmpeg', '-i', input_file, '-vn', '-acodec', 'pcm_s16le', '-ar', '44100', output_audio])

print(f"Video saved to: {output_video}")
print(f"Audio saved to: {output_audio}")
</syntaxhighlight>

Example demonstrating how to combine audio and video:
<syntaxhighlight lang="python" line>
import os
import subprocess

# --- Inputs
video_file = 'tick_rhythm_combined_1min_video_only.mp4' # Your video-only file
audio_file = 'mic_segment.wav' # Your trimmed audio
output_file = 'final_synced_output.mp4' # Output file name

# --- FFmpeg command to combine
subprocess.run([
'ffmpeg',
'-i', video_file,
'-i', audio_file,
'-c:v', 'copy', # Copy video stream as-is
'-c:a', 'aac', # Encode audio with AAC (widely compatible)
'-shortest', # Trim to the shortest stream (prevents overhang)
output_file
])

print(f"Synchronized video saved to: {output_file}")

</syntaxhighlight>

==Video encoding==
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.

===Video Settings===
We recommend using the following settings:
{| class="wikitable"
|-
!File format
|.mp4 (H.264 codec(libx264)) ik wil hier een link naar de dll?
|-
!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)
|enforce a constant frame rate
|-
|}

===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:

right click background → Display settings → 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.

=== Python ===
Example demonstrating how to record a video with a facecam:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10
# -*- coding: utf-8 -*-

import datetime
import cv2
import ctypes
import ffmpegcv

#set sleep to 1ms accuracy
winmm = ctypes.WinDLL('winmm')
winmm.timeBeginPeriod(1)

def configure_webcam(cam_id, width=1920, height=1080, fps=60):
cap = cv2.VideoCapture(cam_id, cv2.CAP_DSHOW)
if not cap.isOpened():
print(f"Error: Couldn't open webcam {cam_id}.")
return None

# Try to set each property
cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
cap.set(cv2.CAP_PROP_FPS, fps)

# Read back the values
actual_width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
actual_height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
actual_fps = cap.get(cv2.CAP_PROP_FPS)

print(f"Resolution set to: {actual_width}x{actual_height}")
print(f"FPS set to: {actual_fps}")

return cap

def getWebcamData():
global frame_width
global frame_height

print("opening webcam...")
camera = configure_webcam(1, frame_width, frame_height)
time_stamp = datetime.datetime.now().strftime('%Y-%m-%d %H-%M-%S')
file_name = time_stamp +'_output.avi'
video_writer = ffmpegcv.VideoWriter(file_name, 'h264', fps=freq)

while True:
grabbed = camera.grab()
if grabbed:
grabbed, frame = camera.retrieve()

video_writer.write(frame) # Write the video to the file system

frame = cv2.resize(frame, (int(frame_width/4),int(frame_height/4)))
cv2.imshow("Frame", frame) # show the frame to our screen

if cv2.waitKey(1) & 0xFF == ord('q'):
break

freq = 60
frame_width = 1920
frame_height = 1080

getWebcamData()

cv2.destroyAllWindows()
</syntaxhighlight>

==Audio encoding==
===Audio Settings===
We recommend using the following settings for audio:
{| class="wikitable"
|-
!Codec
|lossless or high-quality codecs
|-
!PCM (WAV)
|uncompressed
|-
!Sample Rate
|48 kHz
|-
|}

Set your audio for low-latency, high-accuracy playback with ffmpeg:
<pre>
ffmpeg -i input.wav -ar 48000 -ac 2 -sample_fmt s16 output_fixed.wav

Explanation:
-ar 48000 → Set sample rate to 48000 Hz (standard for ASIO/Windows audio, matches most soundcards)
-ac 2 → Set 2 channels (stereo)
-sample_fmt s16 → Use 16-bit signed integer samples

</pre>

===Windows Settings===
Windows 10 Settings to check
<pre>
sound → Playback → right-click → Properties → Advanced Tab:

- Set Default Format to 48000 Hz, 16 bit, Studio Quality.

- Disable sound enhancements.

- In the same properties window, go to Enhancements tab → Disable all enhancements.

- Exclusive Mode:

- In the same Advanced tab.

- Allow applications to take exclusive control of this device → CHECKED

- Give exclusive mode applications priority → CHECKED
</pre>

=== Python ===
Example demonstrating how to check and play your audio:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10

import psychopy
print(psychopy.__version__)
import sys
print(sys.version)

import keyboard
from psychopy import prefs
from psychopy import visual, core, event

from psychopy.sound import backend_ptb
# 0: No special settings (default, not optimized)
# 1: Try low-latency but allow some delay
# 2: Aggressive low-latency
# 3: Exclusive mode, lowest latency but may not work on all systems
backend_ptb.SoundPTB.latencyMode = 2

prefs.hardware['audioLib'] = ['PTB']
prefs.hardware['audioDriver'] = ['ASIO']
prefs.hardware['audioDevice'] = ['ASIO4ALL v2']
from psychopy import sound

# --- OS-level audio device sample rate ---
default_output = sd.query_devices(kind='output')
print("\nDefault output device info (OS level):")
print(f" Name: {default_output['name']}")
print(f" Default Sample Rate: {default_output['default_samplerate']} Hz")
print(f" Max Output Channels: {default_output['max_output_channels']}")

# Confirm the audio library and output settings
print(f"Using {sound.audioLib} for sound playback.")
print(f"Audio library options: {prefs.hardware['audioLib']}")
print(f"Audio driver: {prefs.hardware.get('audioDriver', 'Default')}")
print(f"Audio device: {prefs.hardware.get('audioDevice', 'Default')}")

audio_file = 'tick_rhythm_5min.wav'

print("Creating sound...")
wave_file = sound.Sound(audio_file)

print("Playing sound...")
wave_file.play()

while not keyboard.is_pressed('q'):
pass

# Clean up
print("Exiting...")
win.close()
core.quit()

</syntaxhighlight>

==FFmpeg==
===Synchronization===
Ensure the audio and video streams have consistent timestamps:

FFmpeg Options:

<pre>
-fflags +genpts: Generates accurate presentation timestamps (PTS) for the video.

-async 1: Synchronizes audio and video when they drift.

-map 0:v:0 and -map 0:a:0: Explicitly map video and audio streams to avoid accidental mismatches.
</pre>

=== Python ===
Example demonstrating how to use ffmpeg:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10
# -*- coding: utf-8 -*-
</syntaxhighlight>

===Recommended FFmpeg Command===
Here’s a command that encodes video and audio while maintaining high time accuracy:
<pre>
ffmpeg -i input.mp4 \
-c:v libx264 -preset slow -crf 18 -vsync cfr -g 30 \
-c:a pcm_s16le -ar 44100 \
-fflags +genpts -async 1 \
output.mp4
• -c:v libx264: Encode video using H.264.
• -preset slow: Optimize for quality and compression efficiency.
• -crf 18: Adjusts quality (lower = better; range: 0–51).
• -vsync cfr: Enforces constant frame rate.
• -c:a pcm_s16le: Encodes audio in uncompressed WAV format.
• -ar 44100: Sets audio sample rate to 44.1 kHz.
• -fflags +genpts: Ensures accurate timestamps.
• -async 1: Synchronizes audio and video streams.
</pre>

===Tips===
• Ensure Low Latency: If you're processing video/audio in real time, use low-latency settings (e.g., -tune zerolatency for H.264).
• Avoid Resampling: If possible, use the original frame rate and sample rate to avoid timing mismatches.
• Testing: Always test playback on different devices or players to confirm synchronization.

Alternatively, you can use Shotcut, a simple open-source editor, available here: https://shotcut.org/

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.

==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

==Playback==

=== PsychoPy ===
Example demonstrating how to play a video:
<syntaxhighlight lang="python" line>
#!/usr/bin/env python3.10
# -*- coding: utf-8 -*-

import time
import keyboard
from psychopy import visual
from psychopy import core

## Setup Section
win = visual.Window([720,720], fullscr=False, monitor="testMonitor", units='cm')

# append this stimulus to the list of prepared stimuli
vlc_movies = []
my_movies = ['YourMovie.mp4']#path to your movies from this directory

for movie in my_movies:
mov = visual.VlcMovieStim(win, movie,
size=600, # set as `None` to use the native video size
pos=[0, 0], # pos specifies the /center/ of the movie stim location
flipVert=False, # flip the video picture vertically
flipHoriz=False, # flip the video picture horizontally
loop=False, # replay the video when it reaches the end
autoStart=True) # start the video automatically when first drawn
vlc_movies.append(mov)

print("playing video....")
while not(keyboard.is_pressed('q')) and vlc_movies[0].status != visual.FINISHED:
vlc_movies[0].draw()
win.flip()
buffer_in = vlc_movies[0].frameIndex
print(vlc_movies[0].status)

print("Stop")

## Closing Section
core.quit()
</syntaxhighlight>