Synthetic Video Generator Script - A simple and versatile bash script to generate synthetic video files of a specified duration using ffmpeg. Ideal for creating test videos with custom lengths, the script features optional parameters for setting the video's duration and naming the output file. The generated videos come with standard test pattern…

generate_synthetic_video.sh

#!/bin/bash

# Synthetic Video Generator Script
# ==============================================================================
# This bash script generates a synthetic video file of a specified duration using ffmpeg.
# It's designed to be simple and flexible, allowing users to quickly create video files for testing or other purposes.
#
# Features:
# 1. Optional duration parameter: Specify the length of the video in seconds.
#    - If not provided, defaults to 60 seconds.
# 2. Optional output filename: Define the name of the output video file.
#    - If not provided, defaults to 'output-<duration>-seconds.mp4'.
# 3. Uses ffmpeg to generate a synthetic video with standard test patterns and silent audio.
#
# Usage:
# ./generate_synthetic_video.sh [duration_in_seconds] [output_filename]
# Example: ./generate_synthetic_video.sh 120 custom.mp4
#    - This generates a 2-minute video file named custom.mp4.
#
# Requirements:
# - ffmpeg must be installed and accessible in the system's PATH.
# ==============================================================================

# Usage function
usage() {
    echo "Usage: $0 [duration_in_seconds] [output_filename]"
    echo "Arguments:"
    echo "  duration_in_seconds (Optional) Duration of the video in seconds. Default is 60 seconds."
    echo "  output_filename     (Optional) Name of the output video file. Default is 'output-<duration>-seconds.mp4'"
    echo
    echo "Example:"
    echo "  $0 120              # Generates a 2-minute video file named output-120-seconds.mp4"
    echo "  $0 120 custom.mp4   # Generates a 2-minute video file named custom.mp4"
}

# Assign the arguments to variables with default values
DURATION=${1:-60}
OUTPUT_FILE=${2:-"output-${DURATION}-seconds.mp4"}

# Constants
AUDIO_BITRATE=128000  # Standard audio bitrate (128kbps)
VIDEO_BITRATE=1000000 # Example constant video bitrate (1000kbps)

echo "Audio bitrate (bits/s): $AUDIO_BITRATE"
echo "Video bitrate (bits/s): $VIDEO_BITRATE"
echo "Duration (seconds): $DURATION"

# Generate the video with ffmpeg
ffmpeg -f lavfi -i testsrc=size=1280x720:rate=30 -f lavfi -i anullsrc=r=44100:cl=stereo -c:v libx264 -b:v $(echo "$VIDEO_BITRATE/1000" | bc)k -t $DURATION -c:a aac -b:a $(echo "$AUDIO_BITRATE/1000" | bc)k -y $OUTPUT_FILE

echo "Generated file: $OUTPUT_FILE"
echo "File size: $(stat -c%s "$OUTPUT_FILE") bytes"