contentgen

Video and Audio Test Sequence Generator

This directory contains tools to generate test video and audio suitable for being sent over MoQ (MediaOverQuic) one frame at a time.

Features

Video (Go program)

• Creates x264 video with only I and P frames (no B-frames)
• Video shows bitrate, resolution, time, and frame number
• Video encoded at 400, 600, and 900 kbps
• IDR frames every second (25 frames)
• 10-second duration

Audio (Shell scripts)

• Generates AAC, Opus, and AC-3 stereo audio at 48kHz
• Monotonic beeps: 880Hz beep every second (language code: mon)
• Scale beeps: C-major scale notes, one per second (language code: sca)
• Each beep is 0.5 seconds with fadeout
• AAC and Opus encoded at 128 kbps, AC-3 encoded at 192 kbps
• Outputs fragmented MP4 files with each frame in an individual fragment

Requirements

• Go (1.16 or later recommended)
• FFmpeg installed and available in your PATH (with libfdk_aac for AAC encoding)

Usage

Generate Video

go run videogen.go

Output files in output/:

• video_400kbps_avc.mp4: 400 kbps H.264/AVC video track
• video_600kbps_avc.mp4: 600 kbps H.264/AVC video track
• video_900kbps_avc.mp4: 900 kbps H.264/AVC video track

Generate Audio

Monotonic beeps (880Hz, one per second):

./gen_audio_monotonic.sh

Output files:

• output/audio_monotonic_128kbps_aac.mp4
• output/audio_monotonic_128kbps_opus.mp4
• output/audio_monotonic_192kbps_ac3.mp4

C-major scale beeps (one note per second):

./gen_audio_scale.sh

Output files:

• output/audio_scale_128kbps_aac.mp4
• output/audio_scale_128kbps_opus.mp4
• output/audio_scale_192kbps_ac3.mp4

Actual Bitrates

The actual average bitrates (from the size of the files) are approximately:

• audio: ~171 kbps
• video_400kbps_avc: ~396 kbps
• video_600kbps_avc: ~583 kbps
• video_900kbps_avc: ~868 kbps

There is a relatively high overhead of ~100 bytes per sample corresponding to ~25 kbps for video and ~40 kbps for audio.

MP4 Fragmentation

The tools use the following FFmpeg flags for MP4 fragmentation:

-movflags cmaf+separate_moof+delay_moov+skip_trailer+frag_every_frame

This ensures each frame is in an individual MP4 fragment, suitable for streaming applications.

You can also set a longer fragment duration (in milliseconds) using the --fragment-duration flag:

go run videogen.go --fragment-duration 1000
./gen_audio_monotonic.sh --fragment-duration 1000
./gen_audio_scale.sh --fragment-duration 1000