Video Preparation

FloSync works with most video formats right out of the box. However, if you're using network sync or need frame-perfect synchronization, the way your video is encoded can make a significant difference.

This guide explains what affects sync performance and how to prepare your videos for the best results.

Do I Need to Prepare My Videos? #

For most users, the answer is no. FloSync handles standard video files well, and you may never notice any sync issues.

Consider preparing your videos if:

• You're using network sync across multiple computers
• You're running a professional installation where frame-perfect sync matters
• You've noticed occasional stutters or jumps during synchronized playback
• You're playing the same video on multiple screens and noticing drift

If you're just playing different content on different screens (Independent mode), video preparation isn't necessary.

Understanding the Basics #

When FloSync synchronizes videos, it occasionally needs to "seek" to a specific position. How quickly your video can seek to any frame affects sync quality.

Why Some Videos Sync Better Than Others #

Videos are compressed in two ways:

All-Intra (Every Frame Independent)

• Each frame is stored complete, like a series of photos
• Seeking to any frame is instant and consistent
• Files are larger, but sync is rock-solid

Inter-Frame (Standard Streaming)

• Frames reference each other to save space
• Seeking requires decoding multiple frames first
• Smaller files, but seek times vary (can cause sync drift)

Most videos from phones, cameras, and streaming services use inter-frame compression. This is perfect for watching, but can cause inconsistent sync when multiple computers try to seek to the same position.

Recommended Formats #

For the best sync performance, use one of these formats:

Our Recommendation #

Start with H.264 All-Intra. It offers the best balance of:

• Reliable sync performance
• Reasonable file sizes
• Universal playback support

If you have storage space and need the highest quality, ProRes LT or ProRes 422 are excellent choices, especially on Mac.

Sample Files for Testing #

We provide sample videos encoded in various formats so you can test sync performance on your own hardware before committing to a format for your project.

Download Sample Videos #

All samples are the same 37-second 30fps video (sports car footage) encoded in different formats:

Sync-Optimized Formats (Recommended) #

Standard Formats (For Comparison) #

These are typical streaming/delivery formats. Try them to see if sync meets your needs before transcoding.

How to Test #

1. Download a sync-optimized sample (start with H.264 All-Intra)
2. Download a standard format sample (H.264 Web is typical streaming quality)
3. Set up network sync between two computers
4. Compare sync stability between the two formats
5. Choose the format that meets your quality and storage requirements

Transcoding Your Videos #

If you decide to transcode your videos, FFmpeg is a free, powerful tool that works on Mac, Windows, and Linux.

H.264 All-Intra (Recommended) #

Best balance of file size and sync performance. Works everywhere.

ffmpeg -i input.mp4 \
  -c:v libx264 -preset slow -profile:v high -level 5.2 \
  -g 1 -keyint_min 1 -sc_threshold 0 \
  -b:v 50000k -maxrate 50000k -bufsize 100000k \
  -pix_fmt yuv420p \
  -c:a aac -b:a 256k \
  -y output.mp4

For 1080p content, you can reduce the bitrate:

ffmpeg -i input.mp4 \
  -vf "scale=1920:1080" \
  -c:v libx264 -preset slow -profile:v high \
  -g 1 -keyint_min 1 -sc_threshold 0 \
  -b:v 20000k -maxrate 20000k -bufsize 40000k \
  -pix_fmt yuv420p \
  -c:a aac -b:a 256k \
  -y output-1080p.mp4

ProRes (Mac-Friendly) #

Excellent quality with fast seeking. Native support on macOS.

# ProRes LT (smaller files, great quality)
ffmpeg -i input.mp4 \
  -c:v prores_ks -profile:v 1 -pix_fmt yuv422p10le \
  -c:a pcm_s16le \
  -y output.mov

# ProRes 422 (larger files, higher quality)
ffmpeg -i input.mp4 \
  -c:v prores_ks -profile:v 2 -pix_fmt yuv422p10le \
  -c:a pcm_s16le \
  -y output.mov

DNxHR (Cross-Platform Professional) #

Avid's professional codec with good cross-platform support.

ffmpeg -i input.mp4 \
  -c:v dnxhd -profile:v dnxhr_hq -pix_fmt yuv422p \
  -c:a pcm_s16le \
  -y output.mov

MJPEG (Universal Fallback) #

A simple legacy format that runs great on older hardware. Limited to 8-bit color (no HDR or wide color gamut), but unbeatable for compatibility and seek performance.

ffmpeg -i input.mp4 \
  -c:v mjpeg -q:v 2 \
  -c:a pcm_s16le \
  -y output.mov

File Size Expectations #

Sync-optimized formats produce larger files. Here's what to expect for a typical 1-minute video:

The larger file sizes are the tradeoff for consistent, reliable sync. Plan your storage accordingly.

Storage and Playback Tips #

Use Local Storage #

For best performance:

• Store videos on local SSD storage, not network drives
• Avoid USB 2.0 drives for high-bitrate formats like ProRes or DNxHR
• USB 3.0, Thunderbolt, or internal drives work well

Match Formats Across Computers #

When using network sync:

• Use the same video file on all computers
• Don't mix formats (e.g., ProRes on one, H.264 on another)
• Copy files rather than streaming from a network share

Consider Your Hardware #

• 4K ProRes/DNxHR requires capable hardware and fast storage
• If playback stutters, try 1080p or H.264 All-Intra instead
• Test before your event or installation

Quick Reference #

Just want sync to work? → Transcode to H.264 All-Intra using the command above

Have Mac computers and plenty of storage? → Use ProRes LT for excellent quality and sync

Working with older hardware? → Use MJPEG - a legacy format that's simple, fast, and works everywhere

Want to test before transcoding? → Download our sample files and compare

Related #

• Network Sync - Setting up multi-computer sync
• Troubleshooting - Common issues and solutions
• FAQ - Frequently asked questions