Video Sync on a Budget

Posted on by 1bb

A guide for film, TV, and potentially game composers who need two computers to stay together, without spending money you don’t have.

The Problem

Scoring to picture means your DAW and your video player have to agree on time, frame for frame. Studios solve this with dedicated video hardware. I’m not a studio yet so the budget is $0 basically. Here is one potential way to get the same result with a spare laptop, a cheap switch, and two pieces of free software.

What You Need

  • Computer A (Master): For me this is running Ableton Live. This is my audio machine.
  • Computer B (Slave): runs the video player. This is my picture machine.
  • A basic gigabit switch (~$15) or a single Ethernet cable if it’s just two machines.
  • Two Ethernet cables. I very much recommend that you skip Wi-Fi altogether.  It will introduce jitter you don’t need.

The One Thing That Breaks This Setup

Ableton Live cannot generate or output MIDI Timecode (MTC) on its own. It can receive incoming MTC to follow another device, but it will not send MTC to anything else natively. If your workflow depends on Live pushing timecode out to a video player, you need a workaround. Skip this and your video will drift out of sync, or won’t sync at all — no amount of correct wiring fixes it.

This isn’t unique to Ableton. Before you build any sync setup, confirm whether your DAW can send MTC natively. If it can’t, you need one of these:

  • A Max for Live device that generates MTC (LiveMTC is a common one).
  • An LTC (Linear Timecode) audio track in your session, run through a converter plugin or external box that turns it into MTC.
  • A separate MTC generator tool running alongside your DAW (Horae, Lockstep) that creates the stream independently.
  • A dedicated timecode plug-in loaded into your session that outputs MTC based on your DAW’s clock (this is what TXL20 does — see Tier 2 below).

MIDI-OX in Tier 1 exists specifically to work around this limitation, not as a convenience.

If you’re on a DAW other than Ableton, check whether it needs the same workaround before you assume this guide applies as-is to your setup.

One more thing MTC doesn’t carry: tempo. If your video player (or a second DAW) is following incoming MTC, you have to set its tempo manually to match the master.

MTC syncs position, not musical time.

Tier 1: Free Setup

Software: rtpMIDI, MIDI-OX, VidPlayMTC, HandBrake.

Step 1 :: Prepare the video

I generally downgrade the video in shotcut to a much lower resolution.   I use this for the day-to-day video playback.  Lower resolution means smoother audio playback.  My thinking is only that I am to picture, not delivering picture.

Step 2 :: Wire the computers

Plug both machines into the switch.  The switch doesn’t need to touch your internet router, but if it doesn’t be prepared to do some manually network configuration on each machine.  You do not need the internet for this to work technically.

Step 3 :: Install rtpMIDI on both machines

This creates a virtual MIDI cable over Ethernet.

  1. Install rtpMIDI on both computers.
  2. On Computer A, create a session under “My Sessions,” name it, enable it.
  3. Computer B should appear in the Directory. Click it to connect. Green light means connected.
  4. On Computer B, do the same in reverse.

Step 4 :: Configure Computer A (Ableton) with MIDI-OX

Ableton can’t send MTC by itself, so MIDI-OX is doing the job Live can’t do.  Ableton’s transport doesn’t talk to MIDI-OX’s timecode generator, that’s why you have to hit Play on both.  Now since first figuring this out, I have learned that Ableton can push a “Sort of” timecode, that VidPlayMTC will follow/read.  It does not account for jitter though, so this can still be limiting.  If you are attempting to do broadcast level audio, this would not be acceptable, so…..YMMV

  1. Install MIDI-OX on Computer A only.
  2. Under Options > MIDI Devices, set MIDI Output to the rtpMIDI session.
  3. Open the Timecode window, set frame rate to match your video exactly, and enable Send MTC.
  4. Press Play in MIDI-OX and Play in Ableton at the same time. –>

Step 5 :: Configure Computer B (VidPlayMTC)

  1. Load the converted video.
  2. Set MIDI Input to the rtpMIDI session.
  3. Match the frame rate.
  4. Set Mode to Slave / MTC Chase.
  5. Stop both machines, then press Play on Computer A. The video should start in sync.

Known limitations

  • Looping backward mid-playback won’t chase. Stop, then Play.   That is the only way it forces the video to re-read the start time.
  • If you see a Bonjour Service error on Windows, open services.msc, set Bonjour Service to Automatic, and start it. If that fails, reinstall rtpMIDI as Administrator.

This setup costs nothing but your time, and your time is what you’re spending instead of money. Budget for one full afternoon the first time you set it up.

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