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How to RTMP Stream a Live Cinema with Audio and Video from Multiple Sources Using OBS and VDMX

A comprehensive guide for streaming by combining visual output from VDMX, live audio, and live video feed from another laptop or camera.

Turjo Khan avatar
Written by Turjo Khan
Updated over a week ago

Overview

Software Required:

  • VDMX (for live visual generation)

  • OBS Studio (for compositing and streaming)

  • Optional: NDI Tools (for network video transfer), audio interface drivers

Hardware Required:

  • Laptop running VDMX

  • Audio mixer with USB or analog output

  • Second laptop or camera with HDMI/USB output

  • Capture card (optional if not using NDI)

  • Cables and adapters (XLR, TRS, 3.5mm, HDMI, USB, etc.)

Streaming Platform:
Custom RTMP server (e.g., Viewcy)

Streaming Goal:
Combine VDMX visuals, audio from a mixer, and a live camera feed into a single stream with a split-screen layout and transmit it via RTMP.


Step 1: Set Up Visuals from VDMX to OBS

There are two primary methods for routing visuals from VDMX to OBS: Syphon and NDI.

Option A: Using Syphon (macOS Only)

  1. In VDMX:

    • Set up your visuals as needed.

    • Navigate to Output > Syphon and enable Syphon Output.

  2. In OBS:

    • Install the Syphon plugin for OBS.

    • Add a new Syphon Client source.

    • Select VDMX as the source. Your visuals will now appear in OBS.

Option B: Using NDI (Cross-Platform)

  1. In VDMX:

    • Install and configure the NDI plugin to send output over the network.

  2. In OBS:

    • Install the OBS NDI plugin.

    • Add an NDI Source and select VDMX's output.

    • This option is more CPU-intensive but works on both macOS and Windows.


Step 2: Connect Mixer Audio to OBS

There are three common ways to route live audio into OBS:

Option 1: USB Audio Interface (Recommended)

  • Many digital mixers come with USB output. Simply connect the mixer to your laptop via USB.

  • In OBS:

    • Go to Settings > Audio or add an Audio Input Capture source.

    • Select the mixer or audio interface from the device list.

    • Adjust input levels to avoid clipping.

Option 2: External Audio Interface

  • Connect the mixer’s main output (XLR or TRS) to an external audio interface.

  • Connect the audio interface to the laptop via USB.

  • OBS will detect it as a microphone or line input.

Option 3: 3.5mm AUX Input (Not Ideal)

  • Use a stereo 1/4" to 3.5mm cable from the mixer's headphone or line out to the laptop's mic input.

  • This method is prone to quality loss and grounding issues. Use only as a temporary solution.


Step 3: Bring in a Camera Feed from Another Laptop

There are two approaches for importing a video feed from another device into OBS.

Option A: NDI Scan Converter

  1. On the second laptop:

    • Install NDI Tools and launch NDI Scan Converter.

    • This will broadcast the entire screen or a specific window (e.g., camera feed) over the network.

  2. On the OBS laptop:

    • Add an NDI Source and select the feed from the second laptop.

    • You can crop or resize the feed as needed in the OBS layout.

Option B: Capture Card (HDMI Input) (recommended)

  • Connect the camera to a capture card via HDMI.

  • Plug the capture card into your laptop's USB port.

  • In OBS:

    • Add a Video Capture Device source.

    • Select the capture card as the input device.

    • Adjust resolution and frame rate as required.


Step 4: Create a Split-Screen Layout in OBS

Once all sources are added to OBS, you can arrange them visually in the canvas.

  1. In OBS, create a new scene named "Split Screen" or similar.

  2. Add the following sources:

    • VDMX visuals (via Syphon or NDI)

    • Video feed from the second laptop or camera

    • Audio input from the mixer or interface

  3. Adjust and position each source in the preview window:

    • For side-by-side visuals, resize each video to occupy half the screen.

    • For picture-in-picture, keep one video full screen and overlay the second as a smaller frame in a corner.

    • Use the transform and crop tools in OBS to fine-tune the layout.


Step 5: Configure OBS to Stream to Viewcy

  1. In OBS:

    • Go to Settings > Stream.

    • Set the stream type to Custom.

    • Paste the RTMP Stream URL and Stream Key from your Viewcy event page.

  2. Under Settings > Output > Streaming:

    • Set the video bitrate between 3000–6000 kbps, depending on your upload speed.

    • Set audio bitrate to 160–320 kbps.

  3. Ensure that all sources (video and audio) are active and visible in the current scene.


Step 6: Test the Complete Setup

Before going live:

  • Use Start Recording in OBS to simulate a live stream.

  • Monitor:

    • Video smoothness from VDMX

    • Audio clarity and sync

    • Camera feed positioning

  • Adjust levels and layouts as necessary.

Also, test your network bandwidth to ensure stable upload speeds during the stream.


Step 7: Go Live

Once you have confirmed that all components are working:

  • Click Start Streaming in OBS.

  • Open the RTMP page on Viewcy to monitor the live feed.

  • Observe for dropped frames, sync issues, or any signal loss.

  • Keep OBS and Viewcy open throughout the stream to monitor performance.


Final Considerations

  • Use wired Ethernet connections instead of Wi-Fi wherever possible.

  • Close unnecessary applications to reduce CPU/GPU load.

  • Monitor audio levels throughout the stream to avoid distortion or clipping.

  • Record a backup locally via OBS in case of internet interruptions.

This setup enables a dynamic, professional live stream combining live visuals, audio, and camera input—ideal for performances, film screenings, or multimedia concerts.

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