VDO Streamer can carry audio from any of four sources — Embedded audio riding along with the SDI or NDI® signal, a Microphone (any macOS Core Audio input), System Audio captured from the Mac itself, or None for video-only. This page covers how to set each one up, including the upstream configuration in DaVinci Resolve and the macOS system side, and finishes with the stream-level audio codec, sample rate, and bitrate choices.
NDI® is a registered trademark of Vizrt NDI AB. DaVinci Resolve® is a registered trademark of Blackmagic Design Pty. Ltd.
Audio source mode — pick one
In Streamer, under Audio, the Audio Source dropdown has four options:
Mode
What it uses
When to pick
None
No audio published
Video-only streams, reference monitoring, test patterns
Microphone
Any Core Audio input device
USB interfaces, built-in mic, virtual inputs (Loopback, BlackHole, Rogue Amoeba)
System Audio
macOS's system audio output, captured via ScreenCaptureKit
Screen-share sessions, recording browser-based conference audio, DAW output on the same Mac
Embedded
Audio carried in the SDI or NDI signal
Anything coming off a Blackmagic card or an NDI source that already carries audio
The Streamer remembers the last mode per room type. Colour rooms default to Embedded; Editorial rooms default to Microphone. Override per session in the Audio panel.
Embedded — Blackmagic SDI audio
Blackmagic SDI cards (DeckLink, UltraStudio, Intensity, Mini Recorder) carry up to 16 channels of uncompressed PCM audio embedded in the SDI transport stream. VDO Streamer picks up all channels the card exposes and hands them to the encoder.
What to check on the Blackmagic side
Open Blackmagic Desktop Video Setup, select your device, and switch to the Audio tab.
Confirm Audio Input matches your signal path — typically Embedded SDI/HDMI Audio unless you are using an analogue or AES breakout.
Sample rate should be 48 kHz (standard for SDI embedded audio). Blackmagic does not re-sample, so if your source is 44.1 kHz or 96 kHz you will need to convert upstream.
What to check in VDO Streamer
Set Source to Blackmagic and pick the device.
Set Audio Source to Embedded.
The Audio Channels field auto-populates from the incoming signal. Stereo (2 ch) for most camera feeds; 4, 6, or 8 for multichannel productions; 16 for full SDI group 1–4.
Check the VU meter. If there is signal on the SDI side but the meter is silent, the camera or device is probably sending audio on non-default channels (e.g. channels 3/4 instead of 1/2). Adjust at the source — VDO Streamer publishes the channels as they arrive.
Bit depth is always 24-bit (SDI standard) internally; the encoder reduces to 16-bit for AAC or uses the full float internal representation for Opus.
Embedded — NDI audio
NDI streams carry uncompressed float32 audio at 48 kHz, typically 2 channels but the spec goes up to 16. If the NDI sender has audio enabled, VDO Streamer receives it automatically when you select the source.
What to check on the NDI sender side
Cameras with built-in NDI (BirdDog, PTZOptics, Sony, Panasonic): make sure audio is enabled in the camera's NDI settings and the correct input (XLR, line-in, or embedded HDMI) is routed through.
NDI Scan Converter / OBS with NDI plugin: the "Output" configuration must include audio — some scan converters ship with audio disabled by default.
DaVinci Resolve with the VDO NDI Output OFX plugin: see the DaVinci section below.
What to check in VDO Streamer
Set Source to NDI and pick the source name from the list.
Set Audio Source to Embedded.
Watch the VU meter during playback. Silence with a green pipe icon in the dropdown means the NDI stream is not carrying audio at all.
Mismatched sample rates are rare on NDI (the spec mandates 48 kHz), but if you see dropouts or pitch shifts, verify the sender is publishing at 48 kHz.
DaVinci Resolve audio routing
When DaVinci Resolve is your source, you have to tell Resolve where its audio output goes before VDO Streamer can pick it up. Resolve offers two routing options in Preferences → Video & Audio I/O, and each one has a matching Streamer configuration.
Open DaVinci Resolve → Preferences → Video & Audio I/O, then look at the Audio output section. Pick one of:
Desktop Video — audio is sent out of a connected Blackmagic device (DeckLink, UltraStudio) embedded in the SDI signal.
System Audio — audio goes out through whatever macOS's default audio output is set to.
Route A — Desktop Video (SDI embedded)
The reference path for colour and grading rooms. Audio rides the SDI signal alongside the video, so the two stay sample-accurately in sync.
In Resolve: Preferences → Video & Audio I/O → Audio output = Desktop Video, and pick the Blackmagic device in the Video connection section.
In Project Settings → Fairlight → Main Mix Output, choose the channel count your production uses (Stereo, 5.1, 7.1). Confirm the Main bus meters light up during playback.
Loop the Blackmagic SDI output back to a capture input — either on the same card's loopback, or on a second Blackmagic input device.
In VDO Streamer: Source: Blackmagic, Audio Source: Embedded.
Route B — System Audio (via a virtual audio device)
Use this when you do not have a Blackmagic card, or you want to route Resolve audio alongside an NDI video feed from the same machine. Resolve sends its mix to the macOS default output, so you need to make that default output something the Streamer can capture — not your actual speakers.
The standard approach is a virtual audio cable — a kernel-level loopback device that acts as both an output (for Resolve to send into) and an input (for the Streamer to read from). The two free and widely used options on macOS are:
BlackHole (open source, recommended) — free from existential.audio/blackhole. Available in 2ch, 16ch, or 64ch variants.
Loopback by Rogue Amoeba — paid, with a GUI for routing more complex mixes.
Setup with BlackHole:
Install BlackHole 2ch (or 16ch if you need multichannel).
In macOS System Settings → Sound → Output, temporarily set the default output to BlackHole 2ch. (Alternatively, create a Multi-Output Device in Audio MIDI Setup that includes BlackHole and your speakers, so you can still monitor locally while Resolve sends to the Streamer.)
In Resolve: Preferences → Video & Audio I/O → Audio output = System Audio.
In Resolve: Project Settings → Fairlight → Main Mix Output set to the channel count of the BlackHole device you installed (2 for BlackHole 2ch, 16 for BlackHole 16ch).
In VDO Streamer: Audio Source: Microphone, Audio Input: BlackHole 2ch.
Resolve now plays its audio into the virtual cable; the Streamer reads from the other end; you monitor locally through the Multi-Output Device.
NDI Audio device as an alternative virtual cable
If you already have NDI Tools installed, the NDI Audio virtual device (see the NDI audio section above) can act as the same kind of loopback — route Resolve's System Audio output to NDI Audio, then select NDI Audio as the Streamer's input. It is one fewer third-party install.
Common gotcha — silence even though the VU meter moves in Fairlight
Resolve mutes the Main bus to System Audio by default in some project templates. Check Fairlight page → Main bus and confirm the output meter is lit and not muted. If Fairlight shows levels but the macOS Sound output shows none, the bus is muted to your chosen output.
Via NDI (VDO NDI Output plugin)
The OFX plugin publishes only the video feed from the Fusion node graph or adjustment layer it is attached to. Audio is not carried through the plugin at this time.
To stream Resolve audio alongside its video, the simplest path is to pair the plugin with a second NDI audio source on the network — or to use the SDI loopback option below instead.
Audio-in-plugin support is on our roadmap. In the meantime the SDI path is the supported way to get Resolve audio into the Streamer.
Via SDI loopback to a Blackmagic input
This is the reference path. Resolve plays out video and audio through a Blackmagic UltraStudio or DeckLink output, and VDO Streamer captures both via a second Blackmagic input (or the same card's loopback input, if available).
In Resolve, open Preferences → Video & Audio I/O.
Set For capture and playback use to your output-capable Blackmagic device (e.g. DeckLink 4K Extreme 12G, UltraStudio 4K Mini).
Enable Video connection and Audio connection.
In Project Settings → Image Scaling → Video Monitoring, confirm the resolution, frame rate, and colour space match what the capture device expects.
In Project Settings → Fairlight → Main Mix Output, pick Stereo or the channel layout your production uses. Confirm the Main output is routed to the Blackmagic device's audio output.
In Resolve's Fairlight page, confirm the Main bus meters light up during playback. If they do not, audio is not leaving the project.
Loop the Blackmagic SDI out back to a capture input (either on the same card if it supports loopback, or on a second card/device) and set VDO Streamer to Source: Blackmagic + Audio Source: Embedded.
Monitor, don't double-grade
Resolve will apply Fairlight routing and any Main-bus FX before sending to SDI. Do not run any additional AU plugins on the output bus that weren't part of your grade — anything you add there will end up in the stream.
macOS system audio
System Audio mode captures whatever your Mac would play through its default audio output device. Uses ScreenCaptureKit (macOS 13+) so it does not require third-party kernel extensions like Loopback, BlackHole, or SoundFlower — and it does not require users to install anything.
Enabling system audio capture
In Streamer, set Audio Source to System Audio.
The first time you enable it, macOS will prompt for Screen & System Audio Recording permission. Allow it in System Settings → Privacy & Security → Screen & System Audio Recording.
The Streamer captures whatever is playing out of the Default Output device. Change the default output in System Settings → Sound → Output to pick a different source.
Excluding the Streamer from its own capture
When using System Audio together with Screen Capture as the video source, the Streamer automatically excludes its own window from the capture and its own audio from the system
Audio Settings in VDO Streamer — NDI, Blackmagic, macOS, and Stream Codec