DuoCast: Installation and First Playback

Prepare your Mac and output devices

DuoCast routes one audio source to up to three outputs, each with its own volume, delay and 10-band EQ. The current package requires macOS 14.2 or later on an Apple Silicon Mac. A Windows installer is not available yet.

Connect your headphones or speakers before opening the app. A wired headset paired with a Bluetooth headset is a useful starting setup. Simultaneous playback on two Bluetooth headsets depends on the system and devices; DuoCast does not guarantee this combination.

Download, verify and install

1. Open the download section on the DuoCast product page and download the macOS package. No sign-in is required. The v0.1.0 file is named DuoCast-0.1.0-macOS-arm64.zip.

2. Check the download source and SHA-256. If the file is in your default Downloads folder, run this command in Terminal:

   shasum -a 256 ~/Downloads/DuoCast-0.1.0-macOS-arm64.zip
   

   The complete checksum for v0.1.0 is below. The command output should match it:

   15e932bf5cbe9e29e46c998d58e5d481918a7db1ed1489922d79f56fd4b2edd1
   

   For another version, use its filename and the complete checksum from its release record. If the values differ, download the package again or report the issue before proceeding.

3. Extract the ZIP and move DuoCast.app to Applications.

4. Open the app. This build is ad-hoc signed and has not been notarized by Apple. If macOS cannot verify the developer or check the app for malicious software, first confirm that the source is trustworthy and the checksum matches. Then open System Settings → Privacy & Security, find DuoCast, click Open Anyway and follow the confirmation prompts.

This creates an exception for this app. See Apple's Safely open apps on your Mac ↗. If macOS says the app is damaged, will damage your computer, or moves it to the Trash, stop and report the issue with the exact warning. Keep Gatekeeper enabled and do not run commands that remove quarantine attributes.

Play audio for the first time

1. Choose a headset or speaker from the dropdown at the top of each output card. Start with two outputs, then add a third if needed.
2. Select system audio (「系统声音」) or a local audio file (「音频文件」) at the top left. For system audio, use 「采集：全部 App」 to select the apps you want to capture. For file input, choose a local file.
3. Turn each output's volume down first, then click 「开始分发」 to start routing. For system audio, play audio in the selected app; file mode uses the file you selected.
4. When capturing system audio for the first time, grant Screen & System Audio Recording permission. You can also find DuoCast under System Settings → Privacy & Security → Screen & System Audio Recording, enable access and follow any system prompts.

Without this permission, system audio capture may produce silence. Check permission and the input source before checking each output device and its volume.

Adjust volume, delay and EQ

• Volume: Adjust each output card gradually. Each output has an independent level.
• Delay: Listen for the output that arrives earlier and add delay to that output. With wired and Bluetooth headphones, this usually means delaying the wired output or built-in speakers to match Bluetooth.
• EQ: Adjust the 10-band equalizer for each headset. Volume, delay and EQ settings are saved per device and restored when you use it again.

Devices can be connected or disconnected while routing. Disconnecting one stops only its output. Adding or removing output channels stops routing; start it again after changing the channel count.

Stop playback and troubleshoot

Click 「停止分发」 in the control panel to stop routing. Closing the window does not quit the app. You can also right-click DuoCast in the Dock to stop routing or reopen the control panel. Locking the Mac or putting it to sleep stops routing; start it manually after waking.

If one output is silent, check that the device is connected, its card selects the correct device, and its volume is audible. If all system audio is silent, check capture permission and the selected apps. When only one of two Bluetooth headsets plays, try a wired and Bluetooth combination to distinguish a Bluetooth connection limit from a volume setting.

If the issue persists, send a question with your DuoCast version, macOS version, device combination, input source and steps to reproduce it. Project information and release history are available in the DuoCast GitHub repository ↗.