SurroundStreamer

SurroundStreamer is a desktop streaming tool for musicians, engineers, and spatial-audio creators who want to deliver live music and multichannel audio in surround. It sends audio from an audio interface or audio file to an Icecast/Shoutcast-compatible streaming server as Ogg Opus surround audio, stereo MP3, or both. Monitor output, channel templates up to 7.1, and KU100 near-field HRIR preview help you check the stream before and during playback. The current release supports macOS Apple Silicon, Windows x64, and a Linux x64 AppImage.

Who It Is For

SurroundStreamer is built for people who need more than a standard stereo streaming workflow:

• Musicians and live performers who want to deliver surround audio online.
• Sound engineers testing multichannel routing before a live stream.
• Spatial-audio creators preparing 5.1 or 7.1 material for network playback.
• Virtual venue and online event producers using Icecast/Shoutcast-compatible infrastructure.

Non-REM Studio and Tia Rungray usage notes and case-study materials are in preparation.

DOWNLOAD

Platform	Download
macOS Apple Silicon	SurroundStreamer-0.1.1.dmg
Windows x64	surround-streamer-0.1.1-setup.exe
Linux x64 AppImage	surround-streamer-0.1.1.AppImage

System Requirements

Important

SurroundStreamer now focuses on Audio Input and File sources. App Audio capture has been removed from the current release line.

• macOS: macOS 14.2 or later on Apple Silicon
• Windows: Windows x64
• Linux: x64 desktop with PipeWire/PulseAudio compatibility or ALSA fallback; AppImage is the current Linux package
• Audio Input capture: Core Audio on macOS; ASIO, MMDevice/WASAPI, and DirectShow fallback on Windows; PipeWire/PulseAudio or ALSA through FFmpeg on Linux
• File source: FFmpeg file playback path

Quick Start

1. Download the package for macOS Apple Silicon or Windows x64 from the release page.
2. Open SurroundStreamer.
3. Choose Audio Input for a live audio interface or File for an audio file.
4. Select a stream channel template such as Stereo, 5.1, or 7.1.
5. Enter the Icecast/Shoutcast server host, port, mount point, and password.
6. Enable Monitor Output if you want to check the signal before streaming.
7. Click START STREAM.

For surround Audio Input streaming, use an input device or virtual audio device that exposes enough real input channels for the selected stream layout.

Project Links

• Studio: Non-REM Studio
• Business inquiries: https://non-rem.com/
• GitHub: t-noami
• Repository: https://github.com/t-noami/SurroundStreamer
• Bugs and feature requests: use GitHub Issues
• Setup questions and workflow discussions: use GitHub Discussions

Current Scope

• Primary streaming format: Ogg Opus over Icecast
• Standard channel templates: Mono, Stereo, Stereo + C, 5.1, 7.1
• Default encoding: 48 kHz, 128 kbps stereo-equivalent bitrate
• Main source order: Audio Input, File
• Audio Input capture: macOS uses the Core Audio helper PCM path; Windows uses native ASIO and MMDevice/WASAPI capture with DirectShow fallback; Linux uses the experimental PipeWire/PulseAudio or ALSA FFmpeg bridge.
• File source: file playback and preview monitor support
• Monitor Output: Stereo Pair, Stereo Downmix, KU100 Near-field HRIR

Important Notes

• App Audio capture has been removed from the current release line. Use Audio Input capture with a physical, virtual, or loopback device when application audio needs to be routed into SurroundStreamer.
• Audio Input Monitor Output uses the shared WebAudio direct monitor path when browser audio-device access is available. Windows also has a backend-owned FFmpeg/WASAPI monitor path for ASIO Audio Input and File-source monitoring.
• Opus output is constrained to supported sample rates. 44.1 kHz and 96 kHz sources are converted to 48 kHz for stream output.
• 7.1.2 and 7.1.4 are not part of the standard build. The current production target is up to 7.1 because that maps cleanly to common Opus channel mapping support.
• KU100 near-field HRIR data is included under CC BY 4.0. Attribution is listed below.
• For Windows surround input, use an ASIO-capable audio interface or ASIO virtual audio device with 6 or more input/output channels.
• Linux x64 AppImage is available in v0.1.1. The current Linux path has been smoke-tested on Ubuntu 24.04 with PipeWire/PulseAudio, but broader distribution and device validation is still in progress.

User Manual

SurroundStreamer sends audio from audio inputs or audio files as Ogg Opus, stereo MP3, or both.

Basic Screen

The main screen is organized into these areas:

• Input Source: Selects the streaming source.
• Monitor Output: Configures monitor playback before or during streaming.
• Encoding Settings: Configures bitrate, sample rate, and channel templates.
• Stream Server Settings: Configures Opus Icecast and Stereo MP3 destinations.
• START STREAM / STOP STREAM: Starts or stops the stream.
• Logs: open from the Window menu on macOS, or Window > Show Logs on Windows/Linux.
• GitHub Repository: open from the Help menu on macOS, or Help > GitHub Repository on Windows/Linux.

First-Run Settings

The first-run Opus Icecast defaults are:

• Host: empty
• Port: 8000
• Mount Point: /stream
• Password: empty

Icecast settings are saved after editing and restored on the next launch. If settings are already saved, the saved values are used instead of the first-run defaults.

Stereo MP3 settings are saved with the same settings set. MP3 defaults are Icecast mode, port 8000, mount point /stream.mp3, and 128k bitrate.

Input Sources

File

Use File when streaming audio from a selected audio file.

1. Select File in Input Source.
2. Select an audio file with Browse.
3. Enable Loop if repeated playback is needed.
4. Select a Stream Channel Template that matches the file channel layout.

For File source, Monitor Output is useful only after a playable file has been selected.

Audio Input

Use Audio Input when streaming from an audio interface, virtual input, or microphone input.

1. Select Audio Input in Input Source.
2. Select the audio input in Audio Input.
3. Use Refresh if the device list needs to be updated.

Monitor Output is available for Audio Input source through the shared WebAudio direct monitor path when browser audio-device access is available. Windows also supports ASIO Audio Input monitoring through the backend-owned FFmpeg/WASAPI renderer path; File-source monitoring on Windows uses the same backend renderer to avoid browser-device routing issues.

For surround Audio Input streaming, the input device must expose enough real input channels for the selected stream layout. On macOS, use a Core Audio audio interface or virtual audio device with 6 or more channels for 5.1 or larger layouts. On Windows, use an ASIO-capable audio interface or ASIO virtual audio device with 6 or more input/output channels.

On macOS, audio-input streaming requires microphone permission. If streaming does not capture input audio, confirm that macOS Privacy settings allow microphone access for SurroundStreamer.

Encoding Settings

Encoding Settings controls the stream format.

• Encoding Format: Selects Ogg Opus / Icecast (surround), Ogg Opus + stereo MP3, or Stereo MP3 only.
• Opus Bitrate (Stereo Equivalent): Opus bitrate expressed as a stereo-equivalent value. The actual bitrate increases with the selected channel count. This is hidden when Stereo MP3 only is selected.
• Opus Bitrate Mode: Selects the Opus rate-control mode. CBR is the default and maps to FFmpeg/libopus -vbr off. CVBR maps to -vbr constrained. VBR maps to -vbr on.
• Sample Rate: Opus stream sample rate. The default is 48 kHz.
• Stream Channel Template: Selects the stream channel layout.
• Stream Channels: Selects the channels included in the stream.
• MP3 Audio Source: Selects whether the MP3 output uses the L/R stereo pair, a stereo downmix, or KU100 Near-field HRIR processing.

Use CBR when receiver compatibility is the priority. CVBR and VBR preserve more Opus rate-control flexibility, but silence or very simple audio can still drop to a much lower byte rate than the selected target bitrate. Some live HTTP/Ogg/Opus receivers may treat those low-byte-rate periods as an underrun or disconnect. The MP3 simulcast encoder remains CBR through libmp3lame -b:a.

Standard templates are Mono, Stereo, Stereo + C, 5.1, and 7.1. For multichannel sources, 5.1 is the default practical starting point.

MP3 stereo processing uses the same spatial gain policy as Monitor Output:

• Stereo Pair (L/R): sends the selected stream's first two channels directly to MP3 left/right. Mono is duplicated to left/right.
• Stereo Downmix: applies L/R at 1.0, center at 0.707 to both sides, LFE muted, side/rear channels at 0.707 to their matching side, then applies a 0.707 master gain.
• KU100 Near-field HRIR: applies L/R at 1.0, center and side/rear channels at 0.707, LFE muted, then applies KU100 HRIR convolution with a 0.35 master gain.

The current Stereo Downmix coefficients are shared between Monitor Output and MP3 output for consistency. A more conservative live-music/DJ downmix profile, such as lowering side/rear contribution, may be considered later, but it is not part of the current release.

Monitor Output

Monitor Output is used to check audio before or during streaming.

• Enable monitor output: Enables monitor playback.
• Output Device: Selects the monitor output device.
• Monitor Mode: Selects the monitor processing mode.
• Monitor Source: Selects the channel pair used in Stereo Pair mode.
• Monitor Volume: Controls only the monitor output level.

Monitor modes:

• Stereo Pair: Monitors the selected two-channel pair directly.
• Stereo Downmix: Downmixes multichannel audio to stereo.
• KU100 Near-field HRIR: Renders a binaural monitor signal using KU100 near-field HRIR data.

Monitor Volume is applied after the selected monitor mode processing. It does not affect the streamed audio.

Stream Server Settings

Stream Server Settings configures the active streaming destination fields for the selected encoding format. Ogg Opus + stereo MP3 shows separate Opus Icecast and Stereo MP3 groups.

• Host: Icecast server host name or IP address
• Port: Icecast port
• Mount Point: Stream mount point, for example /stream
• Password: Source password
• MP3 Shoutcast 1: Uses the legacy Shoutcast source handshake directly, so no mount point is configured for that output.

Mount Point should start with /, such as /stream. If the leading / is missing, the app normalizes it when saving.

Starting And Stopping

Click START STREAM to start streaming.

If required settings are blank, the app highlights the invalid fields and does not show the loading overlay. Highlighted fields include input source, stream channel selection, Opus Host/Port/Password, and MP3 Host/Port/Password.

During stream startup, a Starting stream... / Connecting to the streaming server overlay is shown and the START button is temporarily disabled. If the backend reports a connection failure, a Connection failed dialog appears with the error message.

While streaming, the following controls are locked to prevent accidental changes:

• Input Source
• Encoding Settings
• Stream Server Settings

Click STOP STREAM to stop streaming. Closing the window with the macOS close button also quits the app and stops any FFmpeg or helper processes running in the background.

Stream Playback Check

Use the following web player to confirm that audio is reaching the streaming destination:

https://non-rem.com/SurroundWebPlayer/

Enter the Icecast Streaming URL and start playback. If the player remains buffering, check Logs in SurroundStreamer and confirm the mount state on the Icecast server. This web player is an external verification page and is not bundled with the app.

Troubleshooting

If Icecast connection fails:

• Confirm Host, Port, Mount Point, and Password.
• If 403 Forbidden appears, check the password, source user, mount point, and Icecast server permissions.
• Passwords containing @ are URL-encoded by the app.
• If startup fails after connecting, check the Connection failed dialog and the log messages.

If the player remains buffering:

• Confirm that the Icecast server created the expected mount point.
• Check Logs to see whether FFmpeg exits immediately after startup.
• For Audio Input source, confirm that macOS microphone permission is enabled.

If Audio Input source has no audio:

• Confirm that the selected audio input is receiving signal.
• If using a loopback or virtual device, confirm that the routing is not unintentionally mixing system output into the input.
• Confirm macOS microphone permission.

If Monitor Output is unavailable:

• Confirm the selected input source is supported by the current audio backend.
• Confirm the selected Monitor Output device is available, then toggle Enable monitor output off and on.
• If the output device list changes, use Refresh Monitor Devices.

Development

Build instructions are split by operating system:

• Build on macOS
• Build on Windows
• Build on Linux
• Windows Backend Development Guide
• Windows / Linux Portability Assessment

macOS, Windows, and Linux x64 AppImage are the current release artifacts. Linux AppImage/PipeWire validation notes remain in Build on Linux.

Test Stream Config

test_streamconfig.txt is a local convenience note for stream testing. Treat it as sensitive operational data and do not publish it.

License

SurroundStreamer is released under the MIT License. See LICENSE.

The MIT License is a permissive open-source license that allows commercial use, private use, modification, distribution, and sublicensing, while requiring preservation of copyright and license notices.

The MIT License applies to the software code. It does not grant rights to use the SurroundStreamer name, Non-REM Studio name, logos, icons, application artwork, or other brand assets as official branding for modified or redistributed builds. See TRADEMARKS.md.

Third-party materials remain under their own licenses. This includes the packaged FFmpeg binary and its enabled external libraries, including libopus and libmp3lame, plus the bundled KU100 near-field HRIR extraction.

See THIRD_PARTY_NOTICES.md for runtime dependency and bundled resource notices.

Repository Documents

• docs/implementation_plan.md: project history, architecture notes, current plan, and future work
• docs/releases/: release notes used for GitHub Releases
• docs/task.md: current task status and release checklist

Third-Party Notices

Third-party license notices are kept outside this README so the distributed resources stay paired with their own notices:

• THIRD_PARTY_NOTICES.md: application-wide third-party dependency and bundled resource summary
• TRADEMARKS.md: project name, logo, and brand asset guidelines
• resources/ffmpeg/THIRD_PARTY_NOTICES.md: packaged FFmpeg binary details, enabled external libraries, source references, and build configurations
• resources/ffmpeg/licenses/: FFmpeg, libopus, and LAME license texts
• resources/ku100-hrir/NOTICE.md: KU100 near-field HRIR attribution, license, source, DOI, and change statement

Verification Checklist

Before treating a build as usable:

• App launches successfully
• File source stream starts and stops cleanly
• Audio Input stream starts and stops cleanly
• Icecast connection succeeds with the intended mount point
• Peak meters respond quickly
• Monitor Output works for File and Audio Input sources
• Quitting the app stops FFmpeg and helper processes
• codesign --verify --deep --strict passes for the app bundle