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The SRTC C SDK is an audio and video SDK for server-side and embedded scenarios. It exposes a pure C interface (rtc_* functions and rtc_*_t structs, declared with extern "C"), so both C and C++ projects can use it directly.

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Use cases

  • Server-side recording, transcoding, and re-streaming
  • The publishing side of an MCU composite stream
  • Connecting AI agents / voice bots to a channel
  • Publishing and receiving on embedded devices (Linux ARM boards)

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What the SDK does and doesn’t do

This SDK doesn’t include client-side capabilities such as camera capture, microphone capture, video rendering, device management, or beauty filters:
  • Publishing: you handle capture and encoding, and hand the encoded H.264 / H.265 / Opus / AAC raw data to the SDK through rtc_write_sample
  • Receiving: the SDK hands you the remote encoded data through callbacks; decoding and rendering are up to you
If you’re building a desktop client, use the Windows SDK (Chinese) instead. It has a C++ interface and includes capture and rendering.

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SDK package contents

For MSVC (Visual Studio) projects, use librtc.dll + librtc.lib. You can’t link librtc.a directly.

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Supported platforms

Choose the library that matches the target system’s libc. Mainstream distributions (CentOS / Ubuntu / Debian, etc.) use the glibc build, and Alpine uses the musl build. The two can’t be mixed.The Alpine (musl) platform only provides the dynamic library librtc.so, not a static library.
If you need a platform or architecture not listed above, contact us.
When upgrading the SDK, recompile with the new librtc.h—don’t just replace the library files. When struct fields are added or removed (for example, 0.0.9 removed rtc_user_info_t.link_id), a program built with the old header reads the wrong fields. For changes in each version, see the Changelog.

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Compiling and linking

Include the header:
Link the dynamic library with GCC / Clang:
At runtime the system needs to be able to find librtc.so:
You can also hard-code the search path at link time so you don’t have to set the environment variable every time:
If you get error while loading shared libraries: librtc.so at runtime, the library search path isn’t set correctly: check LD_LIBRARY_PATH or -rpath, or copy librtc.so into a system library directory.

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Media streaming engine

Which media streaming engine a channel uses is determined by the channel configuration sent down by the server. Your code doesn’t need to care about it or configure anything. Some capabilities (simulcast layer switching, network quality reporting, active speaker) are only available with the SeaStart engine; with other engines the corresponding callbacks never fire—see SeaStart advanced features. Make sure your application still works without these callbacks.

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Next steps