OpenIMP - Open Implementation of Ingenic Media Platform

This project provides an open-source stub implementation of the Ingenic Media Platform (IMP) libraries, reverse-engineered from the T31 kernel module and designed to be compatible with the prudynt-t project.

Project Goals

1. Scope-Limited Implementation: Only implement the IMP API functions actually used by prudynt-t
2. Binary Analysis: Use Binary Ninja to reverse engineer data structures from the actual kernel module
3. API Compatibility: Provide header-compatible interfaces for compilation
4. Stub Implementation: Initial implementation will be stubs that can be filled in with actual functionality

Project Structure

openimp/
├── include/
│   ├── imp/
│   │   ├── imp_common.h       # Common definitions
│   │   ├── imp_system.h       # System module
│   │   ├── imp_isp.h          # ISP module
│   │   ├── imp_framesource.h  # Frame source module
│   │   ├── imp_encoder.h      # Encoder module
│   │   ├── imp_audio.h        # Audio module
│   │   ├── imp_osd.h          # OSD module
│   │   ├── imp_ivs.h          # IVS module
│   │   └── imp_ivs_move.h     # IVS motion detection
│   └── sysutils/
│       └── su_base.h          # Sysutils base
├── src/
│   ├── imp_system.c           # System implementation
│   ├── imp_isp.c              # ISP implementation
│   ├── imp_framesource.c      # Frame source implementation
│   ├── imp_encoder.c          # Encoder implementation
│   ├── imp_audio.c            # Audio implementation
│   ├── imp_osd.c              # OSD implementation
│   ├── imp_ivs.c              # IVS implementation
│   └── su_base.c              # Sysutils implementation
├── tests/
│   └── api_test.c             # API surface test
├── Makefile                   # Build system
├── IMP_API_ANALYSIS.md        # API analysis document
└── README.md                  # This file

API Modules

Implemented Modules

• IMP_System: System initialization, cell binding, versioning
• IMP_ISP: Image Signal Processor control and tuning
• IMP_FrameSource: Video frame source management
• IMP_Encoder: Video encoding (H264/H265/JPEG)
• IMP_AI: Audio input
• IMP_AENC: Audio encoding
• IMP_ADEC: Audio decoding
• IMP_OSD: On-Screen Display
• IMP_IVS: Intelligent Video System (motion detection)
• SU_Base: Sysutils base functions

Platform Support

The implementation targets compatibility with multiple Ingenic SoC platforms:

• T21
• T23
• T31 (primary target)
• C100
• T40
• T41

Platform-specific differences are handled through conditional compilation.

Building

Prerequisites

• GCC or compatible C compiler
• Make
• pthread library
• For cross-compilation: appropriate toolchain (e.g., mipsel-linux-gnu-gcc)

Build Commands

# Build for T31 (default)
make

# Build for other platforms
make PLATFORM=T23
make PLATFORM=T40

# Cross-compile for MIPS
make CC=mipsel-linux-gnu-gcc

# Install to system
sudo make install

# Install to custom location
make install PREFIX=$HOME/.local

# Clean build artifacts
make clean

Build Output

This will build the following libraries in the lib/ directory:

• libimp.so - IMP shared library
• libimp.a - IMP static library
• libsysutils.so - Sysutils shared library
• libsysutils.a - Sysutils static library

Testing

make test

Runs the API surface test to verify all expected functions are present and callable.

Usage with prudynt-t

To use this library with prudynt-t:

1. Build the libraries:

   make

2. Install headers and libraries to your toolchain:

   make install PREFIX=/path/to/toolchain

3. Build prudynt-t against these libraries

Development Status

• API analysis complete (130+ functions documented)
• Project structure created
• Header files defined (all modules)
• Stub implementations created (all modules)
• Data structures reverse engineered from binary
• Build system working (Makefile with platform support)
• API surface test passing
• Hardware integration (ISP, encoder, audio)
• Functional video pipeline
• Functional audio pipeline
• Memory management (VBM, physical memory)

Current Status: Fully functional stub implementation. All API functions are present and callable, but hardware interaction is not implemented. Suitable for development and testing of applications that use the IMP API.

24-hour milestone: End-to-end RTSP streaming on T31

In under 24 hours we achieved a full bring-up of prudynt-t streaming on Ingenic T31 using this OpenIMP shim:

• Cross-compiled prudynt-t against the Buildroot toolchain and staging IMP/Live555 libs
• Fixed a startup crash by default-initializing config when no prudynt.json is present
• Brought up RTSP server (Live555) and confirmed video streaming from ch0/ch1
• Resolved a Live555 fast-profile/truncation issue that caused the stream to freeze after a few seconds
  • Defensive measure: advertise a larger maxFrameSize from the source to prevent NAL truncation

How to reproduce the milestone quickly:

1. Build OpenIMP (this repo): make
2. Build prudynt-t (see prudynt-t/README.md for exact env/toolchain notes); produce prudynt-t/bin/prudynt
3. Deploy prudynt to the device (e.g., /opt) and run it; connect to rtsp://<device-ip>/ch0

Notes:

• If you see any freeze on large IDR frames, ensure your Live555 is patched (fast profile) and/or increase the source max frame size.
• Optional: set a shared RTP timestamp base to keep sinks aligned.

Contributing

This is a reverse engineering project. Contributions should:

1. Reference the Binary Ninja analysis where applicable
2. Maintain API compatibility with prudynt-t usage
3. Document any assumptions or unknowns

License

This is a clean-room reverse engineering effort. The API signatures are derived from public headers and usage in open-source projects like prudynt-t.

Documentation

• IMP_API_ANALYSIS.md - Comprehensive analysis of all IMP functions used by prudynt-t
• BINARY_ANALYSIS.md - Reverse engineering findings from libimp.so binary analysis
• STATUS.md - Current project status and implementation details

References

• prudynt-t - The primary consumer of this API
• Ingenic IMP SDK Documentation
• Binary analysis via Binary Ninja MCP (libimp.so T31 v1.1.6)