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Building OpenIMP

This document describes how to build OpenIMP for different targets.

Table of Contents

Prerequisites

For Host Build

  • GCC compiler
  • Make
  • pthread library
  • Standard C library

For Cross-Compilation

  • MIPS cross-compiler toolchain (mipsel-linux-gcc)
  • Make
  • Access to the Buildroot toolchain

Building for Host (Development)

To build for your local machine (useful for development and testing):

make clean
make

This will create:

  • lib/libimp.so - Shared library
  • lib/libimp.a - Static library
  • lib/libsysutils.so - SysUtils shared library
  • lib/libsysutils.a - SysUtils static library

Cross-Compiling for Ingenic Devices

Using the Build Script (Recommended)

The easiest way to cross-compile for Ingenic T31 devices:

./build-for-device.sh

This script will:

  1. Set up the cross-compilation environment
  2. Clean previous builds
  3. Build all libraries with the MIPS toolchain
  4. Strip debug symbols for smaller binaries
  5. Display build information

Manual Cross-Compilation

If you need more control or want to build for a different platform:

# Set up environment
export CROSS_COMPILE=mipsel-linux-
export PATH=/path/to/toolchain/bin:$PATH

# Clean and build
make clean
make CROSS_COMPILE=mipsel-linux- PLATFORM=T31

# Optional: Strip debug symbols
make CROSS_COMPILE=mipsel-linux- strip

Supported Platforms

You can specify the target platform with the PLATFORM variable:

  • T21 - Ingenic T21
  • T23 - Ingenic T23
  • T31 - Ingenic T31 (default)
  • C100 - Ingenic C100
  • T40 - Ingenic T40
  • T41 - Ingenic T41

Example:

make CROSS_COMPILE=mipsel-linux- PLATFORM=T40

Build Outputs

After a successful build, you'll find the following in the lib/ directory:

Shared Libraries

  • libimp.so (136KB stripped) - Main IMP library

    • System module
    • Encoder module
    • FrameSource module
    • Audio module
    • OSD module
    • IVS module
    • Hardware encoder integration
    • VBM (Video Buffer Manager)
    • DMA allocator

  • libsysutils.so (66KB stripped) - System utilities library

    • Basic system utilities

Static Libraries

  • libimp.a (139KB) - Static version of libimp
  • libsysutils.a (1.7KB) - Static version of libsysutils

Installation

Local Installation

To install to a custom location:

make install PREFIX=/path/to/install

Default installation paths:

  • Headers: $(PREFIX)/include/imp/ and $(PREFIX)/include/sysutils/
  • Libraries: $(PREFIX)/lib/

Device Installation

To deploy to an Ingenic device:

# Copy libraries to device
scp lib/libimp.so root@device:/usr/lib/
scp lib/libsysutils.so root@device:/usr/lib/

# Copy headers (if needed for development)
scp -r include/imp root@device:/usr/include/
scp -r include/sysutils root@device:/usr/include/

Verifying the Build

Check Binary Type

file lib/libimp.so

Expected output for MIPS:

lib/libimp.so: ELF 32-bit LSB shared object, MIPS, MIPS32 rel2 version 1 (SYSV), dynamically linked, stripped

Check Library Size

ls -lh lib/

Expected sizes (stripped):

  • libimp.so: ~136KB
  • libsysutils.so: ~66KB

Check Dependencies

mipsel-linux-readelf -d lib/libimp.so | grep NEEDED

Expected dependencies:

  • libpthread.so.0
  • librt.so.1
  • libc.so.0

Troubleshooting

Toolchain Not Found

If you get "command not found" errors:

# Verify toolchain path
export PATH=/home/matteius/output/wyze_cam3_t31x_gc2053_rtl8189ftv/per-package/toolchain-external-custom/host/bin/:$PATH

# Verify compiler exists
which mipsel-linux-gcc

Build Warnings

The build may show some warnings about:

  • Unused parameters (normal for stub functions)
  • Array bounds (expected due to structure size differences)
  • Unused functions (normal for helper functions)

These warnings are expected and don't affect functionality.

Clean Build

If you encounter issues, try a clean build:

make clean
./build-for-device.sh

Build Configuration

Compiler Flags

Default flags (can be overridden):

  • -Wall -Wextra - Enable warnings
  • -O2 - Optimization level 2
  • -fPIC - Position independent code (for shared libraries)
  • -DPLATFORM_T31 - Platform-specific defines

Custom Flags

To add custom compiler flags:

make CFLAGS="-Wall -O3 -DCUSTOM_DEFINE"

Development Workflow

For active development:

  1. Edit source files in src/
  2. Rebuild: make
  3. Test locally (if possible)
  4. Cross-compile: ./build-for-device.sh
  5. Deploy to device
  6. Test on device

Performance Optimization

For production builds, consider:

  1. Strip symbols: make strip (already done by build script)
  2. Optimize for size: make CFLAGS="-Os -fPIC -Iinclude -DPLATFORM_T31"
  3. Link-time optimization: Add -flto to CFLAGS

Additional Resources