The maintained line of this project is the aperto branch. main is kept as the original author's line; all current code, documentation and releases (tags vYYYY.MM.DD) live on aperto. Please base work and pull requests on aperto.

OpenIMP

OpenIMP is an open replacement for Ingenic's closed libimp.so (the IMP video, encoder, OSD, IVS and audio API). Together with open-tx-isp (the open ISP kernel driver) and a streamer such as timps it forms an open camera stack for Ingenic T10, T20, T21, T23, T30, T31, T40 and T41 SoCs. The public API is the vendor IMP API, so existing streamers (prudynt, raptor, timps) link against it unchanged.

The aperto branch carries the released open stack (device-test campaign work for T10/T20/T21/T23/T31/T41) on top of the original main line; see Branches and releases.

Status

Open stack = open-tx-isp + OpenIMP + timps. State on aperto (2026-10-04):

SoC	Status
T10	Runs the open stack from a flashed image (H.264, hardware JPEG/MJPEG, second stream, OSD, motion detection, day/night). Image controls and AE/AWB quality only partly documented.
T20	Fully open from a flashed image; long soaks (1 h 44 min at 25 fps) without errors; OEM rate controller default, A/B against the vendor stack measured.
T21	Fully open from a flashed image; vendor-identical rate controller, reference-buffer sharing on.
T23	Fully open, native Helix H.264 encoder, no vendor helper (2 h 34 min soak). Frequent Helix frame drops fixed (residual interrupt 0x100, kernel patch merged upstream); still open: a rare single Helix encode error (errno 5), no real WDR yet.
T30	Builds against a real T30 kernel; H.264 command lists match the vendor in an emulator. No device in the test campaign, so not device-verified here.
T31	Reference SoC. H.264, HEVC, hardware JPEG, OSD, rotation, AEC; 2 h 53 min soak without errors.
T40	Builds; AVPU H.264 path from upstream work. Not part of the device campaign.
T41	Runs from a flashed image with H.264 and H.265. Open: live flip, night column noise, short IVS gaps, OOM with three parallel streams at 30 MB rmem (26 MB in the test image works); day/night and AE/AWB quality untested.

Details per feature and SoC: FEATURE_MATRIX. History: CHANGELOG.md and the full OPEN_STACK_CHANGELOG. Only device-tested behaviour is listed as working; everything else is marked as pending.

Where it is better than the vendor stack

Measured on a T20 at night, same scene, same streamer, only libimp and the ISP driver differ:

Metric	Vendor	Open
streamer CPU (all threads)	25.2 %	10.5 %
snapshot latency (mean of 10)	0.45 s	0.20 s
streamer RSS	6.8 MB	3.7 MB

Other points, all device-tested:

• T20 and T10: about 8 MB more free RAM after the unused V4L2 frame pool was switched off.
• libimp is about 0.5-0.6 MB instead of 1.0-1.3 MB; T21 has 2.76 MB instead of ~1.2 MB free video memory.
• Reference-frame sharing on T21/T23 saves ~1.5 MB.
• Reload and stop robustness: 10 stop/start and reload cycles without an oops.
• Controls and noise reduction that the vendor ignores act on T10/T20/T21; real motion detection on T20/T21/T30; HEVC fails cleanly on SoCs without HEVC hardware.
• Motion detection v2 (per-cell background model, suppression after IR/gain jumps, bounding boxes and strength through the versioned OpenIMP_IVS_MoveGetResultEx API) is on by default; OPENIMP_MOTION_V2=0 restores the vendor algorithm. Device-tested on T20 and T23 over one night.
• Memory diagnostics: rmem peak logging and a shortfall message with a concrete rmem=<n>M suggestion instead of silent degradation (see the wiki page Memory).

Integration notes for streamer authors, env switches and defaults: OPENIMP_BEYOND_VENDOR.

Build

OpenIMP is cross-built for MIPS against a Thingino firmware checkout that already built the target (toolchain and headers come from its output/ tree).

export THINGINO_DIR=/path/to/thingino-firmware      # checkout with a built target
make t31                    # or t20 t21 t23 t30 t40 t41; equivalent: ./build-for-device.sh T31

• Each build-<soc>.sh takes the toolchain from THINGINO_DIR (override with TOOLCHAIN_PREFIX, <SOC>_TARGET, <SOC>_OUTPUT_DIR; T20 reuses the T21 script). T40/T41 additionally need the vendor header root (T41_HEADERS, auto-detected in the Thingino build tree via thingino-raptor-hal).
• Output: build/<soc>/libimp.so and build/<soc>/openimp-tuningd. A build is rejected if the library depends on an OEM libimp.so.
• make t21 OPENIMP_SW_JPEG=1 builds the software JPEG fallback for T20/T21/T23/T30.
• make install PLATFORM=T31 PREFIX=... installs headers, library and tuning daemon.
• make check runs the host tests (rate-control oracles, T23/T30/T31/T40/T41 checks).
• BUILD.md describes an older host build and is outdated; the scripts above are authoritative.

Integration in Thingino

The packages openimp (this repository) and open-tx-isp (kernel driver) are in the upstream thingino-firmware branch aperto (#1756), selected with BR2_PACKAGE_THINGINO_ISP_OPEN (menu "ISP stack") and pinned by commit SHA to the aperto branches of the opensensor repositories. Both replace the proprietary libimp.so and tx-isp-<soc>.ko; the SDK sensor, audio and AVPU modules stay; T23 runs fully on OpenIMP without any vendor helper. The kernel VPU/rmem stability patches (#1748, #1752) and the optional boot guard BR2_PACKAGE_THINGINO_ISP_GUARD (#1749, default off) are merged there as well. The streamer is built with USE_OPENIMP=1 to enable features that exist only in OpenIMP. Once the first date tag exists on aperto, thingino's aperto branch will pin that tag instead of a SHA.

Branches and releases

• main: the original author's line (opensensor). It is left untouched and is a strict ancestor of aperto.
• aperto: the open stack release line: OpenIMP + open-tx-isp, as used by the thingino aperto branch. Fast-forward only; every commit was flashed and checked on cameras. Releases are tagged vYYYY.MM.DD on this branch, and thingino pins a tag instead of a SHA.
• Development and the device-test campaign happen in the Lu-Fi forks (branch next = integration, claude/<topic> = topic branches); tested work reaches aperto from next after a clean soak.
• Companion repository: opensensor/open-tx-isp (branch aperto). Both repositories are released together; use matching tags.

Architecture

The public encoder graph is shared by T23, T30, T31, T40 and T41; the hardware backend is selected only where the SoC ABI differs.

• src/t40/openimp_p2_encoder.c: public encoder lifecycle; src/t40/codec-t40.c: shared AVPU backend.
• include/openimp/openimp_avc.h: that backend without the IMP graph, for contiguous NV12 producers such as V4L2 DMA-BUF.
• include/openimp/openimp_tuning.h and openimp-tuningd: image policy and gain feedback, see docs/TUNING_DAEMON.md.
• src/al_avpu.c, src/device_pool.c, src/fifo.c, src/hw_encoder.c: common hardware path.
• src/t30/: Helix descriptor and /dev/soc_vpu adapter (T20/T21/T23/T30 Helix encoder, native T23 encoder).
• src/t31/, src/framesource/framesource_tseries.c, src/isp/isp_tseries.c, src/kernel_interface.c, src/dma_alloc.c: T31 stock-driver ABI seam.
• src/t40/openimp_p1.c, src/t40/openimp_p2_dma.c: T40/T41 seam.

Platform conditionals are limited to real ABI differences (structure sizes, ioctl layouts, device behaviour, cache maintenance). Status notes per SoC: docs/T30_STATUS.md, docs/T40_STATUS.md, docs/T41_STATUS.md, profiling: docs/PROFILING.md.

Audio processing belongs to libaudioProcess-neo, logging and system libraries to ingenic-system-libs-neo. OpenIMP provides the native IMP audio I/O layer on T31 and T40/T41; HPF, noise suppression and AGC are loaded at runtime from libaudioProcess-neo. Acoustic echo cancellation uses the bundled WebRTC AECM.

Documentation

• Wiki: build and install, module parameters, OPENIMP_* variables, memory sizing, troubleshooting, release scheme (one wiki for OpenIMP and open-tx-isp).
• docs/FEATURE_MATRIX.md (also as feature-matrix.html, rendered): what works on which SoC.
• docs/OPEN_STACK_CHANGELOG.md and CHANGELOG.md: history of the open stack.
• docs/OPENIMP_BEYOND_VENDOR.md and docs/OPENIMP_SOC_DIFFS.md: differences to the vendor stack, for streamer authors.
• docs/PERFORMANCE.md: performance and resources, open stack versus vendor stack, per SoC, with sources and caveats.
• docs/test-reports/: raw device test reports.
• docs/re/: reverse-engineering dumps (vendor libimp.so HLIL, register traces) used by the RE notes.
• docs/archive/: historical status and design notes from the early OpenIMP work (kept for reference, may be outdated).

Reporting problems

Open an issue at opensensor/openimp (library, encoder, streamer integration) or opensensor/open-tx-isp (kernel driver, ISP, memory). Please include the SoC and sensor, the revisions of open-tx-isp, OpenIMP and the streamer, dmesg, the streamer log (including the rmem peak and "effective rate control" lines), the stream set and the rmem/ispmem values. Do not post addresses, credentials or location names. Details: Troubleshooting.

Credits

OpenIMP started as opensensor/openimp. It builds on the Thingino and Ingenic reverse-engineering community: thingino-firmware, ingenic-sdk, libaudioProcess-neo and ingenic-system-libs-neo (gtxaspec). Vendored third-party code: WebRTC AECM (BSD-3-Clause), x264 bitstream helpers (GPL-2.0-or-later).

Licensing

Licensing is per file, and there is no project-wide license yet. See NOTICE for the files that carry a license (LGPL-2.1-or-later, GPL-2.0-or-later x264-derived src/t30/h264enc/, and others) and the "Third-party code" section. The vendored WebRTC AECM in src/audio/webrtc/ is BSD-3-Clause with its own LICENSE, PATENTS and LICENSE_THIRD_PARTY. Files without a header carry no explicit grant.

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_{Not affiliated with or endorsed by Ingenic Semiconductor. "Ingenic" is used only to name the SoCs this project supports.}