TIMELINEDB V0.1

TimelineDB is a low-level C library designed to store and process time-domain data for multi-layered software systems, with an emphasis on embedded use cases, real-time visualization, and SIMD-optimized performance.

👉 See Algorithms Explained for detailed descriptions of the signal processing algorithms used in TimelineDB.

Overview

The library offers:

• Efficient memory layout for high-throughput time series data
• Support for multiple channels (interleaved format)
• Linear sample rate conversion and aggregation (min/max downsampling)
• SIMD-accelerated operations (NEON / SSE planned)
• Simple file-less and GUI integration (e.g. SDL-based waveform display)

It is written entirely in C to ensure maximum portability — including platforms with limited toolchain support (e.g. FPGA soft-CPUs, or bare-metal ARM targets).

Rationale

While modern CPUs offer powerful SIMD instructions, C compilers don't always optimize memory access patterns well. TimelineDB intentionally uses interleaved memory formats to match vector register widths and enable direct, aligned loads for multi-channel data.

This design facilitates operations like:

• Sample rate conversion using vectorized linear interpolation
• Min/max aggregation for zoomed-out waveform rendering
• Efficient data traversal on embedded ARM or Apple M-series CPUs

Features

• RAM-based timeline buffers with:
  • Timebase definition (step + exponent)
  • Interleaved per-sample layout
  • Optional SIMD-ready value types (int16x8, int8x16, etc.)
• Conversion functions:
  • convert_sample_rate_* — SIMD & scalar versions
  • convert_downsample_minmax_* — aggregate for display
• Visualization:
  • Reference SDL2-based frontend with waveform drawing
  • Scalable design up to 32 channels
  • Color-coded, labeled curves with support for font rendering (SDL_ttf)
• Signal generation (for test/demo):
  • Per-channel configurable sine series
  • Randomized frequency, amplitude, harmonics
  • Generates continuous signal based on current timestamp

Build Instructions

Dependencies (via Homebrew on macOS):

brew install sdl2 sdl2_ttf

On Ubuntu:

sudo apt install libsdl2-dev libsdl2-ttf-dev

Build:

make devtest     # console test tool
make devgui      # SDL-based waveform viewer

Architecture

+---------------------------+
|   RawTimelineValuesBuf    | -- stores metadata + raw buffer
+---------------------------+
        |
        v
+---------------------------+
|   convert_sample_rate_*   |
|   convert_downsample_*    |
+---------------------------+
        |
        v
+---------------------------+
|     SDL2 Visualization    |
+---------------------------+

Status

This is an early prototype. API changes, refactoring, and structural cleanups are ongoing. Contributions and feedback are welcome.

License

MvMIT (c) 2025 Barna Faragó