FLAC Downsampler

A command line tool to downsample FLAC files.

• Written in Zig 0.15.1
• Uses no libraries aside from libFLAC statically linked and built with the Zig Build System
• Uses a custom FIR low-pass filtering and decimation by an integer factor

I have some 192kHz music that I wanted to put on my iPod, which only supports up to 48kHz. I also didn’t want to use FFmpeg, because thats boring, so I took it as a chance to learn a new library and a bit of DSP.

Usage

Super basic right now, but it’ll change at some point:

$ flac_downsampler.exe
Usage: flac_downsampler.exe [SAMPLE_RATE] [INPUT_FILE] [OUTPUT_FILE]

$ flac_downsampler.exe 48000 "Equus Caballus - 08 Where I Sit.flac" "[48kHz] Equus Caballus - 08 Where I Sit.flac"

Building

I integrated building libFLAC into the build.zig, bypassing libFLAC’s own CMake configuration, though, I did not do a very thorough porting job. The config I made for building libFLAC only has Windows x64 in mind, so you’ll need to tweak the generated header if you’re on another platform.

But otherwise, building is as simple as:

# cloning the repo and its submodules
$ git clone https://github.com/ethanavatar/flac_downsampler.git --recurse-submodules

# building
$ zig build -Doptimize=ReleaseSafe

# and running
$ .\zig-out\bin\flac_downsampler.exe
Usage: flac_downsampler.exe [SAMPLE_RATE] [INPUT_FILE] [OUTPUT_FILE]