Basic Rust CLI tool to convert LPCM WAV files to C arrays.

Only PCM data is dumped to array; no header information is included. Intended use is for I2S audio playback on embedded systems.

Usage

See the help message for usage information:

cargo run --release -- --help

The source file generated is designed to be included in target sources then declarations declared as externs in the target code.

For example, an audio file audio.wav (16-bit) with wav2c -o audio.c audio.wav will generate audio.c with the following definitions (use --array-name to change the array name). These can be included in the target source as extern:

const size_t AUDIO_SAMPLE_NO = N;
const int16_t audio[N] = { 0, ..N };

extern const size_t AUDIO_SAMPLE_NO;
extern const int16_t audio[];

Alternatively, a header file containing the declarations can be generated with --header.

Input File and Array Size

The input file must be integer LPCM WAV format. Bit rates up to 32-bit are supported and any sample rate. Bare in mind that the array size will be very large for high bit rates/sample rates. The --max-samples option is used to sanity check the array size that will be generated.

Use an audio program to convert audio files to LPCM WAV format and/or downsample for size constraints. For example, using ffmpeg:

# Convert M4A to mono 16-bit 22.05 kHz WAV
ffmpeg -i input.m4a -ar 22050 -ac 1 -sample_fmt s16 output.wav
# Convert M4A to mono 8-bit 8.82 kHz WAV
ffmpeg -i input.m4a -ar 8820 -ac 1 -acodec pcm_u8 output.wav

Other Notes

• The environment variables WAV2C_I8_TYPE, WAV2C_I16_TYPE, WAV2C_I32_TYPE and WAV2C_SIZE_TYPE can be used to change integer types used in the generated C array. Default requires "stdint.h" and "stddef.h" to be included.

Develop

There are integration tests that operate on generated WAV files in the tests directory. A cargo run --bin gen_wav target is used to generate WAV files for testing. See the 'Makefile' targets. The files are made on demand if not existing. make clean && make will regenerate all required test files.

Tests also compile the output with gcc to ensure the generated C code is valid - this requires gcc to be installed.

The 'golden sample' references can be updated with the make golden target. Of course this should only be done with intent otherwise it is the tail wagging the dog...