SDL2/test/testresample.c

/*
  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely.
*/

#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>

int main(int argc, char **argv)
{
    SDL_AudioSpec spec;
    SDL_AudioStream *stream;
    Uint8 *dst_buf = NULL;
    Uint32 len = 0;
    Uint8 *data = NULL;
    int cvtfreq = 0;
    int cvtchans = 0;
    int bitsize = 0;
    int blockalign = 0;
    int avgbytes = 0;
    SDL_RWops *io = NULL;
    int src_samplesize, dst_samplesize;
    int src_len, dst_len, real_dst_len;

    /* Enable standard application logging */
    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);

    if (argc != 5) {
        SDL_Log("USAGE: %s in.wav out.wav newfreq newchans\n", argv[0]);
        return 1;
    }

    cvtfreq = SDL_atoi(argv[3]);
    cvtchans = SDL_atoi(argv[4]);

    if (SDL_Init(SDL_INIT_AUDIO) == -1) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_Init() failed: %s\n", SDL_GetError());
        return 2;
    }

    if (SDL_LoadWAV(argv[1], &spec, &data, &len) == NULL) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "failed to load %s: %s\n", argv[1], SDL_GetError());
        SDL_Quit();
        return 3;
    }


    stream = SDL_CreateAudioStream(spec.format, spec.channels, spec.freq,
                                   spec.format, cvtchans, cvtfreq);
    if (stream == NULL) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "failed to build audio stream: %s\n", SDL_GetError());
        SDL_free(data);
        SDL_Quit();
        return 4;
    }

    src_samplesize = (SDL_AUDIO_BITSIZE(spec.format) / 8) * spec.channels;
    dst_samplesize = (SDL_AUDIO_BITSIZE(spec.format) / 8) * cvtchans;


    src_len = len & ~(src_samplesize - 1);
    dst_len = dst_samplesize * (src_len / src_samplesize);
    if (spec.freq < cvtfreq) {
        const double mult = ((double)cvtfreq) / ((double)spec.freq);
        dst_len *= (int) SDL_ceil(mult);
    }

    dst_len = dst_len & ~(dst_samplesize - 1);
    dst_buf = (Uint8 *)SDL_malloc(dst_len);
    if (dst_buf == NULL) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Out of memory.\n");
        SDL_free(data);
        SDL_Quit();
        return 5;
    }

    /* Run the audio converter */
    if (SDL_PutAudioStreamData(stream, data, src_len) < 0 ||
        SDL_FlushAudioStream(stream) < 0) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Conversion failed: %s\n", SDL_GetError());
        SDL_free(dst_buf);
        SDL_free(data);
        SDL_Quit();
        return 6;

    }

    real_dst_len = SDL_GetAudioStreamData(stream, dst_buf, dst_len);
    if (real_dst_len < 0) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Conversion failed: %s\n", SDL_GetError());
        SDL_free(dst_buf);
        SDL_free(data);
        SDL_Quit();
        return 7;
    }
    dst_len = real_dst_len;

    /* write out a WAV header... */
    io = SDL_RWFromFile(argv[2], "wb");
    if (io == NULL) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "fopen('%s') failed: %s\n", argv[2], SDL_GetError());
        SDL_free(dst_buf);
        SDL_free(data);
        SDL_Quit();
        return 8;
    }

    bitsize = SDL_AUDIO_BITSIZE(spec.format);
    blockalign = (bitsize / 8) * cvtchans;
    avgbytes = cvtfreq * blockalign;

    SDL_WriteLE32(io, 0x46464952); /* RIFF */
    SDL_WriteLE32(io, dst_len + 36);
    SDL_WriteLE32(io, 0x45564157);                             /* WAVE */
    SDL_WriteLE32(io, 0x20746D66);                             /* fmt */
    SDL_WriteLE32(io, 16);                                     /* chunk size */
    SDL_WriteLE16(io, SDL_AUDIO_ISFLOAT(spec.format) ? 3 : 1); /* uncompressed */
    SDL_WriteLE16(io, cvtchans);                               /* channels */
    SDL_WriteLE32(io, cvtfreq);                                /* sample rate */
    SDL_WriteLE32(io, avgbytes);                               /* average bytes per second */
    SDL_WriteLE16(io, blockalign);                             /* block align */
    SDL_WriteLE16(io, bitsize);                                /* significant bits per sample */
    SDL_WriteLE32(io, 0x61746164);                             /* data */
    SDL_WriteLE32(io, dst_len);                                /* size */
    SDL_RWwrite(io, dst_buf, dst_len);

    if (SDL_RWclose(io) == -1) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "fclose('%s') failed: %s\n", argv[2], SDL_GetError());
        SDL_free(dst_buf);
        SDL_free(data);
        SDL_Quit();
        return 9;
    } /* if */

    SDL_free(dst_buf);
    SDL_free(data);
    SDL_Quit();
    return 0;
} /* main */

/* end of testresample.c ... */