Function WaveReadFormat

deps/SDL2/src/audio/SDL_wave.c:1617–1677

}

static int
WaveReadFormat(WaveFile *file)
{
    WaveChunk *chunk = &file->chunk;
    WaveFormat *format = &file->format;
    SDL_RWops *fmtsrc;
    size_t fmtlen = chunk->size;

    if (fmtlen > SDL_MAX_SINT32) {
        /* Limit given by SDL_RWFromConstMem. */
        return SDL_SetError("Data of WAVE fmt chunk too big");
    }
    fmtsrc = SDL_RWFromConstMem(chunk->data, (int)chunk->size);
    if (fmtsrc == NULL) {
        return SDL_OutOfMemory();
    }

    format->formattag = SDL_ReadLE16(fmtsrc);
    format->encoding = format->formattag;
    format->channels = SDL_ReadLE16(fmtsrc);
    format->frequency = SDL_ReadLE32(fmtsrc);
    format->byterate = SDL_ReadLE32(fmtsrc);
    format->blockalign = SDL_ReadLE16(fmtsrc);

    /* This is PCM specific in the first version of the specification. */
    if (fmtlen >= 16) {
        format->bitspersample = SDL_ReadLE16(fmtsrc);
    } else if (format->encoding == PCM_CODE) {
        SDL_RWclose(fmtsrc);
        return SDL_SetError("Missing wBitsPerSample field in WAVE fmt chunk");
    }

    /* The earlier versions also don't have this field. */
    if (fmtlen >= 18) {
        format->extsize = SDL_ReadLE16(fmtsrc);
    }

    if (format->formattag == EXTENSIBLE_CODE) {
        /* note that this ignores channel masks, smaller valid bit counts
         * inside a larger container, and most subtypes. This is just enough
         * to get things that didn't really _need_ WAVE_FORMAT_EXTENSIBLE
         * to be useful working when they use this format flag.
         */

        /* Extensible header must be at least 22 bytes. */
        if (fmtlen < 40 || format->extsize < 22) {
            SDL_RWclose(fmtsrc);
            return SDL_SetError("Extensible WAVE header too small");
        }

        format->validsamplebits = SDL_ReadLE16(fmtsrc);
        format->samplesperblock = format->validsamplebits;
        format->channelmask = SDL_ReadLE32(fmtsrc);
        SDL_RWread(fmtsrc, format->subformat, 1, 16);
        format->encoding = WaveGetFormatGUIDEncoding(format);
    }

    SDL_RWclose(fmtsrc);