audio.c

AAC编解码源码

    /* WAVEFORMATEXTENSIBLE */

    /* wValidBitsPerSample */
    *p++ = (unsigned char)(aufile->bits_per_sample >> 0);
    *p++ = (unsigned char)(aufile->bits_per_sample >> 8);

    /* dwChannelMask */
    word32 = channelMask;
    *p++ = (unsigned char)(word32 >>  0);
    *p++ = (unsigned char)(word32 >>  8);
    *p++ = (unsigned char)(word32 >> 16);
    *p++ = (unsigned char)(word32 >> 24);

    /* SubFormat */
    if (aufile->outputFormat == FAAD_FMT_FLOAT)
    {
        /* KSDATAFORMAT_SUBTYPE_IEEE_FLOAT: 00000003-0000-0010-8000-00aa00389b71 */
        *p++ = 0x03;
        *p++ = 0x00;
        *p++ = 0x00;
        *p++ = 0x00;
        *p++ = 0x00; *p++ = 0x00; *p++ = 0x10; *p++ = 0x00; *p++ = 0x80; *p++ = 0x00;
        *p++ = 0x00; *p++ = 0xaa; *p++ = 0x00; *p++ = 0x38; *p++ = 0x9b; *p++ = 0x71;
    } else {
        /* KSDATAFORMAT_SUBTYPE_PCM: 00000001-0000-0010-8000-00aa00389b71 */
        *p++ = 0x01;
        *p++ = 0x00;
        *p++ = 0x00;
        *p++ = 0x00;
        *p++ = 0x00; *p++ = 0x00; *p++ = 0x10; *p++ = 0x00; *p++ = 0x80; *p++ = 0x00;
        *p++ = 0x00; *p++ = 0xaa; *p++ = 0x00; *p++ = 0x38; *p++ = 0x9b; *p++ = 0x71;
    }

    /* end WAVEFORMATEXTENSIBLE */

    *p++ = 'd'; *p++ = 'a'; *p++ = 't'; *p++ = 'a';

    word32 = data_size < MAXWAVESIZE ?
        (unsigned long)data_size : (unsigned long)MAXWAVESIZE;
    *p++ = (unsigned char)(word32 >>  0);
    *p++ = (unsigned char)(word32 >>  8);
    *p++ = (unsigned char)(word32 >> 16);
    *p++ = (unsigned char)(word32 >> 24);

    return fwrite(header, sizeof(header), 1, aufile->sndfile);
}

static int write_audio_16bit(audio_file *aufile, void *sample_buffer,
                             unsigned int samples)
{
    int ret;
    unsigned int i;
    short *sample_buffer16 = (short*)sample_buffer;
    char *data = malloc(samples*aufile->bits_per_sample*sizeof(char)/8);

    aufile->total_samples += samples;

    if (aufile->channels == 6 && aufile->channelMask)
    {
        for (i = 0; i < samples; i += aufile->channels)
        {
            short r1, r2, r3, r4, r5, r6;
            r1 = sample_buffer16[i];
            r2 = sample_buffer16[i+1];
            r3 = sample_buffer16[i+2];
            r4 = sample_buffer16[i+3];
            r5 = sample_buffer16[i+4];
            r6 = sample_buffer16[i+5];
            sample_buffer16[i] = r2;
            sample_buffer16[i+1] = r3;
            sample_buffer16[i+2] = r1;
            sample_buffer16[i+3] = r6;
            sample_buffer16[i+4] = r4;
            sample_buffer16[i+5] = r5;
        }
    }

    for (i = 0; i < samples; i++)
    {
        data[i*2] = (char)(sample_buffer16[i] & 0xFF);
        data[i*2+1] = (char)((sample_buffer16[i] >> 8) & 0xFF);
    }

    ret = fwrite(data, samples, aufile->bits_per_sample/8, aufile->sndfile);

    if (data) free(data);

    return ret;
}

static int write_audio_24bit(audio_file *aufile, void *sample_buffer,
                             unsigned int samples)
{
    int ret;
    unsigned int i;
    long *sample_buffer24 = (long*)sample_buffer;
    char *data = malloc(samples*aufile->bits_per_sample*sizeof(char)/8);

    aufile->total_samples += samples;

    if (aufile->channels == 6 && aufile->channelMask)
    {
        for (i = 0; i < samples; i += aufile->channels)
        {
            long r1, r2, r3, r4, r5, r6;
            r1 = sample_buffer24[i];
            r2 = sample_buffer24[i+1];
            r3 = sample_buffer24[i+2];
            r4 = sample_buffer24[i+3];
            r5 = sample_buffer24[i+4];
            r6 = sample_buffer24[i+5];
            sample_buffer24[i] = r2;
            sample_buffer24[i+1] = r3;
            sample_buffer24[i+2] = r1;
            sample_buffer24[i+3] = r6;
            sample_buffer24[i+4] = r4;
            sample_buffer24[i+5] = r5;
        }
    }

    for (i = 0; i < samples; i++)
    {
        data[i*3] = (char)(sample_buffer24[i] & 0xFF);
        data[i*3+1] = (char)((sample_buffer24[i] >> 8) & 0xFF);
        data[i*3+2] = (char)((sample_buffer24[i] >> 16) & 0xFF);
    }

    ret = fwrite(data, samples, aufile->bits_per_sample/8, aufile->sndfile);

    if (data) free(data);

    return ret;
}

static int write_audio_32bit(audio_file *aufile, void *sample_buffer,
                             unsigned int samples)
{
    int ret;
    unsigned int i;
    long *sample_buffer32 = (long*)sample_buffer;
    char *data = malloc(samples*aufile->bits_per_sample*sizeof(char)/8);

    aufile->total_samples += samples;

    if (aufile->channels == 6 && aufile->channelMask)
    {
        for (i = 0; i < samples; i += aufile->channels)
        {
            long r1, r2, r3, r4, r5, r6;
            r1 = sample_buffer32[i];
            r2 = sample_buffer32[i+1];
            r3 = sample_buffer32[i+2];
            r4 = sample_buffer32[i+3];
            r5 = sample_buffer32[i+4];
            r6 = sample_buffer32[i+5];
            sample_buffer32[i] = r2;
            sample_buffer32[i+1] = r3;
            sample_buffer32[i+2] = r1;
            sample_buffer32[i+3] = r6;
            sample_buffer32[i+4] = r4;
            sample_buffer32[i+5] = r5;
        }
    }

    for (i = 0; i < samples; i++)
    {
        data[i*4] = (char)(sample_buffer32[i] & 0xFF);
        data[i*4+1] = (char)((sample_buffer32[i] >> 8) & 0xFF);
        data[i*4+2] = (char)((sample_buffer32[i] >> 16) & 0xFF);
        data[i*4+3] = (char)((sample_buffer32[i] >> 24) & 0xFF);
    }

    ret = fwrite(data, samples, aufile->bits_per_sample/8, aufile->sndfile);

    if (data) free(data);

    return ret;
}

static int write_audio_float(audio_file *aufile, void *sample_buffer,
                             unsigned int samples)
{
    int ret;
    unsigned int i;
    float *sample_buffer_f = (float*)sample_buffer;
    unsigned char *data = malloc(samples*aufile->bits_per_sample*sizeof(char)/8);

    aufile->total_samples += samples;

    if (aufile->channels == 6 && aufile->channelMask)
    {
        for (i = 0; i < samples; i += aufile->channels)
        {
            float r1, r2, r3, r4, r5, r6;
            r1 = sample_buffer_f[i];
            r2 = sample_buffer_f[i+1];
            r3 = sample_buffer_f[i+2];
            r4 = sample_buffer_f[i+3];
            r5 = sample_buffer_f[i+4];
            r6 = sample_buffer_f[i+5];
            sample_buffer_f[i] = r2;
            sample_buffer_f[i+1] = r3;
            sample_buffer_f[i+2] = r1;
            sample_buffer_f[i+3] = r6;
            sample_buffer_f[i+4] = r4;
            sample_buffer_f[i+5] = r5;
        }
    }

    for (i = 0; i < samples; i++)
    {
        int exponent, mantissa, negative = 0 ;
        float in = sample_buffer_f[i];

        data[i*4] = 0; data[i*4+1] = 0; data[i*4+2] = 0; data[i*4+3] = 0;
        if (in == 0.0)
            continue;

        if (in < 0.0)
        {
            in *= -1.0;
            negative = 1;
        }
        in = (float)frexp(in, &exponent);
        exponent += 126;
        in *= (float)0x1000000;
        mantissa = (((int)in) & 0x7FFFFF);

        if (negative)
            data[i*4+3] |= 0x80;

        if (exponent & 0x01)
            data[i*4+2] |= 0x80;

        data[i*4] = mantissa & 0xFF;
        data[i*4+1] = (mantissa >> 8) & 0xFF;
        data[i*4+2] |= (mantissa >> 16) & 0x7F;
        data[i*4+3] |= (exponent >> 1) & 0x7F;
    }

    ret = fwrite(data, samples, aufile->bits_per_sample/8, aufile->sndfile);

    if (data) free(data);

    return ret;
}