downmix.c

这是著名的TCPMP播放器在WINDWOWS,和WINCE下编译通过的源程序.笔者对其中的LIBMAD库做了针对ARM MPU的优化. 并增加了词幕功能.

static void mix4to1 (sample_t * samples, sample_t bias)
{
    int i;

    for (i = 0; i < 256; i++)
	samples[i] += BIAS (samples[i + 256] + samples[i + 512] +
			    samples[i + 768]);
}

static void mix5to1 (sample_t * samples, sample_t bias)
{
    int i;

    for (i = 0; i < 256; i++)
	samples[i] += BIAS (samples[i + 256] + samples[i + 512] +
			    samples[i + 768] + samples[i + 1024]);
}

static void mix3to2 (sample_t * samples, sample_t bias)
{
    int i;
    sample_t common;

    for (i = 0; i < 256; i++) {
	common = BIAS (samples[i + 256]);
	samples[i] += common;
	samples[i + 256] = samples[i + 512] + common;
    }
}

static void mix21to2 (sample_t * left, sample_t * right, sample_t bias)
{
    int i;
    sample_t common;

    for (i = 0; i < 256; i++) {
	common = BIAS (right[i + 256]);
	left[i] += common;
	right[i] += common;
    }
}

static void mix21toS (sample_t * samples, sample_t bias)
{
    int i;
    sample_t surround;

    for (i = 0; i < 256; i++) {
	surround = samples[i + 512];
	samples[i] += BIAS (-surround);
	samples[i + 256] += BIAS (surround);
    }
}

static void mix31to2 (sample_t * samples, sample_t bias)
{
    int i;
    sample_t common;

    for (i = 0; i < 256; i++) {
	common = BIAS (samples[i + 256] + samples[i + 768]);
	samples[i] += common;
	samples[i + 256] = samples[i + 512] + common;
    }
}

static void mix31toS (sample_t * samples, sample_t bias)
{
    int i;
    sample_t common, surround;

    for (i = 0; i < 256; i++) {
	common = BIAS (samples[i + 256]);
	surround = samples[i + 768];
	samples[i] += common - surround;
	samples[i + 256] = samples[i + 512] + common + surround;
    }
}

static void mix22toS (sample_t * samples, sample_t bias)
{
    int i;
    sample_t surround;

    for (i = 0; i < 256; i++) {
	surround = samples[i + 512] + samples[i + 768];
	samples[i] += BIAS (-surround);
	samples[i + 256] += BIAS (surround);
    }
}

static void mix32to2 (sample_t * samples, sample_t bias)
{
    int i;
    sample_t common;

    for (i = 0; i < 256; i++) {
	common = BIAS (samples[i + 256]);
	samples[i] += common + samples[i + 768];
	samples[i + 256] = common + samples[i + 512] + samples[i + 1024];
    }
}

static void mix32toS (sample_t * samples, sample_t bias)
{
    int i;
    sample_t common, surround;

    for (i = 0; i < 256; i++) {
	common = BIAS (samples[i + 256]);
	surround = samples[i + 768] + samples[i + 1024];
	samples[i] += common - surround;
	samples[i + 256] = samples[i + 512] + common + surround;
    }
}

static void move2to1 (sample_t * src, sample_t * dest, sample_t bias)
{
    int i;

    for (i = 0; i < 256; i++)
	dest[i] = BIAS (src[i] + src[i + 256]);
}

static void zero (sample_t * samples)
{
    int i;

    for (i = 0; i < 256; i++)
	samples[i] = 0;
}

void a52_downmix (sample_t * samples, int acmod, int output, sample_t bias,
		  level_t clev, level_t slev)
{
    switch (CONVERT (acmod, output & A52_CHANNEL_MASK)) {

    case CONVERT (A52_CHANNEL, A52_CHANNEL2):
	memcpy (samples, samples + 256, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_CHANNEL, A52_MONO):
    case CONVERT (A52_STEREO, A52_MONO):
    mix_2to1:
	mix2to1 (samples, samples + 256, bias);
	break;

    case CONVERT (A52_2F1R, A52_MONO):
	if (slev == 0)
	    goto mix_2to1;
    case CONVERT (A52_3F, A52_MONO):
    mix_3to1:
	mix3to1 (samples, bias);
	break;

    case CONVERT (A52_3F1R, A52_MONO):
	if (slev == 0)
	    goto mix_3to1;
    case CONVERT (A52_2F2R, A52_MONO):
	if (slev == 0)
	    goto mix_2to1;
	mix4to1 (samples, bias);
	break;

    case CONVERT (A52_3F2R, A52_MONO):
	if (slev == 0)
	    goto mix_3to1;
	mix5to1 (samples, bias);
	break;

    case CONVERT (A52_MONO, A52_DOLBY):
	memcpy (samples + 256, samples, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_3F, A52_STEREO):
    case CONVERT (A52_3F, A52_DOLBY):
    mix_3to2:
	mix3to2 (samples, bias);
	break;

    case CONVERT (A52_2F1R, A52_STEREO):
	if (slev == 0)
	    break;
	mix21to2 (samples, samples + 256, bias);
	break;

    case CONVERT (A52_2F1R, A52_DOLBY):
	mix21toS (samples, bias);
	break;

    case CONVERT (A52_3F1R, A52_STEREO):
	if (slev == 0)
	    goto mix_3to2;
	mix31to2 (samples, bias);
	break;

    case CONVERT (A52_3F1R, A52_DOLBY):
	mix31toS (samples, bias);
	break;

    case CONVERT (A52_2F2R, A52_STEREO):
	if (slev == 0)
	    break;
	mix2to1 (samples, samples + 512, bias);
	mix2to1 (samples + 256, samples + 768, bias);
	break;

    case CONVERT (A52_2F2R, A52_DOLBY):
	mix22toS (samples, bias);
	break;

    case CONVERT (A52_3F2R, A52_STEREO):
	if (slev == 0)
	    goto mix_3to2;
	mix32to2 (samples, bias);
	break;

    case CONVERT (A52_3F2R, A52_DOLBY):
	mix32toS (samples, bias);
	break;

    case CONVERT (A52_3F1R, A52_3F):
	if (slev == 0)
	    break;
	mix21to2 (samples, samples + 512, bias);
	break;

    case CONVERT (A52_3F2R, A52_3F):
	if (slev == 0)
	    break;
	mix2to1 (samples, samples + 768, bias);
	mix2to1 (samples + 512, samples + 1024, bias);
	break;

    case CONVERT (A52_3F1R, A52_2F1R):
	mix3to2 (samples, bias);
	memcpy (samples + 512, samples + 768, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_2F2R, A52_2F1R):
	mix2to1 (samples + 512, samples + 768, bias);
	break;

    case CONVERT (A52_3F2R, A52_2F1R):
	mix3to2 (samples, bias);
	move2to1 (samples + 768, samples + 512, bias);
	break;

    case CONVERT (A52_3F2R, A52_3F1R):
	mix2to1 (samples + 768, samples + 1024, bias);
	break;

    case CONVERT (A52_2F1R, A52_2F2R):
	memcpy (samples + 768, samples + 512, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_3F1R, A52_2F2R):
	mix3to2 (samples, bias);
	memcpy (samples + 512, samples + 768, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_3F2R, A52_2F2R):
	mix3to2 (samples, bias);
	memcpy (samples + 512, samples + 768, 256 * sizeof (sample_t));
	memcpy (samples + 768, samples + 1024, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_3F1R, A52_3F2R):
	memcpy (samples + 1024, samples + 768, 256 * sizeof (sample_t));
	break;
    }
}

void a52_upmix (sample_t * samples, int acmod, int output)
{
    switch (CONVERT (acmod, output & A52_CHANNEL_MASK)) {

    case CONVERT (A52_CHANNEL, A52_CHANNEL2):
	memcpy (samples + 256, samples, 256 * sizeof (sample_t));
	break;

    case CONVERT (A52_3F2R, A52_MONO):
	zero (samples + 1024);
    case CONVERT (A52_3F1R, A52_MONO):
    case CONVERT (A52_2F2R, A52_MONO):
	zero (samples + 768);
    case CONVERT (A52_3F, A52_MONO):
    case CONVERT (A52_2F1R, A52_MONO):
	zero (samples + 512);
    case CONVERT (A52_CHANNEL, A52_MONO):
    case CONVERT (A52_STEREO, A52_MONO):
	zero (samples + 256);
	break;

    case CONVERT (A52_3F2R, A52_STEREO):
    case CONVERT (A52_3F2R, A52_DOLBY):
	zero (samples + 1024);
    case CONVERT (A52_3F1R, A52_STEREO):
    case CONVERT (A52_3F1R, A52_DOLBY):
	zero (samples + 768);
    case CONVERT (A52_3F, A52_STEREO):
    case CONVERT (A52_3F, A52_DOLBY):
    mix_3to2:
	memcpy (samples + 512, samples + 256, 256 * sizeof (sample_t));
	zero (samples + 256);
	break;

    case CONVERT (A52_2F2R, A52_STEREO):
    case CONVERT (A52_2F2R, A52_DOLBY):
	zero (samples + 768);
    case CONVERT (A52_2F1R, A52_STEREO):
    case CONVERT (A52_2F1R, A52_DOLBY):
	zero (samples + 512);
	break;

    case CONVERT (A52_3F2R, A52_3F):
	zero (samples + 1024);
    case CONVERT (A52_3F1R, A52_3F):
    case CONVERT (A52_2F2R, A52_2F1R):
	zero (samples + 768);
	break;

    case CONVERT (A52_3F2R, A52_3F1R):
	zero (samples + 1024);
	break;

    case CONVERT (A52_3F2R, A52_2F1R):
	zero (samples + 1024);
    case CONVERT (A52_3F1R, A52_2F1R):
    mix_31to21:
	memcpy (samples + 768, samples + 512, 256 * sizeof (sample_t));
	goto mix_3to2;

    case CONVERT (A52_3F2R, A52_2F2R):
	memcpy (samples + 1024, samples + 768, 256 * sizeof (sample_t));
	goto mix_31to21;
    }
}