plugin_2pass2.c

TMS320C6713Xvid视频压缩算法源代码.rar

		rc->param.overflow_control_strength *= 3;
	} else if (scaler > 0.6) {
		rc->param.max_overflow_degradation *= 2;
		rc->param.max_overflow_improvement *= 2;
		rc->param.overflow_control_strength *= 2;
	} else {
		rc->min_quant = 2;
	}
#endif

	/* Compute min frame lengths (for each frame type) according to the number
	 * of MBs. We sum all block type counters of frame 0, this gives us the
	 * number of MBs.
	 *
	 * We compare these hardcoded values with observed values in first pass
	 * (determined in pre_process0).Then we keep the real minimum. */

	/* Number of MBs */
	num_MBs  = rc->stats[0].blks[0];
	num_MBs += rc->stats[0].blks[1];
	num_MBs += rc->stats[0].blks[2];

	/* Minimum for I frames */
	if(rc->min_length[XVID_TYPE_IVOP-1] > ((num_MBs*22) + 240) / 8)
		rc->min_length[XVID_TYPE_IVOP-1] = ((num_MBs*22) + 240) / 8;

	/* Minimum for P/S frames */
	if(rc->min_length[XVID_TYPE_PVOP-1] > ((num_MBs) + 88)  / 8)
		rc->min_length[XVID_TYPE_PVOP-1] = ((num_MBs) + 88)  / 8;

	/* Minimum for B frames */
	if(rc->min_length[XVID_TYPE_BVOP-1] > 8)
		rc->min_length[XVID_TYPE_BVOP-1] = 8;

	/* Perform an initial scale pass.
	 *
	 * If a frame size is scaled underneath our hardcoded minimums, then we
	 * force the frame size to the minimum, and deduct the original & scaled
	 * frame length from the original and target total lengths */
	for (i=0; i<rc->num_frames; i++) {
		twopass_stat_t * s = &rc->stats[i];
		int len;

		/* No need to scale frame length for which a specific quantizer is
		 * specified thanks to zones */
		if (s->zone_mode == XVID_ZONE_QUANT) {
			s->scaled_length = s->length;
			continue;
		}

		/* Compute the scaled length -- only non invariant data length is scaled */
		len = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);

		/* Compare with the computed minimum */
		if (len < rc->min_length[s->type-1]) {
			/* This is a 'forced size' frame, set its frame size to the
			 * computed minimum */
			s->scaled_length = rc->min_length[s->type-1];

			/* Remove both scaled and original size from their respective
			 * total counters, as we prepare a second pass for 'regular'
			 * frames */
			target -= s->scaled_length;
		} else {
			/* Do nothing for now, we'll scale this later */
			s->scaled_length = 0;
		}
	}

	/* The first pass on data substracted all 'forced size' frames from the
	 * total counters. Now, it's possible to scale the 'regular' frames. */

	/* Scaling factor for 'regular' frames */
	scaler = (double)(target - total_invariant) / (double)(rc->tot_weighted);

	/* Do another pass with the new scaler */
	for (i=0; i<rc->num_frames; i++) {
		twopass_stat_t * s = &rc->stats[i];

		/* Ignore frame with forced frame sizes */
		if (s->scaled_length == 0)
			s->scaled_length = s->invariant + (int)((double)(s->length-s->invariant) * scaler * s->weight);
	}

	/* Job done */
	return;
}

/* Apply all user settings to the scaled curve
 * This implies:
 *   keyframe boosting
 *   high/low compression */
static void
scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc)
{
	int i;
	int64_t ivop_boost_total;

	/* Reset the rate controller (per frame type) total byte counters */
	for (i=0; i<3; i++) rc->tot_scaled_length[i] = 0;

	/* Compute total bytes for each frame type */
	for (i=0; i<rc->num_frames;i++) {
		twopass_stat_t *s = &rc->stats[i];
		rc->tot_scaled_length[s->type-1] += s->scaled_length;
	}

	/* First we compute the total amount of bits needed, as being described by
	 * the scaled distribution. During this pass over the complete stats data,
	 * we see how much bits two user settings will get/give from/to p&b frames:
	 *  - keyframe boosting
	 *  - keyframe distance penalty */
	rc->KF_idx = 0;
	ivop_boost_total = 0;
	for (i=0; i<rc->num_frames; i++) {
		twopass_stat_t * s = &rc->stats[i];

		/* Some more work is needed for I frames */
		if (s->type == XVID_TYPE_IVOP) {
			int ivop_boost;

			/* Accumulate bytes needed for keyframe boosting */
			ivop_boost = s->scaled_length*rc->param.keyframe_boost/100;

#if 0 /* ToDo: decide how to apply kfthresholding */
#endif
			/* If the frame size drops under the minimum length, then cap ivop_boost */
			if (ivop_boost + s->scaled_length < rc->min_length[XVID_TYPE_IVOP-1])
				ivop_boost = rc->min_length[XVID_TYPE_IVOP-1] - s->scaled_length;

			/* Accumulate the ivop boost */
			ivop_boost_total += ivop_boost;

			/* Don't forget to update the keyframe index */
			rc->KF_idx++;
		}
	}

	/* Initialize the IBoost tax ratio for P/S/B frames
	 *
	 * This ratio has to be applied to p/b/s frames in order to reserve
	 * additional bits for keyframes (keyframe boosting) or if too much
	 * keyframe distance is applied, bits retrieved from the keyframes.
	 *
	 * ie pb_length *= rc->pb_iboost_tax_ratio;
	 *
	 *    gives the ideal length of a p/b frame */

	/* Compute the total length of p/b/s frames (temporary storage into
	 * movie_curve) */
	rc->pb_iboost_tax_ratio  = (double)rc->tot_scaled_length[XVID_TYPE_PVOP-1];
	rc->pb_iboost_tax_ratio += (double)rc->tot_scaled_length[XVID_TYPE_BVOP-1];

	/* Compute the ratio described above
	 *     taxed_total = sum(0, n, tax*scaled_length)
	 * <=> taxed_total = tax.sum(0, n, scaled_length)
	 * <=> tax = taxed_total / original_total */
	rc->pb_iboost_tax_ratio =
		(rc->pb_iboost_tax_ratio - ivop_boost_total) /
		rc->pb_iboost_tax_ratio;

	DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- IFrame boost tax ratio:%.2f\n",
			rc->pb_iboost_tax_ratio);

	/* Compute the average size of frames per frame type */
	for(i=0; i<3; i++) {
		/* Special case for missing type or weird case */
		if (rc->count[i] == 0 || rc->pb_iboost_tax_ratio == 0) {
			rc->avg_length[i] = 1;
		} else {
			rc->avg_length[i] = rc->tot_scaled_length[i];

			if (i == (XVID_TYPE_IVOP-1)) {
				/* I Frames total has to be added the boost total */
				rc->avg_length[i] += ivop_boost_total;
			} else {
				/* P/B frames has to taxed */
				rc->avg_length[i] *= rc->pb_iboost_tax_ratio;
			}

			/* Finally compute the average frame size */
			rc->avg_length[i] /= (double)rc->count[i];
		}
	}

	/* Assymetric curve compression */
	if (rc->param.curve_compression_high || rc->param.curve_compression_low) {
		double symetric_total;
		double assymetric_delta_total;

		/* Like I frame boosting, assymetric curve compression modifies the total
		 * amount of needed bits, we must compute the ratio so we can prescale
		 lengths */
		symetric_total = 0;
		assymetric_delta_total = 0;
		for (i=0; i<rc->num_frames; i++) {
			double assymetric_delta;
			double dbytes;
			twopass_stat_t * s = &rc->stats[i];

			/* I Frames are not concerned by assymetric scaling */
			if (s->type == XVID_TYPE_IVOP)
				continue;

			/* During the real run, we would have to apply the iboost tax */
			dbytes = s->scaled_length * rc->pb_iboost_tax_ratio;

			/* Update the symmetric curve compression total */
			symetric_total += dbytes;

			/* Apply assymetric curve compression */
			if (dbytes > rc->avg_length[s->type-1])
				assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_high / 100.0f;
			else
				assymetric_delta = (rc->avg_length[s->type-1] - dbytes) * (double)rc->param.curve_compression_low  / 100.0f;

			/* Cap to the minimum frame size if needed */
			if (dbytes + assymetric_delta < rc->min_length[s->type-1])
				assymetric_delta = rc->min_length[s->type-1] - dbytes;

			/* Accumulate after assymetric curve compression */
			assymetric_delta_total += assymetric_delta;
		}

		/* Compute the tax that all p/b frames have to pay in order to respect the
		 * bit distribution changes that the assymetric compression curve imposes
		 * We want assymetric_total = sum(0, n-1, tax.scaled_length)
		 *      ie assymetric_total = ratio.sum(0, n-1, scaled_length)
		 *         ratio = assymetric_total / symmetric_total */
		rc->assymetric_tax_ratio = ((double)symetric_total - (double)assymetric_delta_total) / (double)symetric_total;
	} else {
		rc->assymetric_tax_ratio = 1.0f;
	}

	DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- Assymetric tax ratio:%.2f\n", rc->assymetric_tax_ratio);

	/* Last bits that need to be reset */
	rc->overflow = 0;
	rc->KFoverflow = 0;
	rc->KFoverflow_partial = 0;
	rc->KF_idx = 0;
	rc->desired_total = 0;
	rc->real_total = 0;

	/* Job done */
	return;
}

/*****************************************************************************
 * Still more low level stuff (nothing to do with stats treatment)
 ****************************************************************************/

/* This function returns an allocated string containing a complete line read
 * from the file starting at the current position */
static char *
readline(FILE *f)
{
	char *buffer = NULL;
	int buffer_size = 0;
	int pos = 0;

	do {
		int c;

		/* Read a character from the stream */
		c = fgetc(f);

		/* Is that EOF or new line ? */
		if(c == EOF || c == '\n')
			break;

		/* Do we have to update buffer ? */
		if(pos >= buffer_size - 1) {
			buffer_size += BUF_SZ;
			buffer = (char*)realloc(buffer, buffer_size);
			if (buffer == NULL)
				return(NULL);
		}

		buffer[pos] = c;
		pos++;
	} while(1);

	/* Read \n or EOF */
	if (buffer == NULL) {
		/* EOF, so we reached the end of the file, return NULL */
		if(feof(f))
			return(NULL);

		/* Just an empty line with just a newline, allocate a 1 byte buffer to
		 * store a zero length string */
		buffer = (char*)malloc(1);
		if(buffer == NULL)
			return(NULL);
	}

	/* Zero terminated string */
	buffer[pos] = '\0';

	return(buffer);
}

/* This function returns a pointer to the first non space char in the given
 * string */
static char *
skipspaces(char *string)
{
	const char spaces[] =
		{
			' ','\t','\0'
		};
	const char *spacechar = spaces;

	if (string == NULL) return(NULL);

	while (*string != '\0') {
		/* Test against space chars */
		while (*spacechar != '\0') {
			if (*string == *spacechar) {
				string++;
				spacechar = spaces;
				break;
			}
			spacechar++;
		}

		/* No space char */
		if (*spacechar == '\0') return(string);
	}

	return(string);
}

/* This function returns a boolean that tells if the string is only a
 * comment */
static int
iscomment(char *string)
{
	const char comments[] =
		{
			'#',';', '%', '\0'
		};
	const char *cmtchar = comments;
	int iscomment = 0;

	if (string == NULL) return(1);

	string = skipspaces(string);

	while(*cmtchar != '\0') {
		if(*string == *cmtchar) {
			iscomment = 1;
			break;
		}
		cmtchar++;
	}

	return(iscomment);
}

#if 0
static void
stats_print(rc_2pass2_t * rc)
{
	int i;
	const char frame_type[4] = { 'i', 'p', 'b', 's'};

	for (i=0; i<rc->num_frames; i++) {
		twopass_stat_t *s = &rc->stats[i];
		DPRINTF(XVID_DEBUG_RC, "[xvid rc] -- frame:%d type:%c quant:%d stats:%d scaled:%d desired:%d actual:%d overflow(%c):%.2f\n",
				i, frame_type[s->type-1], -1, s->length, s->scaled_length,
				s->desired_length, -1, frame_type[s->type-1], -1.0f);
	}
}
#endif