From: Andre Noll <maan@systemlinux.org>
Date: Sat, 9 Feb 2008 19:32:36 +0000 (+0100)
Subject: compress.c: Simplify volume adjusting code.
X-Git-Tag: v0.3.1~29
X-Git-Url: http://git.tue.mpg.de/?a=commitdiff_plain;h=64e8616027238f6ef1933ccef14a2e031552db79;p=paraslash.git

compress.c: Simplify volume adjusting code.

There's no need to distinguish the cases sample > 0 and
sample < 0. Work with its absolute value instead and get
rid of some similar code in the hot path.

Also print a log message in case clipping occurs.
---

diff --git a/compress.c b/compress.c
index 1ea41107..579a6ab6 100644
--- a/compress.c
+++ b/compress.c
@@ -51,30 +51,18 @@ static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
 		/* be careful in that heat, my dear */
 		int sample = *ip++, adjusted_sample;
 
-		if (sample > 0) {
-			adjusted_sample = (sample * pcd->current_gain)
-				>> gain_shift;
-			if (unlikely(adjusted_sample > 32767)) {
-				adjusted_sample = 32767;
-				pcd->current_gain = (3 * pcd->current_gain +
-					(1 << pcd->conf->inertia_arg)) / 4;
-				pcd->peak = 0;
-			} else
-				if (adjusted_sample > pcd->peak)
-					pcd->peak = adjusted_sample;
-		} else {
-			adjusted_sample = -((-sample * pcd->current_gain)
-				>> gain_shift);
-			if (unlikely(adjusted_sample < -32768)) {
-				adjusted_sample = -32768;
-				pcd->current_gain = (3 * pcd->current_gain +
-					(1 << pcd->conf->inertia_arg)) / 4;
-				pcd->peak = 0;
-			} else
-				if (-adjusted_sample > pcd->peak)
-					pcd->peak = -adjusted_sample;
-		}
-		*op++ = adjusted_sample;
+		adjusted_sample = (PARA_ABS(sample) * pcd->current_gain)
+			>> gain_shift;
+		if (unlikely(adjusted_sample > 32767)) { /* clip */
+			PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
+				sample, adjusted_sample);
+			adjusted_sample = 32767;
+			pcd->current_gain = (3 * pcd->current_gain +
+				(1 << pcd->conf->inertia_arg)) / 4;
+			pcd->peak = 0;
+		} else
+			pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
+		*op++ = sample >= 0? adjusted_sample : -adjusted_sample;
 		if (likely(++pcd->num_samples & mask))
 			continue;
 		if (pcd->peak < pcd->conf->target_level_arg) {
@@ -84,10 +72,9 @@ static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
 			if (pcd->current_gain > pcd->min_gain + 1)
 				pcd->current_gain -= 2;
 		}
-//		PARA_DEBUG_LOG("gain: %lu, peak: %d\n", pcd->current_gain,
-//			pcd->peak);
+		PARA_DEBUG_LOG("gain: %lu, peak: %d\n", pcd->current_gain,
+			pcd->peak);
 		pcd->peak = 0;
-//		PARA_INFO_LOG("sample: %lu\n", ABS(sample));
 	}
 	fn->loaded += length;
 	return length;