From a0fece94bda85861676115dcd942430f77bac253 Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <PromyLOPh@gmail.com>
Date: Thu, 24 Jul 2008 11:27:37 +0200
Subject: Initial ReplayGain work (including anti-clipping)

Could be tuned...
---
 src/Makefile.am |  2 +-
 src/main.c      |  1 +
 src/player.c    | 27 +++++++++++++++++++++++++++
 src/player.h    |  1 +
 4 files changed, 30 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/Makefile.am b/src/Makefile.am
index e3a98a4..06c8e59 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -6,5 +6,5 @@ pianobar_CPPFLAGS = ${LIBCURL_CFLAGS} ${LIBAO_CFLAGS} ${LIBXML_CFLAGS} \
 		-I../libpiano/src -I../libwardrobe/src
 pianobar_LDADD = ${LIBCURL_LIBS} ${LIBAO_LIBS} ${LIBFAAD_LIBS} \
 		${LIBREADLINE_LIBS} ${LIBXML_LIBS} -lpthread \
-		../libpiano/src/libpiano.la ../libwardrobe/src/libwardrobe.la
+		../libpiano/src/libpiano.la ../libwardrobe/src/libwardrobe.la -lm
 dist_man1_MANS = pianobar.1
diff --git a/src/main.c b/src/main.c
index 4f3e3b0..eaa93d5 100644
--- a/src/main.c
+++ b/src/main.c
@@ -438,6 +438,7 @@ int main (int argc, char **argv) {
 
 					memset (&player, 0, sizeof (player));
 					player.url = strdup (curSong->audioUrl);
+					player.gain = curSong->fileGain;
 		
 					/* start player */
 					pthread_create (&playerThread, NULL, BarPlayerThread,
diff --git a/src/player.c b/src/player.c
index d72979d..086fcad 100644
--- a/src/player.c
+++ b/src/player.c
@@ -22,6 +22,8 @@ THE SOFTWARE.
 
 #include <unistd.h>
 #include <string.h>
+#include <math.h>
+#include <stdint.h>
 
 #include "player.h"
 #include "config.h"
@@ -40,6 +42,16 @@ unsigned int BarChangeByteorderUI32 (char buf[4]) {
 	return ret;
 }
 
+/*	compute replaygain scale factor
+ *	algo taken from here: http://www.dsprelated.com/showmessage/29246/1.php
+ *	mpd does the same
+ *	@param apply this gain
+ *	@return this * yourvalue = newgain value
+ */
+inline float computeReplayGainScale (float applyGain) {
+	return pow (10.0, applyGain / 20.0);
+}
+
 /*	our heart: plays streamed music
  *	@param streamed data
  *	@param block size
@@ -89,6 +101,21 @@ size_t BarPlayerCurlCb (void *ptr, size_t size, size_t nmemb, void *stream) {
 						NeAACDecGetErrorMessage (frameInfo.error));
 				break;
 			}
+			short int *replayBuf = (short int *) aacDecoded;
+			int tmpReplayBuf;
+			size_t i;
+			for (i = 0; i < frameInfo.samples; i++) {
+				tmpReplayBuf = (float) (replayBuf[i]) *
+						computeReplayGainScale (player->gain);
+				/* avoid clipping */
+				if (tmpReplayBuf > INT16_MAX) {
+					replayBuf[i] = INT16_MAX;
+				} else if (tmpReplayBuf < INT16_MIN) {
+					replayBuf[i] = INT16_MIN;
+				} else {
+					replayBuf[i] = tmpReplayBuf;
+				}
+			}
 			/* ao_play needs bytes: 1 sample = 16 bits = 2 bytes */
 			ao_play (player->audioOutDevice, aacDecoded,
 					frameInfo.samples * 16 / 8);
diff --git a/src/player.h b/src/player.h
index 9e44bef..9d0908b 100644
--- a/src/player.h
+++ b/src/player.h
@@ -41,6 +41,7 @@ struct aacPlayer {
 	NeAACDecHandle aacHandle;
 	unsigned long samplerate;
 	unsigned char channels;
+	float gain;
 	/* audio out */
 	ao_device *audioOutDevice;
 	char *url;
-- 
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