compress.c: Simplify volume adjusting code.

[paraslash.git] / compress.c

diff --git a/compress.c b/compress.c
index 3e605d0e091a2bf4ffcfb99f21adf19550188036..579a6ab643e479eb55156bdd3280f0d246dcee54 100644 (file)
--- a/compress.c
+++ b/compress.c
@@ -1,49 +1,38 @@
 /*
- * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
  *
- *     This program is free software; you can redistribute it and/or modify
- *     it under the terms of the GNU General Public License as published by
- *     the Free Software Foundation; either version 2 of the License, or
- *     (at your option) any later version.
- *
- *     This program is distributed in the hope that it will be useful,
- *     but WITHOUT ANY WARRANTY; without even the implied warranty of
- *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *     GNU General Public License for more details.
- *
- *     You should have received a copy of the GNU General Public License
- *     along with this program; if not, write to the Free Software
- *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ * Licensed under the GPL v2. For licencing details see COPYING.
  */
 
-/** \file compress.c paraslash's dynamic audio range compressor */
+/** \file compress.c Paraslash's dynamic audio range compressor. */
 
 /*
- * Used ideas of AudioCompress, (C) 2002-2004  M. Hari Nezumi <magenta@trikuare.cx>
+ * Uses ideas of AudioCompress, (C) 2002-2004  M. Hari Nezumi <magenta@trikuare.cx>
  */
 
 #include "para.h"
 #include "compress_filter.cmdline.h"
 #include "list.h"
+#include "sched.h"
 #include "filter.h"
 #include "string.h"
 
-/** the size of the output data buffer */
+/** The size of the output data buffer. */
 #define COMPRESS_CHUNK_SIZE 40960
 
-/** data specific to the compress filter */
+/** Data specific to the compress filter. */
 struct private_compress_data {
-       /** the current multiplier */
+       /** The current multiplier. */
        unsigned current_gain;
-       /** points to the configuration data for this instance of the compress filter */
+       /** Points to the configuration data for this instance of the compress filter. */
        struct compress_filter_args_info *conf;
-       /** minimal admissible gain */
+       /** Minimal admissible gain. */
        unsigned min_gain;
-       /** maximal admissible gain */
+       /** Maximal admissible gain. */
        unsigned max_gain;
-       /** number of samples already seen */
+       /** Number of samples already seen. */
        unsigned num_samples;
-       /** absolute value of the maximal sample in the current block */
+       /** Absolute value of the maximal sample in the current block. */
        unsigned peak;
 };
 
@@ -62,30 +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 = 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) {
@@ -95,10 +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;
@@ -132,7 +108,11 @@ static void open_compress(struct filter_node *fn)
        pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 }
 
-/** the init function of the compress filter */
+/**
+ * The init function of the compress filter.
+ *
+ * \param f Pointer to the struct to initialize.
+ */
 void compress_init(struct filter *f)
 {
        f->open = open_compress;