From 6aec61637ba2c148e626f7e8aa5019313d1fcf8f Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Mon, 29 Sep 2008 17:26:07 +0200
Subject: pcm_utils: 24 bit support
Add support for 24 bit PCM samples to all functions. Note that
pcm_convertAudioFormat() converts 24 bit samples to 16 bit; to
preserve full quality, support for "real" 24 bit conversion should be
added.
---
src/pcm_utils.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)
(limited to 'src')
diff --git a/src/pcm_utils.c b/src/pcm_utils.c
index a1f79f430..6c0da8817 100644
--- a/src/pcm_utils.c
+++ b/src/pcm_utils.c
@@ -71,6 +71,20 @@ pcm_volume_change_16(int16_t *buffer, unsigned num_samples,
}
}
+static void
+pcm_volume_change_24(int32_t *buffer, unsigned num_samples,
+ unsigned volume)
+{
+ while (num_samples > 0) {
+ int64_t sample = *buffer;
+
+ sample = (sample * volume + pcm_dither() + 500) / 1000;
+
+ *buffer++ = pcm_range(sample, 24);
+ --num_samples;
+ }
+}
+
void pcm_volumeChange(char *buffer, int bufferSize,
const struct audio_format *format,
int volume)
@@ -93,6 +107,11 @@ void pcm_volumeChange(char *buffer, int bufferSize,
volume);
break;
+ case 24:
+ pcm_volume_change_24((int32_t*)buffer, bufferSize / 4,
+ volume);
+ break;
+
default:
FATAL("%i bits not supported by pcm_volumeChange!\n",
format->bits);
@@ -131,6 +150,22 @@ pcm_add_16(int16_t *buffer1, const int16_t *buffer2,
}
}
+static void
+pcm_add_24(int32_t *buffer1, const int32_t *buffer2,
+ unsigned num_samples, unsigned volume1, unsigned volume2)
+{
+ while (num_samples > 0) {
+ int64_t sample1 = *buffer1;
+ int64_t sample2 = *buffer2++;
+
+ sample1 = ((sample1 * volume1 + sample2 * volume2) +
+ pcm_dither() + 500) / 1000;
+
+ *buffer1++ = pcm_range(sample1, 24);
+ --num_samples;
+ }
+}
+
static void pcm_add(char *buffer1, const char *buffer2, size_t size,
int vol1, int vol2,
const struct audio_format *format)
@@ -146,6 +181,12 @@ static void pcm_add(char *buffer1, const char *buffer2, size_t size,
size / 2, vol1, vol2);
break;
+ case 24:
+ pcm_add_24((int32_t*)buffer1,
+ (const int32_t*)buffer2,
+ size / 4, vol1, vol2);
+ break;
+
default:
FATAL("%i bits not supported by pcm_add!\n", format->bits);
}
@@ -385,6 +426,16 @@ pcm_convert_8_to_16(int16_t *out, const int8_t *in,
}
}
+static void
+pcm_convert_24_to_16(int16_t *out, const int32_t *in,
+ unsigned num_samples)
+{
+ while (num_samples > 0) {
+ *out++ = *in++ >> 8;
+ --num_samples;
+ }
+}
+
static const char *pcm_convertTo16bit(int8_t bits, const char *inBuffer,
size_t inSize, size_t *outSize)
{
@@ -409,6 +460,19 @@ static const char *pcm_convertTo16bit(int8_t bits, const char *inBuffer,
case 16:
*outSize = inSize;
return inBuffer;
+
+ case 24:
+ num_samples = inSize / 4;
+ *outSize = num_samples * 2;
+ if (*outSize > len) {
+ len = *outSize;
+ buf = xrealloc(buf, len);
+ }
+
+ pcm_convert_24_to_16((int16_t *)buf,
+ (const int32_t *)inBuffer,
+ num_samples);
+ return buf;
}
ERROR("only 8 or 16 bits are supported for conversion!\n");
@@ -468,6 +532,9 @@ size_t pcm_sizeOfConvBuffer(const struct audio_format *inFormat, size_t inSize,
break;
case 16:
break;
+ case 24:
+ outSize = (outSize / 4) * 2;
+ break;
default:
FATAL("only 8 or 16 bits are supported for conversion!\n");
}
--
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