1 files changed, 122 insertions, 0 deletions
diff --git a/wsutil/mpeg-audio.c b/wsutil/mpeg-audio.c
new file mode 100644
index 0000000..8e80a13
--- /dev/null
+++ b/wsutil/mpeg-audio.c
@@ -0,0 +1,122 @@
+/* mpeg-audio.c
+ *
+ * MPEG Audio header dissection
+ * Written by Shaun Jackman <sjackman@gmail.com>
+ * Copyright 2007 Shaun Jackman
+ *
+ * Wiretap Library
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "mpeg-audio.h"
+
+static const int mpa_versions[4] = { 2, -1, 1, 0 };
+static const int mpa_layers[4] = { -1, 2, 1, 0 };
+
+static const unsigned int mpa_samples_data[3][3] = {
+	{ 384, 1152, 1152 },
+	{ 384, 1152, 576 },
+	{ 384, 1152, 576 },
+};
+
+static const unsigned int mpa_bitrates[3][3][16] = { /* kb/s */
+	{
+		{ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 },
+		{ 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256, 320, 384 },
+		{ 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224, 256, 320 },
+	},
+	{
+		{ 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192, 224, 256 },
+		{ 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128, 144, 160 },
+		{ 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128, 144, 160 },
+	},
+	{
+		{ 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192, 224, 256 },
+		{ 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128, 144, 160 },
+		{ 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128, 144, 160 },
+	},
+};
+
+static const unsigned int mpa_frequencies[3][4] = {
+	{ 44100, 48000, 32000 },
+	{ 22050, 24000, 16000 },
+	{ 11025, 12000, 8000 },
+};
+
+static const unsigned int mpa_padding_data[3] = { 4, 1, 1 };
+
+int
+mpa_version(const struct mpa *mpa)
+{
+	return mpa_versions[mpa->version];
+}
+
+int
+mpa_layer(const struct mpa *mpa)
+{
+	return mpa_layers[mpa->layer];
+}
+
+unsigned
+mpa_samples(const struct mpa *mpa)
+{
+	return mpa_samples_data[mpa_versions[mpa->version]][mpa_layer(mpa)];
+}
+
+unsigned
+mpa_bitrate(const struct mpa *mpa)
+{
+	return (1000 * (mpa_bitrates[mpa_versions[mpa->version]][mpa_layers[mpa->layer]][mpa->bitrate]));
+}
+
+unsigned
+mpa_frequency(const struct mpa *mpa)
+{
+	return(mpa_frequencies[mpa_versions[mpa->version]][mpa->frequency]);
+}
+
+unsigned
+mpa_padding(const struct mpa *mpa)
+{
+	return(mpa->padding ? mpa_padding_data[mpa_layers[mpa->layer]] : 0);
+}
+
+/* Decode an ID3v2 synchsafe integer.
+ * See https://id3.org/id3v2.4.0-structure section 6.2.
+ */
+uint32_t
+decode_synchsafe_int(uint32_t input)
+{
+	uint32_t value;
+
+	/* High-order byte */
+	value = (input >> 24) & 0x7f;
+	/* Shift the result left to make room for the next 7 bits */
+	value <<= 7;
+
+	/* Now OR in the 2nd byte */
+	value |= (input >> 16) & 0x7f;
+	value <<= 7;
+
+	/* ... and the 3rd */
+	value |= (input >> 8) & 0x7f;
+	value <<= 7;
+
+	/* For the 4th byte don't do the shift */
+	value |= input & 0x7f;
+
+	return value;
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 8
+ * tab-width: 8
+ * indent-tabs-mode: t
+ * End:
+ *
+ * vi: set shiftwidth=8 tabstop=8 noexpandtab:
+ * :indentSize=8:tabSize=8:noTabs=false:
+ */