1 files changed, 109 insertions, 0 deletions
diff --git a/plugins/codecs/G729/G729decode.c b/plugins/codecs/G729/G729decode.c
new file mode 100644
index 00000000..7bb564e6
--- /dev/null
+++ b/plugins/codecs/G729/G729decode.c
@@ -0,0 +1,109 @@
+/* G729decode.c
+ * G.729 codec
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "config.h"
+
+#include <glib.h>
+
+#include "bcg729/decoder.h"
+#include "wsutil/codecs.h"
+#include "ws_attributes.h"
+
+void codec_register_g729(void);
+
+static void *
+codec_g729_init(codec_context_t *ctx _U_)
+{
+    return initBcg729DecoderChannel();
+}
+
+static void
+codec_g729_release(codec_context_t *ctx)
+{
+    closeBcg729DecoderChannel((bcg729DecoderChannelContextStruct *)ctx->priv);
+}
+
+static unsigned
+codec_g729_get_channels(codec_context_t *ctx _U_)
+{
+    return 1;
+}
+
+static unsigned
+codec_g729_get_frequency(codec_context_t *ctx _U_)
+{
+    return 8000;
+}
+
+static size_t
+codec_g729_decode(codec_context_t *ctx,
+        const void *inputBytes, size_t inputBytesSize,
+        void *outputSamples, size_t *outputSamplesSize)
+{
+    bcg729DecoderChannelContextStruct *state = (bcg729DecoderChannelContextStruct *)ctx->priv;
+    const guint8 *dataIn = (const guint8 *) inputBytes;
+    gint16 *dataOut = (gint16 *) outputSamples;
+    size_t i;
+
+    if (!ctx) {
+        return 0;
+    }
+
+    size_t full_frames = inputBytesSize / 10;
+    /* Almost surely only one SID frame. SID frames come at the end of
+       the payload, and 10 ms packets can be used when transitioning to
+       avoid ambiguity. (RFC 3551 4.5.6 "G729")
+     */
+    size_t sid_frames = (inputBytesSize % 10) / 2;
+
+    if (!outputSamples || !outputSamplesSize) {
+        return 80*2*(full_frames + sid_frames);
+    }
+
+    /* The G729 algorithm encodes 10ms of voice into 80bit (10 bytes).
+       Based on the RTP packetization period (usually 20ms), we need to
+       pass to the bcg729 decoder chunks of 10ms (10 bytes)
+    */
+    for (i = 0; i < full_frames; i++) {
+        /* As of version 1.1.0, the bcg729 decoder library declares the second
+           argument to bcg729Decoder() to be a const pointer, but prior to
+           that it did not (though it didn't modify the input and could be
+           fixed to accept a const pointer.) Cast away the problem for now;
+           in the future we could check the version of the library.
+        */
+        bcg729Decoder(state, (guint8 *)dataIn + i*10, 10, 0, 0, 0, dataOut + i*80);
+    }
+
+    for (; i < full_frames + sid_frames; i++) {
+        bcg729Decoder(state, (guint8 *)dataIn + full_frames*10 + (i - full_frames)*2, 2, 0, 1, 0, dataOut + i*80);
+    }
+    *outputSamplesSize = 80*2*(full_frames + sid_frames);
+    return *outputSamplesSize;
+}
+
+void
+codec_register_g729(void)
+{
+    register_codec("g729", codec_g729_init, codec_g729_release,
+            codec_g729_get_channels, codec_g729_get_frequency, codec_g729_decode);
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */