Initial import of NFC GNSS SDK project

2026-09-15 16:10:12 +08:00
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+/*
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *  Copyright (c) 2016 Daniel Pirch.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef FVAD_H_
+#define FVAD_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stddef.h>
+
+/*
+ * Type for a VAD instance, an opaque object created using fvad_new().
+ */
+typedef struct Fvad Fvad;
+
+
+/*
+ * Creates and initializes a VAD instance.
+ *
+ * On success, returns a pointer to the new VAD instance, which should
+ * eventually be deleted using fvad_free().
+ *
+ * Returns NULL in case of a memory allocation error.
+ */
+Fvad *fvad_new(void);
+
+/*
+ * Frees the dynamic memory of a specified VAD instance.
+ */
+void fvad_free(Fvad *inst);
+
+
+/*
+ * Reinitializes a VAD instance, clearing all state and resetting mode and
+ * sample rate to defaults.
+ */
+void fvad_reset(Fvad *inst);
+
+
+/*
+ * Changes the VAD operating ("aggressiveness") mode of a VAD instance.
+ *
+ * A more aggressive (higher mode) VAD is more restrictive in reporting speech.
+ * Put in other words the probability of being speech when the VAD returns 1 is
+ * increased with increasing mode. As a consequence also the missed detection
+ * rate goes up.
+ *
+ * Valid modes are 0 ("quality"), 1 ("low bitrate"), 2 ("aggressive"), and 3
+ * ("very aggressive"). The default mode is 0.
+ *
+ * Returns 0 on success, or -1 if the specified mode is invalid.
+ */
+int fvad_set_mode(Fvad* inst, int mode);
+
+
+/*
+ * Sets the input sample rate in Hz for a VAD instance.
+ *
+ * Valid values are 8000, 16000, 32000 and 48000. The default is 8000. Note
+ * that internally all processing will be done 8000 Hz; input data in higher
+ * sample rates will just be downsampled first.
+ *
+ * Returns 0 on success, or -1 if the passed value is invalid.
+ */
+int fvad_set_sample_rate(Fvad* inst, int sample_rate);
+
+
+/*
+ * Calculates a VAD decision for an audio frame.
+ *
+ * `frame` is an array of `length` signed 16-bit samples. Only frames with a
+ * length of 10, 20 or 30 ms are supported, so for example at 8 kHz, `length`
+ * must be either 80, 160 or 240.
+ *
+ * Returns              : 1 - (active voice),
+ *                        0 - (non-active Voice),
+ *                       -1 - (invalid frame length).
+ */
+int fvad_process(Fvad* inst, const int16_t* frame, size_t length);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // FVAD_H_