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Diffstat (limited to 'gr-cvsd-vocoder/src/lib/cvsd_encode_sb.h')
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1 files changed, 0 insertions, 173 deletions
diff --git a/gr-cvsd-vocoder/src/lib/cvsd_encode_sb.h b/gr-cvsd-vocoder/src/lib/cvsd_encode_sb.h deleted file mode 100644 index a7994d4ed..000000000 --- a/gr-cvsd-vocoder/src/lib/cvsd_encode_sb.h +++ /dev/null @@ -1,173 +0,0 @@ -/* -*- c++ -*- */ -/* - * Copyright 2007 Free Software Foundation, Inc. - * - * This file is part of GNU Radio - * - * GNU Radio 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 3, or (at your option) - * any later version. - * - * GNU Radio 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 GNU Radio; see the file COPYING. If not, write to - * the Free Software Foundation, Inc., 51 Franklin Street, - * Boston, MA 02110-1301, USA. - */ -#ifndef INCLUDED_CVSD_ENCODER_SB_H -#define INCLUDED_CVSD_ENCODER_SB_H - -#include <gr_sync_decimator.h> - -class cvsd_encode_sb; - -typedef boost::shared_ptr<cvsd_encode_sb> cvsd_encode_sb_sptr; - - /*! - * \brief Constructor parameters to initialize the CVSD encoder. The default - * values are modeled after the Bluetooth standard and should not be changed - * except by an advanced user - * - * \param min_step Minimum step size used to update the internal reference. Default: "10" - * \param max_step Maximum step size used to update the internal reference. Default: "1280" - * \param step_decay Decay factor applied to step size when there is not a run of J output 1s or 0s. Default: "0.9990234375" (i.e. 1-1/1024) - * \param accum_decay Decay factor applied to the internal reference during every interation of the codec. Default: "0.96875" (i.e. 1-1/32) - * \param K; Size of shift register; the number of output bits remembered by codec (must be less or equal to 32). Default: "32" - * \param J; Number of bits in the shift register that are equal; i.e. the size of a run of 1s, 0s. Default: "4" - * \param pos_accum_max Maximum integer value allowed for the internal reference. Default: "32767" (2^15 - 1 or MAXSHORT) - * \param neg_accum_max Minimum integer value allowed for the internal reference. Default: "-32767" (-2^15 + 1 or MINSHORT+1) - * - */ - -cvsd_encode_sb_sptr cvsd_make_encode_sb (short min_step=10, - short max_step=1280, - double step_decay=0.9990234375, - double accum_decay= 0.96875, - int K=32, - int J=4, - short pos_accum_max=32767, - short neg_accum_max=-32767); - -/*! - * \brief This block performs CVSD audio encoding. Its design and implementation - * is modeled after the CVSD encoder/decoder specifications defined in the - * Bluetooth standard. - * - * \ingroup vocoder_blk - * - * CVSD is a method for encoding speech that seeks to reduce the - * bandwidth required for digital voice transmission. CVSD takes - * advantage of strong correlation between samples, quantizing the - * difference in amplitude between two consecutive samples. This - * difference requires fewer quantization levels as compared to other - * methods that quantize the actual amplitude level, reducing the - * bandwidth. CVSD employs a two level quantizer (one bit) and an - * adaptive algorithm that allows for continuous step size adjustment. - * - * The coder can represent low amplitude signals with accuracy without - * sacrificing performance on large amplitude signals, a trade off that - * occurs in some non-adaptive modulations. - * - * The CVSD encoder effectively provides 8-to-1 compression. More - * specifically, each incoming audio sample is compared to an internal - * reference value. If the input is greater or equal to the reference, - * the encoder outputs a "1" bit. If the input is less than the reference, - * the encoder outputs a "0" bit. The reference value is then updated - * accordingly based on the frequency of outputted "1" or "0" bits. By - * grouping 8 outputs bits together, the encoder essentially produce one - * output byte for every 8 input audio samples. - * - * This encoder requires that input audio samples are 2-byte short signed - * integers. The result bandwidth conversion, therefore, is 16 input bytes - * of raw audio data to 1 output byte of encoded audio data. - * - * The CVSD encoder module must be prefixed by an up-converter to over-sample - * the audio data prior to encoding. The Bluetooth standard specifically - * calls for a 1-to-8 interpolating up-converter. While this reduces the - * overall compression of the codec, this is required so that the encoder - * can accurately compute the slope between adjacent audio samples and - * correctly update its internal reference value. - * - * References: - * - * 1. Continuously Variable Slope Delta Modulation (CVSD) A Tutorial, - * Available: http://www.eetkorea.com/ARTICLES/2003AUG/A/2003AUG29_NTEK_RFD_AN02.PDF. - * - * 2. Specification of The Bluetooth System - * Available: http://grouper.ieee.org/groups/802/15/Bluetooth/core_10_b.pdf. - * - * 3. McGarrity, S., Bluetooth Full Duplex Voice and Data Transmission. 2002. - * Bluetooth Voice Simulink® Model, Available: - * http://www.mathworks.com/company/newsletters/digest/nov01/bluetooth.html - * - */ - -class cvsd_encode_sb : public gr_sync_decimator -{ -private: - friend cvsd_encode_sb_sptr cvsd_make_encode_sb (short min_step, - short max_step, - double step_decay, - double accum_decay, - int K, - int J, - short pos_accum_max, - short neg_accum_max); - - cvsd_encode_sb (short min_step, short max_step, double step_decay, - double accum_decay, int K, int J, - short pos_accum_max, short neg_accum_max); - - //! Member functions required by the encoder/decoder - //! \brief Rounding function specific to CVSD - //! \return the input value rounded to the nearest integer - int cvsd_round(double input); - - //! \brief A power function specific to CVSD data formats - //! \return (radix)^power, where radix and power are short integers - unsigned int cvsd_pow (short radix, short power); - - //! \brief Sums number of 1's in the input - //! \return the number of 1s in the four bytes of an input unsigned integer - unsigned char cvsd_bitwise_sum (unsigned int input); - - // Members variables related to the CVSD encoder use to update interal reference value - short d_min_step; - short d_max_step; - double d_step_decay; - double d_accum_decay; - - int d_K; //!< \brief Size of shift register; the number of output bits remembered in shift register - int d_J; //!< \brief Number of bits in the shift register that are equal; size of run of 1s, 0s - - short d_pos_accum_max; - short d_neg_accum_max; - - int d_accum; //!< \brief Current value of internal reference - int d_loop_counter; //!< \brief Current value of the loop counter - unsigned int d_runner; //!< \brief Current value of the shift register - short d_stepsize; //!< \brief Current value of the step sizer - - public: - ~cvsd_encode_sb (); // public destructor - - short min_step() { return d_min_step; } - short max_step() { return d_max_step; } - double step_decay() { return d_step_decay; } - double accum_decay() { return d_accum_decay; } - int K() { return d_K; } - int J() { return d_J; } - short pos_accum_max() { return d_pos_accum_max; } - short neg_accum_max() { return d_neg_accum_max; } - - int work (int noutput_items, - gr_vector_const_void_star &input_items, - gr_vector_void_star &output_items); -}; - -#endif /* INCLUDED_CVSD_ENCODE_SB_H */ |