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195 lines
5 KiB
C
195 lines
5 KiB
C
/*
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** Copyright (c) 2002-2016, Erik de Castro Lopo <erikd@mega-nerd.com>
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** All rights reserved.
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**
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** This code is released under 2-clause BSD license. Please see the
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** file at : https://github.com/erikd/libsamplerate/blob/master/COPYING
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*/
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#include "precomp.h"
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static int zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
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static void zoh_reset (SRC_PRIVATE *psrc) ;
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/*========================================================================================
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*/
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#define ZOH_MAGIC_MARKER MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h')
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typedef struct
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{ int zoh_magic_marker ;
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int channels ;
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int reset ;
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long in_count, in_used ;
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long out_count, out_gen ;
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float last_value [1] ;
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} ZOH_DATA ;
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/*----------------------------------------------------------------------------------------
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*/
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static int
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zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
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{ ZOH_DATA *priv ;
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double src_ratio, input_index, rem ;
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int ch ;
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if (data->input_frames <= 0)
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return SRC_ERR_NO_ERROR ;
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if (psrc->private_data == NULL)
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return SRC_ERR_NO_PRIVATE ;
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priv = (ZOH_DATA*) psrc->private_data ;
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if (priv->reset)
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{ /* If we have just been reset, set the last_value data. */
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for (ch = 0 ; ch < priv->channels ; ch++)
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priv->last_value [ch] = data->data_in [ch] ;
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priv->reset = 0 ;
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} ;
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priv->in_count = data->input_frames * priv->channels ;
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priv->out_count = data->output_frames * priv->channels ;
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priv->in_used = priv->out_gen = 0 ;
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src_ratio = psrc->last_ratio ;
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if (is_bad_src_ratio (src_ratio))
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return SRC_ERR_BAD_INTERNAL_STATE ;
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input_index = psrc->last_position ;
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/* Calculate samples before first sample in input array. */
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while (input_index < 1.0 && priv->out_gen < priv->out_count)
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{
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if (priv->in_used + priv->channels * input_index >= priv->in_count)
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break ;
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if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
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src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
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for (ch = 0 ; ch < priv->channels ; ch++)
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{ data->data_out [priv->out_gen] = priv->last_value [ch] ;
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priv->out_gen ++ ;
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} ;
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/* Figure out the next index. */
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input_index += 1.0 / src_ratio ;
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} ;
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rem = fmod_one (input_index) ;
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priv->in_used += priv->channels * lrint (input_index - rem) ;
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input_index = rem ;
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/* Main processing loop. */
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while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index <= priv->in_count)
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{
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if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
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src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
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for (ch = 0 ; ch < priv->channels ; ch++)
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{ data->data_out [priv->out_gen] = data->data_in [priv->in_used - priv->channels + ch] ;
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priv->out_gen ++ ;
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} ;
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/* Figure out the next index. */
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input_index += 1.0 / src_ratio ;
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rem = fmod_one (input_index) ;
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priv->in_used += priv->channels * lrint (input_index - rem) ;
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input_index = rem ;
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} ;
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if (priv->in_used > priv->in_count)
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{ input_index += (priv->in_used - priv->in_count) / priv->channels ;
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priv->in_used = priv->in_count ;
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} ;
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psrc->last_position = input_index ;
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if (priv->in_used > 0)
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for (ch = 0 ; ch < priv->channels ; ch++)
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priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ;
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/* Save current ratio rather then target ratio. */
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psrc->last_ratio = src_ratio ;
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data->input_frames_used = priv->in_used / priv->channels ;
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data->output_frames_gen = priv->out_gen / priv->channels ;
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return SRC_ERR_NO_ERROR ;
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} /* zoh_vari_process */
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/*------------------------------------------------------------------------------
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*/
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const char*
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zoh_get_name (int src_enum)
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{
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if (src_enum == SRC_ZERO_ORDER_HOLD)
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return "ZOH Interpolator" ;
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return NULL ;
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} /* zoh_get_name */
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const char*
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zoh_get_description (int src_enum)
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{
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if (src_enum == SRC_ZERO_ORDER_HOLD)
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return "Zero order hold interpolator, very fast, poor quality." ;
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return NULL ;
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} /* zoh_get_descrition */
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int
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zoh_set_converter (SRC_PRIVATE *psrc, int src_enum)
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{ ZOH_DATA *priv = NULL ;
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if (src_enum != SRC_ZERO_ORDER_HOLD)
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return SRC_ERR_BAD_CONVERTER ;
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if (psrc->private_data != NULL)
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{ free (psrc->private_data) ;
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psrc->private_data = NULL ;
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} ;
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if (psrc->private_data == NULL)
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{ priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ;
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psrc->private_data = priv ;
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} ;
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if (priv == NULL)
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return SRC_ERR_MALLOC_FAILED ;
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priv->zoh_magic_marker = ZOH_MAGIC_MARKER ;
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priv->channels = psrc->channels ;
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psrc->const_process = zoh_vari_process ;
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psrc->vari_process = zoh_vari_process ;
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psrc->reset = zoh_reset ;
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zoh_reset (psrc) ;
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return SRC_ERR_NO_ERROR ;
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} /* zoh_set_converter */
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/*===================================================================================
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*/
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static void
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zoh_reset (SRC_PRIVATE *psrc)
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{ ZOH_DATA *priv ;
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priv = (ZOH_DATA*) psrc->private_data ;
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if (priv == NULL)
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return ;
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priv->channels = psrc->channels ;
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priv->reset = 1 ;
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memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ;
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return ;
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} /* zoh_reset */
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