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+/* $Id$ */
+/*
+ * Based on:
+ * resample-1.8.tar.gz from the
+ * Digital Audio Resampling Home Page located at
+ * http://www-ccrma.stanford.edu/~jos/resample/.
+ *
+ * SOFTWARE FOR SAMPLING-RATE CONVERSION AND FIR DIGITAL FILTER DESIGN
+ *
+ * Snippet from the resample.1 man page:
+ *
+ * HISTORY
+ *
+ * The first version of this software was written by Julius O. Smith III
+ * <jos@ccrma.stanford.edu> at CCRMA <http://www-ccrma.stanford.edu> in
+ * 1981. It was called SRCONV and was written in SAIL for PDP-10
+ * compatible machines. The algorithm was first published in
+ *
+ * Smith, Julius O. and Phil Gossett. ``A Flexible Sampling-Rate
+ * Conversion Method,'' Proceedings (2): 19.4.1-19.4.4, IEEE Conference
+ * on Acoustics, Speech, and Signal Processing, San Diego, March 1984.
+ *
+ * An expanded tutorial based on this paper is available at the Digital
+ * Audio Resampling Home Page given above.
+ *
+ * Circa 1988, the SRCONV program was translated from SAIL to C by
+ * Christopher Lee Fraley working with Roger Dannenberg at CMU.
+ *
+ * Since then, the C version has been maintained by jos.
+ *
+ * Sndlib support was added 6/99 by John Gibson <jgg9c@virginia.edu>.
+ *
+ * The resample program is free software distributed in accordance
+ * with the Lesser GNU Public License (LGPL). There is NO warranty; not
+ * even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+/* PJMEDIA modification:
+ * - remove resample(), just use SrcUp, SrcUD, and SrcLinear directly.
+ * - move FilterUp() and FilterUD() from filterkit.c
+ * - move stddefs.h and resample.h to this file.
+ * - const correctness.
+ */
+#include <pjmedia/resample.h>
+#include <pjmedia/errno.h>
+#include <pj/assert.h>
+#include <pj/log.h>
+#include <pj/pool.h>
+
+
+#define THIS_FILE "resample.c"
+
+
+/*
+ * Taken from stddefs.h
+ */
+#ifndef PI
+#define PI (3.14159265358979232846)
+#endif
+
+#ifndef PI2
+#define PI2 (6.28318530717958465692)
+#endif
+
+#define D2R (0.01745329348) /* (2*pi)/360 */
+#define R2D (57.29577951) /* 360/(2*pi) */
+
+#ifndef MAX
+#define MAX(x,y) ((x)>(y) ?(x):(y))
+#endif
+#ifndef MIN
+#define MIN(x,y) ((x)<(y) ?(x):(y))
+#endif
+
+#ifndef ABS
+#define ABS(x) ((x)<0 ?(-(x)):(x))
+#endif
+
+#ifndef SGN
+#define SGN(x) ((x)<0 ?(-1):((x)==0?(0):(1)))
+#endif
+
+typedef char RES_BOOL;
+typedef short RES_HWORD;
+typedef int RES_WORD;
+typedef unsigned short RES_UHWORD;
+typedef unsigned int RES_UWORD;
+
+#define MAX_HWORD (32767)
+#define MIN_HWORD (-32768)
+
+#ifdef DEBUG
+#define INLINE
+#else
+#define INLINE inline
+#endif
+
+/*
+ * Taken from resample.h
+ *
+ * The configuration constants below govern
+ * the number of bits in the input sample and filter coefficients, the
+ * number of bits to the right of the binary-point for fixed-point math, etc.
+ *
+ */
+
+/* Conversion constants */
+#define Nhc 8
+#define Na 7
+#define Np (Nhc+Na)
+#define Npc (1<<Nhc)
+#define Amask ((1<<Na)-1)
+#define Pmask ((1<<Np)-1)
+#define Nh 16
+#define Nb 16
+#define Nhxn 14
+#define Nhg (Nh-Nhxn)
+#define NLpScl 13
+
+/* Description of constants:
+ *
+ * Npc - is the number of look-up values available for the lowpass filter
+ * between the beginning of its impulse response and the "cutoff time"
+ * of the filter. The cutoff time is defined as the reciprocal of the
+ * lowpass-filter cut off frequence in Hz. For example, if the
+ * lowpass filter were a sinc function, Npc would be the index of the
+ * impulse-response lookup-table corresponding to the first zero-
+ * crossing of the sinc function. (The inverse first zero-crossing
+ * time of a sinc function equals its nominal cutoff frequency in Hz.)
+ * Npc must be a power of 2 due to the details of the current
+ * implementation. The default value of 512 is sufficiently high that
+ * using linear interpolation to fill in between the table entries
+ * gives approximately 16-bit accuracy in filter coefficients.
+ *
+ * Nhc - is log base 2 of Npc.
+ *
+ * Na - is the number of bits devoted to linear interpolation of the
+ * filter coefficients.
+ *
+ * Np - is Na + Nhc, the number of bits to the right of the binary point
+ * in the integer "time" variable. To the left of the point, it indexes
+ * the input array (X), and to the right, it is interpreted as a number
+ * between 0 and 1 sample of the input X. Np must be less than 16 in
+ * this implementation.
+ *
+ * Nh - is the number of bits in the filter coefficients. The sum of Nh and
+ * the number of bits in the input data (typically 16) cannot exceed 32.
+ * Thus Nh should be 16. The largest filter coefficient should nearly
+ * fill 16 bits (32767).
+ *
+ * Nb - is the number of bits in the input data. The sum of Nb and Nh cannot
+ * exceed 32.
+ *
+ * Nhxn - is the number of bits to right shift after multiplying each input
+ * sample times a filter coefficient. It can be as great as Nh and as
+ * small as 0. Nhxn = Nh-2 gives 2 guard bits in the multiply-add
+ * accumulation. If Nhxn=0, the accumulation will soon overflow 32 bits.
+ *
+ * Nhg - is the number of guard bits in mpy-add accumulation (equal to Nh-Nhxn)
+ *
+ * NLpScl - is the number of bits allocated to the unity-gain normalization
+ * factor. The output of the lowpass filter is multiplied by LpScl and
+ * then right-shifted NLpScl bits. To avoid overflow, we must have
+ * Nb+Nhg+NLpScl < 32.
+ */
+
+
+#ifdef _MSC_VER
+# pragma warning(push, 3)
+//# pragma warning(disable: 4245) // Conversion from uint to ushort
+# pragma warning(disable: 4244) // Conversion from double to uint
+# pragma warning(disable: 4146) // unary minus operator applied to unsigned type, result still unsigned
+# pragma warning(disable: 4761) // integral size mismatch in argument; conversion supplied
+#endif
+
+#if defined(PJMEDIA_HAS_SMALL_FILTER) && PJMEDIA_HAS_SMALL_FILTER!=0
+# include "smallfilter.h"
+#else
+# define SMALL_FILTER_NMULT 0
+# define SMALL_FILTER_SCALE 0
+# define SMALL_FILTER_NWING 0
+# define SMALL_FILTER_IMP NULL
+# define SMALL_FILTER_IMPD NULL
+#endif
+
+#if defined(PJMEDIA_HAS_LARGE_FILTER) && PJMEDIA_HAS_LARGE_FILTER!=0
+# include "largefilter.h"
+#else
+# define LARGE_FILTER_NMULT 0
+# define LARGE_FILTER_SCALE 0
+# define LARGE_FILTER_NWING 0
+# define LARGE_FILTER_IMP NULL
+# define LARGE_FILTER_IMPD NULL
+#endif
+
+
+#undef INLINE
+#define INLINE
+#define HAVE_FILTER 0
+
+#ifndef NULL
+# define NULL 0
+#endif
+
+
+static INLINE RES_HWORD WordToHword(RES_WORD v, int scl)
+{
+ RES_HWORD out;
+ RES_WORD llsb = (1<<(scl-1));
+ v += llsb; /* round */
+ v >>= scl;
+ if (v>MAX_HWORD) {
+ v = MAX_HWORD;
+ } else if (v < MIN_HWORD) {
+ v = MIN_HWORD;
+ }
+ out = (RES_HWORD) v;
+ return out;
+}
+
+/* Sampling rate conversion using linear interpolation for maximum speed.
+ */
+static int
+ SrcLinear(const RES_HWORD X[], RES_HWORD Y[], double pFactor, RES_UHWORD nx)
+{
+ RES_HWORD iconst;
+ RES_UWORD time = 0;
+ const RES_HWORD *xp;
+ RES_HWORD *Ystart, *Yend;
+ RES_WORD v,x1,x2;
+
+ double dt; /* Step through input signal */
+ RES_UWORD dtb; /* Fixed-point version of Dt */
+ RES_UWORD endTime; /* When time reaches EndTime, return to user */
+
+ dt = 1.0/pFactor; /* Output sampling period */
+ dtb = dt*(1<<Np) + 0.5; /* Fixed-point representation */
+
+ Ystart = Y;
+ Yend = Ystart + (unsigned)(nx * pFactor);
+ endTime = time + (1<<Np)*(RES_WORD)nx;
+ while (time < endTime)
+ {
+ iconst = (time) & Pmask;
+ xp = &X[(time)>>Np]; /* Ptr to current input sample */
+ x1 = *xp++;
+ x2 = *xp;
+ x1 *= ((1<<Np)-iconst);
+ x2 *= iconst;
+ v = x1 + x2;
+ *Y++ = WordToHword(v,Np); /* Deposit output */
+ time += dtb; /* Move to next sample by time increment */
+ }
+ return (Y - Ystart); /* Return number of output samples */
+}
+
+static RES_WORD FilterUp(const RES_HWORD Imp[], const RES_HWORD ImpD[],
+ RES_UHWORD Nwing, RES_BOOL Interp,
+ const RES_HWORD *Xp, RES_HWORD Ph, RES_HWORD Inc)
+{
+ const RES_HWORD *Hp;
+ const RES_HWORD *Hdp = NULL;
+ const RES_HWORD *End;
+ RES_HWORD a = 0;
+ RES_WORD v, t;
+
+ v=0;
+ Hp = &Imp[Ph>>Na];
+ End = &Imp[Nwing];
+ if (Interp) {
+ Hdp = &ImpD[Ph>>Na];
+ a = Ph & Amask;
+ }
+ if (Inc == 1) /* If doing right wing... */
+ { /* ...drop extra coeff, so when Ph is */
+ End--; /* 0.5, we don't do too many mult's */
+ if (Ph == 0) /* If the phase is zero... */
+ { /* ...then we've already skipped the */
+ Hp += Npc; /* first sample, so we must also */
+ Hdp += Npc; /* skip ahead in Imp[] and ImpD[] */
+ }
+ }
+ if (Interp)
+ while (Hp < End) {
+ t = *Hp; /* Get filter coeff */
+ t += (((RES_WORD)*Hdp)*a)>>Na; /* t is now interp'd filter coeff */
+ Hdp += Npc; /* Filter coeff differences step */
+ t *= *Xp; /* Mult coeff by input sample */
+ if (t & (1<<(Nhxn-1))) /* Round, if needed */
+ t += (1<<(Nhxn-1));
+ t >>= Nhxn; /* Leave some guard bits, but come back some */
+ v += t; /* The filter output */
+ Hp += Npc; /* Filter coeff step */
+
+ Xp += Inc; /* Input signal step. NO CHECK ON BOUNDS */
+ }
+ else
+ while (Hp < End) {
+ t = *Hp; /* Get filter coeff */
+ t *= *Xp; /* Mult coeff by input sample */
+ if (t & (1<<(Nhxn-1))) /* Round, if needed */
+ t += (1<<(Nhxn-1));
+ t >>= Nhxn; /* Leave some guard bits, but come back some */
+ v += t; /* The filter output */
+ Hp += Npc; /* Filter coeff step */
+ Xp += Inc; /* Input signal step. NO CHECK ON BOUNDS */
+ }
+ return(v);
+}
+
+
+static RES_WORD FilterUD(const RES_HWORD Imp[], const RES_HWORD ImpD[],
+ RES_UHWORD Nwing, RES_BOOL Interp,
+ const RES_HWORD *Xp, RES_HWORD Ph, RES_HWORD Inc, RES_UHWORD dhb)
+{
+ RES_HWORD a;
+ const RES_HWORD *Hp, *Hdp, *End;
+ RES_WORD v, t;
+ RES_UWORD Ho;
+
+ v=0;
+ Ho = (Ph*(RES_UWORD)dhb)>>Np;
+ End = &Imp[Nwing];
+ if (Inc == 1) /* If doing right wing... */
+ { /* ...drop extra coeff, so when Ph is */
+ End--; /* 0.5, we don't do too many mult's */
+ if (Ph == 0) /* If the phase is zero... */
+ Ho += dhb; /* ...then we've already skipped the */
+ } /* first sample, so we must also */
+ /* skip ahead in Imp[] and ImpD[] */
+ if (Interp)
+ while ((Hp = &Imp[Ho>>Na]) < End) {
+ t = *Hp; /* Get IR sample */
+ Hdp = &ImpD[Ho>>Na]; /* get interp (lower Na) bits from diff table*/
+ a = Ho & Amask; /* a is logically between 0 and 1 */
+ t += (((RES_WORD)*Hdp)*a)>>Na; /* t is now interp'd filter coeff */
+ t *= *Xp; /* Mult coeff by input sample */
+ if (t & 1<<(Nhxn-1)) /* Round, if needed */
+ t += 1<<(Nhxn-1);
+ t >>= Nhxn; /* Leave some guard bits, but come back some */
+ v += t; /* The filter output */
+ Ho += dhb; /* IR step */
+ Xp += Inc; /* Input signal step. NO CHECK ON BOUNDS */
+ }
+ else
+ while ((Hp = &Imp[Ho>>Na]) < End) {
+ t = *Hp; /* Get IR sample */
+ t *= *Xp; /* Mult coeff by input sample */
+ if (t & 1<<(Nhxn-1)) /* Round, if needed */
+ t += 1<<(Nhxn-1);
+ t >>= Nhxn; /* Leave some guard bits, but come back some */
+ v += t; /* The filter output */
+ Ho += dhb; /* IR step */
+ Xp += Inc; /* Input signal step. NO CHECK ON BOUNDS */
+ }
+ return(v);
+}
+
+/* Sampling rate up-conversion only subroutine;
+ * Slightly faster than down-conversion;
+ */
+static int SrcUp(const RES_HWORD X[], RES_HWORD Y[], double pFactor,
+ RES_UHWORD nx, RES_UHWORD pNwing, RES_UHWORD pLpScl,
+ const RES_HWORD pImp[], const RES_HWORD pImpD[], RES_BOOL Interp)
+{
+ const RES_HWORD *xp;
+ RES_HWORD *Ystart, *Yend;
+ RES_WORD v;
+
+ double dt; /* Step through input signal */
+ RES_UWORD dtb; /* Fixed-point version of Dt */
+ RES_UWORD time = 0;
+ RES_UWORD endTime; /* When time reaches EndTime, return to user */
+
+ dt = 1.0/pFactor; /* Output sampling period */
+ dtb = dt*(1<<Np) + 0.5; /* Fixed-point representation */
+
+ Ystart = Y;
+ Yend = Ystart + (unsigned)(nx * pFactor);
+ endTime = time + (1<<Np)*(RES_WORD)nx;
+ while (time < endTime)
+ {
+ xp = &X[time>>Np]; /* Ptr to current input sample */
+ /* Perform left-wing inner product */
+ v = 0;
+ v = FilterUp(pImp, pImpD, pNwing, Interp, xp, (RES_HWORD)(time&Pmask),-1);
+
+ /* Perform right-wing inner product */
+ v += FilterUp(pImp, pImpD, pNwing, Interp, xp+1, (RES_HWORD)((-time)&Pmask),1);
+
+ v >>= Nhg; /* Make guard bits */
+ v *= pLpScl; /* Normalize for unity filter gain */
+ *Y++ = WordToHword(v,NLpScl); /* strip guard bits, deposit output */
+ time += dtb; /* Move to next sample by time increment */
+ }
+ return (Y - Ystart); /* Return the number of output samples */
+}
+
+
+/* Sampling rate conversion subroutine */
+
+static int SrcUD(const RES_HWORD X[], RES_HWORD Y[], double pFactor,
+ RES_UHWORD nx, RES_UHWORD pNwing, RES_UHWORD pLpScl,
+ const RES_HWORD pImp[], const RES_HWORD pImpD[], RES_BOOL Interp)
+{
+ const RES_HWORD *xp;
+ RES_HWORD *Ystart, *Yend;
+ RES_WORD v;
+
+ double dh; /* Step through filter impulse response */
+ double dt; /* Step through input signal */
+ RES_UWORD time = 0;
+ RES_UWORD endTime; /* When time reaches EndTime, return to user */
+ RES_UWORD dhb, dtb; /* Fixed-point versions of Dh,Dt */
+
+ dt = 1.0/pFactor; /* Output sampling period */
+ dtb = dt*(1<<Np) + 0.5; /* Fixed-point representation */
+
+ dh = MIN(Npc, pFactor*Npc); /* Filter sampling period */
+ dhb = dh*(1<<Na) + 0.5; /* Fixed-point representation */
+
+ Ystart = Y;
+ Yend = Ystart + (unsigned)(nx * pFactor);
+ endTime = time + (1<<Np)*(RES_WORD)nx;
+ while (time < endTime)
+ {
+ xp = &X[time>>Np]; /* Ptr to current input sample */
+ v = FilterUD(pImp, pImpD, pNwing, Interp, xp, (RES_HWORD)(time&Pmask),
+ -1, dhb); /* Perform left-wing inner product */
+ v += FilterUD(pImp, pImpD, pNwing, Interp, xp+1, (RES_HWORD)((-time)&Pmask),
+ 1, dhb); /* Perform right-wing inner product */
+ v >>= Nhg; /* Make guard bits */
+ v *= pLpScl; /* Normalize for unity filter gain */
+ *Y++ = WordToHword(v,NLpScl); /* strip guard bits, deposit output */
+ time += dtb; /* Move to next sample by time increment */
+ }
+ return (Y - Ystart); /* Return the number of output samples */
+}
+
+
+/* ***************************************************************************
+ *
+ * PJMEDIA RESAMPLE
+ *
+ * ***************************************************************************
+ */
+
+struct pjmedia_resample
+{
+ double factor; /* Conversion factor = rate_out / rate_in. */
+ pj_bool_t large_filter; /* Large filter? */
+ pj_bool_t high_quality; /* Not fast? */
+ unsigned xoff; /* History and lookahead size, in samples */
+ unsigned frame_size; /* Samples per frame. */
+ pj_int16_t *buffer; /* Input buffer. */
+};
+
+
+PJ_DEF(pj_status_t) pjmedia_resample_create( pj_pool_t *pool,
+ pj_bool_t high_quality,
+ pj_bool_t large_filter,
+ unsigned channel_count,
+ unsigned rate_in,
+ unsigned rate_out,
+ unsigned samples_per_frame,
+ pjmedia_resample **p_resample)
+{
+ pjmedia_resample *resample;
+
+ PJ_ASSERT_RETURN(pool && p_resample && rate_in &&
+ rate_out && samples_per_frame, PJ_EINVAL);
+
+ resample = pj_pool_alloc(pool, sizeof(pjmedia_resample));
+ PJ_ASSERT_RETURN(resample, PJ_ENOMEM);
+
+ PJ_UNUSED_ARG(channel_count);
+
+ /*
+ * If we're downsampling, always use the fast algorithm since it seems
+ * to yield the same quality.
+ */
+ if (rate_out < rate_in) {
+ //no this is not a good idea. It sounds pretty good with speech,
+ //but very poor with background noise etc.
+ //high_quality = 0;
+ }
+
+#if !defined(PJMEDIA_HAS_LARGE_FILTER) || PJMEDIA_HAS_LARGE_FILTER==0
+ /*
+ * If large filter is excluded in the build, then prevent application
+ * from using it.
+ */
+ if (high_quality && large_filter) {
+ large_filter = PJ_FALSE;
+ PJ_LOG(5,(THIS_FILE,
+ "Resample uses small filter because large filter is "
+ "disabled"));
+ }
+#endif
+
+#if !defined(PJMEDIA_HAS_SMALL_FILTER) || PJMEDIA_HAS_SMALL_FILTER==0
+ /*
+ * If small filter is excluded in the build and application wants to
+ * use it, then drop to linear conversion.
+ */
+ if (high_quality && large_filter == 0) {
+ high_quality = PJ_FALSE;
+ PJ_LOG(4,(THIS_FILE,
+ "Resample uses linear because small filter is disabled"));
+ }
+#endif
+
+ resample->factor = rate_out * 1.0 / rate_in;
+ resample->large_filter = large_filter;
+ resample->high_quality = high_quality;
+ resample->frame_size = samples_per_frame;
+
+ if (high_quality) {
+ unsigned size;
+
+ /* This is a bug in xoff calculation, thanks Stephane Lussier
+ * of Macadamian dot com.
+ * resample->xoff = large_filter ? 32 : 6;
+ */
+ if (large_filter)
+ resample->xoff = (LARGE_FILTER_NMULT + 1) / 2.0 *
+ MAX(1.0, 1.0/resample->factor);
+ else
+ resample->xoff = (SMALL_FILTER_NMULT + 1) / 2.0 *
+ MAX(1.0, 1.0/resample->factor);
+
+
+ size = (samples_per_frame + 2*resample->xoff) * sizeof(pj_int16_t);
+ resample->buffer = pj_pool_alloc(pool, size);
+ PJ_ASSERT_RETURN(resample->buffer, PJ_ENOMEM);
+
+ pjmedia_zero_samples(resample->buffer, resample->xoff*2);
+
+
+ } else {
+ resample->xoff = 0;
+ }
+
+ *p_resample = resample;
+
+ PJ_LOG(5,(THIS_FILE, "resample created: %s qualiy, %s filter, in/out "
+ "rate=%d/%d",
+ (high_quality?"high":"low"),
+ (large_filter?"large":"small"),
+ rate_in, rate_out));
+ return PJ_SUCCESS;
+}
+
+
+
+PJ_DEF(void) pjmedia_resample_run( pjmedia_resample *resample,
+ const pj_int16_t *input,
+ pj_int16_t *output )
+{
+ PJ_ASSERT_ON_FAIL(resample, return);
+
+ if (resample->high_quality) {
+ pj_int16_t *dst_buf;
+ const pj_int16_t *src_buf;
+
+ /* Okay chaps, here's how we do resampling.
+ *
+ * The original resample algorithm requires xoff samples *before* the
+ * input buffer as history, and another xoff samples *after* the
+ * end of the input buffer as lookahead. Since application can only
+ * supply framesize buffer on each run, PJMEDIA needs to arrange the
+ * buffer to meet these requirements.
+ *
+ * So here comes the trick.
+ *
+ * First of all, because of the history and lookahead requirement,
+ * resample->buffer need to accomodate framesize+2*xoff samples in its
+ * buffer. This is done when the buffer is created.
+ *
+ * On the first run, the input frame (supplied by application) is
+ * copied to resample->buffer at 2*xoff position. The first 2*xoff
+ * samples are initially zeroed (in the initialization). The resample
+ * algorithm then invoked at resample->buffer+xoff ONLY, thus giving
+ * it one xoff at the beginning as zero, and one xoff at the end
+ * as the end of the original input. The resample algorithm will see
+ * that the first xoff samples in the input as zero.
+ *
+ * So here's the layout of resample->buffer on the first run.
+ *
+ * run 0
+ * +------+------+--------------+
+ * | 0000 | 0000 | frame0... |
+ * +------+------+--------------+
+ * ^ ^ ^ ^
+ * 0 xoff 2*xoff size+2*xoff
+ *
+ * (Note again: resample algorithm is called at resample->buffer+xoff)
+ *
+ * At the end of the run, 2*xoff samples from the end of
+ * resample->buffer are copied to the beginning of resample->buffer.
+ * The first xoff part of this will be used as history for the next
+ * run, and the second xoff part of this is actually the start of
+ * resampling for the next run.
+ *
+ * And the first run completes, the function returns.
+ *
+ *
+ * On the next run, the input frame supplied by application is again
+ * copied at 2*xoff position in the resample->buffer, and the
+ * resample algorithm is again invoked at resample->buffer+xoff
+ * position. So effectively, the resample algorithm will start its
+ * operation on the last xoff from the previous frame, and gets the
+ * history from the last 2*xoff of the previous frame, and the look-
+ * ahead from the last xoff of current frame.
+ *
+ * So on this run, the buffer layout is:
+ *
+ * run 1
+ * +------+------+--------------+
+ * | frm0 | frm0 | frame1... |
+ * +------+------+--------------+
+ * ^ ^ ^ ^
+ * 0 xoff 2*xoff size+2*xoff
+ *
+ * As you can see from above diagram, the resampling algorithm is
+ * actually called from the last xoff part of previous frame (frm0).
+ *
+ * And so on the process continues for the next frame, and the next,
+ * and the next, ...
+ *
+ */
+ dst_buf = resample->buffer + resample->xoff*2;
+ pjmedia_copy_samples(dst_buf, input, resample->frame_size);
+
+ if (resample->factor >= 1) {
+
+ if (resample->large_filter) {
+ SrcUp(resample->buffer + resample->xoff, output,
+ resample->factor, resample->frame_size,
+ LARGE_FILTER_NWING, LARGE_FILTER_SCALE,
+ LARGE_FILTER_IMP, LARGE_FILTER_IMPD,
+ PJ_TRUE);
+ } else {
+ SrcUp(resample->buffer + resample->xoff, output,
+ resample->factor, resample->frame_size,
+ SMALL_FILTER_NWING, SMALL_FILTER_SCALE,
+ SMALL_FILTER_IMP, SMALL_FILTER_IMPD,
+ PJ_TRUE);
+ }
+
+ } else {
+
+ if (resample->large_filter) {
+
+ SrcUD( resample->buffer + resample->xoff, output,
+ resample->factor, resample->frame_size,
+ LARGE_FILTER_NWING,
+ LARGE_FILTER_SCALE * resample->factor + 0.5,
+ LARGE_FILTER_IMP, LARGE_FILTER_IMPD,
+ PJ_TRUE);
+
+ } else {
+
+ SrcUD( resample->buffer + resample->xoff, output,
+ resample->factor, resample->frame_size,
+ SMALL_FILTER_NWING,
+ SMALL_FILTER_SCALE * resample->factor + 0.5,
+ SMALL_FILTER_IMP, SMALL_FILTER_IMPD,
+ PJ_TRUE);
+
+ }
+
+ }
+
+ dst_buf = resample->buffer;
+ src_buf = input + resample->frame_size - resample->xoff*2;
+ pjmedia_copy_samples(dst_buf, src_buf, resample->xoff * 2);
+
+ } else {
+ SrcLinear( input, output, resample->factor, resample->frame_size);
+ }
+}
+
+PJ_DEF(unsigned) pjmedia_resample_get_input_size(pjmedia_resample *resample)
+{
+ PJ_ASSERT_RETURN(resample != NULL, 0);
+ return resample->frame_size;
+}
+
+PJ_DEF(void) pjmedia_resample_destroy(pjmedia_resample *resample)
+{
+ PJ_UNUSED_ARG(resample);
+}
+
+