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cog/Frameworks/WavPack/Files/write_words.c

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////////////////////////////////////////////////////////////////////////////
// **** WAVPACK **** //
// Hybrid Lossless Wavefile Compressor //
// Copyright (c) 1998 - 2013 Conifer Software. //
// All Rights Reserved. //
// Distributed under the BSD Software License (see license.txt) //
////////////////////////////////////////////////////////////////////////////
// write_words.c
// This module provides entropy word encoding functions using
// a variation on the Rice method. This was introduced in version 3.93
// because it allows splitting the data into a "lossy" stream and a
// "correction" stream in a very efficient manner and is therefore ideal
// for the "hybrid" mode. For 4.0, the efficiency of this method was
// significantly improved by moving away from the normal Rice restriction of
// using powers of two for the modulus divisions and now the method can be
// used for both hybrid and pure lossless encoding.
// Samples are divided by median probabilities at 5/7 (71.43%), 10/49 (20.41%),
// and 20/343 (5.83%). Each zone has 3.5 times fewer samples than the
// previous. Using standard Rice coding on this data would result in 1.4
// bits per sample average (not counting sign bit). However, there is a
// very simple encoding that is over 99% efficient with this data and
// results in about 1.22 bits per sample.
#include <stdlib.h>
#include <string.h>
#include "wavpack_local.h"
///////////////////////////// executable code ////////////////////////////////
// Initialize entropy encoder for the specified stream. In lossless mode there
// are no parameters to select; in hybrid mode the bitrate mode and value need
// be initialized.
static void word_set_bitrate (WavpackStream *wps);
void init_words (WavpackStream *wps)
{
CLEAR (wps->w);
if (wps->wphdr.flags & HYBRID_FLAG)
word_set_bitrate (wps);
}
// Set up parameters for hybrid mode based on header flags and "bits" field.
// This is currently only set up for the HYBRID_BITRATE mode in which the
// allowed error varies with the residual level (from "slow_level"). The
// simpler mode (which is not used yet) has the error level directly
// controlled from the metadata.
static void word_set_bitrate (WavpackStream *wps)
{
int bitrate_0, bitrate_1;
if (wps->wphdr.flags & HYBRID_BITRATE) {
if (wps->wphdr.flags & FALSE_STEREO)
bitrate_0 = (wps->bits * 2 - 512) < 568 ? 0 : (wps->bits * 2 - 512) - 568;
else
bitrate_0 = wps->bits < 568 ? 0 : wps->bits - 568;
if (!(wps->wphdr.flags & MONO_DATA)) {
if (wps->wphdr.flags & HYBRID_BALANCE)
bitrate_1 = (wps->wphdr.flags & JOINT_STEREO) ? 256 : 0;
else {
bitrate_1 = bitrate_0;
if (wps->wphdr.flags & JOINT_STEREO) {
if (bitrate_0 < 128) {
bitrate_1 += bitrate_0;
bitrate_0 = 0;
}
else {
bitrate_0 -= 128;
bitrate_1 += 128;
}
}
}
}
else
bitrate_1 = 0;
}
else
bitrate_0 = bitrate_1 = 0;
wps->w.bitrate_acc [0] = (int32_t) bitrate_0 << 16;
wps->w.bitrate_acc [1] = (int32_t) bitrate_1 << 16;
}
// Allocates the correct space in the metadata structure and writes the
// current median values to it. Values are converted from 32-bit unsigned
// to our internal 16-bit wp_log2 values, and read_entropy_vars () is called
// to read the values back because we must compensate for the loss through
// the log function.
void write_entropy_vars (WavpackStream *wps, WavpackMetadata *wpmd)
{
unsigned char *byteptr;
int temp;
byteptr = wpmd->data = malloc (12);
wpmd->id = ID_ENTROPY_VARS;
*byteptr++ = temp = wp_log2 (wps->w.c [0].median [0]);
*byteptr++ = temp >> 8;
*byteptr++ = temp = wp_log2 (wps->w.c [0].median [1]);
*byteptr++ = temp >> 8;
*byteptr++ = temp = wp_log2 (wps->w.c [0].median [2]);
*byteptr++ = temp >> 8;
if (!(wps->wphdr.flags & MONO_DATA)) {
*byteptr++ = temp = wp_log2 (wps->w.c [1].median [0]);
*byteptr++ = temp >> 8;
*byteptr++ = temp = wp_log2 (wps->w.c [1].median [1]);
*byteptr++ = temp >> 8;
*byteptr++ = temp = wp_log2 (wps->w.c [1].median [2]);
*byteptr++ = temp >> 8;
}
wpmd->byte_length = (int32_t)(byteptr - (unsigned char *) wpmd->data);
read_entropy_vars (wps, wpmd);
}
// Allocates enough space in the metadata structure and writes the current
// high word of the bitrate accumulator and the slow_level values to it. The
// slow_level values are converted from 32-bit unsigned to our internal 16-bit
// wp_log2 values. Afterward, read_entropy_vars () is called to read the values
// back because we must compensate for the loss through the log function and
// the truncation of the bitrate.
void write_hybrid_profile (WavpackStream *wps, WavpackMetadata *wpmd)
{
unsigned char *byteptr;
int temp;
word_set_bitrate (wps);
byteptr = wpmd->data = malloc (512);
wpmd->id = ID_HYBRID_PROFILE;
if (wps->wphdr.flags & HYBRID_BITRATE) {
*byteptr++ = temp = wp_log2s (wps->w.c [0].slow_level);
*byteptr++ = temp >> 8;
if (!(wps->wphdr.flags & MONO_DATA)) {
*byteptr++ = temp = wp_log2s (wps->w.c [1].slow_level);
*byteptr++ = temp >> 8;
}
}
*byteptr++ = temp = wps->w.bitrate_acc [0] >> 16;
*byteptr++ = temp >> 8;
if (!(wps->wphdr.flags & MONO_DATA)) {
*byteptr++ = temp = wps->w.bitrate_acc [1] >> 16;
*byteptr++ = temp >> 8;
}
if (wps->w.bitrate_delta [0] | wps->w.bitrate_delta [1]) {
*byteptr++ = temp = wp_log2s (wps->w.bitrate_delta [0]);
*byteptr++ = temp >> 8;
if (!(wps->wphdr.flags & MONO_DATA)) {
*byteptr++ = temp = wp_log2s (wps->w.bitrate_delta [1]);
*byteptr++ = temp >> 8;
}
}
wpmd->byte_length = (int32_t)(byteptr - (unsigned char *) wpmd->data);
read_hybrid_profile (wps, wpmd);
}
// This function writes the specified word to the open bitstream "wvbits" and,
// if the bitstream "wvcbits" is open, writes any correction data there. This
// function will work for either lossless or hybrid but because a version
// optimized for lossless exits below, it would normally be used for the hybrid
// mode only. The return value is the actual value stored to the stream (even
// if a correction file is being created) and is used as feedback to the
// predictor.
int32_t FASTCALL send_word (WavpackStream *wps, int32_t value, int chan)
{
struct entropy_data *c = wps->w.c + chan;
uint32_t ones_count, low, mid, high;
int sign = (value < 0) ? 1 : 0;
if (wps->w.c [0].median [0] < 2 && !wps->w.holding_zero && wps->w.c [1].median [0] < 2) {
if (wps->w.zeros_acc) {
if (value)
flush_word (wps);
else {
c->slow_level -= (c->slow_level + SLO) >> SLS;
wps->w.zeros_acc++;
return 0;
}
}
else if (value)
putbit_0 (&wps->wvbits);
else {
c->slow_level -= (c->slow_level + SLO) >> SLS;
CLEAR (wps->w.c [0].median);
CLEAR (wps->w.c [1].median);
wps->w.zeros_acc = 1;
return 0;
}
}
if (sign)
value = ~value;
if ((wps->wphdr.flags & HYBRID_FLAG) && !chan)
update_error_limit (wps);
if (value < (int32_t) GET_MED (0)) {
ones_count = low = 0;
high = GET_MED (0) - 1;
DEC_MED0 ();
}
else {
low = GET_MED (0);
INC_MED0 ();
if (value - low < GET_MED (1)) {
ones_count = 1;
high = low + GET_MED (1) - 1;
DEC_MED1 ();
}
else {
low += GET_MED (1);
INC_MED1 ();
if (value - low < GET_MED (2)) {
ones_count = 2;
high = low + GET_MED (2) - 1;
DEC_MED2 ();
}
else {
ones_count = 2 + (value - low) / GET_MED (2);
low += (ones_count - 2) * GET_MED (2);
high = low + GET_MED (2) - 1;
INC_MED2 ();
}
}
}
mid = (high + low + 1) >> 1;
if (wps->w.holding_zero) {
if (ones_count)
wps->w.holding_one++;
flush_word (wps);
if (ones_count) {
wps->w.holding_zero = 1;
ones_count--;
}
else
wps->w.holding_zero = 0;
}
else
wps->w.holding_zero = 1;
wps->w.holding_one = ones_count * 2;
if (!c->error_limit) {
if (high != low) {
uint32_t maxcode = high - low, code = value - low;
int bitcount = count_bits (maxcode);
uint32_t extras = bitset [bitcount] - maxcode - 1;
if (code < extras) {
wps->w.pend_data |= code << wps->w.pend_count;
wps->w.pend_count += bitcount - 1;
}
else {
wps->w.pend_data |= ((code + extras) >> 1) << wps->w.pend_count;
wps->w.pend_count += bitcount - 1;
wps->w.pend_data |= ((code + extras) & 1) << wps->w.pend_count++;
}
}
mid = value;
}
else
while (high - low > c->error_limit)
if (value < (int32_t) mid) {
mid = ((high = mid - 1) + low + 1) >> 1;
wps->w.pend_count++;
}
else {
mid = (high + (low = mid) + 1) >> 1;
wps->w.pend_data |= bitset [wps->w.pend_count++];
}
wps->w.pend_data |= ((int32_t) sign << wps->w.pend_count++);
if (!wps->w.holding_zero)
flush_word (wps);
if (bs_is_open (&wps->wvcbits) && c->error_limit) {
uint32_t code = value - low, maxcode = high - low;
int bitcount = count_bits (maxcode);
uint32_t extras = bitset [bitcount] - maxcode - 1;
if (bitcount) {
if (code < extras)
putbits (code, bitcount - 1, &wps->wvcbits);
else {
putbits ((code + extras) >> 1, bitcount - 1, &wps->wvcbits);
putbit ((code + extras) & 1, &wps->wvcbits);
}
}
}
if (wps->wphdr.flags & HYBRID_BITRATE) {
c->slow_level -= (c->slow_level + SLO) >> SLS;
c->slow_level += wp_log2 (mid);
}
return sign ? ~mid : mid;
}
// This function is an optimized version of send_word() that only handles
// lossless (error_limit == 0) and sends an entire buffer of either mono or
// stereo data rather than a single sample. Unlike the generalized
// send_word(), it does not return values because it always encodes
// the exact value passed.
void send_words_lossless (WavpackStream *wps, int32_t *buffer, int32_t nsamples)
{
struct entropy_data *c = wps->w.c;
int32_t value, csamples;
if (!(wps->wphdr.flags & MONO_DATA))
nsamples *= 2;
for (csamples = 0; csamples < nsamples; ++csamples) {
int sign = ((value = *buffer++) < 0) ? 1 : 0;
uint32_t ones_count, low, high;
if (!(wps->wphdr.flags & MONO_DATA))
c = wps->w.c + (csamples & 1);
if (wps->w.c [0].median [0] < 2 && !wps->w.holding_zero && wps->w.c [1].median [0] < 2) {
if (wps->w.zeros_acc) {
if (value)
flush_word (wps);
else {
wps->w.zeros_acc++;
continue;
}
}
else if (value)
putbit_0 (&wps->wvbits);
else {
CLEAR (wps->w.c [0].median);
CLEAR (wps->w.c [1].median);
wps->w.zeros_acc = 1;
continue;
}
}
if (sign)
value = ~value;
if (value < (int32_t) GET_MED (0)) {
ones_count = low = 0;
high = GET_MED (0) - 1;
DEC_MED0 ();
}
else {
low = GET_MED (0);
INC_MED0 ();
if (value - low < GET_MED (1)) {
ones_count = 1;
high = low + GET_MED (1) - 1;
DEC_MED1 ();
}
else {
low += GET_MED (1);
INC_MED1 ();
if (value - low < GET_MED (2)) {
ones_count = 2;
high = low + GET_MED (2) - 1;
DEC_MED2 ();
}
else {
ones_count = 2 + (value - low) / GET_MED (2);
low += (ones_count - 2) * GET_MED (2);
high = low + GET_MED (2) - 1;
INC_MED2 ();
}
}
}
if (wps->w.holding_zero) {
if (ones_count)
wps->w.holding_one++;
flush_word (wps);
if (ones_count) {
wps->w.holding_zero = 1;
ones_count--;
}
else
wps->w.holding_zero = 0;
}
else
wps->w.holding_zero = 1;
wps->w.holding_one = ones_count * 2;
if (high != low) {
uint32_t maxcode = high - low, code = value - low;
int bitcount = count_bits (maxcode);
uint32_t extras = bitset [bitcount] - maxcode - 1;
if (code < extras) {
wps->w.pend_data |= code << wps->w.pend_count;
wps->w.pend_count += bitcount - 1;
}
else {
wps->w.pend_data |= ((code + extras) >> 1) << wps->w.pend_count;
wps->w.pend_count += bitcount - 1;
wps->w.pend_data |= ((code + extras) & 1) << wps->w.pend_count++;
}
}
wps->w.pend_data |= ((int32_t) sign << wps->w.pend_count++);
if (!wps->w.holding_zero)
flush_word (wps);
}
}
// Used by send_word() and send_word_lossless() to actually send most the
// accumulated data onto the bitstream. This is also called directly from
// clients when all words have been sent.
void flush_word (WavpackStream *wps)
{
if (wps->w.zeros_acc) {
int cbits = count_bits (wps->w.zeros_acc);
while (cbits--)
putbit_1 (&wps->wvbits);
putbit_0 (&wps->wvbits);
while (wps->w.zeros_acc > 1) {
putbit (wps->w.zeros_acc & 1, &wps->wvbits);
wps->w.zeros_acc >>= 1;
}
wps->w.zeros_acc = 0;
}
if (wps->w.holding_one) {
#ifdef LIMIT_ONES
if (wps->w.holding_one >= LIMIT_ONES) {
int cbits;
putbits ((1L << LIMIT_ONES) - 1, LIMIT_ONES + 1, &wps->wvbits);
wps->w.holding_one -= LIMIT_ONES;
cbits = count_bits (wps->w.holding_one);
while (cbits--)
putbit_1 (&wps->wvbits);
putbit_0 (&wps->wvbits);
while (wps->w.holding_one > 1) {
putbit (wps->w.holding_one & 1, &wps->wvbits);
wps->w.holding_one >>= 1;
}
wps->w.holding_zero = 0;
}
else
putbits (bitmask [wps->w.holding_one], wps->w.holding_one, &wps->wvbits);
wps->w.holding_one = 0;
#else
do {
putbit_1 (&wps->wvbits);
} while (--wps->w.holding_one);
#endif
}
if (wps->w.holding_zero) {
putbit_0 (&wps->wvbits);
wps->w.holding_zero = 0;
}
if (wps->w.pend_count) {
putbits (wps->w.pend_data, wps->w.pend_count, &wps->wvbits);
wps->w.pend_data = wps->w.pend_count = 0;
}
}
// This function is similar to send_word() except that no data is actually
// written to any stream, but it does return the value that would have been
// sent to a hybrid stream. It is used to determine beforehand how much noise
// will be added to samples.
int32_t nosend_word (WavpackStream *wps, int32_t value, int chan)
{
struct entropy_data *c = wps->w.c + chan;
uint32_t ones_count, low, mid, high;
int sign = (value < 0) ? 1 : 0;
if (sign)
value = ~value;
if ((wps->wphdr.flags & HYBRID_FLAG) && !chan)
update_error_limit (wps);
if (value < (int32_t) GET_MED (0)) {
low = 0;
high = GET_MED (0) - 1;
DEC_MED0 ();
}
else {
low = GET_MED (0);
INC_MED0 ();
if (value - low < GET_MED (1)) {
high = low + GET_MED (1) - 1;
DEC_MED1 ();
}
else {
low += GET_MED (1);
INC_MED1 ();
if (value - low < GET_MED (2)) {
high = low + GET_MED (2) - 1;
DEC_MED2 ();
}
else {
ones_count = 2 + (value - low) / GET_MED (2);
low += (ones_count - 2) * GET_MED (2);
high = low + GET_MED (2) - 1;
INC_MED2 ();
}
}
}
mid = (high + low + 1) >> 1;
if (!c->error_limit)
mid = value;
else
while (high - low > c->error_limit)
if (value < (int32_t) mid)
mid = ((high = mid - 1) + low + 1) >> 1;
else
mid = (high + (low = mid) + 1) >> 1;
c->slow_level -= (c->slow_level + SLO) >> SLS;
c->slow_level += wp_log2 (mid);
return sign ? ~mid : mid;
}
// This function is used to scan some number of samples to set the variables
// "slow_level" and the "median" array. In pure symetrical encoding mode this
// would not be needed because these values would simply be continued from the
// previous block. However, in the -X modes and the 32-bit modes we cannot do
// this because parameters may change between blocks and the variables might
// not apply. This function can work in mono or stereo and can scan a block
// in either direction.
void scan_word (WavpackStream *wps, int32_t *samples, uint32_t num_samples, int dir)
{
uint32_t flags = wps->wphdr.flags, value, low;
struct entropy_data *c = wps->w.c;
int chan;
init_words (wps);
if (flags & MONO_DATA) {
if (dir < 0) {
samples += (num_samples - 1);
dir = -1;
}
else
dir = 1;
}
else {
if (dir < 0) {
samples += (num_samples - 1) * 2;
dir = -2;
}
else
dir = 2;
}
while (num_samples--) {
value = labs (samples [chan = 0]);
if (flags & HYBRID_BITRATE) {
wps->w.c [0].slow_level -= (wps->w.c [0].slow_level + SLO) >> SLS;
wps->w.c [0].slow_level += wp_log2 (value);
}
if (value < GET_MED (0)) {
DEC_MED0 ();
}
else {
low = GET_MED (0);
INC_MED0 ();
if (value - low < GET_MED (1)) {
DEC_MED1 ();
}
else {
low += GET_MED (1);
INC_MED1 ();
if (value - low < GET_MED (2)) {
DEC_MED2 ();
}
else {
INC_MED2 ();
}
}
}
if (!(flags & MONO_DATA)) {
value = labs (samples [chan = 1]);
c++;
if (wps->wphdr.flags & HYBRID_BITRATE) {
wps->w.c [1].slow_level -= (wps->w.c [1].slow_level + SLO) >> SLS;
wps->w.c [1].slow_level += wp_log2 (value);
}
if (value < GET_MED (0)) {
DEC_MED0 ();
}
else {
low = GET_MED (0);
INC_MED0 ();
if (value - low < GET_MED (1)) {
DEC_MED1 ();
}
else {
low += GET_MED (1);
INC_MED1 ();
if (value - low < GET_MED (2)) {
DEC_MED2 ();
}
else {
INC_MED2 ();
}
}
}
c--;
}
samples += dir;
}
}
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