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ffmpeg/libavcodec/lagarith.c

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/*
* Lagarith lossless decoder
* Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Lagarith lossless decoder
* @author Nathan Caldwell
*/
#include "avcodec.h"
#include "get_bits.h"
#include "mathops.h"
#include "dsputil.h"
#include "lagarithrac.h"
enum LagarithFrameType {
FRAME_RAW = 1, /**< uncompressed */
FRAME_U_RGB24 = 2, /**< unaligned RGB24 */
FRAME_ARITH_YUY2 = 3, /**< arithmetic coded YUY2 */
FRAME_ARITH_RGB24 = 4, /**< arithmetic coded RGB24 */
FRAME_SOLID_GRAY = 5, /**< solid grayscale color frame */
FRAME_SOLID_COLOR = 6, /**< solid non-grayscale color frame */
FRAME_OLD_ARITH_RGB = 7, /**< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */
FRAME_ARITH_RGBA = 8, /**< arithmetic coded RGBA */
FRAME_SOLID_RGBA = 9, /**< solid RGBA color frame */
FRAME_ARITH_YV12 = 10, /**< arithmetic coded YV12 */
FRAME_REDUCED_RES = 11, /**< reduced resolution YV12 frame */
};
typedef struct LagarithContext {
AVCodecContext *avctx;
AVFrame picture;
DSPContext dsp;
int zeros; /**< number of consecutive zero bytes encountered */
int zeros_rem; /**< number of zero bytes remaining to output */
uint8_t *rgb_planes;
int rgb_stride;
} LagarithContext;
/**
* Compute the 52bit mantissa of 1/(double)denom.
* This crazy format uses floats in an entropy coder and we have to match x86
* rounding exactly, thus ordinary floats aren't portable enough.
* @param denom denominator
* @return 52bit mantissa
* @see softfloat_mul
*/
static uint64_t softfloat_reciprocal(uint32_t denom)
{
int shift = av_log2(denom - 1) + 1;
uint64_t ret = (1ULL << 52) / denom;
uint64_t err = (1ULL << 52) - ret * denom;
ret <<= shift;
err <<= shift;
err += denom / 2;
return ret + err / denom;
}
/**
* (uint32_t)(x*f), where f has the given mantissa, and exponent 0
* Used in combination with softfloat_reciprocal computes x/(double)denom.
* @param x 32bit integer factor
* @param mantissa mantissa of f with exponent 0
* @return 32bit integer value (x*f)
* @see softfloat_reciprocal
*/
static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
{
uint64_t l = x * (mantissa & 0xffffffff);
uint64_t h = x * (mantissa >> 32);
h += l >> 32;
l &= 0xffffffff;
l += 1 << av_log2(h >> 21);
h += l >> 32;
return h >> 20;
}
static uint8_t lag_calc_zero_run(int8_t x)
{
return (x << 1) ^ (x >> 7);
}
static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
{
static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
int i;
int bit = 0;
int bits = 0;
int prevbit = 0;
unsigned val;
for (i = 0; i < 7; i++) {
if (prevbit && bit)
break;
prevbit = bit;
bit = get_bits1(gb);
if (bit && !prevbit)
bits += series[i];
}
bits--;
if (bits < 0 || bits > 31) {
*value = 0;
return -1;
} else if (bits == 0) {
*value = 0;
return 0;
}
val = get_bits_long(gb, bits);
val |= 1 << bits;
*value = val - 1;
return 0;
}
static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
{
int i, j, scale_factor;
unsigned prob, cumulative_target;
unsigned cumul_prob = 0;
unsigned scaled_cumul_prob = 0;
rac->prob[0] = 0;
rac->prob[257] = UINT_MAX;
/* Read probabilities from bitstream */
for (i = 1; i < 257; i++) {
if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
return -1;
}
if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
return -1;
}
cumul_prob += rac->prob[i];
if (!rac->prob[i]) {
if (lag_decode_prob(gb, &prob)) {
av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
return -1;
}
if (prob > 257 - i)
prob = 257 - i;
for (j = 0; j < prob; j++)
rac->prob[++i] = 0;
}
}
if (!cumul_prob) {
av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
return -1;
}
/* Scale probabilities so cumulative probability is an even power of 2. */
scale_factor = av_log2(cumul_prob);
if (cumul_prob & (cumul_prob - 1)) {
uint64_t mul = softfloat_reciprocal(cumul_prob);
for (i = 1; i < 257; i++) {
rac->prob[i] = softfloat_mul(rac->prob[i], mul);
scaled_cumul_prob += rac->prob[i];
}
scale_factor++;
cumulative_target = 1 << scale_factor;
if (scaled_cumul_prob > cumulative_target) {
av_log(rac->avctx, AV_LOG_ERROR,
"Scaled probabilities are larger than target!\n");
return -1;
}
scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
if (rac->prob[i]) {
rac->prob[i]++;
scaled_cumul_prob--;
}
/* Comment from reference source:
* if (b & 0x80 == 0) { // order of operations is 'wrong'; it has been left this way
* // since the compression change is negligable and fixing it
* // breaks backwards compatibilty
* b =- (signed int)b;
* b &= 0xFF;
* } else {
* b++;
* b &= 0x7f;
* }
*/
}
}
rac->scale = scale_factor;
/* Fill probability array with cumulative probability for each symbol. */
for (i = 1; i < 257; i++)
rac->prob[i] += rac->prob[i - 1];
return 0;
}
static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
uint8_t *diff, int w, int *left,
int *left_top)
{
/* This is almost identical to add_hfyu_median_prediction in dsputil.h.
* However the &0xFF on the gradient predictor yealds incorrect output
* for lagarith.
*/
int i;
uint8_t l, lt;
l = *left;
lt = *left_top;
for (i = 0; i < w; i++) {
l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
lt = src1[i];
dst[i] = l;
}
*left = l;
*left_top = lt;
}
static void lag_pred_line(LagarithContext *l, uint8_t *buf,
int width, int stride, int line)
{
int L, TL;
/* Left pixel is actually prev_row[width] */
L = buf[width - stride - 1];
if (!line) {
/* Left prediction only for first line */
L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
width - 1, buf[0]);
return;
} else if (line == 1) {
/* Second line, left predict first pixel, the rest of the line is median predicted
* NOTE: In the case of RGB this pixel is top predicted */
TL = l->avctx->pix_fmt == PIX_FMT_YUV420P ? buf[-stride] : L;
} else {
/* Top left is 2 rows back, last pixel */
TL = buf[width - (2 * stride) - 1];
}
add_lag_median_prediction(buf, buf - stride, buf,
width, &L, &TL);
}
static int lag_decode_line(LagarithContext *l, lag_rac *rac,
uint8_t *dst, int width, int stride,
int esc_count)
{
int i = 0;
int ret = 0;
if (!esc_count)
esc_count = -1;
/* Output any zeros remaining from the previous run */
handle_zeros:
if (l->zeros_rem) {
int count = FFMIN(l->zeros_rem, width - i);
memset(dst + i, 0, count);
i += count;
l->zeros_rem -= count;
}
while (i < width) {
dst[i] = lag_get_rac(rac);
ret++;
if (dst[i])
l->zeros = 0;
else
l->zeros++;
i++;
if (l->zeros == esc_count) {
int index = lag_get_rac(rac);
ret++;
l->zeros = 0;
l->zeros_rem = lag_calc_zero_run(index);
goto handle_zeros;
}
}
return ret;
}
static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
const uint8_t *src, int width,
int esc_count)
{
int i = 0;
int count;
uint8_t zero_run = 0;
const uint8_t *start = src;
uint8_t mask1 = -(esc_count < 2);
uint8_t mask2 = -(esc_count < 3);
uint8_t *end = dst + (width - 2);
output_zeros:
if (l->zeros_rem) {
count = FFMIN(l->zeros_rem, width - i);
memset(dst, 0, count);
l->zeros_rem -= count;
dst += count;
}
while (dst < end) {
i = 0;
while (!zero_run && dst + i < end) {
i++;
zero_run =
!(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
}
if (zero_run) {
zero_run = 0;
i += esc_count;
memcpy(dst, src, i);
dst += i;
l->zeros_rem = lag_calc_zero_run(src[i]);
src += i + 1;
goto output_zeros;
} else {
memcpy(dst, src, i);
src += i;
}
}
return start - src;
}
static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
int width, int height, int stride,
const uint8_t *src, int src_size)
{
int i = 0;
int read = 0;
uint32_t length;
uint32_t offset = 1;
int esc_count = src[0];
GetBitContext gb;
lag_rac rac;
rac.avctx = l->avctx;
l->zeros = 0;
if (esc_count < 4) {
length = width * height;
if (esc_count && AV_RL32(src + 1) < length) {
length = AV_RL32(src + 1);
offset += 4;
}
init_get_bits(&gb, src + offset, src_size * 8);
if (lag_read_prob_header(&rac, &gb) < 0)
return -1;
lag_rac_init(&rac, &gb, length - stride);
for (i = 0; i < height; i++)
read += lag_decode_line(l, &rac, dst + (i * stride), width,
stride, esc_count);
if (read > length)
av_log(l->avctx, AV_LOG_WARNING,
"Output more bytes than length (%d of %d)\n", read,
length);
} else if (esc_count < 8) {
esc_count -= 4;
if (esc_count > 0) {
/* Zero run coding only, no range coding. */
for (i = 0; i < height; i++)
src += lag_decode_zero_run_line(l, dst + (i * stride), src,
width, esc_count);
} else {
/* Plane is stored uncompressed */
for (i = 0; i < height; i++) {
memcpy(dst + (i * stride), src, width);
src += width;
}
}
} else if (esc_count == 0xff) {
/* Plane is a solid run of given value */
for (i = 0; i < height; i++)
memset(dst + i * stride, src[1], width);
/* Do not apply prediction.
Note: memset to 0 above, setting first value to src[1]
and applying prediction gives the same result. */
return 0;
} else {
av_log(l->avctx, AV_LOG_ERROR,
"Invalid zero run escape code! (%#x)\n", esc_count);
return -1;
}
for (i = 0; i < height; i++) {
lag_pred_line(l, dst, width, stride, i);
dst += stride;
}
return 0;
}
/**
* Decode a frame.
* @param avctx codec context
* @param data output AVFrame
* @param data_size size of output data or 0 if no picture is returned
* @param avpkt input packet
* @return number of consumed bytes on success or negative if decode fails
*/
static int lag_decode_frame(AVCodecContext *avctx,
void *data, int *data_size, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
LagarithContext *l = avctx->priv_data;
AVFrame *const p = &l->picture;
uint8_t frametype = 0;
uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
int offs[4];
uint8_t *srcs[4], *dst;
int i, j;
AVFrame *picture = data;
if (p->data[0])
avctx->release_buffer(avctx, p);
p->reference = 0;
p->key_frame = 1;
frametype = buf[0];
offset_gu = AV_RL32(buf + 1);
offset_bv = AV_RL32(buf + 5);
switch (frametype) {
case FRAME_SOLID_RGBA:
avctx->pix_fmt = PIX_FMT_RGB32;
if (avctx->get_buffer(avctx, p) < 0) {
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
dst = p->data[0];
for (j = 0; j < avctx->height; j++) {
for (i = 0; i < avctx->width; i++)
AV_WN32(dst + i * 4, offset_gu);
dst += p->linesize[0];
}
break;
case FRAME_ARITH_RGBA:
avctx->pix_fmt = PIX_FMT_RGB32;
if (avctx->get_buffer(avctx, p) < 0) {
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
offs[0] = offset_bv;
offs[1] = offset_gu;
offs[2] = 13;
offs[3] = AV_RL32(buf + 9);
if (!l->rgb_planes) {
l->rgb_stride = FFALIGN(avctx->width, 16);
l->rgb_planes = av_malloc(l->rgb_stride * avctx->height * 4);
if (!l->rgb_planes) {
av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
return AVERROR(ENOMEM);
}
}
for (i = 0; i < 4; i++)
srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
for (i = 0; i < 4; i++)
lag_decode_arith_plane(l, srcs[i],
avctx->width, avctx->height,
-l->rgb_stride, buf + offs[i],
buf_size);
dst = p->data[0];
for (i = 0; i < 4; i++)
srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
for (j = 0; j < avctx->height; j++) {
for (i = 0; i < avctx->width; i++) {
uint8_t r, g, b, a;
r = srcs[0][i];
g = srcs[1][i];
b = srcs[2][i];
a = srcs[3][i];
r += g;
b += g;
AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
}
dst += p->linesize[0];
for (i = 0; i < 4; i++)
srcs[i] += l->rgb_stride;
}
break;
case FRAME_ARITH_YV12:
avctx->pix_fmt = PIX_FMT_YUV420P;
if (avctx->get_buffer(avctx, p) < 0) {
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
p->linesize[0], buf + offset_ry,
buf_size);
lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
avctx->height / 2, p->linesize[2],
buf + offset_gu, buf_size);
lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
avctx->height / 2, p->linesize[1],
buf + offset_bv, buf_size);
break;
default:
av_log(avctx, AV_LOG_ERROR,
"Unsupported Lagarith frame type: %#x\n", frametype);
return -1;
}
*picture = *p;
*data_size = sizeof(AVFrame);
return buf_size;
}
static av_cold int lag_decode_init(AVCodecContext *avctx)
{
LagarithContext *l = avctx->priv_data;
l->avctx = avctx;
dsputil_init(&l->dsp, avctx);
return 0;
}
static av_cold int lag_decode_end(AVCodecContext *avctx)
{
LagarithContext *l = avctx->priv_data;
if (l->picture.data[0])
avctx->release_buffer(avctx, &l->picture);
av_freep(&l->rgb_planes);
return 0;
}
AVCodec ff_lagarith_decoder = {
.name = "lagarith",
.type = AVMEDIA_TYPE_VIDEO,
.id = CODEC_ID_LAGARITH,
.priv_data_size = sizeof(LagarithContext),
.init = lag_decode_init,
.close = lag_decode_end,
.decode = lag_decode_frame,
.capabilities = CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
};
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