// Copyright 2010 Google Inc.
//
// This code is licensed under the same terms as WebM:
// Software License Agreement: http://www.webmproject.org/license/software/
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// Main decoding functions for WEBP images.
//
// Author: Skal (pascal.massimino@gmail.com)
#include <stdlib.h>
#include "vp8i.h"
#include "yuv.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define FANCY_UPSCALING // undefined to remove fancy upscaling support
//-----------------------------------------------------------------------------
// RIFF layout is:
// 0ffset tag
// 0...3 "RIFF" 4-byte tag
// 4...7 size of image data (including metadata) starting at offset 8
// 8...11 "WEBP" our form-type signature
// 12..15 "VP8 ": 4-bytes tags, describing the raw video format used
// 16..19 size of the raw VP8 image data, starting at offset 20
// 20.... the VP8 bytes
// There can be extra chunks after the "VP8 " chunk (ICMT, ICOP, ...)
// All 32-bits sizes are in little-endian order.
// Note: chunk data must be padded to multiple of 2 in size
static inline uint32_t get_le32(const uint8_t* const data) {
return data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
}
// If a RIFF container is detected, validate it and skip over it.
static uint32_t CheckRIFFHeader(const uint8_t** data_ptr,
uint32_t *data_size_ptr) {
uint32_t chunk_size = 0xffffffffu;
if (*data_size_ptr >= 10 + 20 && !memcmp(*data_ptr, "RIFF", 4)) {
if (memcmp(*data_ptr + 8, "WEBP", 4)) {
return 0; // wrong image file signature
} else {
const uint32_t riff_size = get_le32(*data_ptr + 4);
if (memcmp(*data_ptr + 12, "VP8 ", 4)) {
return 0; // invalid compression format
}
chunk_size = get_le32(*data_ptr + 16);
if ((chunk_size > riff_size + 8) || (chunk_size & 1)) {
return 0; // inconsistent size information.
}
// We have a IFF container. Skip it.
*data_ptr += 20;
*data_size_ptr -= 20;
}
return chunk_size;
}
return *data_size_ptr;
}
//-----------------------------------------------------------------------------
// Fancy upscaling
typedef enum { MODE_RGB = 0, MODE_RGBA = 1,
MODE_BGR = 2, MODE_BGRA = 3,
MODE_YUV = 4 } CSP_MODE;
#ifdef FANCY_UPSCALING
// Given samples laid out in a square as:
// [a b]
// [c d]
// we interpolate u/v as:
// ([9*a + 3*b + 3*c + d 3*a + 9*b + 3*c + d] + [8 8]) / 16
// ([3*a + b + 9*c + 3*d a + 3*b + 3*c + 9*d] [8 8]) / 16
// We process u and v together stashed into 32bit (16bit each).
#define LOAD_UV(u,v) ((u) | ((v) << 16))
#define UPSCALE_FUNC(FUNC_NAME, FUNC, XSTEP) \
static inline void FUNC_NAME(const uint8_t* top_y, const uint8_t* bottom_y, \
const uint8_t* top_u, const uint8_t* top_v, \
const uint8_t* cur_u, const uint8_t* cur_v, \
uint8_t* top_dst, uint8_t* bottom_dst, int len) { \
int x; \
const int last_pixel_pair = (len - 1) >> 1; \
uint32_t tl_uv = LOAD_UV(top_u[0], top_v[0]); /* top-left sample */ \
uint32_t l_uv = LOAD_UV(cur_u[0], cur_v[0]); /* left-sample */ \
if (top_y) { \
const uint32_t uv0 = (3 * tl_uv + l_uv + 0x00020002u) >> 2; \
FUNC(top_y[0], uv0 & 0xff, (uv0 >> 16), top_dst); \
} \
if (bottom_y) { \
const uint32_t uv0 = (3 * l_uv + tl_uv + 0x00020002u) >> 2; \
FUNC(bottom_y[0], uv0 & 0xff, (uv0 >> 16), bottom_dst); \
} \
for (x = 1; x <= last_pixel_pair; ++x) { \
const uint32_t t_uv = LOAD_UV(top_u[x], top_v[x]); /* top sample */ \
const uint32_t uv = LOAD_UV(cur_u[x], cur_v[x]); /* sample */ \
/* precompute invariant values associated with first and second diagonals*/\
const uint32_t avg = tl_uv + t_uv + l_uv + uv + 0x00080008u; \
const uint32_t diag_12 = (avg + 2 * (t_uv + l_uv)) >> 3; \
const uint32_t diag_03 = (avg + 2 * (tl_uv + uv)) >> 3; \
if (top_y) { \
const uint32_t uv0 = (diag_12 + tl_uv) >> 1; \
const uint32_t uv1 = (diag_03 + t_uv) >> 1; \
FUNC(top_y[2 * x - 1], uv0 & 0xff, (uv0 >> 16), \
top_dst + (2 * x - 1) * XSTEP); \
FUNC(top_y[2 * x - 0], uv1 & 0xff, (uv1 >> 16), \
top_dst + (2 * x - 0) * XSTEP); \
} \
if (bottom_y) { \
const uint32_t uv0 = (diag_03 + l_uv) >> 1; \
const uint32_t uv1 = (diag_12 + uv) >> 1; \
FUNC(bottom_y[2 * x - 1], uv0 & 0xff, (uv0 >> 16), \
bottom_dst + (2 * x - 1) * XSTEP); \
FUNC(bottom_y[2 * x + 0], uv1 & 0xff, (uv1 >> 16), \
bottom_dst + (2 * x + 0) * XSTEP); \
} \
tl_uv = t_uv; \
l_uv = uv; \
} \
if (!(len & 1)) { \
if (top_y) { \
const uint32_t uv0 = (3 * tl_uv + l_uv + 0x00020002u) >> 2; \
FUNC(top_y[len - 1], uv0 & 0xff, (uv0 >> 16), \
top_dst + (len - 1) * XSTEP); \
} \
if (bottom_y) { \
const uint32_t uv0 = (3 * l_uv + tl_uv + 0x00020002u) >> 2; \
FUNC(bottom_y[len - 1], uv0 & 0xff, (uv0 >> 16), \
bottom_dst + (len - 1) * XSTEP); \
} \
} \
}
// All variants implemented.
UPSCALE_FUNC(UpscaleRgbLinePair, VP8YuvToRgb, 3)
UPSCALE_FUNC(UpscaleBgrLinePair, VP8YuvToBgr, 3)
UPSCALE_FUNC(UpscaleRgbaLinePair, VP8YuvToRgba, 4)
UPSCALE_FUNC(UpscaleBgraLinePair, VP8YuvToBgra, 4)
// Main driver function.
static inline
void UpscaleLinePair(const uint8_t* top_y, const uint8_t* bottom_y,
const uint8_t* top_u, const uint8_t* top_v,
const uint8_t* cur_u, const uint8_t* cur_v,
uint8_t* top_dst, uint8_t* bottom_dst, int len,
CSP_MODE mode) {
if (mode == MODE_RGB) {
UpscaleRgbLinePair(top_y, bottom_y, top_u, top_v, cur_u, cur_v,
top_dst, bottom_dst, len);
} else if (mode == MODE_BGR) {
UpscaleBgrLinePair(top_y, bottom_y, top_u, top_v, cur_u, cur_v,
top_dst, bottom_dst, len);
} else if (mode == MODE_RGBA) {
UpscaleRgbaLinePair(top_y, bottom_y, top_u, top_v, cur_u, cur_v,
top_dst, bottom_dst, len);
} else {
assert(mode == MODE_BGRA);
UpscaleBgraLinePair(top_y, bottom_y, top_u, top_v, cur_u, cur_v,
top_dst, bottom_dst, len);
}
}
#undef LOAD_UV
#undef UPSCALE_FUNC
#endif // FANCY_UPSCALING
//-----------------------------------------------------------------------------
// Main conversion driver.
typedef struct {
uint8_t* output; // rgb(a) or luma
uint8_t *u, *v;
uint8_t *top_y, *top_u, *top_v;
int stride; // rgb(a) stride or luma stride
int u_stride;
int v_stride;
CSP_MODE mode;
} Params;
static void CustomPut(const VP8Io* io) {
Params *p = (Params*)io->opaque;
const int w = io->width;
const int mb_h = io->mb_h;
const int uv_w = (w + 1) / 2;
assert(!(io->mb_y & 1));
if (w <= 0 || mb_h <= 0) return;
if (p->mode == MODE_YUV) {
uint8_t* const y_dst = p->output + io->mb_y * p->stride;
uint8_t* const u_dst = p->u + (io->mb_y >> 1) * p->u_stride;
uint8_t* const v_dst = p->v + (io->mb_y >> 1) * p->v_stride;
int j;
for (j = 0; j < mb_h; ++j) {
memcpy(y_dst + j * p->stride, io->y + j * io->y_stride, w);
}
for (j = 0; j < (mb_h + 1) / 2; ++j) {
memcpy(u_dst + j * p->u_stride, io->u + j * io->uv_stride, uv_w);
memcpy(v_dst + j * p->v_stride, io->v + j * io->uv_stride, uv_w);
}
} else {
uint8_t* dst = p->output + io->mb_y * p->stride;
if (io->fancy_upscaling) {
#ifdef FANCY_UPSCALING
const uint8_t* cur_y = io->y;
const uint8_t* cur_u = io->u;
const uint8_t* cur_v = io->v;
const uint8_t* top_u = p->top_u;
const uint8_t* top_v = p->top_v;
int y = io->mb_y;
int y_end = io->mb_y + io->mb_h;
if (y == 0) {
// First line is special cased. We mirror the u/v samples at boundary.
UpscaleLinePair(NULL, cur_y, cur_u, cur_v, cur_u, cur_v,
NULL, dst, w, p->mode);
} else {
// We can finish the left-over line from previous call
UpscaleLinePair(p->top_y, cur_y, top_u, top_v, cur_u, cur_v,
dst - p->stride, dst, w, p->mode);
}
// Loop over each output pairs of row.
for (; y + 2 < y_end; y += 2) {
top_u = cur_u;
top_v = cur_v;
cur_u += io->uv_stride;
cur_v += io->uv_stride;
dst += 2 * p->stride;
cur_y += 2 * io->y_stride;
UpscaleLinePair(cur_y - io->y_stride, cur_y,
top_u, top_v, cur_u, cur_v,
dst - p->stride, dst, w, p->mode);
}
// move to last row
cur_y += io->y_stride;
if (y_end != io->height) {
// Save the unfinished samples for next call (as we're not done yet).
memcpy(p->top_y, cur_y, w * sizeof(*p->top_y));
memcpy(p->top_u, cur_u, uv_w * sizeof(*p->top_u));
memcpy(p->top_v, cur_v, uv_w * sizeof(*p->top_v));
} else {
// Process the very last row of even-sized picture
if (!(y_end & 1)) {
UpscaleLinePair(cur_y, NULL, cur_u, cur_v, cur_u, cur_v,
dst + p->stride, NULL, w, p->mode);
}
}
#else
assert(0); // shouldn't happen.
#endif
} else {
// Point-sampling U/V upscaler.
int j;
for (j = 0; j < mb_h; ++j) {
const uint8_t* y_src = io->y + j * io->y_stride;
int i;
for (i = 0; i < w; ++i) {
const int y = y_src[i];
const int u = io->u[(j / 2) * io->uv_stride + (i / 2)];
const int v = io->v[(j / 2) * io->uv_stride + (i / 2)];
if (p->mode == MODE_RGB) {
VP8YuvToRgb(y, u, v, dst + i * 3);
} else if (p->mode == MODE_BGR) {
VP8YuvToBgr(y, u, v, dst + i * 3);
} else if (p->mode == MODE_RGBA) {
VP8YuvToRgba(y, u, v, dst + i * 4);
} else {
VP8YuvToBgra(y, u, v, dst + i * 4);
}
}
dst += p->stride;
}
}
}
}
//-----------------------------------------------------------------------------
static int CustomSetup(VP8Io* io) {
#ifdef FANCY_UPSCALING
Params *p = (Params*)io->opaque;
p->top_y = p->top_u = p->top_v = NULL;
if (p->mode != MODE_YUV) {
const int uv_width = (io->width + 1) >> 1;
p->top_y = (uint8_t*)malloc(io->width + 2 * uv_width);
if (p->top_y == NULL) {
return 0; // memory error.
}
p->top_u = p->top_y + io->width;
p->top_v = p->top_u + uv_width;
io->fancy_upscaling = 1; // activate fancy upscaling
}
#endif
return 1;
}
static void CustomTeardown(const VP8Io* io) {
#ifdef FANCY_UPSCALING
Params *p = (Params*)io->opaque;
if (p->top_y) {
free(p->top_y);
p->top_y = p->top_u = p->top_v = NULL;
}
#endif
}
//-----------------------------------------------------------------------------
// "Into" variants
static uint8_t* DecodeInto(CSP_MODE mode,
const uint8_t* data, uint32_t data_size,
Params* params, int output_size,
int output_u_size, int output_v_size) {
VP8Decoder* dec = VP8New();
VP8Io io;
int ok = 1;
if (dec == NULL) {
return NULL;
}
VP8InitIo(&io);
io.data = data;
io.data_size = data_size;
params->mode = mode;
io.opaque = params;
io.put = CustomPut;
io.setup = CustomSetup;
io.teardown = CustomTeardown;
if (!VP8GetHeaders(dec, &io)) {
VP8Delete(dec);
return NULL;
}
// check output buffers
ok &= (params->stride * io.height <= output_size);
if (mode == MODE_RGB || mode == MODE_BGR) {
ok &= (params->stride >= io.width * 3);
} else if (mode == MODE_RGBA || mode == MODE_BGRA) {
ok &= (params->stride >= io.width * 4);
} else {
// some extra checks for U/V
const int u_size = params->u_stride * ((io.height + 1) / 2);
const int v_size = params->v_stride * ((io.height + 1) / 2);
ok &= (params->stride >= io.width);
ok &= (params->u_stride >= (io.width + 1) / 2) &&
(params->v_stride >= (io.width + 1) / 2);
ok &= (u_size <= output_u_size && v_size <= output_v_size);
}
if (!ok) {
VP8Delete(dec);
return NULL;
}
if (mode != MODE_YUV) {
VP8YUVInit();
}
ok = VP8Decode(dec, &io);
VP8Delete(dec);
return ok ? params->output : NULL;
}
uint8_t* WebPDecodeRGBInto(const uint8_t* data, uint32_t data_size,
uint8_t* output, int output_size,
int output_stride) {
Params params;
if (output == NULL) {
return NULL;
}
params.output = output;
params.stride = output_stride;
return DecodeInto(MODE_RGB, data, data_size, ¶ms, output_size, 0, 0);
}
uint8_t* WebPDecodeRGBAInto(const uint8_t* data, uint32_t data_size,
uint8_t* output, int output_size,
int output_stride) {
Params params;
if (output == NULL) {
return NULL;
}
params.output = output;
params.stride = output_stride;
return DecodeInto(MODE_RGBA, data, data_size, ¶ms, output_size, 0, 0);
}
uint8_t* WebPDecodeBGRInto(const uint8_t* data, uint32_t data_size,
uint8_t* output, int output_size,
int output_stride) {
Params params;
if (output == NULL) {
return NULL;
}
params.output = output;
params.stride = output_stride;
return DecodeInto(MODE_BGR, data, data_size, ¶ms, output_size, 0, 0);
}
uint8_t* WebPDecodeBGRAInto(const uint8_t* data, uint32_t data_size,
uint8_t* output, int output_size,
int output_stride) {
Params params;
if (output == NULL) {
return NULL;
}
params.output = output;
params.stride = output_stride;
return DecodeInto(MODE_BGRA, data, data_size, ¶ms, output_size, 0, 0);
}
uint8_t* WebPDecodeYUVInto(const uint8_t* data, uint32_t data_size,
uint8_t* luma, int luma_size, int luma_stride,
uint8_t* u, int u_size, int u_stride,
uint8_t* v, int v_size, int v_stride) {
Params params;
if (luma == NULL) {
return NULL;
}
params.output = luma;
params.stride = luma_stride;
params.u = u;
params.u_stride = u_stride;
params.v = v;
params.v_stride = v_stride;
return DecodeInto(MODE_YUV, data, data_size, ¶ms,
luma_size, u_size, v_size);
}
//-----------------------------------------------------------------------------
static uint8_t* Decode(CSP_MODE mode, const uint8_t* data, uint32_t data_size,
int* width, int* height, Params* params_out) {
int w, h, stride;
int uv_size = 0;
int uv_stride = 0;
int size;
uint8_t* output;
Params params = { 0 };
if (!WebPGetInfo(data, data_size, &w, &h)) {
return NULL;
}
if (width) *width = w;
if (height) *height = h;
// initialize output buffer, now that dimensions are known.
stride = (mode == MODE_RGB || mode == MODE_BGR) ? 3 * w
: (mode == MODE_RGBA || mode == MODE_BGRA) ? 4 * w
: w;
size = stride * h;
if (mode == MODE_YUV) {
uv_stride = (w + 1) / 2;
uv_size = uv_stride * ((h + 1) / 2);
}
output = (uint8_t*)malloc(size + 2 * uv_size);
if (!output) {
return NULL;
}
params.output = output;
params.stride = stride;
if (mode == MODE_YUV) {
params.u = output + size;
params.u_stride = uv_stride;
params.v = output + size + uv_size;
params.v_stride = uv_stride;
}
if (params_out) *params_out = params;
return DecodeInto(mode, data, data_size, ¶ms, size, uv_size, uv_size);
}
uint8_t* WebPDecodeRGB(const uint8_t* data, uint32_t data_size,
int *width, int *height) {
return Decode(MODE_RGB, data, data_size, width, height, NULL);
}
uint8_t* WebPDecodeRGBA(const uint8_t* data, uint32_t data_size,
int *width, int *height) {
return Decode(MODE_RGBA, data, data_size, width, height, NULL);
}
uint8_t* WebPDecodeBGR(const uint8_t* data, uint32_t data_size,
int *width, int *height) {
return Decode(MODE_BGR, data, data_size, width, height, NULL);
}
uint8_t* WebPDecodeBGRA(const uint8_t* data, uint32_t data_size,
int *width, int *height) {
return Decode(MODE_BGRA, data, data_size, width, height, NULL);
}
uint8_t* WebPDecodeYUV(const uint8_t* data, uint32_t data_size,
int *width, int *height, uint8_t** u, uint8_t** v,
int *stride, int* uv_stride) {
Params params;
uint8_t* const out = Decode(MODE_YUV, data, data_size,
width, height, ¶ms);
if (out) {
*u = params.u;
*v = params.v;
*stride = params.stride;
*uv_stride = params.u_stride;
assert(params.u_stride == params.v_stride);
}
return out;
}
//-----------------------------------------------------------------------------
// WebPGetInfo()
int WebPGetInfo(const uint8_t* data, uint32_t data_size,
int *width, int *height) {
const uint32_t chunk_size = CheckRIFFHeader(&data, &data_size);
if (!chunk_size) {
return 0; // unsupported RIFF header
}
// Validate raw video data
if (data_size < 10) {
return 0; // not enough data
}
// check signature
if (data[3] != 0x9d || data[4] != 0x01 || data[5] != 0x2a) {
return 0; // Wrong signature.
} else {
const uint32_t bits = data[0] | (data[1] << 8) | (data[2] << 16);
const int key_frame = !(bits & 1);
const int w = ((data[7] << 8) | data[6]) & 0x3fff;
const int h = ((data[9] << 8) | data[8]) & 0x3fff;
if (!key_frame) { // Not a keyframe.
return 0;
}
if (((bits >> 1) & 7) > 3) {
return 0; // unknown profile
}
if (!((bits >> 4) & 1)) {
return 0; // first frame is invisible!
}
if (((bits >> 5)) >= chunk_size) { // partition_length
return 0; // inconsistent size information.
}
if (width) {
*width = w;
}
if (height) {
*height = h;
}
return 1;
}
}
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif