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// Copyright 2010 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// main entry for the decoder
//
// Author: Skal (pascal.massimino@gmail.com)
#include <stdlib.h>
#include "src/dec/alphai_dec.h"
#include "src/dec/vp8i_dec.h"
#include "src/dec/vp8li_dec.h"
#include "src/dec/webpi_dec.h"
#include "src/utils/bit_reader_inl_utils.h"
#include "src/utils/utils.h"
//------------------------------------------------------------------------------
int WebPGetDecoderVersion(void) {
return (DEC_MAJ_VERSION << 16) | (DEC_MIN_VERSION << 8) | DEC_REV_VERSION;
}
//------------------------------------------------------------------------------
// Signature and pointer-to-function for GetCoeffs() variants below.
typedef int (*GetCoeffsFunc)(VP8BitReader* const br,
const VP8BandProbas* const prob[],
int ctx, const quant_t dq, int n, int16_t* out);
static volatile GetCoeffsFunc GetCoeffs = NULL;
static void InitGetCoeffs(void);
//------------------------------------------------------------------------------
// VP8Decoder
static void SetOk(VP8Decoder* const dec) {
dec->status_ = VP8_STATUS_OK;
dec->error_msg_ = "OK";
}
int VP8InitIoInternal(VP8Io* const io, int version) {
if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
return 0; // mismatch error
}
if (io != NULL) {
memset(io, 0, sizeof(*io));
}
return 1;
}
VP8Decoder* VP8New(void) {
VP8Decoder* const dec = (VP8Decoder*)WebPSafeCalloc(1ULL, sizeof(*dec));
if (dec != NULL) {
SetOk(dec);
WebPGetWorkerInterface()->Init(&dec->worker_);
dec->ready_ = 0;
dec->num_parts_minus_one_ = 0;
InitGetCoeffs();
}
return dec;
}
VP8StatusCode VP8Status(VP8Decoder* const dec) {
if (!dec) return VP8_STATUS_INVALID_PARAM;
return dec->status_;
}
const char* VP8StatusMessage(VP8Decoder* const dec) {
if (dec == NULL) return "no object";
if (!dec->error_msg_) return "OK";
return dec->error_msg_;
}
void VP8Delete(VP8Decoder* const dec) {
if (dec != NULL) {
VP8Clear(dec);
WebPSafeFree(dec);
}
}
int VP8SetError(VP8Decoder* const dec,
VP8StatusCode error, const char* const msg) {
// VP8_STATUS_SUSPENDED is only meaningful in incremental decoding.
assert(dec->incremental_ || error != VP8_STATUS_SUSPENDED);
// The oldest error reported takes precedence over the new one.
if (dec->status_ == VP8_STATUS_OK) {
dec->status_ = error;
dec->error_msg_ = msg;
dec->ready_ = 0;
}
return 0;
}
//------------------------------------------------------------------------------
int VP8CheckSignature(const uint8_t* const data, size_t data_size) {
return (data_size >= 3 &&
data[0] == 0x9d && data[1] == 0x01 && data[2] == 0x2a);
}
int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
int* const width, int* const height) {
if (data == NULL || data_size < VP8_FRAME_HEADER_SIZE) {
return 0; // not enough data
}
// check signature
if (!VP8CheckSignature(data + 3, data_size - 3)) {
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 (w == 0 || h == 0) {
return 0; // We don't support both width and height to be zero.
}
if (width) {
*width = w;
}
if (height) {
*height = h;
}
return 1;
}
}
//------------------------------------------------------------------------------
// Header parsing
static void ResetSegmentHeader(VP8SegmentHeader* const hdr) {
assert(hdr != NULL);
hdr->use_segment_ = 0;
hdr->update_map_ = 0;
hdr->absolute_delta_ = 1;
memset(hdr->quantizer_, 0, sizeof(hdr->quantizer_));
memset(hdr->filter_strength_, 0, sizeof(hdr->filter_strength_));
}
// Paragraph 9.3
static int ParseSegmentHeader(VP8BitReader* br,
VP8SegmentHeader* hdr, VP8Proba* proba) {
assert(br != NULL);
assert(hdr != NULL);
hdr->use_segment_ = VP8Get(br, "global-header");
if (hdr->use_segment_) {
hdr->update_map_ = VP8Get(br, "global-header");
if (VP8Get(br, "global-header")) { // update data
int s;
hdr->absolute_delta_ = VP8Get(br, "global-header");
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
hdr->quantizer_[s] = VP8Get(br, "global-header") ?
VP8GetSignedValue(br, 7, "global-header") : 0;
}
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
hdr->filter_strength_[s] = VP8Get(br, "global-header") ?
VP8GetSignedValue(br, 6, "global-header") : 0;
}
}
if (hdr->update_map_) {
int s;
for (s = 0; s < MB_FEATURE_TREE_PROBS; ++s) {
proba->segments_[s] = VP8Get(br, "global-header") ?
VP8GetValue(br, 8, "global-header") : 255u;
}
}
} else {
hdr->update_map_ = 0;
}
return !br->eof_;
}
// Paragraph 9.5
// If we don't have all the necessary data in 'buf', this function returns
// VP8_STATUS_SUSPENDED in incremental decoding, VP8_STATUS_NOT_ENOUGH_DATA
// otherwise.
// In incremental decoding, this case is not necessarily an error. Still, no
// bitreader is ever initialized to make it possible to read unavailable memory.
// If we don't even have the partitions' sizes, then VP8_STATUS_NOT_ENOUGH_DATA
// is returned, and this is an unrecoverable error.
// If the partitions were positioned ok, VP8_STATUS_OK is returned.
static VP8StatusCode ParsePartitions(VP8Decoder* const dec,
const uint8_t* buf, size_t size) {
VP8BitReader* const br = &dec->br_;
const uint8_t* sz = buf;
const uint8_t* buf_end = buf + size;
const uint8_t* part_start;
size_t size_left = size;
size_t last_part;
size_t p;
dec->num_parts_minus_one_ = (1 << VP8GetValue(br, 2, "global-header")) - 1;
last_part = dec->num_parts_minus_one_;
if (size < 3 * last_part) {
// we can't even read the sizes with sz[]! That's a failure.
return VP8_STATUS_NOT_ENOUGH_DATA;
}
part_start = buf + last_part * 3;
size_left -= last_part * 3;
for (p = 0; p < last_part; ++p) {
size_t psize = sz[0] | (sz[1] << 8) | (sz[2] << 16);
if (psize > size_left) psize = size_left;
VP8InitBitReader(dec->parts_ + p, part_start, psize);
part_start += psize;
size_left -= psize;
sz += 3;
}
VP8InitBitReader(dec->parts_ + last_part, part_start, size_left);
if (part_start < buf_end) return VP8_STATUS_OK;
return dec->incremental_
? VP8_STATUS_SUSPENDED // Init is ok, but there's not enough data
: VP8_STATUS_NOT_ENOUGH_DATA;
}
// Paragraph 9.4
static int ParseFilterHeader(VP8BitReader* br, VP8Decoder* const dec) {
VP8FilterHeader* const hdr = &dec->filter_hdr_;
hdr->simple_ = VP8Get(br, "global-header");
hdr->level_ = VP8GetValue(br, 6, "global-header");
hdr->sharpness_ = VP8GetValue(br, 3, "global-header");
hdr->use_lf_delta_ = VP8Get(br, "global-header");
if (hdr->use_lf_delta_) {
if (VP8Get(br, "global-header")) { // update lf-delta?
int i;
for (i = 0; i < NUM_REF_LF_DELTAS; ++i) {
if (VP8Get(br, "global-header")) {
hdr->ref_lf_delta_[i] = VP8GetSignedValue(br, 6, "global-header");
}
}
for (i = 0; i < NUM_MODE_LF_DELTAS; ++i) {
if (VP8Get(br, "global-header")) {
hdr->mode_lf_delta_[i] = VP8GetSignedValue(br, 6, "global-header");
}
}
}
}
dec->filter_type_ = (hdr->level_ == 0) ? 0 : hdr->simple_ ? 1 : 2;
return !br->eof_;
}
// Topmost call
int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io) {
const uint8_t* buf;
size_t buf_size;
VP8FrameHeader* frm_hdr;
VP8PictureHeader* pic_hdr;
VP8BitReader* br;
VP8StatusCode status;
if (dec == NULL) {
return 0;
}
SetOk(dec);
if (io == NULL) {
return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
"null VP8Io passed to VP8GetHeaders()");
}
buf = io->data;
buf_size = io->data_size;
if (buf_size < 4) {
return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
"Truncated header.");
}
// Paragraph 9.1
{
const uint32_t bits = buf[0] | (buf[1] << 8) | (buf[2] << 16);
frm_hdr = &dec->frm_hdr_;
frm_hdr->key_frame_ = !(bits & 1);
frm_hdr->profile_ = (bits >> 1) & 7;
frm_hdr->show_ = (bits >> 4) & 1;
frm_hdr->partition_length_ = (bits >> 5);
if (frm_hdr->profile_ > 3) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
"Incorrect keyframe parameters.");
}
if (!frm_hdr->show_) {
return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
"Frame not displayable.");
}
buf += 3;
buf_size -= 3;
}
pic_hdr = &dec->pic_hdr_;
if (frm_hdr->key_frame_) {
// Paragraph 9.2
if (buf_size < 7) {
return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
"cannot parse picture header");
}
if (!VP8CheckSignature(buf, buf_size)) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
"Bad code word");
}
pic_hdr->width_ = ((buf[4] << 8) | buf[3]) & 0x3fff;
pic_hdr->xscale_ = buf[4] >> 6; // ratio: 1, 5/4 5/3 or 2
pic_hdr->height_ = ((buf[6] << 8) | buf[5]) & 0x3fff;
pic_hdr->yscale_ = buf[6] >> 6;
buf += 7;
buf_size -= 7;
dec->mb_w_ = (pic_hdr->width_ + 15) >> 4;
dec->mb_h_ = (pic_hdr->height_ + 15) >> 4;
// Setup default output area (can be later modified during io->setup())
io->width = pic_hdr->width_;
io->height = pic_hdr->height_;
// IMPORTANT! use some sane dimensions in crop_* and scaled_* fields.
// So they can be used interchangeably without always testing for
// 'use_cropping'.
io->use_cropping = 0;
io->crop_top = 0;
io->crop_left = 0;
io->crop_right = io->width;
io->crop_bottom = io->height;
io->use_scaling = 0;
io->scaled_width = io->width;
io->scaled_height = io->height;
io->mb_w = io->width; // for soundness
io->mb_h = io->height; // ditto
VP8ResetProba(&dec->proba_);
ResetSegmentHeader(&dec->segment_hdr_);
}
// Check if we have all the partition #0 available, and initialize dec->br_
// to read this partition (and this partition only).
if (frm_hdr->partition_length_ > buf_size) {
return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
"bad partition length");
}
br = &dec->br_;
VP8InitBitReader(br, buf, frm_hdr->partition_length_);
buf += frm_hdr->partition_length_;
buf_size -= frm_hdr->partition_length_;
if (frm_hdr->key_frame_) {
pic_hdr->colorspace_ = VP8Get(br, "global-header");
pic_hdr->clamp_type_ = VP8Get(br, "global-header");
}
if (!ParseSegmentHeader(br, &dec->segment_hdr_, &dec->proba_)) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
"cannot parse segment header");
}
// Filter specs
if (!ParseFilterHeader(br, dec)) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
"cannot parse filter header");
}
status = ParsePartitions(dec, buf, buf_size);
if (status != VP8_STATUS_OK) {
return VP8SetError(dec, status, "cannot parse partitions");
}
// quantizer change
VP8ParseQuant(dec);
// Frame buffer marking
if (!frm_hdr->key_frame_) {
return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
"Not a key frame.");
}
VP8Get(br, "global-header"); // ignore the value of update_proba_
VP8ParseProba(br, dec);
// sanitized state
dec->ready_ = 1;
return 1;
}
//------------------------------------------------------------------------------
// Residual decoding (Paragraph 13.2 / 13.3)
static const uint8_t kCat3[] = { 173, 148, 140, 0 };
static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
static const uint8_t kCat6[] =
{ 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0 };
static const uint8_t* const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
static const uint8_t kZigzag[16] = {
0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
};
static int GetLargeValue(VP8BitReader* const br, const uint8_t* const p) {
int v;
if (!VP8GetBit(br, p[3], "coeffs")) {
if (!VP8GetBit(br, p[4], "coeffs")) {
v = 2;
} else {
v = 3 + VP8GetBit(br, p[5], "coeffs");
}
} else {
if (!VP8GetBit(br, p[6], "coeffs")) {
if (!VP8GetBit(br, p[7], "coeffs")) {
v = 5 + VP8GetBit(br, 159, "coeffs");
} else {
v = 7 + 2 * VP8GetBit(br, 165, "coeffs");
v += VP8GetBit(br, 145, "coeffs");
}
} else {
const uint8_t* tab;
const int bit1 = VP8GetBit(br, p[8], "coeffs");
const int bit0 = VP8GetBit(br, p[9 + bit1], "coeffs");
const int cat = 2 * bit1 + bit0;
v = 0;
for (tab = kCat3456[cat]; *tab; ++tab) {
v += v + VP8GetBit(br, *tab, "coeffs");
}
v += 3 + (8 << cat);
}
}
return v;
}
// Returns the position of the last non-zero coeff plus one
static int GetCoeffsFast(VP8BitReader* const br,
const VP8BandProbas* const prob[],
int ctx, const quant_t dq, int n, int16_t* out) {
const uint8_t* p = prob[n]->probas_[ctx];
for (; n < 16; ++n) {
if (!VP8GetBit(br, p[0], "coeffs")) {
return n; // previous coeff was last non-zero coeff
}
while (!VP8GetBit(br, p[1], "coeffs")) { // sequence of zero coeffs
p = prob[++n]->probas_[0];
if (n == 16) return 16;
}
{ // non zero coeff
const VP8ProbaArray* const p_ctx = &prob[n + 1]->probas_[0];
int v;
if (!VP8GetBit(br, p[2], "coeffs")) {
v = 1;
p = p_ctx[1];
} else {
v = GetLargeValue(br, p);
p = p_ctx[2];
}
out[kZigzag[n]] = VP8GetSigned(br, v, "coeffs") * dq[n > 0];
}
}
return 16;
}
// This version of GetCoeffs() uses VP8GetBitAlt() which is an alternate version
// of VP8GetBitAlt() targeting specific platforms.
static int GetCoeffsAlt(VP8BitReader* const br,
const VP8BandProbas* const prob[],
int ctx, const quant_t dq, int n, int16_t* out) {
const uint8_t* p = prob[n]->probas_[ctx];
for (; n < 16; ++n) {
if (!VP8GetBitAlt(br, p[0], "coeffs")) {
return n; // previous coeff was last non-zero coeff
}
while (!VP8GetBitAlt(br, p[1], "coeffs")) { // sequence of zero coeffs
p = prob[++n]->probas_[0];
if (n == 16) return 16;
}
{ // non zero coeff
const VP8ProbaArray* const p_ctx = &prob[n + 1]->probas_[0];
int v;
if (!VP8GetBitAlt(br, p[2], "coeffs")) {
v = 1;
p = p_ctx[1];
} else {
v = GetLargeValue(br, p);
p = p_ctx[2];
}
out[kZigzag[n]] = VP8GetSigned(br, v, "coeffs") * dq[n > 0];
}
}
return 16;
}
extern VP8CPUInfo VP8GetCPUInfo;
WEBP_DSP_INIT_FUNC(InitGetCoeffs) {
if (VP8GetCPUInfo != NULL && VP8GetCPUInfo(kSlowSSSE3)) {
GetCoeffs = GetCoeffsAlt;
} else {
GetCoeffs = GetCoeffsFast;
}
}
static WEBP_INLINE uint32_t NzCodeBits(uint32_t nz_coeffs, int nz, int dc_nz) {
nz_coeffs <<= 2;
nz_coeffs |= (nz > 3) ? 3 : (nz > 1) ? 2 : dc_nz;
return nz_coeffs;
}
static int ParseResiduals(VP8Decoder* const dec,
VP8MB* const mb, VP8BitReader* const token_br) {
const VP8BandProbas* (* const bands)[16 + 1] = dec->proba_.bands_ptr_;
const VP8BandProbas* const * ac_proba;
VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
const VP8QuantMatrix* const q = &dec->dqm_[block->segment_];
int16_t* dst = block->coeffs_;
VP8MB* const left_mb = dec->mb_info_ - 1;
uint8_t tnz, lnz;
uint32_t non_zero_y = 0;
uint32_t non_zero_uv = 0;
int x, y, ch;
uint32_t out_t_nz, out_l_nz;
int first;
memset(dst, 0, 384 * sizeof(*dst));
if (!block->is_i4x4_) { // parse DC
int16_t dc[16] = { 0 };
const int ctx = mb->nz_dc_ + left_mb->nz_dc_;
const int nz = GetCoeffs(token_br, bands[1], ctx, q->y2_mat_, 0, dc);
mb->nz_dc_ = left_mb->nz_dc_ = (nz > 0);
if (nz > 1) { // more than just the DC -> perform the full transform
VP8TransformWHT(dc, dst);
} else { // only DC is non-zero -> inlined simplified transform
int i;
const int dc0 = (dc[0] + 3) >> 3;
for (i = 0; i < 16 * 16; i += 16) dst[i] = dc0;
}
first = 1;
ac_proba = bands[0];
} else {
first = 0;
ac_proba = bands[3];
}
tnz = mb->nz_ & 0x0f;
lnz = left_mb->nz_ & 0x0f;
for (y = 0; y < 4; ++y) {
int l = lnz & 1;
uint32_t nz_coeffs = 0;
for (x = 0; x < 4; ++x) {
const int ctx = l + (tnz & 1);
const int nz = GetCoeffs(token_br, ac_proba, ctx, q->y1_mat_, first, dst);
l = (nz > first);
tnz = (tnz >> 1) | (l << 7);
nz_coeffs = NzCodeBits(nz_coeffs, nz, dst[0] != 0);
dst += 16;
}
tnz >>= 4;
lnz = (lnz >> 1) | (l << 7);
non_zero_y = (non_zero_y << 8) | nz_coeffs;
}
out_t_nz = tnz;
out_l_nz = lnz >> 4;
for (ch = 0; ch < 4; ch += 2) {
uint32_t nz_coeffs = 0;
tnz = mb->nz_ >> (4 + ch);
lnz = left_mb->nz_ >> (4 + ch);
for (y = 0; y < 2; ++y) {
int l = lnz & 1;
for (x = 0; x < 2; ++x) {
const int ctx = l + (tnz & 1);
const int nz = GetCoeffs(token_br, bands[2], ctx, q->uv_mat_, 0, dst);
l = (nz > 0);
tnz = (tnz >> 1) | (l << 3);
nz_coeffs = NzCodeBits(nz_coeffs, nz, dst[0] != 0);
dst += 16;
}
tnz >>= 2;
lnz = (lnz >> 1) | (l << 5);
}
// Note: we don't really need the per-4x4 details for U/V blocks.
non_zero_uv |= nz_coeffs << (4 * ch);
out_t_nz |= (tnz << 4) << ch;
out_l_nz |= (lnz & 0xf0) << ch;
}
mb->nz_ = out_t_nz;
left_mb->nz_ = out_l_nz;
block->non_zero_y_ = non_zero_y;
block->non_zero_uv_ = non_zero_uv;
// We look at the mode-code of each block and check if some blocks have less
// than three non-zero coeffs (code < 2). This is to avoid dithering flat and
// empty blocks.
block->dither_ = (non_zero_uv & 0xaaaa) ? 0 : q->dither_;
return !(non_zero_y | non_zero_uv); // will be used for further optimization
}
//------------------------------------------------------------------------------
// Main loop
int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br) {
VP8MB* const left = dec->mb_info_ - 1;
VP8MB* const mb = dec->mb_info_ + dec->mb_x_;
VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
int skip = dec->use_skip_proba_ ? block->skip_ : 0;
if (!skip) {
skip = ParseResiduals(dec, mb, token_br);
} else {
left->nz_ = mb->nz_ = 0;
if (!block->is_i4x4_) {
left->nz_dc_ = mb->nz_dc_ = 0;
}
block->non_zero_y_ = 0;
block->non_zero_uv_ = 0;
block->dither_ = 0;
}
if (dec->filter_type_ > 0) { // store filter info
VP8FInfo* const finfo = dec->f_info_ + dec->mb_x_;
*finfo = dec->fstrengths_[block->segment_][block->is_i4x4_];
finfo->f_inner_ |= !skip;
}
return !token_br->eof_;
}
void VP8InitScanline(VP8Decoder* const dec) {
VP8MB* const left = dec->mb_info_ - 1;
left->nz_ = 0;
left->nz_dc_ = 0;
memset(dec->intra_l_, B_DC_PRED, sizeof(dec->intra_l_));
dec->mb_x_ = 0;
}
static int ParseFrame(VP8Decoder* const dec, VP8Io* io) {
for (dec->mb_y_ = 0; dec->mb_y_ < dec->br_mb_y_; ++dec->mb_y_) {
// Parse bitstream for this row.
VP8BitReader* const token_br =
&dec->parts_[dec->mb_y_ & dec->num_parts_minus_one_];
if (!VP8ParseIntraModeRow(&dec->br_, dec)) {
return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
"Premature end-of-partition0 encountered.");
}
for (; dec->mb_x_ < dec->mb_w_; ++dec->mb_x_) {
if (!VP8DecodeMB(dec, token_br)) {
return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
"Premature end-of-file encountered.");
}
}
VP8InitScanline(dec); // Prepare for next scanline
// Reconstruct, filter and emit the row.
if (!VP8ProcessRow(dec, io)) {
return VP8SetError(dec, VP8_STATUS_USER_ABORT, "Output aborted.");
}
}
if (dec->mt_method_ > 0) {
if (!WebPGetWorkerInterface()->Sync(&dec->worker_)) return 0;
}
return 1;
}
// Main entry point
int VP8Decode(VP8Decoder* const dec, VP8Io* const io) {
int ok = 0;
if (dec == NULL) {
return 0;
}
if (io == NULL) {
return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
"NULL VP8Io parameter in VP8Decode().");
}
if (!dec->ready_) {
if (!VP8GetHeaders(dec, io)) {
return 0;
}
}
assert(dec->ready_);
// Finish setting up the decoding parameter. Will call io->setup().
ok = (VP8EnterCritical(dec, io) == VP8_STATUS_OK);
if (ok) { // good to go.
// Will allocate memory and prepare everything.
if (ok) ok = VP8InitFrame(dec, io);
// Main decoding loop
if (ok) ok = ParseFrame(dec, io);
// Exit.
ok &= VP8ExitCritical(dec, io);
}
if (!ok) {
VP8Clear(dec);
return 0;
}
dec->ready_ = 0;
return ok;
}
void VP8Clear(VP8Decoder* const dec) {
if (dec == NULL) {
return;
}
WebPGetWorkerInterface()->End(&dec->worker_);
WebPDeallocateAlphaMemory(dec);
WebPSafeFree(dec->mem_);
dec->mem_ = NULL;
dec->mem_size_ = 0;
memset(&dec->br_, 0, sizeof(dec->br_));
dec->ready_ = 0;
}
//------------------------------------------------------------------------------