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godot/drivers/webp/dec/vp8.c

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// Copyright 2010 Google Inc. All Rights Reserved.
//
// 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 entry for the decoder
//
// Author: Skal (pascal.massimino@gmail.com)
#include <stdlib.h>
#include "./vp8i.h"
#include "./vp8li.h"
#include "./webpi.h"
#include "../utils/bit_reader.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
//------------------------------------------------------------------------------
int WebPGetDecoderVersion(void) {
return (DEC_MAJ_VERSION << 16) | (DEC_MIN_VERSION << 8) | DEC_REV_VERSION;
}
//------------------------------------------------------------------------------
// 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*)calloc(1, sizeof(*dec));
if (dec != NULL) {
SetOk(dec);
WebPWorkerInit(&dec->worker_);
dec->ready_ = 0;
dec->num_parts_ = 1;
}
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);
free(dec);
}
}
int VP8SetError(VP8Decoder* const dec,
VP8StatusCode error, const char* const msg) {
// TODO This check would be unnecessary if alpha decompression was separated
// from VP8ProcessRow/FinishRow. This avoids setting 'dec->status_' to
// something other than VP8_STATUS_BITSTREAM_ERROR on alpha decompression
// failure.
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 (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);
if (hdr->use_segment_) {
hdr->update_map_ = VP8Get(br);
if (VP8Get(br)) { // update data
int s;
hdr->absolute_delta_ = VP8Get(br);
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
hdr->quantizer_[s] = VP8Get(br) ? VP8GetSignedValue(br, 7) : 0;
}
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
hdr->filter_strength_[s] = VP8Get(br) ? VP8GetSignedValue(br, 6) : 0;
}
}
if (hdr->update_map_) {
int s;
for (s = 0; s < MB_FEATURE_TREE_PROBS; ++s) {
proba->segments_[s] = VP8Get(br) ? VP8GetValue(br, 8) : 255u;
}
}
} else {
hdr->update_map_ = 0;
}
return !br->eof_;
}
// Paragraph 9.5
// This function returns VP8_STATUS_SUSPENDED if we don't have all the
// necessary data in 'buf'.
// This case is not necessarily an error (for incremental decoding).
// Still, no bitreader is ever initialized to make it possible to read
// unavailable memory.
// If we don't even have the partitions' sizes, than 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;
int last_part;
int p;
dec->num_parts_ = 1 << VP8GetValue(br, 2);
last_part = dec->num_parts_ - 1;
part_start = buf + last_part * 3;
if (buf_end < part_start) {
// we can't even read the sizes with sz[]! That's a failure.
return VP8_STATUS_NOT_ENOUGH_DATA;
}
for (p = 0; p < last_part; ++p) {
const uint32_t psize = sz[0] | (sz[1] << 8) | (sz[2] << 16);
const uint8_t* part_end = part_start + psize;
if (part_end > buf_end) part_end = buf_end;
VP8InitBitReader(dec->parts_ + p, part_start, part_end);
part_start = part_end;
sz += 3;
}
VP8InitBitReader(dec->parts_ + last_part, part_start, buf_end);
return (part_start < buf_end) ? VP8_STATUS_OK :
VP8_STATUS_SUSPENDED; // Init is ok, but there's not enough data
}
// Paragraph 9.4
static int ParseFilterHeader(VP8BitReader* br, VP8Decoder* const dec) {
VP8FilterHeader* const hdr = &dec->filter_hdr_;
hdr->simple_ = VP8Get(br);
hdr->level_ = VP8GetValue(br, 6);
hdr->sharpness_ = VP8GetValue(br, 3);
hdr->use_lf_delta_ = VP8Get(br);
if (hdr->use_lf_delta_) {
if (VP8Get(br)) { // update lf-delta?
int i;
for (i = 0; i < NUM_REF_LF_DELTAS; ++i) {
if (VP8Get(br)) {
hdr->ref_lf_delta_[i] = VP8GetSignedValue(br, 6);
}
}
for (i = 0; i < NUM_MODE_LF_DELTAS; ++i) {
if (VP8Get(br)) {
hdr->mode_lf_delta_[i] = VP8GetSignedValue(br, 6);
}
}
}
}
dec->filter_type_ = (hdr->level_ == 0) ? 0 : hdr->simple_ ? 1 : 2;
if (dec->filter_type_ > 0) { // precompute filter levels per segment
if (dec->segment_hdr_.use_segment_) {
int s;
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
int strength = dec->segment_hdr_.filter_strength_[s];
if (!dec->segment_hdr_.absolute_delta_) {
strength += hdr->level_;
}
dec->filter_levels_[s] = strength;
}
} else {
dec->filter_levels_[0] = hdr->level_;
}
}
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;
WebPHeaderStructure headers;
if (dec == NULL) {
return 0;
}
SetOk(dec);
if (io == NULL) {
return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
"null VP8Io passed to VP8GetHeaders()");
}
// Process Pre-VP8 chunks.
headers.data = io->data;
headers.data_size = io->data_size;
status = WebPParseHeaders(&headers);
if (status != VP8_STATUS_OK) {
return VP8SetError(dec, status, "Incorrect/incomplete header.");
}
if (headers.is_lossless) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
"Unexpected lossless format encountered.");
}
if (dec->alpha_data_ == NULL) {
assert(dec->alpha_data_size_ == 0);
// We have NOT set alpha data yet. Set it now.
// (This is to ensure that dec->alpha_data_ is NOT reset to NULL if
// WebPParseHeaders() is called more than once, as in incremental decoding
// case.)
dec->alpha_data_ = headers.alpha_data;
dec->alpha_data_size_ = headers.alpha_data_size;
}
// Process the VP8 frame header.
buf = headers.data + headers.offset;
buf_size = headers.data_size - headers.offset;
assert(headers.data_size >= headers.offset); // WebPParseHeaders' guarantee
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_;
io->use_scaling = 0;
io->use_cropping = 0;
io->crop_top = 0;
io->crop_left = 0;
io->crop_right = io->width;
io->crop_bottom = io->height;
io->mb_w = io->width; // sanity check
io->mb_h = io->height; // ditto
VP8ResetProba(&dec->proba_);
ResetSegmentHeader(&dec->segment_hdr_);
dec->segment_ = 0; // default for intra
}
// 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, 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);
pic_hdr->clamp_type_ = VP8Get(br);
}
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_) {
// Paragraph 9.7
#ifndef ONLY_KEYFRAME_CODE
dec->buffer_flags_ = VP8Get(br) << 0; // update golden
dec->buffer_flags_ |= VP8Get(br) << 1; // update alt ref
if (!(dec->buffer_flags_ & 1)) {
dec->buffer_flags_ |= VP8GetValue(br, 2) << 2;
}
if (!(dec->buffer_flags_ & 2)) {
dec->buffer_flags_ |= VP8GetValue(br, 2) << 4;
}
dec->buffer_flags_ |= VP8Get(br) << 6; // sign bias golden
dec->buffer_flags_ |= VP8Get(br) << 7; // sign bias alt ref
#else
return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
"Not a key frame.");
#endif
} else {
dec->buffer_flags_ = 0x003 | 0x100;
}
// Paragraph 9.8
#ifndef ONLY_KEYFRAME_CODE
dec->update_proba_ = VP8Get(br);
if (!dec->update_proba_) { // save for later restore
dec->proba_saved_ = dec->proba_;
}
dec->buffer_flags_ &= 1 << 8;
dec->buffer_flags_ |=
(frm_hdr->key_frame_ || VP8Get(br)) << 8; // refresh last frame
#else
VP8Get(br); // just ignore the value of update_proba_
#endif
VP8ParseProba(br, dec);
#ifdef WEBP_EXPERIMENTAL_FEATURES
// Extensions
if (dec->pic_hdr_.colorspace_) {
const size_t kTrailerSize = 8;
const uint8_t kTrailerMarker = 0x01;
const uint8_t* ext_buf = buf - kTrailerSize;
size_t size;
if (frm_hdr->partition_length_ < kTrailerSize ||
ext_buf[kTrailerSize - 1] != kTrailerMarker) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
"RIFF: Inconsistent extra information.");
}
// Layer
size = (ext_buf[0] << 0) | (ext_buf[1] << 8) | (ext_buf[2] << 16);
dec->layer_data_size_ = size;
dec->layer_data_ = NULL; // will be set later
dec->layer_colorspace_ = ext_buf[3];
}
#endif
// sanitized state
dec->ready_ = 1;
return 1;
}
//------------------------------------------------------------------------------
// Residual decoding (Paragraph 13.2 / 13.3)
static const uint8_t kBands[16 + 1] = {
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
0 // extra entry as sentinel
};
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
};
typedef const uint8_t (*ProbaArray)[NUM_CTX][NUM_PROBAS]; // for const-casting
// Returns the position of the last non-zero coeff plus one
// (and 0 if there's no coeff at all)
static int GetCoeffs(VP8BitReader* const br, ProbaArray prob,
int ctx, const quant_t dq, int n, int16_t* out) {
// n is either 0 or 1 here. kBands[n] is not necessary for extracting '*p'.
const uint8_t* p = prob[n][ctx];
if (!VP8GetBit(br, p[0])) { // first EOB is more a 'CBP' bit.
return 0;
}
while (1) {
++n;
if (!VP8GetBit(br, p[1])) {
p = prob[kBands[n]][0];
} else { // non zero coeff
int v, j;
if (!VP8GetBit(br, p[2])) {
p = prob[kBands[n]][1];
v = 1;
} else {
if (!VP8GetBit(br, p[3])) {
if (!VP8GetBit(br, p[4])) {
v = 2;
} else {
v = 3 + VP8GetBit(br, p[5]);
}
} else {
if (!VP8GetBit(br, p[6])) {
if (!VP8GetBit(br, p[7])) {
v = 5 + VP8GetBit(br, 159);
} else {
v = 7 + 2 * VP8GetBit(br, 165);
v += VP8GetBit(br, 145);
}
} else {
const uint8_t* tab;
const int bit1 = VP8GetBit(br, p[8]);
const int bit0 = VP8GetBit(br, p[9 + bit1]);
const int cat = 2 * bit1 + bit0;
v = 0;
for (tab = kCat3456[cat]; *tab; ++tab) {
v += v + VP8GetBit(br, *tab);
}
v += 3 + (8 << cat);
}
}
p = prob[kBands[n]][2];
}
j = kZigzag[n - 1];
out[j] = VP8GetSigned(br, v) * dq[j > 0];
if (n == 16 || !VP8GetBit(br, p[0])) { // EOB
return n;
}
}
if (n == 16) {
return 16;
}
}
}
// Alias-safe way of converting 4bytes to 32bits.
typedef union {
uint8_t i8[4];
uint32_t i32;
} PackedNz;
// Table to unpack four bits into four bytes
static const PackedNz kUnpackTab[16] = {
{{0, 0, 0, 0}}, {{1, 0, 0, 0}}, {{0, 1, 0, 0}}, {{1, 1, 0, 0}},
{{0, 0, 1, 0}}, {{1, 0, 1, 0}}, {{0, 1, 1, 0}}, {{1, 1, 1, 0}},
{{0, 0, 0, 1}}, {{1, 0, 0, 1}}, {{0, 1, 0, 1}}, {{1, 1, 0, 1}},
{{0, 0, 1, 1}}, {{1, 0, 1, 1}}, {{0, 1, 1, 1}}, {{1, 1, 1, 1}} };
// Macro to pack four LSB of four bytes into four bits.
#if defined(__PPC__) || defined(_M_PPC) || defined(_ARCH_PPC) || \
defined(__BIG_ENDIAN__)
#define PACK_CST 0x08040201U
#else
#define PACK_CST 0x01020408U
#endif
#define PACK(X, S) ((((X).i32 * PACK_CST) & 0xff000000) >> (S))
static void ParseResiduals(VP8Decoder* const dec,
VP8MB* const mb, VP8BitReader* const token_br) {
int out_t_nz, out_l_nz, first;
ProbaArray ac_prob;
const VP8QuantMatrix* q = &dec->dqm_[dec->segment_];
int16_t* dst = dec->coeffs_;
VP8MB* const left_mb = dec->mb_info_ - 1;
PackedNz nz_ac, nz_dc;
PackedNz tnz, lnz;
uint32_t non_zero_ac = 0;
uint32_t non_zero_dc = 0;
int x, y, ch;
nz_dc.i32 = nz_ac.i32 = 0;
memset(dst, 0, 384 * sizeof(*dst));
if (!dec->is_i4x4_) { // parse DC
int16_t dc[16] = { 0 };
const int ctx = mb->dc_nz_ + left_mb->dc_nz_;
mb->dc_nz_ = left_mb->dc_nz_ =
(GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[1],
ctx, q->y2_mat_, 0, dc) > 0);
first = 1;
ac_prob = (ProbaArray)dec->proba_.coeffs_[0];
VP8TransformWHT(dc, dst);
} else {
first = 0;
ac_prob = (ProbaArray)dec->proba_.coeffs_[3];
}
tnz = kUnpackTab[mb->nz_ & 0xf];
lnz = kUnpackTab[left_mb->nz_ & 0xf];
for (y = 0; y < 4; ++y) {
int l = lnz.i8[y];
for (x = 0; x < 4; ++x) {
const int ctx = l + tnz.i8[x];
const int nz = GetCoeffs(token_br, ac_prob, ctx,
q->y1_mat_, first, dst);
tnz.i8[x] = l = (nz > 0);
nz_dc.i8[x] = (dst[0] != 0);
nz_ac.i8[x] = (nz > 1);
dst += 16;
}
lnz.i8[y] = l;
non_zero_dc |= PACK(nz_dc, 24 - y * 4);
non_zero_ac |= PACK(nz_ac, 24 - y * 4);
}
out_t_nz = PACK(tnz, 24);
out_l_nz = PACK(lnz, 24);
tnz = kUnpackTab[mb->nz_ >> 4];
lnz = kUnpackTab[left_mb->nz_ >> 4];
for (ch = 0; ch < 4; ch += 2) {
for (y = 0; y < 2; ++y) {
int l = lnz.i8[ch + y];
for (x = 0; x < 2; ++x) {
const int ctx = l + tnz.i8[ch + x];
const int nz =
GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[2],
ctx, q->uv_mat_, 0, dst);
tnz.i8[ch + x] = l = (nz > 0);
nz_dc.i8[y * 2 + x] = (dst[0] != 0);
nz_ac.i8[y * 2 + x] = (nz > 1);
dst += 16;
}
lnz.i8[ch + y] = l;
}
non_zero_dc |= PACK(nz_dc, 8 - ch * 2);
non_zero_ac |= PACK(nz_ac, 8 - ch * 2);
}
out_t_nz |= PACK(tnz, 20);
out_l_nz |= PACK(lnz, 20);
mb->nz_ = out_t_nz;
left_mb->nz_ = out_l_nz;
dec->non_zero_ac_ = non_zero_ac;
dec->non_zero_ = non_zero_ac | non_zero_dc;
mb->skip_ = !dec->non_zero_;
}
#undef PACK
//------------------------------------------------------------------------------
// Main loop
int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br) {
VP8BitReader* const br = &dec->br_;
VP8MB* const left = dec->mb_info_ - 1;
VP8MB* const info = dec->mb_info_ + dec->mb_x_;
// Note: we don't save segment map (yet), as we don't expect
// to decode more than 1 keyframe.
if (dec->segment_hdr_.update_map_) {
// Hardcoded tree parsing
dec->segment_ = !VP8GetBit(br, dec->proba_.segments_[0]) ?
VP8GetBit(br, dec->proba_.segments_[1]) :
2 + VP8GetBit(br, dec->proba_.segments_[2]);
}
info->skip_ = dec->use_skip_proba_ ? VP8GetBit(br, dec->skip_p_) : 0;
VP8ParseIntraMode(br, dec);
if (br->eof_) {
return 0;
}
if (!info->skip_) {
ParseResiduals(dec, info, token_br);
} else {
left->nz_ = info->nz_ = 0;
if (!dec->is_i4x4_) {
left->dc_nz_ = info->dc_nz_ = 0;
}
dec->non_zero_ = 0;
dec->non_zero_ac_ = 0;
}
return (!token_br->eof_);
}
void VP8InitScanline(VP8Decoder* const dec) {
VP8MB* const left = dec->mb_info_ - 1;
left->nz_ = 0;
left->dc_nz_ = 0;
memset(dec->intra_l_, B_DC_PRED, sizeof(dec->intra_l_));
dec->filter_row_ =
(dec->filter_type_ > 0) &&
(dec->mb_y_ >= dec->tl_mb_y_) && (dec->mb_y_ <= dec->br_mb_y_);
}
static int ParseFrame(VP8Decoder* const dec, VP8Io* io) {
for (dec->mb_y_ = 0; dec->mb_y_ < dec->br_mb_y_; ++dec->mb_y_) {
VP8BitReader* const token_br =
&dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
VP8InitScanline(dec);
for (dec->mb_x_ = 0; 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.");
}
VP8ReconstructBlock(dec);
// Store data and save block's filtering params
VP8StoreBlock(dec);
}
if (!VP8ProcessRow(dec, io)) {
return VP8SetError(dec, VP8_STATUS_USER_ABORT, "Output aborted.");
}
}
if (dec->use_threads_ && !WebPWorkerSync(&dec->worker_)) {
return 0;
}
// Finish
#ifndef ONLY_KEYFRAME_CODE
if (!dec->update_proba_) {
dec->proba_ = dec->proba_saved_;
}
#endif
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (dec->layer_data_size_ > 0) {
if (!VP8DecodeLayer(dec)) {
return 0;
}
}
#endif
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;
}
if (dec->use_threads_) {
WebPWorkerEnd(&dec->worker_);
}
if (dec->mem_) {
free(dec->mem_);
}
dec->mem_ = NULL;
dec->mem_size_ = 0;
memset(&dec->br_, 0, sizeof(dec->br_));
dec->ready_ = 0;
}
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
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