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Add Alpha Encode support from WebPEncode.

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Extend WebP Encode functionality to encode Alpha data and produce
bit-stream (RIFF+VP8X+ALPH+VP8) corresponding to WebP-Alpha.

Change-Id: I983b4cd97be94a86a8e6d03b3b9c728db851bf48
This commit is contained in:
Vikas Arora 2011-12-01 12:14:15 +05:30
parent 16612ddd30
commit 9523f2a5de
9 changed files with 207 additions and 138 deletions
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2
src/enc/Makefile.am
View File

@ -6,7 +6,7 @@ libwebpencode_la_SOURCES = analysis.c config.c cost.c cost.h filter.c \
layer.c
libwebpencode_la_LDFLAGS = -version-info 2:0:0 -lm
libwebpencode_la_CPPFLAGS = $(USE_EXPERIMENTAL_CODE)
libwebpencodeinclude_HEADERS = ../webp/encode.h ../webp/types.h
libwebpencodeinclude_HEADERS = ../webp/encode.h ../webp/types.h ../webp/mux.h
libwebpencodeincludedir = $(includedir)/webp
noinst_LTLIBRARIES = libwebpencode.la

80
src/enc/alpha.c
View File

@ -12,92 +12,38 @@
#include <assert.h>
#include <stdlib.h>
#include "vp8enci.h"
#ifdef WEBP_EXPERIMENTAL_FEATURES
#include "zlib.h"
#endif
#include "../utils/alpha.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#ifdef WEBP_EXPERIMENTAL_FEATURES
#define CHUNK_SIZE 8192
//------------------------------------------------------------------------------
static int CompressAlpha(const uint8_t* data, size_t data_size,
uint8_t** output, size_t* output_size,
int algo) {
int ret = Z_OK;
z_stream strm;
unsigned char chunk[CHUNK_SIZE];
*output = NULL;
*output_size = 0;
memset(&strm, 0, sizeof(strm));
if (deflateInit(&strm, algo ? Z_BEST_SPEED : Z_BEST_COMPRESSION) != Z_OK) {
return 0;
}
strm.next_in = (unsigned char*)data;
strm.avail_in = data_size;
do {
size_t size_out;
strm.next_out = chunk;
strm.avail_out = CHUNK_SIZE;
ret = deflate(&strm, Z_FINISH);
if (ret == Z_STREAM_ERROR) {
break;
}
size_out = CHUNK_SIZE - strm.avail_out;
if (size_out) {
size_t new_size = *output_size + size_out;
uint8_t* new_output = realloc(*output, new_size);
if (new_output == NULL) {
ret = Z_MEM_ERROR;
break;
}
memcpy(new_output + *output_size, chunk, size_out);
*output_size = new_size;
*output = new_output;
}
} while (ret != Z_STREAM_END || strm.avail_out == 0);
deflateEnd(&strm);
if (ret != Z_STREAM_END) {
free(*output);
output_size = 0;
return 0;
}
return 1;
}
#endif /* WEBP_EXPERIMENTAL_FEATURES */
void VP8EncInitAlpha(VP8Encoder* enc) {
enc->has_alpha_ = (enc->pic_->a != NULL);
enc->alpha_data_ = NULL;
enc->alpha_data_size_ = 0;
}
void VP8EncCodeAlphaBlock(VP8EncIterator* it) {
(void)it;
// Nothing for now. We just ZLIB-compress in the end.
}
int VP8EncFinishAlpha(VP8Encoder* enc) {
if (enc->has_alpha_) {
#ifdef WEBP_EXPERIMENTAL_FEATURES
const WebPConfig* config = enc->config_;
const WebPPicture* pic = enc->pic_;
uint8_t* tmp_data = NULL;
size_t tmp_size = 0;
assert(pic->a);
if (!CompressAlpha(pic->a, pic->width * pic->height,
&enc->alpha_data_, &enc->alpha_data_size_,
enc->config_->alpha_compression)) {
if (!EncodeAlpha(pic->a, pic->width, pic->height, pic->a_stride,
config->alpha_quality, config->alpha_compression,
&tmp_data, &tmp_size)) {
return 0;
}
#endif
if (tmp_size != (uint32_t)tmp_size) { // Sanity check.
free(tmp_data);
return 0;
}
enc->alpha_data_size_ = (uint32_t)tmp_size;
enc->alpha_data_ = tmp_data;
}
return 1;
}

5
src/enc/config.c
View File

@ -41,8 +41,9 @@ int WebPConfigInitInternal(WebPConfig* const config,
config->show_compressed = 0;
config->preprocessing = 0;
config->autofilter = 0;
config->alpha_compression = 0;
config->partition_limit = 0;
config->alpha_compression = 1;
config->alpha_quality = 100;
// TODO(skal): tune.
switch (preset) {
@ -111,6 +112,8 @@ int WebPValidateConfig(const WebPConfig* const config) {
return 0;
if (config->alpha_compression < 0)
return 0;
if (config->alpha_quality < 0 || config->alpha_quality > 100)
return 0;
return 1;
}

3
src/enc/frame.c
View File

@ -588,9 +588,6 @@ int VP8EncLoop(VP8Encoder* const enc) {
ResetAfterSkip(&it);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (enc->has_alpha_) {
VP8EncCodeAlphaBlock(&it);
}
if (enc->use_layer_) {
VP8EncCodeLayerBlock(&it);
}

8
src/enc/picture.c
View File

@ -147,11 +147,11 @@ int WebPPictureCopy(const WebPPicture* const src, WebPPicture* const dst) {
dst->u, dst->uv_stride, HALVE(dst->width), HALVE(dst->height));
CopyPlane(src->v, src->uv_stride,
dst->v, dst->uv_stride, HALVE(dst->width), HALVE(dst->height));
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (dst->a != NULL) {
CopyPlane(src->a, src->a_stride,
dst->a, dst->a_stride, dst->width, dst->height);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (dst->u0 != NULL) {
int uv0_width = src->width;
if ((dst->colorspace & WEBP_CSP_UV_MASK) == WEBP_YUV422) {
@ -194,12 +194,12 @@ int WebPPictureCrop(WebPPicture* const pic,
tmp.v, tmp.uv_stride, HALVE(width), HALVE(height));
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (tmp.a) {
const int a_offset = top * pic->a_stride + left;
CopyPlane(pic->a + a_offset, pic->a_stride,
tmp.a, tmp.a_stride, width, height);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (tmp.u0) {
int w = width;
int l = left;
@ -347,11 +347,11 @@ int WebPPictureRescale(WebPPicture* const pic, int width, int height) {
tmp.v,
HALVE(width), HALVE(height), tmp.uv_stride, work);
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (tmp.a) {
RescalePlane(pic->a, prev_width, prev_height, pic->a_stride,
tmp.a, width, height, tmp.a_stride, work);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (tmp.u0) {
int s = 1;
if ((tmp.colorspace & WEBP_CSP_UV_MASK) == WEBP_YUV422) {
@ -547,7 +547,6 @@ static int Import(WebPPicture* const picture,
}
if (import_alpha) {
#ifdef WEBP_EXPERIMENTAL_FEATURES
const uint8_t* const a_ptr = rgb + 3;
assert(step >= 4);
for (y = 0; y < height; ++y) {
@ -556,7 +555,6 @@ static int Import(WebPPicture* const picture,
a_ptr[step * x + y * rgb_stride];
}
}
#endif
}
return 1;
}

232
src/enc/syntax.c
View File

@ -12,24 +12,21 @@
#include <assert.h>
#include <math.h>
#include "vp8enci.h"
#include "./vp8enci.h"
#include "../dec/webpi.h" // For chunk-size constants.
#include "../webp/mux.h" // For 'ALPHA_FLAG' constant.
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define KSIGNATURE 0x9d012a
#define KHEADER_SIZE 10
#define KRIFF_SIZE 20
#define KSIZE_OFFSET (KRIFF_SIZE - 8)
#define MAX_PARTITION0_SIZE (1 << 19) // max size of mode partition
#define MAX_PARTITION_SIZE (1 << 24) // max size for token partition
//------------------------------------------------------------------------------
// Writers for header's various pieces (in order of appearance)
// Main keyframe header
//------------------------------------------------------------------------------
// Helper functions
static void PutLE32(uint8_t* const data, uint32_t val) {
data[0] = (val >> 0) & 0xff;
@ -38,46 +35,162 @@ static void PutLE32(uint8_t* const data, uint32_t val) {
data[3] = (val >> 24) & 0xff;
}
static int PutHeader(int profile, size_t size0, size_t total_size,
WebPPicture* const pic) {
uint8_t buf[KHEADER_SIZE];
uint8_t RIFF[KRIFF_SIZE] = {
'R', 'I', 'F', 'F', 0, 0, 0, 0, 'W', 'E', 'B', 'P', 'V', 'P', '8', ' '
static int IsVP8XNeeded(const VP8Encoder* const enc) {
return !!enc->has_alpha_; // Currently the only case when VP8X is needed.
// This could change in the future.
}
static int PutPaddingByte(const WebPPicture* const pic) {
const uint8_t pad_byte[1] = { 0 };
return !!pic->writer(pad_byte, 1, pic);
}
//------------------------------------------------------------------------------
// Writers for header's various pieces (in order of appearance)
static WebPEncodingError PutRIFFHeader(const VP8Encoder* const enc,
size_t riff_size) {
const WebPPicture* const pic = enc->pic_;
uint8_t riff[RIFF_HEADER_SIZE] = {
'R', 'I', 'F', 'F', 0, 0, 0, 0, 'W', 'E', 'B', 'P'
};
PutLE32(riff + TAG_SIZE, riff_size);
if (!pic->writer(riff, sizeof(riff), pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
return VP8_ENC_OK;
}
static WebPEncodingError PutVP8XHeader(const VP8Encoder* const enc) {
const WebPPicture* const pic = enc->pic_;
uint8_t vp8x[CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE] = {
'V', 'P', '8', 'X'
};
uint32_t flags = 0;
assert(IsVP8XNeeded(enc));
if (enc->has_alpha_) {
flags |= ALPHA_FLAG;
}
PutLE32(vp8x + TAG_SIZE, VP8X_CHUNK_SIZE);
PutLE32(vp8x + CHUNK_HEADER_SIZE, flags);
PutLE32(vp8x + CHUNK_HEADER_SIZE + 4 , pic->width);
PutLE32(vp8x + CHUNK_HEADER_SIZE + 8 , pic->height);
if(!pic->writer(vp8x, sizeof(vp8x), pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
return VP8_ENC_OK;
}
static WebPEncodingError PutAlphaChunk(const VP8Encoder* const enc) {
const WebPPicture* const pic = enc->pic_;
uint8_t alpha_chunk_hdr[CHUNK_HEADER_SIZE] = {
'A', 'L', 'P', 'H'
};
assert(enc->has_alpha_);
// Alpha chunk header.
PutLE32(alpha_chunk_hdr + TAG_SIZE, enc->alpha_data_size_);
if (!pic->writer(alpha_chunk_hdr, sizeof(alpha_chunk_hdr), pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
// Alpha chunk data.
if (!pic->writer(enc->alpha_data_, enc->alpha_data_size_, pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
// Padding.
if ((enc->alpha_data_size_ & 1) && !PutPaddingByte(pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
return VP8_ENC_OK;
}
static WebPEncodingError PutVP8Header(const WebPPicture* const pic,
size_t vp8_size) {
uint8_t vp8_chunk_hdr[CHUNK_HEADER_SIZE] = {
'V', 'P', '8', ' '
};
PutLE32(vp8_chunk_hdr + TAG_SIZE, vp8_size);
if (!pic->writer(vp8_chunk_hdr, sizeof(vp8_chunk_hdr), pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
return VP8_ENC_OK;
}
static WebPEncodingError PutVP8FrameHeader(const WebPPicture* const pic,
int profile, size_t size0) {
uint8_t vp8_frm_hdr[VP8_FRAME_HEADER_SIZE];
uint32_t bits;
if (size0 >= MAX_PARTITION0_SIZE) { // partition #0 is too big to fit
return WebPEncodingSetError(pic, VP8_ENC_ERROR_PARTITION0_OVERFLOW);
}
if (total_size > 0xfffffffeU - KRIFF_SIZE) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_FILE_TOO_BIG);
}
PutLE32(RIFF + 4, (uint32_t)(total_size + KSIZE_OFFSET));
PutLE32(RIFF + 16, (uint32_t)total_size);
if (!pic->writer(RIFF, sizeof(RIFF), pic)) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_WRITE);
return VP8_ENC_ERROR_PARTITION0_OVERFLOW;
}
bits = 0 // keyframe (1b)
| (profile << 1) // profile (3b)
| (1 << 4) // visible (1b)
| ((uint32_t)size0 << 5); // partition length (19b)
buf[0] = bits & 0xff;
buf[1] = (bits >> 8) & 0xff;
buf[2] = (bits >> 16) & 0xff;
| ((uint32_t)size0 << 5); // partition length (19b)
vp8_frm_hdr[0] = bits & 0xff;
vp8_frm_hdr[1] = (bits >> 8) & 0xff;
vp8_frm_hdr[2] = (bits >> 16) & 0xff;
// signature
buf[3] = (KSIGNATURE >> 16) & 0xff;
buf[4] = (KSIGNATURE >> 8) & 0xff;
buf[5] = (KSIGNATURE >> 0) & 0xff;
vp8_frm_hdr[3] = (KSIGNATURE >> 16) & 0xff;
vp8_frm_hdr[4] = (KSIGNATURE >> 8) & 0xff;
vp8_frm_hdr[5] = (KSIGNATURE >> 0) & 0xff;
// dimensions
buf[6] = pic->width & 0xff;
buf[7] = pic->width >> 8;
buf[8] = pic->height & 0xff;
buf[9] = pic->height >> 8;
vp8_frm_hdr[6] = pic->width & 0xff;
vp8_frm_hdr[7] = pic->width >> 8;
vp8_frm_hdr[8] = pic->height & 0xff;
vp8_frm_hdr[9] = pic->height >> 8;
return pic->writer(buf, sizeof(buf), pic);
if (!pic->writer(vp8_frm_hdr, sizeof(vp8_frm_hdr), pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
return VP8_ENC_OK;
}
// WebP Headers.
static int PutWebPHeaders(const VP8Encoder* const enc, size_t size0,
size_t vp8_size, size_t riff_size) {
WebPPicture* const pic = enc->pic_;
WebPEncodingError err = VP8_ENC_OK;
// RIFF header.
err = PutRIFFHeader(enc, riff_size);
if (err != VP8_ENC_OK) goto Error;
// VP8X.
if (IsVP8XNeeded(enc)) {
err = PutVP8XHeader(enc);
if (err != VP8_ENC_OK) goto Error;
}
// Alpha.
if (enc->has_alpha_) {
err = PutAlphaChunk(enc);
if (err != VP8_ENC_OK) goto Error;
}
// VP8 header.
err = PutVP8Header(pic, vp8_size);
if (err != VP8_ENC_OK) goto Error;
// VP8 frame header.
err = PutVP8FrameHeader(pic, enc->profile_, size0);
if (err != VP8_ENC_OK) goto Error;
// All OK.
return 1;
// Error.
Error:
return WebPEncodingSetError(pic, err);
}
// Segmentation header
@ -186,14 +299,6 @@ static int WriteExtensions(VP8Encoder* const enc) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY);
}
}
// Alpha (bytes 4..6)
PutLE24(buffer + 4, enc->alpha_data_size_);
if (enc->alpha_data_size_ > 0) {
assert(enc->has_alpha_);
if (!VP8BitWriterAppend(bw, enc->alpha_data_, enc->alpha_data_size_)) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY);
}
}
buffer[KTRAILER_SIZE - 1] = 0x01; // marker
if (!VP8BitWriterAppend(bw, buffer, KTRAILER_SIZE)) {
@ -211,7 +316,7 @@ static size_t GeneratePartition0(VP8Encoder* const enc) {
const int mb_size = enc->mb_w_ * enc->mb_h_;
uint64_t pos1, pos2, pos3;
#ifdef WEBP_EXPERIMENTAL_FEATURES
const int need_extensions = enc->has_alpha_ || enc->use_layer_;
const int need_extensions = enc->use_layer_;
#endif
pos1 = VP8BitWriterPos(bw);
@ -254,25 +359,43 @@ int VP8EncWrite(VP8Encoder* const enc) {
WebPPicture* const pic = enc->pic_;
VP8BitWriter* const bw = &enc->bw_;
int ok = 0;
size_t coded_size, pad;
size_t vp8_size, pad, riff_size;
int p;
// Partition #0 with header and partition sizes
ok = !!GeneratePartition0(enc);
// Compute total size (for the RIFF header)
coded_size = KHEADER_SIZE + VP8BitWriterSize(bw) + 3 * (enc->num_parts_ - 1);
// Compute VP8 size
vp8_size = VP8_FRAME_HEADER_SIZE +
VP8BitWriterSize(bw) +
3 * (enc->num_parts_ - 1);
for (p = 0; p < enc->num_parts_; ++p) {
coded_size += VP8BitWriterSize(enc->parts_ + p);
vp8_size += VP8BitWriterSize(enc->parts_ + p);
}
pad = vp8_size & 1;
vp8_size += pad;
// Computer RIFF size
// At the minimum it is: "WEBPVP8 nnnn" + VP8 data size.
riff_size = TAG_SIZE + CHUNK_HEADER_SIZE + vp8_size;
if (IsVP8XNeeded(enc)) { // Add size for: VP8X header + data.
riff_size += CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
}
if (enc->has_alpha_) { // Add size for: ALPH header + data.
const uint32_t padded_alpha_size = enc->alpha_data_size_ +
(enc->alpha_data_size_ & 1);
riff_size += CHUNK_HEADER_SIZE + padded_alpha_size;
}
// Sanity check.
if (riff_size > 0xfffffffeU) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_FILE_TOO_BIG);
}
pad = coded_size & 1;
coded_size += pad;
// Emit headers and partition #0
{
const uint8_t* const part0 = VP8BitWriterBuf(bw);
const size_t size0 = VP8BitWriterSize(bw);
ok = ok && PutHeader(enc->profile_, size0, coded_size, pic)
ok = ok && PutWebPHeaders(enc, size0, vp8_size, riff_size)
&& pic->writer(part0, size0, pic)
&& EmitPartitionsSize(enc, pic);
free((void*)part0);
@ -289,11 +412,10 @@ int VP8EncWrite(VP8Encoder* const enc) {
// Padding byte
if (ok && pad) {
const uint8_t pad_byte[1] = { 0 };
ok = pic->writer(pad_byte, 1, pic);
ok = PutPaddingByte(pic);
}
enc->coded_size_ = (int)coded_size + KRIFF_SIZE;
enc->coded_size_ = (int)(CHUNK_HEADER_SIZE + riff_size);
return ok;
}

3
src/enc/vp8enci.h
View File

@ -333,7 +333,7 @@ struct VP8Encoder {
// transparency blob
int has_alpha_;
uint8_t* alpha_data_; // non-NULL if transparency is present
size_t alpha_data_size_;
uint32_t alpha_data_size_;
// enhancement layer
int use_layer_;
@ -436,7 +436,6 @@ int VP8Decimate(VP8EncIterator* const it, VP8ModeScore* const rd, int rd_opt);
// in alpha.c
void VP8EncInitAlpha(VP8Encoder* enc); // initialize alpha compression
void VP8EncCodeAlphaBlock(VP8EncIterator* it); // analyze or code a macroblock
int VP8EncFinishAlpha(VP8Encoder* enc); // finalize compressed data
void VP8EncDeleteAlpha(VP8Encoder* enc); // delete compressed data

6
src/enc/webpenc.c
View File

@ -250,8 +250,8 @@ static VP8Encoder* InitEncoder(const WebPConfig* const config,
ResetFilterHeader(enc);
ResetBoundaryPredictions(enc);
#ifdef WEBP_EXPERIMENTAL_FEATURES
VP8EncInitAlpha(enc);
#ifdef WEBP_EXPERIMENTAL_FEATURES
VP8EncInitLayer(enc);
#endif
@ -260,8 +260,8 @@ static VP8Encoder* InitEncoder(const WebPConfig* const config,
static void DeleteEncoder(VP8Encoder* enc) {
if (enc) {
#ifdef WEBP_EXPERIMENTAL_FEATURES
VP8EncDeleteAlpha(enc);
#ifdef WEBP_EXPERIMENTAL_FEATURES
VP8EncDeleteLayer(enc);
#endif
free(enc);
@ -335,8 +335,8 @@ int WebPEncode(const WebPConfig* const config, WebPPicture* const pic) {
ok = VP8EncAnalyze(enc)
&& VP8StatLoop(enc)
&& VP8EncLoop(enc)
#ifdef WEBP_EXPERIMENTAL_FEATURES
&& VP8EncFinishAlpha(enc)
#ifdef WEBP_EXPERIMENTAL_FEATURES
&& VP8EncFinishLayer(enc)
#endif
&& VP8EncWrite(enc);

6
src/webp/encode.h
View File

@ -71,7 +71,11 @@ typedef struct {
// Default is set to 0 for easier progressive decoding.
int partition_limit; // quality degradation allowed to fit the 512k limit on
// prediction modes coding (0=no degradation, 100=full)
int alpha_compression; // Algorithm for optimizing the alpha plane (0 = none)
int alpha_compression; // Algorithm for encoding the alpha plane (0 = none,
// 1 = Backward reference counts encoded with
// Arithmetic encoder). Default is 1.
int alpha_quality; // Between 0 (smallest size) and 100 (lossless).
// Default is 100.
} WebPConfig;
// Enumerate some predefined settings for WebPConfig, depending on the type