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Intertwined decoding of alpha and RGB

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This will reduce the time to first decoded pixel.

Change-Id: I07b900c0ed4af3aac806b2731e11cd18ec16d016
This commit is contained in:
Urvang Joshi
2013-06-11 16:04:54 -07:00
parent 3fa595a571
commit 068db59e26
11 changed files with 250 additions and 88 deletions
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73
src/dec/vp8l.c
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@ -14,6 +14,7 @@
#include <stdio.h>
#include <stdlib.h>
#include "./alphai.h"
#include "./vp8li.h"
#include "../dsp/lossless.h"
#include "../dsp/yuv.h"
@ -1125,52 +1126,72 @@ static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) {
dec->last_row_ = dec->last_out_row_ = row;
}
int VP8LDecodeAlphaImageStream(int width, int height, const uint8_t* const data,
size_t data_size, uint8_t* const output) {
VP8Io io;
int ok = 0;
VP8LDecoder* const dec = VP8LNew();
size_t bytes_per_pixel = sizeof(uint32_t); // Default: BGRA mode.
if (dec == NULL) return 0;
int VP8LDecodeAlphaHeader(ALPHDecoder* const alph_dec,
const uint8_t* const data, size_t data_size,
uint8_t* const output) {
VP8LDecoder* dec;
VP8Io* io;
assert(alph_dec != NULL);
alph_dec->vp8l_dec_ = VP8LNew();
if (alph_dec->vp8l_dec_ == NULL) return 0;
dec = alph_dec->vp8l_dec_;
dec->width_ = width;
dec->height_ = height;
dec->io_ = &io;
alph_dec->bytes_per_pixel_ = sizeof(uint32_t); // Default: BGRA mode.
VP8InitIo(&io);
WebPInitCustomIo(NULL, &io); // Just a sanity Init. io won't be used.
io.opaque = output;
io.width = width;
io.height = height;
dec->width_ = alph_dec->width_;
dec->height_ = alph_dec->height_;
dec->io_ = &alph_dec->io_;
io = dec->io_;
VP8InitIo(io);
WebPInitCustomIo(NULL, io); // Just a sanity Init. io won't be used.
io->opaque = output;
io->width = alph_dec->width_;
io->height = alph_dec->height_;
dec->status_ = VP8_STATUS_OK;
VP8LInitBitReader(&dec->br_, data, data_size);
dec->action_ = READ_HDR;
if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Err;
if (!DecodeImageStream(alph_dec->width_, alph_dec->height_, 1, dec, NULL)) {
goto Err;
}
// Special case: if alpha data contains only the color indexing transform
// (a frequent case), we will use DecodeAlphaData() method that only needs
// allocation of 1 byte per pixel (alpha channel).
if (dec->next_transform_ == 1 &&
dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM) {
bytes_per_pixel = sizeof(uint8_t);
alph_dec->bytes_per_pixel_ = sizeof(uint8_t);
}
// Allocate internal buffers (note that dec->width_ may have changed here).
if (!AllocateInternalBuffers(dec, width, bytes_per_pixel)) goto Err;
if (!AllocateInternalBuffers(dec, alph_dec->width_,
alph_dec->bytes_per_pixel_)) {
goto Err;
}
// Decode (with special row processing).
dec->action_ = READ_DATA;
ok = (bytes_per_pixel == sizeof(uint8_t)) ?
DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_,
dec->height_, ExtractPalettedAlphaRows) :
DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
dec->height_, ExtractAlphaRows);
return 1;
Err:
VP8LDelete(dec);
return ok;
VP8LDelete(alph_dec->vp8l_dec_);
alph_dec->vp8l_dec_ = NULL;
return 0;
}
int VP8LDecodeAlphaImageStream(ALPHDecoder* const alph_dec, int last_row) {
VP8LDecoder* const dec = alph_dec->vp8l_dec_;
assert(dec != NULL);
assert(dec->action_ == READ_DATA);
assert(last_row <= dec->height_);
// Decode (with special row processing).
return (alph_dec->bytes_per_pixel_ == sizeof(uint8_t)) ?
DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_,
last_row, ExtractPalettedAlphaRows) :
DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, last_row,
ExtractAlphaRows);
}
//------------------------------------------------------------------------------