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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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18
src/dec/idec.c
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@ -15,6 +15,7 @@
#include <string.h>
#include <stdlib.h>
#include "./alphai.h"
#include "./webpi.h"
#include "./vp8i.h"
#include "../utils/utils.h"
@ -143,7 +144,22 @@ static void DoRemap(WebPIDecoder* const idec, ptrdiff_t offset) {
}
assert(last_part >= 0);
dec->parts_[last_part].buf_end_ = mem->buf_ + mem->end_;
if (NeedCompressedAlpha(idec)) dec->alpha_data_ += offset;
if (NeedCompressedAlpha(idec)) {
ALPHDecoder* const alph_dec = dec->alph_dec_;
dec->alpha_data_ += offset;
if (alph_dec != NULL) {
if (alph_dec->method_ == ALPHA_LOSSLESS_COMPRESSION) {
VP8LDecoder* const alph_vp8l_dec = alph_dec->vp8l_dec_;
assert(alph_vp8l_dec != NULL);
assert(dec->alpha_data_size_ >= ALPHA_HEADER_LEN);
VP8LBitReaderSetBuffer(&alph_vp8l_dec->br_,
dec->alpha_data_ + ALPHA_HEADER_LEN,
dec->alpha_data_size_ - ALPHA_HEADER_LEN);
} else { // alph_dec->method_ == ALPHA_NO_COMPRESSION
// Nothing special to do in this case.
}
}
}
} else { // Resize lossless bitreader
VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
VP8LBitReaderSetBuffer(&dec->br_, new_base, MemDataSize(mem));