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further simplification for the meta-Huffman coding

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* don't transmit the number of Huffman tree group explicitly
* move color-cache information before the meta-Huffman block

* also add a check that color_cache_bits is in [1..11] range, as per spec.

Change-Id: I81d7711068653b509cdbc1151d93e229c4254580
This commit is contained in:
Pascal Massimino
2012-04-25 09:40:41 +00:00
committed by James Zern
parent e491729905
commit 8415ddf3be
2 changed files with 58 additions and 72 deletions
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73
src/enc/vp8l.c
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@ -27,18 +27,12 @@
extern "C" {
#endif
static const uint32_t kImageSizeBits = 14;
static const int kImageSizeBits = 14;
static int CompareColors(const void* p1, const void* p2) {
const uint32_t a = *(const uint32_t*)p1;
const uint32_t b = *(const uint32_t*)p2;
if (a < b) {
return -1;
}
if (a == b) {
return 0;
}
return 1;
return (a < b) ? -1 : (a > b) ? 1 : 0;
}
// If number of colors in the image is less than or equal to MAX_PALETTE_SIZE,
@ -511,14 +505,6 @@ static int GetHuffBitLengthsAndCodes(
return 0;
}
static void ShiftHistogramImage(uint32_t* image , int image_size) {
int i;
for (i = 0; i < image_size; ++i) {
image[i] <<= 8;
image[i] |= 0xff000000;
}
}
static void ClearHuffmanTreeIfOnlyOneSymbol(const int num_symbols,
uint8_t* lengths,
uint16_t* symbols) {
@ -758,8 +744,8 @@ static int EncodeImageInternal(VP8LBitWriter* const bw,
VP8LSubSampleSize(height, histogram_bits);
VP8LHistogram** histogram_image;
PixOrCopy* backward_refs;
uint32_t* histogram_symbols = (uint32_t*)
calloc(histogram_image_xysize, sizeof(*histogram_symbols));
const size_t histo_size = histogram_image_xysize * sizeof(uint32_t);
uint32_t* const histogram_symbols = (uint32_t*)calloc(1, histo_size);
if (histogram_symbols == NULL) goto Error;
@ -790,38 +776,37 @@ static int EncodeImageInternal(VP8LBitWriter* const bw,
goto Error;
}
// Huffman image + meta huffman.
write_histogram_image = (histogram_image_size > 1);
VP8LWriteBits(bw, 1, write_histogram_image);
if (write_histogram_image) {
int image_size_bits;
uint32_t* histogram_argb = (uint32_t*)
malloc(histogram_image_xysize * sizeof(*histogram_argb));
if (histogram_argb == NULL) goto Error;
memcpy(histogram_argb, histogram_symbols,
histogram_image_xysize * sizeof(*histogram_argb));
ShiftHistogramImage(histogram_argb, histogram_image_xysize);
VP8LWriteBits(bw, 4, histogram_bits);
if (!EncodeImageInternal(bw, histogram_argb,
VP8LSubSampleSize(width, histogram_bits),
VP8LSubSampleSize(height, histogram_bits),
quality, 0, 0)) {
free(histogram_argb);
goto Error;
}
image_size_bits = VP8LBitsLog2Ceiling(histogram_image_size - 1);
VP8LWriteBits(bw, 4, image_size_bits);
VP8LWriteBits(bw, image_size_bits, histogram_image_size - 2);
free(histogram_argb);
}
// Color Cache parameters.
VP8LWriteBits(bw, 1, use_color_cache);
if (use_color_cache) {
VP8LWriteBits(bw, 4, cache_bits);
}
// Huffman image + meta huffman.
write_histogram_image = (histogram_image_size > 1);
VP8LWriteBits(bw, 1, write_histogram_image);
if (write_histogram_image) {
uint32_t* const histogram_argb = (uint32_t*)malloc(histo_size);
int max_index = 0;
if (histogram_argb == NULL) goto Error;
for (i = 0; i < histogram_image_xysize; ++i) {
const int index = histogram_symbols[i] & 0xffff;
histogram_argb[i] = 0xff000000 | (index << 8);
if (index >= max_index) {
max_index = index + 1;
}
}
histogram_image_size = max_index;
VP8LWriteBits(bw, 4, histogram_bits);
ok = EncodeImageInternal(bw, histogram_argb,
VP8LSubSampleSize(width, histogram_bits),
VP8LSubSampleSize(height, histogram_bits),
quality, 0, 0);
free(histogram_argb);
if (!ok) goto Error;
}
// Store Huffman codes.
for (i = 0; i < histogram_image_size; ++i) {
int k;