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webp_quality: detect lossless format and features

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lossless bitstream are returned as quality 101

Change-Id: I8b28287169b710ecf8d4d694abbf0cedc6447908
This commit is contained in:
Pascal Massimino 2016-07-22 00:02:17 -07:00
parent ebee57f4d1
commit eb98d8d87c
3 changed files with 13 additions and 3 deletions
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4
extras/extras.h
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@ -46,7 +46,9 @@ WEBP_EXTERN(int) WebPImportRGB4444(const uint8_t* rgb4444, WebPPicture* pic);
// Parse a bitstream, search for VP8 (lossy) header and report a
// rough estimation of the quality factor used for compressing the bitstream.
// Any error (invalid bitstream, lossless compression, incomplete header, etc.)
// If the bitstream is in lossless format, the special value '101' is returned.
// Otherwise (lossy bitstream), the returned value is in the range [0..100].
// Any error (invalid bitstream, animated WebP, incomplete header, etc.)
// will return a value of -1.
WEBP_EXTERN(int) VP8EstimateQuality(const uint8_t* const data, size_t size);

8
extras/quality_estimate.c
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@ -12,6 +12,7 @@
// Author: Skal (pascal.massimino@gmail.com)
#include "./extras.h"
#include "webp/decode.h"
#include <math.h>
@ -46,9 +47,16 @@ int VP8EstimateQuality(const uint8_t* const data, size_t size) {
uint64_t sig = 0x00;
int ok = 0;
int Q = -1;
WebPBitstreamFeatures features;
if (data == NULL) return -1;
if (WebPGetFeatures(data, size, &features) != VP8_STATUS_OK) {
return -1; // invalid file
}
if (features.format == 2) return 101; // lossless
if (features.format == 0 || features.has_animation) return -1; // mixed
while (pos < size) {
sig = (sig >> 8) | ((uint64_t)data[pos++] << 40);
if ((sig >> 24) == 0x2a019dull) {

4
makefile.unix
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@ -389,13 +389,13 @@ examples/webpmux: src/mux/libwebpmux.a src/libwebpdecoder.a
extras/get_disto: extras/get_disto.o
extras/get_disto: imageio/libimagedec.a
extras/get_disto: imageio/libimageio_util.a
extras/get_disto: src/libwebp.a $(EXTRA_LIB)
extras/get_disto: $(EXTRA_LIB) src/libwebp.a
extras/get_disto: EXTRA_LIBS += $(CWEBP_LIBS)
extras/webp_quality: extras/webp_quality.o
extras/webp_quality: imageio/libimagedec.a
extras/webp_quality: imageio/libimageio_util.a
extras/webp_quality: src/libwebp.a $(EXTRA_LIB)
extras/webp_quality: $(EXTRA_LIB) src/libwebp.a
extras/get_disto: EXTRA_LIBS += $(CWEBP_LIBS)
$(OUT_EXAMPLES) $(EXTRA_EXAMPLES) $(OTHER_EXAMPLES):