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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <stdint.h>
#include "media/base/media_export.h"
namespace media {
// It's not a full featured JPEG parser implememtation. It only parses JPEG
// baseline sequential process. For explanations of each struct and its
// members, see JPEG specification at
enum JpegMarker {
JPEG_SOF0 = 0xC0, // start of frame (baseline)
JPEG_SOF1 = 0xC1, // start of frame (extended sequential)
JPEG_SOF2 = 0xC2, // start of frame (progressive)
JPEG_SOF3 = 0xC3, // start of frame (lossless))
JPEG_DHT = 0xC4, // define huffman table
JPEG_SOF5 = 0xC5, // start of frame (differential, sequential)
JPEG_SOF6 = 0xC6, // start of frame (differential, progressive)
JPEG_SOF7 = 0xC7, // start of frame (differential, lossless)
JPEG_SOF9 = 0xC9, // start of frame (arithmetic coding, extended)
JPEG_SOF10 = 0xCA, // start of frame (arithmetic coding, progressive)
JPEG_SOF11 = 0xCB, // start of frame (arithmetic coding, lossless)
JPEG_SOF13 = 0xCD, // start of frame (differential, arithmetic, sequential)
JPEG_SOF14 = 0xCE, // start of frame (differential, arithmetic, progressive)
JPEG_SOF15 = 0xCF, // start of frame (differential, arithmetic, lossless)
JPEG_RST0 = 0xD0, // restart
JPEG_RST1 = 0xD1, // restart
JPEG_RST2 = 0xD2, // restart
JPEG_RST3 = 0xD3, // restart
JPEG_RST4 = 0xD4, // restart
JPEG_RST5 = 0xD5, // restart
JPEG_RST6 = 0xD6, // restart
JPEG_RST7 = 0xD7, // restart
JPEG_SOI = 0xD8, // start of image
JPEG_EOI = 0xD9, // end of image
JPEG_SOS = 0xDA, // start of scan
JPEG_DQT = 0xDB, // define quantization table
JPEG_DRI = 0xDD, // define restart internal
JPEG_MARKER_PREFIX = 0xFF, // jpeg marker prefix
const size_t kJpegMaxHuffmanTableNumBaseline = 2;
const size_t kJpegMaxComponents = 4;
const size_t kJpegMaxQuantizationTableNum = 4;
// Parsing result of JPEG DHT marker.
struct JpegHuffmanTable {
bool valid;
uint8_t code_length[16];
uint8_t code_value[256];
// Parsing result of JPEG DQT marker.
struct JpegQuantizationTable {
bool valid;
uint8_t value[64]; // baseline only supports 8 bits quantization table
// Parsing result of a JPEG component.
struct JpegComponent {
uint8_t id;
uint8_t horizontal_sampling_factor;
uint8_t vertical_sampling_factor;
uint8_t quantization_table_selector;
// Parsing result of a JPEG SOF marker.
struct JpegFrameHeader {
uint16_t visible_width;
uint16_t visible_height;
uint16_t coded_width;
uint16_t coded_height;
uint8_t num_components;
JpegComponent components[kJpegMaxComponents];
// Parsing result of JPEG SOS marker.
struct JpegScanHeader {
uint8_t num_components;
struct Component {
uint8_t component_selector;
uint8_t dc_selector;
uint8_t ac_selector;
} components[kJpegMaxComponents];
struct JpegParseResult {
JpegFrameHeader frame_header;
JpegHuffmanTable dc_table[kJpegMaxHuffmanTableNumBaseline];
JpegHuffmanTable ac_table[kJpegMaxHuffmanTableNumBaseline];
JpegQuantizationTable q_table[kJpegMaxQuantizationTableNum];
uint16_t restart_interval;
JpegScanHeader scan;
const char* data;
// The size of compressed data of the first image.
size_t data_size;
// The size of the first entire image including header.
size_t image_size;
// Parses JPEG picture in |buffer| with |length|. Returns true iff header is
// valid and JPEG baseline sequential process is present. If parsed
// successfully, |result| is the parsed result.
MEDIA_EXPORT bool ParseJpegPicture(const uint8_t* buffer,
size_t length,
JpegParseResult* result);
// Parses the first image of JPEG stream in |buffer| with |length|. Returns
// true iff header is valid and JPEG baseline sequential process is present.
// If parsed successfully, |result| is the parsed result.
MEDIA_EXPORT bool ParseJpegStream(const uint8_t* buffer,
size_t length,
JpegParseResult* result);
} // namespace media