chromium/media/parsers/jpeg_parser.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_PARSERS_JPEG_PARSER_H_
#define MEDIA_PARSERS_JPEG_PARSER_H_

#include <stddef.h>
#include <stdint.h>

#include "base/containers/span.h"
#include "media/base/media_export.h"

namespace media {

// It's not a full featured JPEG parser implementation. It only parses JPEG
// baseline sequential process (invalid or progressive JPEGs should fail but not
// crash). For explanations of each struct and its members, see JPEG
// specification at http://www.w3.org/Graphics/JPEG/itu-t81.pdf.

enum JpegMarker { … };

// JPEG format uses 2 bytes to denote the size of a segment, and the size
// includes the 2 bytes used for specifying it. Therefore, maximum data size
// allowed is: 65535 - 2 = 65533.
constexpr size_t kMaxMarkerSizeAllowed = …;

// JPEG header only uses 2 bytes to represent width and height.
constexpr int kMaxDimension = …;

constexpr size_t kDctSize = …;
constexpr size_t kNumDcRunSizeBits = …;
constexpr size_t kNumAcRunSizeBits = …;
constexpr size_t kNumDcCodeWordsHuffVal = …;
constexpr size_t kNumAcCodeWordsHuffVal = …;
constexpr size_t kJpegDefaultHeaderSize = …;
constexpr size_t kJFIFApp0Size = …;
constexpr size_t kJFIFApp1HeaderSize = …;

const size_t kJpegMaxHuffmanTableNumBaseline = …;
const size_t kJpegMaxComponents = …;
const size_t kJpegMaxQuantizationTableNum = …;

// Parsing result of JPEG DHT marker.
struct JpegHuffmanTable { … };

// K.3.3.1 "Specification of typical tables for DC difference coding"
MEDIA_EXPORT
extern const JpegHuffmanTable kDefaultDcTable[kJpegMaxHuffmanTableNumBaseline];

// K.3.3.2 "Specification of typical tables for AC coefficient coding"
MEDIA_EXPORT
extern const JpegHuffmanTable kDefaultAcTable[kJpegMaxHuffmanTableNumBaseline];

// Parsing result of JPEG DQT marker.
struct JpegQuantizationTable { … };

MEDIA_EXPORT extern const uint8_t kZigZag8x8[64];

// Table K.1 Luminance quantization table
// Table K.2 Chrominance quantization table
MEDIA_EXPORT
extern const JpegQuantizationTable kDefaultQuantTable[2];

// Parsing result of a JPEG component.
struct JpegComponent { … };

// Parsing result of a JPEG SOF marker.
struct JpegFrameHeader { … };

// Parsing result of JPEG SOS marker.
struct JpegScanHeader { … };

struct JpegParseResult { … };

// 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(base::span<const uint8_t> buffer,
                      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(base::span<const uint8_t> buffer, JpegParseResult* result);

}  // namespace media

#endif  // MEDIA_PARSERS_JPEG_PARSER_H_