Add JPEG parser for JPEG decode acceleration

content/common/gpu/media/vaapi_jpeg_parser.h

+// Copyright 2014 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.
+//
+#ifndef CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_PARSER_H_
+#define CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_PARSER_H_
+
+#include "base/big_endian.h"
+#include "base/macros.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+static const int kJpegHuffmanTableNum_baseline = 2;
+static const int kJpegComponentNum = 4;
+static const int kJpegQuantizationTableNum = 4;
+
+enum JpegMarker {
+  SOF0 = 0xC0,     // start of image (baseline)

[wuchengli, 2014/12/17 09:03:02]

s/image/frame/

[kcwu, 2014/12/24 11:32:37]

Done.

+  DHT = 0xC4,      // define huffman table
+  SOI = 0xD8,      // start of image
+  SOS = 0xDA,      // start of scan
+  DQT = 0xDB,      // define quantization table
+  DRI = 0xDD,      // define restart internal
+  MARKER1 = 0xFF,  // jpeg marker prefix
+};
+
+// 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];  // only support 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 JPEG SOS marker
+struct JpegScan {
+  uint8_t num_component;
+  struct Component {
+    uint8_t component_selector;
+    uint8_t dc_selector;
+    uint8_t ac_selector;
+  } components[kJpegComponentNum];
+  const char* data;
+  size_t data_size;
+};
+
+struct JpegParseResult {
+  uint16_t visible_width;
+  uint16_t visible_height;
+  uint8_t num_component;
+  JpegComponent components[kJpegComponentNum];
+  JpegHuffmanTable dc_table[kJpegHuffmanTableNum_baseline];
+  JpegHuffmanTable ac_table[kJpegHuffmanTableNum_baseline];
+  JpegQuantizationTable q_table[kJpegQuantizationTableNum];
+  uint16_t restart_interval;
+  JpegScan scan;
+};
+
+// VaapiJpegParser parses JPEG header. It's not a full feature JPEG parser
+// implememtation. It only parses subset of JPEG baseline mode needed by
+// VAAPI JPEG decoder. For explanations of each struct and its members,
+// see JPEG specification at http://www.w3.org/Graphics/JPEG/itu-t81.pdf.
+class CONTENT_EXPORT VaapiJpegParser {
+ public:
+  // JPEG buffer and its size. The parser doesn't own the memory.
+  VaapiJpegParser(const uint8_t* buffer, size_t length);
+  ~VaapiJpegParser();
+
+  // Parse JPEG header. Returns the parsed result iff header is valid and
+  // supported by VAAPI. Otherwise returns NULL. The parser still owns
+  // the returned result memory.
+  const JpegParseResult* Parse();
+
+ private:
+  bool ParseSOF(base::BigEndianReader reader);
+  bool ParseDQT(base::BigEndianReader reader);
+  bool ParseDHT(base::BigEndianReader reader);
+  bool ParseDRI(base::BigEndianReader reader);
+  bool ParseSOS(base::BigEndianReader reader);
+  bool ParseSOI(base::BigEndianReader reader);
+
+  // JPEG buffer. It is still owned by caller.

[wuchengli, 2014/12/17 09:03:02]

It's not obviously who the caller is here. Maybe change to "The parser doesn't
own the memory."

[kcwu, 2014/12/24 11:32:37]

Done.

+  const uint8_t* buffer_;
+  // Length of data in buffer
+  size_t length_;
+
+  // Parsed result
+  JpegParseResult result_;
+
+  DISALLOW_COPY_AND_ASSIGN(VaapiJpegParser);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_PARSER_H_