Hendrik Dahlkamp | 33cfdeb | 2013-01-23 18:27:37 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2012 The LibYuv Project Authors. All rights reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | #ifndef INCLUDE_LIBYUV_MJPEG_DECODER_H_ // NOLINT |
| 12 | #define INCLUDE_LIBYUV_MJPEG_DECODER_H_ |
| 13 | |
| 14 | #include "libyuv/basic_types.h" |
| 15 | |
| 16 | // NOTE: For a simplified public API use convert.h MJPGToI420(). |
| 17 | |
| 18 | struct jpeg_common_struct; |
| 19 | struct jpeg_decompress_struct; |
| 20 | struct jpeg_source_mgr; |
| 21 | |
| 22 | namespace libyuv { |
| 23 | |
| 24 | static const uint32 kUnknownDataSize = 0xFFFFFFFF; |
| 25 | |
| 26 | enum JpegSubsamplingType { |
| 27 | kJpegYuv420, |
| 28 | kJpegYuv422, |
| 29 | kJpegYuv411, |
| 30 | kJpegYuv444, |
| 31 | kJpegYuv400, |
| 32 | kJpegUnknown |
| 33 | }; |
| 34 | |
| 35 | struct SetJmpErrorMgr; |
| 36 | |
| 37 | // MJPEG ("Motion JPEG") is a pseudo-standard video codec where the frames are |
| 38 | // simply independent JPEG images with a fixed huffman table (which is omitted). |
| 39 | // It is rarely used in video transmission, but is common as a camera capture |
| 40 | // format, especially in Logitech devices. This class implements a decoder for |
| 41 | // MJPEG frames. |
| 42 | // |
| 43 | // See http://tools.ietf.org/html/rfc2435 |
| 44 | class MJpegDecoder { |
| 45 | public: |
| 46 | typedef void (*CallbackFunction)(void* opaque, |
| 47 | const uint8* const* data, |
| 48 | const int* strides, |
| 49 | int rows); |
| 50 | |
| 51 | static const int kColorSpaceUnknown; |
| 52 | static const int kColorSpaceGrayscale; |
| 53 | static const int kColorSpaceRgb; |
| 54 | static const int kColorSpaceYCbCr; |
| 55 | static const int kColorSpaceCMYK; |
| 56 | static const int kColorSpaceYCCK; |
| 57 | |
| 58 | MJpegDecoder(); |
| 59 | ~MJpegDecoder(); |
| 60 | |
| 61 | // Loads a new frame, reads its headers, and determines the uncompressed |
| 62 | // image format. Returns true if image looks valid and format is supported. |
| 63 | // If return value is true, then the values for all the following getters |
| 64 | // are populated. |
| 65 | // src_len is the size of the compressed mjpeg frame in bytes. |
| 66 | bool LoadFrame(const uint8* src, size_t src_len); |
| 67 | |
| 68 | // Returns width of the last loaded frame in pixels. |
| 69 | int GetWidth(); |
| 70 | |
| 71 | // Returns height of the last loaded frame in pixels. |
| 72 | int GetHeight(); |
| 73 | |
| 74 | // Returns format of the last loaded frame. The return value is one of the |
| 75 | // kColorSpace* constants. |
| 76 | int GetColorSpace(); |
| 77 | |
| 78 | // Number of color components in the color space. |
| 79 | int GetNumComponents(); |
| 80 | |
| 81 | // Sample factors of the n-th component. |
| 82 | int GetHorizSampFactor(int component); |
| 83 | |
| 84 | int GetVertSampFactor(int component); |
| 85 | |
| 86 | int GetHorizSubSampFactor(int component); |
| 87 | |
| 88 | int GetVertSubSampFactor(int component); |
| 89 | |
| 90 | // Public for testability. |
| 91 | int GetImageScanlinesPerImcuRow(); |
| 92 | |
| 93 | // Public for testability. |
| 94 | int GetComponentScanlinesPerImcuRow(int component); |
| 95 | |
| 96 | // Width of a component in bytes. |
| 97 | int GetComponentWidth(int component); |
| 98 | |
| 99 | // Height of a component. |
| 100 | int GetComponentHeight(int component); |
| 101 | |
| 102 | // Width of a component in bytes with padding for DCTSIZE. Public for testing. |
| 103 | int GetComponentStride(int component); |
| 104 | |
| 105 | // Size of a component in bytes. |
| 106 | int GetComponentSize(int component); |
| 107 | |
| 108 | // Call this after LoadFrame() if you decide you don't want to decode it |
| 109 | // after all. |
| 110 | bool UnloadFrame(); |
| 111 | |
| 112 | // Decodes the entire image into a one-buffer-per-color-component format. |
| 113 | // dst_width must match exactly. dst_height must be <= to image height; if |
| 114 | // less, the image is cropped. "planes" must have size equal to at least |
| 115 | // GetNumComponents() and they must point to non-overlapping buffers of size |
| 116 | // at least GetComponentSize(i). The pointers in planes are incremented |
| 117 | // to point to after the end of the written data. |
| 118 | // TODO(fbarchard): Add dst_x, dst_y to allow specific rect to be decoded. |
| 119 | bool DecodeToBuffers(uint8** planes, int dst_width, int dst_height); |
| 120 | |
| 121 | // Decodes the entire image and passes the data via repeated calls to a |
| 122 | // callback function. Each call will get the data for a whole number of |
| 123 | // image scanlines. |
| 124 | // TODO(fbarchard): Add dst_x, dst_y to allow specific rect to be decoded. |
| 125 | bool DecodeToCallback(CallbackFunction fn, void* opaque, |
| 126 | int dst_width, int dst_height); |
| 127 | |
| 128 | // The helper function which recognizes the jpeg sub-sampling type. |
| 129 | static JpegSubsamplingType JpegSubsamplingTypeHelper( |
| 130 | int* subsample_x, int* subsample_y, int number_of_components); |
| 131 | |
| 132 | private: |
| 133 | struct Buffer { |
| 134 | const uint8* data; |
| 135 | int len; |
| 136 | }; |
| 137 | |
| 138 | struct BufferVector { |
| 139 | Buffer* buffers; |
| 140 | int len; |
| 141 | int pos; |
| 142 | }; |
| 143 | |
| 144 | // Methods that are passed to jpeglib. |
| 145 | static int fill_input_buffer(jpeg_decompress_struct* cinfo); |
| 146 | static void init_source(jpeg_decompress_struct* cinfo); |
| 147 | static void skip_input_data(jpeg_decompress_struct* cinfo, |
| 148 | long num_bytes); // NOLINT |
| 149 | static void term_source(jpeg_decompress_struct* cinfo); |
| 150 | |
| 151 | static void ErrorHandler(jpeg_common_struct* cinfo); |
| 152 | |
| 153 | void AllocOutputBuffers(int num_outbufs); |
| 154 | void DestroyOutputBuffers(); |
| 155 | |
| 156 | bool StartDecode(); |
| 157 | bool FinishDecode(); |
| 158 | |
| 159 | void SetScanlinePointers(uint8** data); |
| 160 | bool DecodeImcuRow(); |
| 161 | |
| 162 | int GetComponentScanlinePadding(int component); |
| 163 | |
| 164 | // A buffer holding the input data for a frame. |
| 165 | Buffer buf_; |
| 166 | BufferVector buf_vec_; |
| 167 | |
| 168 | jpeg_decompress_struct* decompress_struct_; |
| 169 | jpeg_source_mgr* source_mgr_; |
| 170 | SetJmpErrorMgr* error_mgr_; |
| 171 | |
| 172 | // true iff at least one component has scanline padding. (i.e., |
| 173 | // GetComponentScanlinePadding() != 0.) |
| 174 | bool has_scanline_padding_; |
| 175 | |
| 176 | // Temporaries used to point to scanline outputs. |
| 177 | int num_outbufs_; // Outermost size of all arrays below. |
| 178 | uint8*** scanlines_; |
| 179 | int* scanlines_sizes_; |
| 180 | // Temporary buffer used for decoding when we can't decode directly to the |
| 181 | // output buffers. Large enough for just one iMCU row. |
| 182 | uint8** databuf_; |
| 183 | int* databuf_strides_; |
| 184 | }; |
| 185 | |
| 186 | } // namespace libyuv |
| 187 | |
| 188 | #endif // INCLUDE_LIBYUV_MJPEG_DECODER_H_ NOLINT |