196 lines
5.8 KiB
C++
196 lines
5.8 KiB
C++
/*
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* Copyright 2012 The LibYuv Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef INCLUDE_LIBYUV_MJPEG_DECODER_H_
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#define INCLUDE_LIBYUV_MJPEG_DECODER_H_
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#include "libyuv/basic_types.h"
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#ifdef __cplusplus
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// NOTE: For a simplified public API use convert.h MJPGToI420().
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struct jpeg_common_struct;
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struct jpeg_decompress_struct;
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struct jpeg_source_mgr;
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namespace libyuv {
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#ifdef __cplusplus
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extern "C" {
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#endif
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LIBYUV_BOOL ValidateJpeg(const uint8* sample, size_t sample_size);
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#ifdef __cplusplus
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} // extern "C"
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#endif
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static const uint32 kUnknownDataSize = 0xFFFFFFFF;
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enum JpegSubsamplingType {
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kJpegYuv420,
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kJpegYuv422,
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kJpegYuv444,
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kJpegYuv400,
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kJpegUnknown
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};
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struct Buffer {
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const uint8* data;
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int len;
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};
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struct BufferVector {
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Buffer* buffers;
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int len;
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int pos;
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};
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struct SetJmpErrorMgr;
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// MJPEG ("Motion JPEG") is a pseudo-standard video codec where the frames are
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// simply independent JPEG images with a fixed huffman table (which is omitted).
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// It is rarely used in video transmission, but is common as a camera capture
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// format, especially in Logitech devices. This class implements a decoder for
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// MJPEG frames.
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//
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// See http://tools.ietf.org/html/rfc2435
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class LIBYUV_API MJpegDecoder {
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public:
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typedef void (*CallbackFunction)(void* opaque,
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const uint8* const* data,
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const int* strides,
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int rows);
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static const int kColorSpaceUnknown;
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static const int kColorSpaceGrayscale;
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static const int kColorSpaceRgb;
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static const int kColorSpaceYCbCr;
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static const int kColorSpaceCMYK;
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static const int kColorSpaceYCCK;
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MJpegDecoder();
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~MJpegDecoder();
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// Loads a new frame, reads its headers, and determines the uncompressed
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// image format.
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// Returns LIBYUV_TRUE if image looks valid and format is supported.
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// If return value is LIBYUV_TRUE, then the values for all the following
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// getters are populated.
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// src_len is the size of the compressed mjpeg frame in bytes.
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LIBYUV_BOOL LoadFrame(const uint8* src, size_t src_len);
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// Returns width of the last loaded frame in pixels.
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int GetWidth();
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// Returns height of the last loaded frame in pixels.
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int GetHeight();
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// Returns format of the last loaded frame. The return value is one of the
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// kColorSpace* constants.
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int GetColorSpace();
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// Number of color components in the color space.
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int GetNumComponents();
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// Sample factors of the n-th component.
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int GetHorizSampFactor(int component);
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int GetVertSampFactor(int component);
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int GetHorizSubSampFactor(int component);
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int GetVertSubSampFactor(int component);
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// Public for testability.
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int GetImageScanlinesPerImcuRow();
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// Public for testability.
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int GetComponentScanlinesPerImcuRow(int component);
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// Width of a component in bytes.
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int GetComponentWidth(int component);
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// Height of a component.
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int GetComponentHeight(int component);
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// Width of a component in bytes with padding for DCTSIZE. Public for testing.
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int GetComponentStride(int component);
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// Size of a component in bytes.
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int GetComponentSize(int component);
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// Call this after LoadFrame() if you decide you don't want to decode it
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// after all.
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LIBYUV_BOOL UnloadFrame();
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// Decodes the entire image into a one-buffer-per-color-component format.
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// dst_width must match exactly. dst_height must be <= to image height; if
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// less, the image is cropped. "planes" must have size equal to at least
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// GetNumComponents() and they must point to non-overlapping buffers of size
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// at least GetComponentSize(i). The pointers in planes are incremented
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// to point to after the end of the written data.
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// TODO(fbarchard): Add dst_x, dst_y to allow specific rect to be decoded.
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LIBYUV_BOOL DecodeToBuffers(uint8** planes, int dst_width, int dst_height);
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// Decodes the entire image and passes the data via repeated calls to a
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// callback function. Each call will get the data for a whole number of
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// image scanlines.
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// TODO(fbarchard): Add dst_x, dst_y to allow specific rect to be decoded.
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LIBYUV_BOOL DecodeToCallback(CallbackFunction fn,
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void* opaque,
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int dst_width,
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int dst_height);
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// The helper function which recognizes the jpeg sub-sampling type.
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static JpegSubsamplingType JpegSubsamplingTypeHelper(
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int* subsample_x,
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int* subsample_y,
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int number_of_components);
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private:
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void AllocOutputBuffers(int num_outbufs);
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void DestroyOutputBuffers();
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LIBYUV_BOOL StartDecode();
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LIBYUV_BOOL FinishDecode();
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void SetScanlinePointers(uint8** data);
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LIBYUV_BOOL DecodeImcuRow();
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int GetComponentScanlinePadding(int component);
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// A buffer holding the input data for a frame.
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Buffer buf_;
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BufferVector buf_vec_;
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jpeg_decompress_struct* decompress_struct_;
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jpeg_source_mgr* source_mgr_;
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SetJmpErrorMgr* error_mgr_;
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// LIBYUV_TRUE iff at least one component has scanline padding. (i.e.,
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// GetComponentScanlinePadding() != 0.)
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LIBYUV_BOOL has_scanline_padding_;
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// Temporaries used to point to scanline outputs.
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int num_outbufs_; // Outermost size of all arrays below.
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uint8*** scanlines_;
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int* scanlines_sizes_;
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// Temporary buffer used for decoding when we can't decode directly to the
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// output buffers. Large enough for just one iMCU row.
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uint8** databuf_;
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int* databuf_strides_;
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};
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} // namespace libyuv
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#endif // __cplusplus
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#endif // INCLUDE_LIBYUV_MJPEG_DECODER_H_
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