// encode image.YCbCr func encodeYCbCr(cinfo *C.struct_jpeg_compress_struct, src *image.YCbCr, p *EncoderOptions) (err error) { // Set up compression parameters cinfo.image_width = C.JDIMENSION(src.Bounds().Dx()) cinfo.image_height = C.JDIMENSION(src.Bounds().Dy()) cinfo.input_components = 3 cinfo.in_color_space = C.JCS_YCbCr C.jpeg_set_defaults(cinfo) setupEncoderOptions(cinfo, p) compInfo := (*[3]C.jpeg_component_info)(unsafe.Pointer(cinfo.comp_info)) colorVDiv := 1 switch src.SubsampleRatio { case image.YCbCrSubsampleRatio444: // 1x1,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 1, 1 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 case image.YCbCrSubsampleRatio440: // 1x2,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 1, 2 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 colorVDiv = 2 case image.YCbCrSubsampleRatio422: // 2x1,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 2, 1 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 case image.YCbCrSubsampleRatio420: // 2x2,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 2, 2 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 colorVDiv = 2 } // libjpeg raw data in is in planar format, which avoids unnecessary // planar->packed->planar conversions. cinfo.raw_data_in = C.TRUE // Start compression C.jpeg_start_compress(cinfo, C.TRUE) C.encode_ycbcr( cinfo, C.JSAMPROW(unsafe.Pointer(&src.Y[0])), C.JSAMPROW(unsafe.Pointer(&src.Cb[0])), C.JSAMPROW(unsafe.Pointer(&src.Cr[0])), C.int(src.YStride), C.int(src.CStride), C.int(colorVDiv), ) C.jpeg_finish_compress(cinfo) return }
// encode image.Gray func encodeGray(cinfo *C.struct_jpeg_compress_struct, src *image.Gray, p *EncoderOptions) (err error) { // Set up compression parameters cinfo.image_width = C.JDIMENSION(src.Bounds().Dx()) cinfo.image_height = C.JDIMENSION(src.Bounds().Dy()) cinfo.input_components = 1 cinfo.in_color_space = C.JCS_GRAYSCALE C.jpeg_set_defaults(cinfo) setupEncoderOptions(cinfo, p) compInfo := (*C.jpeg_component_info)(unsafe.Pointer(cinfo.comp_info)) compInfo.h_samp_factor, compInfo.v_samp_factor = 1, 1 // libjpeg raw data in is in planar format, which avoids unnecessary // planar->packed->planar conversions. cinfo.raw_data_in = C.TRUE // Start compression C.jpeg_start_compress(cinfo, C.TRUE) // Allocate JSAMPIMAGE to hold pointers to one iMCU worth of image data // this is a safe overestimate; we use the return value from // jpeg_read_raw_data to figure out what is the actual iMCU row count. var rowPtr [AlignSize]C.JSAMPROW arrayPtr := [1]C.JSAMPARRAY{ C.JSAMPARRAY(unsafe.Pointer(&rowPtr[0])), } var rows C.JDIMENSION for rows = 0; rows < cinfo.image_height; { // First fill in the pointers into the plane data buffers for j := 0; j < int(C.DCTSIZE*compInfo.v_samp_factor); j++ { rowPtr[j] = C.JSAMPROW(unsafe.Pointer(&src.Pix[src.Stride*(int(rows)+j)])) } // Get the data rows += C.jpeg_write_raw_data(cinfo, C.JSAMPIMAGE(unsafe.Pointer(&arrayPtr[0])), C.JDIMENSION(C.DCTSIZE*compInfo.v_samp_factor)) } C.jpeg_finish_compress(cinfo) return }
// encode image.Gray func encodeGray(cinfo *C.struct_jpeg_compress_struct, src *image.Gray, p *EncoderOptions) (err error) { // Set up compression parameters cinfo.image_width = C.JDIMENSION(src.Bounds().Dx()) cinfo.image_height = C.JDIMENSION(src.Bounds().Dy()) cinfo.input_components = 1 cinfo.in_color_space = C.JCS_GRAYSCALE C.jpeg_set_defaults(cinfo) setupEncoderOptions(cinfo, p) compInfo := (*C.jpeg_component_info)(unsafe.Pointer(cinfo.comp_info)) compInfo.h_samp_factor, compInfo.v_samp_factor = 1, 1 // libjpeg raw data in is in planar format, which avoids unnecessary // planar->packed->planar conversions. cinfo.raw_data_in = C.TRUE // Start compression C.jpeg_start_compress(cinfo, C.TRUE) C.encode_gray(cinfo, C.JSAMPROW(unsafe.Pointer(&src.Pix[0])), C.int(src.Stride)) C.jpeg_finish_compress(cinfo) return }
// encode image.YCbCr func encodeYCbCr(cinfo *C.struct_jpeg_compress_struct, src *image.YCbCr, p *EncoderOptions) (err error) { // Set up compression parameters cinfo.image_width = C.JDIMENSION(src.Bounds().Dx()) cinfo.image_height = C.JDIMENSION(src.Bounds().Dy()) cinfo.input_components = 3 cinfo.in_color_space = C.JCS_YCbCr C.jpeg_set_defaults(cinfo) setupEncoderOptions(cinfo, p) compInfo := (*[3]C.jpeg_component_info)(unsafe.Pointer(cinfo.comp_info)) colorVDiv := 1 switch src.SubsampleRatio { case image.YCbCrSubsampleRatio444: // 1x1,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 1, 1 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 case image.YCbCrSubsampleRatio440: // 1x2,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 1, 2 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 colorVDiv = 2 case image.YCbCrSubsampleRatio422: // 2x1,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 2, 1 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 case image.YCbCrSubsampleRatio420: // 2x2,1x1,1x1 compInfo[Y].h_samp_factor, compInfo[Y].v_samp_factor = 2, 2 compInfo[Cb].h_samp_factor, compInfo[Cb].v_samp_factor = 1, 1 compInfo[Cr].h_samp_factor, compInfo[Cr].v_samp_factor = 1, 1 colorVDiv = 2 } // libjpeg raw data in is in planar format, which avoids unnecessary // planar->packed->planar conversions. cinfo.raw_data_in = C.TRUE // Start compression C.jpeg_start_compress(cinfo, C.TRUE) // Allocate JSAMPIMAGE to hold pointers to one iMCU worth of image data // this is a safe overestimate; we use the return value from // jpeg_read_raw_data to figure out what is the actual iMCU row count. var yRowPtr [AlignSize]C.JSAMPROW var cbRowPtr [AlignSize]C.JSAMPROW var crRowPtr [AlignSize]C.JSAMPROW yCbCrPtr := [3]C.JSAMPARRAY{ C.JSAMPARRAY(unsafe.Pointer(&yRowPtr[0])), C.JSAMPARRAY(unsafe.Pointer(&cbRowPtr[0])), C.JSAMPARRAY(unsafe.Pointer(&crRowPtr[0])), } var rows C.JDIMENSION for rows = 0; rows < cinfo.image_height; { // First fill in the pointers into the plane data buffers for j := 0; j < int(C.DCTSIZE*compInfo[Y].v_samp_factor); j++ { yRowPtr[j] = C.JSAMPROW(unsafe.Pointer(&src.Y[src.YStride*(int(rows)+j)])) } for j := 0; j < int(C.DCTSIZE*compInfo[Cb].v_samp_factor); j++ { cbRowPtr[j] = C.JSAMPROW(unsafe.Pointer(&src.Cb[src.CStride*(int(rows)/colorVDiv+j)])) crRowPtr[j] = C.JSAMPROW(unsafe.Pointer(&src.Cr[src.CStride*(int(rows)/colorVDiv+j)])) } // Get the data rows += C.jpeg_write_raw_data(cinfo, C.JSAMPIMAGE(unsafe.Pointer(&yCbCrPtr[0])), C.JDIMENSION(C.DCTSIZE*compInfo[0].v_samp_factor)) } C.jpeg_finish_compress(cinfo) return }