1 // Copyright 2011 Google Inc. 2 // 3 // This code is licensed under the same terms as WebM: 4 // Software License Agreement: http://www.webmproject.org/license/software/ 5 // Additional IP Rights Grant: http://www.webmproject.org/license/additional/ 6 // ----------------------------------------------------------------------------- 7 // 8 // Internal header: WebP decoding parameters and custom IO on buffer 9 // 10 // Author: somnath (at) google.com (Somnath Banerjee) 11 12 #ifndef WEBP_DEC_WEBPI_H 13 #define WEBP_DEC_WEBPI_H 14 15 #if defined(__cplusplus) || defined(c_plusplus) 16 extern "C" { 17 #endif 18 19 #include "webp/decode_vp8.h" 20 21 //------------------------------------------------------------------------------ 22 // WebPDecParams: Decoding output parameters. Transcient internal object. 23 24 typedef struct WebPDecParams WebPDecParams; 25 typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p); 26 27 // Structure use for on-the-fly rescaling 28 typedef struct { 29 int x_expand; // true if we're expanding in the x direction 30 int fy_scale, fx_scale; // fixed-point scaling factor 31 int64_t fxy_scale; // '' 32 // we need hpel-precise add/sub increments, for the downsampled U/V planes. 33 int y_accum; // vertical accumulator 34 int y_add, y_sub; // vertical increments (add ~= src, sub ~= dst) 35 int x_add, x_sub; // horizontal increments (add ~= src, sub ~= dst) 36 int src_width, src_height; // source dimensions 37 int dst_width, dst_height; // destination dimensions 38 uint8_t* dst; 39 int dst_stride; 40 int32_t* irow, *frow; // work buffer 41 } WebPRescaler; 42 43 struct WebPDecParams { 44 WebPDecBuffer* output; // output buffer. 45 uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler 46 // or used for tmp rescaling 47 48 int last_y; // coordinate of the line that was last output 49 const WebPDecoderOptions* options; // if not NULL, use alt decoding features 50 // rescalers 51 WebPRescaler scaler_y, scaler_u, scaler_v, scaler_a; 52 void* memory; // overall scratch memory for the output work. 53 OutputFunc emit; // output RGB or YUV samples 54 OutputFunc emit_alpha; // output alpha channel 55 }; 56 57 // Should be called first, before any use of the WebPDecParams object. 58 void WebPResetDecParams(WebPDecParams* const params); 59 60 //------------------------------------------------------------------------------ 61 // Upsampler function to overwrite fancy upsampler. 62 63 typedef void (*WebPUpsampleLinePairFunc)( 64 const uint8_t* top_y, const uint8_t* bottom_y, 65 const uint8_t* top_u, const uint8_t* top_v, 66 const uint8_t* cur_u, const uint8_t* cur_v, 67 uint8_t* top_dst, uint8_t* bottom_dst, int len); 68 69 // Upsampler functions to be used to convert YUV to RGB(A) modes 70 extern WebPUpsampleLinePairFunc WebPUpsamplers[MODE_LAST]; 71 extern WebPUpsampleLinePairFunc WebPUpsamplersKeepAlpha[MODE_LAST]; 72 73 // Initializes SSE2 version of the fancy upsamplers. 74 void WebPInitUpsamplersSSE2(void); 75 76 //------------------------------------------------------------------------------ 77 // Misc utils 78 79 // If a RIFF container is detected, validate it and skip over it. Returns 80 // VP8 bit-stream size if RIFF header is valid else returns 0 81 uint32_t WebPCheckRIFFHeader(const uint8_t** data_ptr, 82 uint32_t* data_size_ptr); 83 84 // Initializes VP8Io with custom setup, io and teardown functions. The default 85 // hooks will use the supplied 'params' as io->opaque handle. 86 void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io); 87 88 //------------------------------------------------------------------------------ 89 // Internal functions regarding WebPDecBuffer memory (in buffer.c). 90 // Don't really need to be externally visible for now. 91 92 // Prepare 'buffer' with the requested initial dimensions width/height. 93 // If no external storage is supplied, initializes buffer by allocating output 94 // memory and setting up the stride information. Validate the parameters. Return 95 // an error code in case of problem (no memory, or invalid stride / size / 96 // dimension / etc.). If *options is not NULL, also verify that the options' 97 // parameters are valid and apply them to the width/height dimensions of the 98 // output buffer. This takes cropping / scaling / rotation into account. 99 VP8StatusCode WebPAllocateDecBuffer(int width, int height, 100 const WebPDecoderOptions* const options, 101 WebPDecBuffer* const buffer); 102 103 // Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the 104 // memory (still held by 'src'). 105 void WebPCopyDecBuffer(const WebPDecBuffer* const src, 106 WebPDecBuffer* const dst); 107 108 // Copy and transfer ownership from src to dst (beware of parameter order!) 109 void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst); 110 111 //------------------------------------------------------------------------------ 112 113 #if defined(__cplusplus) || defined(c_plusplus) 114 } // extern "C" 115 #endif 116 117 #endif // WEBP_DEC_WEBPI_H 118
