diff options
Diffstat (limited to 'media/libwebp/src/dec/vp8_dec.h')
| -rw-r--r-- | media/libwebp/src/dec/vp8_dec.h | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/media/libwebp/src/dec/vp8_dec.h b/media/libwebp/src/dec/vp8_dec.h new file mode 100644 index 0000000000..a05405df72 --- /dev/null +++ b/media/libwebp/src/dec/vp8_dec.h @@ -0,0 +1,185 @@ +// Copyright 2010 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Low-level API for VP8 decoder +// +// Author: Skal (pascal.massimino@gmail.com) + +#ifndef WEBP_DEC_VP8_DEC_H_ +#define WEBP_DEC_VP8_DEC_H_ + +#include "src/webp/decode.h" + +#ifdef __cplusplus +extern "C" { +#endif + +//------------------------------------------------------------------------------ +// Lower-level API +// +// These functions provide fine-grained control of the decoding process. +// The call flow should resemble: +// +// VP8Io io; +// VP8InitIo(&io); +// io.data = data; +// io.data_size = size; +// /* customize io's functions (setup()/put()/teardown()) if needed. */ +// +// VP8Decoder* dec = VP8New(); +// int ok = VP8Decode(dec, &io); +// if (!ok) printf("Error: %s\n", VP8StatusMessage(dec)); +// VP8Delete(dec); +// return ok; + +// Input / Output +typedef struct VP8Io VP8Io; +typedef int (*VP8IoPutHook)(const VP8Io* io); +typedef int (*VP8IoSetupHook)(VP8Io* io); +typedef void (*VP8IoTeardownHook)(const VP8Io* io); + +struct VP8Io { + // set by VP8GetHeaders() + int width, height; // picture dimensions, in pixels (invariable). + // These are the original, uncropped dimensions. + // The actual area passed to put() is stored + // in mb_w / mb_h fields. + + // set before calling put() + int mb_y; // position of the current rows (in pixels) + int mb_w; // number of columns in the sample + int mb_h; // number of rows in the sample + const uint8_t* y, *u, *v; // rows to copy (in yuv420 format) + int y_stride; // row stride for luma + int uv_stride; // row stride for chroma + + void* opaque; // user data + + // called when fresh samples are available. Currently, samples are in + // YUV420 format, and can be up to width x 24 in size (depending on the + // in-loop filtering level, e.g.). Should return false in case of error + // or abort request. The actual size of the area to update is mb_w x mb_h + // in size, taking cropping into account. + VP8IoPutHook put; + + // called just before starting to decode the blocks. + // Must return false in case of setup error, true otherwise. If false is + // returned, teardown() will NOT be called. But if the setup succeeded + // and true is returned, then teardown() will always be called afterward. + VP8IoSetupHook setup; + + // Called just after block decoding is finished (or when an error occurred + // during put()). Is NOT called if setup() failed. + VP8IoTeardownHook teardown; + + // this is a recommendation for the user-side yuv->rgb converter. This flag + // is set when calling setup() hook and can be overwritten by it. It then + // can be taken into consideration during the put() method. + int fancy_upsampling; + + // Input buffer. + size_t data_size; + const uint8_t* data; + + // If true, in-loop filtering will not be performed even if present in the + // bitstream. Switching off filtering may speed up decoding at the expense + // of more visible blocking. Note that output will also be non-compliant + // with the VP8 specifications. + int bypass_filtering; + + // Cropping parameters. + int use_cropping; + int crop_left, crop_right, crop_top, crop_bottom; + + // Scaling parameters. + int use_scaling; + int scaled_width, scaled_height; + + // If non NULL, pointer to the alpha data (if present) corresponding to the + // start of the current row (That is: it is pre-offset by mb_y and takes + // cropping into account). + const uint8_t* a; +}; + +// Internal, version-checked, entry point +int VP8InitIoInternal(VP8Io* const, int); + +// Set the custom IO function pointers and user-data. The setter for IO hooks +// should be called before initiating incremental decoding. Returns true if +// WebPIDecoder object is successfully modified, false otherwise. +int WebPISetIOHooks(WebPIDecoder* const idec, + VP8IoPutHook put, + VP8IoSetupHook setup, + VP8IoTeardownHook teardown, + void* user_data); + +// Main decoding object. This is an opaque structure. +typedef struct VP8Decoder VP8Decoder; + +// Create a new decoder object. +VP8Decoder* VP8New(void); + +// Must be called to make sure 'io' is initialized properly. +// Returns false in case of version mismatch. Upon such failure, no other +// decoding function should be called (VP8Decode, VP8GetHeaders, ...) +static WEBP_INLINE int VP8InitIo(VP8Io* const io) { + return VP8InitIoInternal(io, WEBP_DECODER_ABI_VERSION); +} + +// Decode the VP8 frame header. Returns true if ok. +// Note: 'io->data' must be pointing to the start of the VP8 frame header. +int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io); + +// Decode a picture. Will call VP8GetHeaders() if it wasn't done already. +// Returns false in case of error. +int VP8Decode(VP8Decoder* const dec, VP8Io* const io); + +// Return current status of the decoder: +VP8StatusCode VP8Status(VP8Decoder* const dec); + +// return readable string corresponding to the last status. +const char* VP8StatusMessage(VP8Decoder* const dec); + +// Resets the decoder in its initial state, reclaiming memory. +// Not a mandatory call between calls to VP8Decode(). +void VP8Clear(VP8Decoder* const dec); + +// Destroy the decoder object. +void VP8Delete(VP8Decoder* const dec); + +//------------------------------------------------------------------------------ +// Miscellaneous VP8/VP8L bitstream probing functions. + +// Returns true if the next 3 bytes in data contain the VP8 signature. +WEBP_EXTERN int VP8CheckSignature(const uint8_t* const data, size_t data_size); + +// Validates the VP8 data-header and retrieves basic header information viz +// width and height. Returns 0 in case of formatting error. *width/*height +// can be passed NULL. +WEBP_EXTERN int VP8GetInfo( + const uint8_t* data, + size_t data_size, // data available so far + size_t chunk_size, // total data size expected in the chunk + int* const width, int* const height); + +// Returns true if the next byte(s) in data is a VP8L signature. +WEBP_EXTERN int VP8LCheckSignature(const uint8_t* const data, size_t size); + +// Validates the VP8L data-header and retrieves basic header information viz +// width, height and alpha. Returns 0 in case of formatting error. +// width/height/has_alpha can be passed NULL. +WEBP_EXTERN int VP8LGetInfo( + const uint8_t* data, size_t data_size, // data available so far + int* const width, int* const height, int* const has_alpha); + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif // WEBP_DEC_VP8_DEC_H_ |