115 lines
5.0 KiB
C
115 lines
5.0 KiB
C
// Copyright 2011 Google Inc. All Rights Reserved.
|
|
//
|
|
// This code is licensed under the same terms as WebM:
|
|
// Software License Agreement: http://www.webmproject.org/license/software/
|
|
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// Internal header: WebP decoding parameters and custom IO on buffer
|
|
//
|
|
// Author: somnath@google.com (Somnath Banerjee)
|
|
|
|
#ifndef WEBP_DEC_WEBPI_H_
|
|
#define WEBP_DEC_WEBPI_H_
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
extern "C" {
|
|
#endif
|
|
|
|
#include "../utils/rescaler.h"
|
|
#include "./decode_vp8.h"
|
|
|
|
//------------------------------------------------------------------------------
|
|
// WebPDecParams: Decoding output parameters. Transient internal object.
|
|
|
|
typedef struct WebPDecParams WebPDecParams;
|
|
typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p);
|
|
typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos);
|
|
|
|
struct WebPDecParams {
|
|
WebPDecBuffer* output; // output buffer.
|
|
uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler
|
|
// or used for tmp rescaling
|
|
|
|
int last_y; // coordinate of the line that was last output
|
|
const WebPDecoderOptions* options; // if not NULL, use alt decoding features
|
|
// rescalers
|
|
WebPRescaler scaler_y, scaler_u, scaler_v, scaler_a;
|
|
void* memory; // overall scratch memory for the output work.
|
|
|
|
OutputFunc emit; // output RGB or YUV samples
|
|
OutputFunc emit_alpha; // output alpha channel
|
|
OutputRowFunc emit_alpha_row; // output one line of rescaled alpha values
|
|
};
|
|
|
|
// Should be called first, before any use of the WebPDecParams object.
|
|
void WebPResetDecParams(WebPDecParams* const params);
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Header parsing helpers
|
|
|
|
// Structure storing a description of the RIFF headers.
|
|
typedef struct {
|
|
const uint8_t* data; // input buffer
|
|
size_t data_size; // input buffer size
|
|
size_t offset; // offset to main data chunk (VP8 or VP8L)
|
|
const uint8_t* alpha_data; // points to alpha chunk (if present)
|
|
size_t alpha_data_size; // alpha chunk size
|
|
size_t compressed_size; // VP8/VP8L compressed data size
|
|
size_t riff_size; // size of the riff payload (or 0 if absent)
|
|
int is_lossless; // true if a VP8L chunk is present
|
|
} WebPHeaderStructure;
|
|
|
|
// Skips over all valid chunks prior to the first VP8/VP8L frame header.
|
|
// Returns VP8_STATUS_OK on success,
|
|
// VP8_STATUS_BITSTREAM_ERROR if an invalid header/chunk is found, and
|
|
// VP8_STATUS_NOT_ENOUGH_DATA if case of insufficient data.
|
|
// In 'headers', compressed_size, offset, alpha_data, alpha_size and lossless
|
|
// fields are updated appropriately upon success.
|
|
VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers);
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Misc utils
|
|
|
|
// Initializes VP8Io with custom setup, io and teardown functions. The default
|
|
// hooks will use the supplied 'params' as io->opaque handle.
|
|
void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io);
|
|
|
|
// Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers
|
|
// to the *compressed* format, not the output one.
|
|
int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
|
|
VP8Io* const io, WEBP_CSP_MODE src_colorspace);
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Internal functions regarding WebPDecBuffer memory (in buffer.c).
|
|
// Don't really need to be externally visible for now.
|
|
|
|
// Prepare 'buffer' with the requested initial dimensions width/height.
|
|
// If no external storage is supplied, initializes buffer by allocating output
|
|
// memory and setting up the stride information. Validate the parameters. Return
|
|
// an error code in case of problem (no memory, or invalid stride / size /
|
|
// dimension / etc.). If *options is not NULL, also verify that the options'
|
|
// parameters are valid and apply them to the width/height dimensions of the
|
|
// output buffer. This takes cropping / scaling / rotation into account.
|
|
VP8StatusCode WebPAllocateDecBuffer(int width, int height,
|
|
const WebPDecoderOptions* const options,
|
|
WebPDecBuffer* const buffer);
|
|
|
|
// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the
|
|
// memory (still held by 'src').
|
|
void WebPCopyDecBuffer(const WebPDecBuffer* const src,
|
|
WebPDecBuffer* const dst);
|
|
|
|
// Copy and transfer ownership from src to dst (beware of parameter order!)
|
|
void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst);
|
|
|
|
|
|
|
|
//------------------------------------------------------------------------------
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
} // extern "C"
|
|
#endif
|
|
|
|
#endif /* WEBP_DEC_WEBPI_H_ */
|