1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
// Copyright 2011 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.
// -----------------------------------------------------------------------------
//
// Internal header: WebP decoding parameters and custom IO on buffer
//
// Author: somnath@google.com (Somnath Banerjee)
#ifndef WEBP_DEC_WEBPI_DEC_H_
#define WEBP_DEC_WEBPI_DEC_H_
#ifdef __cplusplus
extern "C" {
#endif
#include "../utils/rescaler_utils.h"
#include "../dec/vp8_dec.h"
//------------------------------------------------------------------------------
// WebPDecParams: Decoding output parameters. Transient internal object.
typedef struct WebPDecParams WebPDecParams;
typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p);
typedef int (*OutputAlphaFunc)(const VP8Io* const io, WebPDecParams* const p,
int expected_num_out_lines);
typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos,
int max_out_lines);
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
WebPRescaler* scaler_y, *scaler_u, *scaler_v, *scaler_a; // rescalers
void* memory; // overall scratch memory for the output work.
OutputFunc emit; // output RGB or YUV samples
OutputAlphaFunc 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
int have_all_data; // true if all data is known to be available
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, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk),
// VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE
// in the case of non-decodable features (animation for instance).
// 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.
// Also incorporates the options->flip flag to flip the buffer parameters if
// needed.
VP8StatusCode WebPAllocateDecBuffer(int width, int height,
const WebPDecoderOptions* const options,
WebPDecBuffer* const buffer);
// Flip buffer vertically by negating the various strides.
VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer);
// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the
// memory (still held by 'src'). No pixels are copied.
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);
// Copy pixels from 'src' into a *preallocated* 'dst' buffer. Returns
// VP8_STATUS_INVALID_PARAM if the 'dst' is not set up correctly for the copy.
VP8StatusCode WebPCopyDecBufferPixels(const WebPDecBuffer* const src,
WebPDecBuffer* const dst);
// Returns true if decoding will be slow with the current configuration
// and bitstream features.
int WebPAvoidSlowMemory(const WebPDecBuffer* const output,
const WebPBitstreamFeatures* const features);
//------------------------------------------------------------------------------
#ifdef __cplusplus
} // extern "C"
#endif
#endif // WEBP_DEC_WEBPI_DEC_H_
|
