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