Convert .tgs with go libraries (and cgo) (telegram) (#1569)

This commit adds support for go/cgo tgs conversion when building with the -tags `cgo`
The default binaries are still "pure" go and uses the old way of converting.

* Move lottie_convert.py conversion code to its own file

* Add optional libtgsconverter

* Update vendor

* Apply suggestions from code review

* Update bridge/helper/libtgsconverter.go

Co-authored-by: Wim <wim@42.be>

1 files changed, 686 insertions, 0 deletions

diff --git a/vendor/github.com/sizeofint/webpanimation/dsp_dsp.h b/vendor/github.com/sizeofint/webpanimation/dsp_dsp.h
new file mode 100644
index 00000000..33ec5971
--- /dev/null
+++ b/vendor/github.com/sizeofint/webpanimation/dsp_dsp.h
@@ -0,0 +1,686 @@
+// 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.
+// -----------------------------------------------------------------------------
+//
+//   Speed-critical functions.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_DSP_DSP_H_
+#define WEBP_DSP_DSP_H_
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "webp_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define BPS 32   // this is the common stride for enc/dec
+
+//------------------------------------------------------------------------------
+// CPU detection
+
+#if defined(__GNUC__)
+# define LOCAL_GCC_VERSION ((__GNUC__ << 8) | __GNUC_MINOR__)
+# define LOCAL_GCC_PREREQ(maj, min) \
+    (LOCAL_GCC_VERSION >= (((maj) << 8) | (min)))
+#else
+# define LOCAL_GCC_VERSION 0
+# define LOCAL_GCC_PREREQ(maj, min) 0
+#endif
+
+#if defined(__clang__)
+# define LOCAL_CLANG_VERSION ((__clang_major__ << 8) | __clang_minor__)
+# define LOCAL_CLANG_PREREQ(maj, min) \
+    (LOCAL_CLANG_VERSION >= (((maj) << 8) | (min)))
+#else
+# define LOCAL_CLANG_VERSION 0
+# define LOCAL_CLANG_PREREQ(maj, min) 0
+#endif
+
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
+#if !defined(HAVE_CONFIG_H)
+#if defined(_MSC_VER) && _MSC_VER > 1310 && \
+    (defined(_M_X64) || defined(_M_IX86))
+#define WEBP_MSC_SSE2  // Visual C++ SSE2 targets
+#endif
+
+#if defined(_MSC_VER) && _MSC_VER >= 1500 && \
+    (defined(_M_X64) || defined(_M_IX86))
+#define WEBP_MSC_SSE41  // Visual C++ SSE4.1 targets
+#endif
+#endif
+
+// WEBP_HAVE_* are used to indicate the presence of the instruction set in dsp
+// files without intrinsics, allowing the corresponding Init() to be called.
+// Files containing intrinsics will need to be built targeting the instruction
+// set so should succeed on one of the earlier tests.
+#if defined(__SSE2__) || defined(WEBP_MSC_SSE2) || defined(WEBP_HAVE_SSE2)
+#define WEBP_USE_SSE2
+#endif
+
+#if defined(__SSE4_1__) || defined(WEBP_MSC_SSE41) || defined(WEBP_HAVE_SSE41)
+#define WEBP_USE_SSE41
+#endif
+
+#undef WEBP_MSC_SSE41
+#undef WEBP_MSC_SSE2
+
+// The intrinsics currently cause compiler errors with arm-nacl-gcc and the
+// inline assembly would need to be modified for use with Native Client.
+#if (defined(__ARM_NEON__) || \
+     defined(__aarch64__) || defined(WEBP_HAVE_NEON)) && \
+    !defined(__native_client__)
+#define WEBP_USE_NEON
+#endif
+
+#if !defined(WEBP_USE_NEON) && defined(__ANDROID__) && \
+    defined(__ARM_ARCH_7A__) && defined(HAVE_CPU_FEATURES_H)
+#define WEBP_ANDROID_NEON  // Android targets that may have NEON
+#define WEBP_USE_NEON
+#endif
+
+#if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_M_ARM)
+#define WEBP_USE_NEON
+#define WEBP_USE_INTRINSICS
+#endif
+
+#if defined(__mips__) && !defined(__mips64) && \
+    defined(__mips_isa_rev) && (__mips_isa_rev >= 1) && (__mips_isa_rev < 6)
+#define WEBP_USE_MIPS32
+#if (__mips_isa_rev >= 2)
+#define WEBP_USE_MIPS32_R2
+#if defined(__mips_dspr2) || (defined(__mips_dsp_rev) && __mips_dsp_rev >= 2)
+#define WEBP_USE_MIPS_DSP_R2
+#endif
+#endif
+#endif
+
+#if defined(__mips_msa) && defined(__mips_isa_rev) && (__mips_isa_rev >= 5)
+#define WEBP_USE_MSA
+#endif
+
+#ifndef WEBP_DSP_OMIT_C_CODE
+#define WEBP_DSP_OMIT_C_CODE 1
+#endif
+
+#if (defined(__aarch64__) || defined(__ARM_NEON__)) && WEBP_DSP_OMIT_C_CODE
+#define WEBP_NEON_OMIT_C_CODE 1
+#else
+#define WEBP_NEON_OMIT_C_CODE 0
+#endif
+
+#if !(LOCAL_CLANG_PREREQ(3,8) || LOCAL_GCC_PREREQ(4,8) || defined(__aarch64__))
+#define WEBP_NEON_WORK_AROUND_GCC 1
+#else
+#define WEBP_NEON_WORK_AROUND_GCC 0
+#endif
+
+// This macro prevents thread_sanitizer from reporting known concurrent writes.
+#define WEBP_TSAN_IGNORE_FUNCTION
+#if defined(__has_feature)
+#if __has_feature(thread_sanitizer)
+#undef WEBP_TSAN_IGNORE_FUNCTION
+#define WEBP_TSAN_IGNORE_FUNCTION __attribute__((no_sanitize_thread))
+#endif
+#endif
+
+#if defined(WEBP_USE_THREAD) && !defined(_WIN32)
+#include <pthread.h>  // NOLINT
+
+#define WEBP_DSP_INIT(func) do {                                    \
+  static volatile VP8CPUInfo func ## _last_cpuinfo_used =           \
+      (VP8CPUInfo)&func ## _last_cpuinfo_used;                      \
+  static pthread_mutex_t func ## _lock = PTHREAD_MUTEX_INITIALIZER; \
+  if (pthread_mutex_lock(&func ## _lock)) break;                    \
+  if (func ## _last_cpuinfo_used != VP8GetCPUInfo) func();          \
+  func ## _last_cpuinfo_used = VP8GetCPUInfo;                       \
+  (void)pthread_mutex_unlock(&func ## _lock);                       \
+} while (0)
+#else  // !(defined(WEBP_USE_THREAD) && !defined(_WIN32))
+#define WEBP_DSP_INIT(func) do {                                    \
+  static volatile VP8CPUInfo func ## _last_cpuinfo_used =           \
+      (VP8CPUInfo)&func ## _last_cpuinfo_used;                      \
+  if (func ## _last_cpuinfo_used == VP8GetCPUInfo) break;           \
+  func();                                                           \
+  func ## _last_cpuinfo_used = VP8GetCPUInfo;                       \
+} while (0)
+#endif  // defined(WEBP_USE_THREAD) && !defined(_WIN32)
+
+// Defines an Init + helper function that control multiple initialization of
+// function pointers / tables.
+/* Usage:
+   WEBP_DSP_INIT_FUNC(InitFunc) {
+     ...function body
+   }
+*/
+#define WEBP_DSP_INIT_FUNC(name)                             \
+  static WEBP_TSAN_IGNORE_FUNCTION void name ## _body(void); \
+  WEBP_TSAN_IGNORE_FUNCTION void name(void) {                \
+    WEBP_DSP_INIT(name ## _body);                            \
+  }                                                          \
+  static WEBP_TSAN_IGNORE_FUNCTION void name ## _body(void)
+
+#define WEBP_UBSAN_IGNORE_UNDEF
+#define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
+#if defined(__clang__) && defined(__has_attribute)
+#if __has_attribute(no_sanitize)
+// This macro prevents the undefined behavior sanitizer from reporting
+// failures. This is only meant to silence unaligned loads on platforms that
+// are known to support them.
+#undef WEBP_UBSAN_IGNORE_UNDEF
+#define WEBP_UBSAN_IGNORE_UNDEF \
+  __attribute__((no_sanitize("undefined")))
+
+// This macro prevents the undefined behavior sanitizer from reporting
+// failures related to unsigned integer overflows. This is only meant to
+// silence cases where this well defined behavior is expected.
+#undef WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
+#define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW \
+  __attribute__((no_sanitize("unsigned-integer-overflow")))
+#endif
+#endif
+
+// If 'ptr' is NULL, returns NULL. Otherwise returns 'ptr + off'.
+// Prevents undefined behavior sanitizer nullptr-with-nonzero-offset warning.
+#if !defined(WEBP_OFFSET_PTR)
+#define WEBP_OFFSET_PTR(ptr, off) (((ptr) == NULL) ? NULL : ((ptr) + (off)))
+#endif
+
+// Regularize the definition of WEBP_SWAP_16BIT_CSP (backward compatibility)
+#if !defined(WEBP_SWAP_16BIT_CSP)
+#define WEBP_SWAP_16BIT_CSP 0
+#endif
+
+// some endian fix (e.g.: mips-gcc doesn't define __BIG_ENDIAN__)
+#if !defined(WORDS_BIGENDIAN) && \
+    (defined(__BIG_ENDIAN__) || defined(_M_PPC) || \
+     (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)))
+#define WORDS_BIGENDIAN
+#endif
+
+typedef enum {
+  kSSE2,
+  kSSE3,
+  kSlowSSSE3,  // special feature for slow SSSE3 architectures
+  kSSE4_1,
+  kAVX,
+  kAVX2,
+  kNEON,
+  kMIPS32,
+  kMIPSdspR2,
+  kMSA
+} CPUFeature;
+// returns true if the CPU supports the feature.
+typedef int (*VP8CPUInfo)(CPUFeature feature);
+WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
+
+//------------------------------------------------------------------------------
+// Init stub generator
+
+// Defines an init function stub to ensure each module exposes a symbol,
+// avoiding a compiler warning.
+#define WEBP_DSP_INIT_STUB(func) \
+  extern void func(void); \
+  void func(void) {}
+
+//------------------------------------------------------------------------------
+// Encoding
+
+// Transforms
+// VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
+//          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
+typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
+                        int do_two);
+typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
+typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
+extern VP8Idct VP8ITransform;
+extern VP8Fdct VP8FTransform;
+extern VP8Fdct VP8FTransform2;   // performs two transforms at a time
+extern VP8WHT VP8FTransformWHT;
+// Predictions
+// *dst is the destination block. *top and *left can be NULL.
+typedef void (*VP8IntraPreds)(uint8_t* dst, const uint8_t* left,
+                              const uint8_t* top);
+typedef void (*VP8Intra4Preds)(uint8_t* dst, const uint8_t* top);
+extern VP8Intra4Preds VP8EncPredLuma4;
+extern VP8IntraPreds VP8EncPredLuma16;
+extern VP8IntraPreds VP8EncPredChroma8;
+
+typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref);
+extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4;
+typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref,
+                          const uint16_t* const weights);
+// The weights for VP8TDisto4x4 and VP8TDisto16x16 contain a row-major
+// 4 by 4 symmetric matrix.
+extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16;
+
+// Compute the average (DC) of four 4x4 blocks.
+// Each sub-4x4 block #i sum is stored in dc[i].
+typedef void (*VP8MeanMetric)(const uint8_t* ref, uint32_t dc[4]);
+extern VP8MeanMetric VP8Mean16x4;
+
+typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst);
+extern VP8BlockCopy VP8Copy4x4;
+extern VP8BlockCopy VP8Copy16x8;
+// Quantization
+struct VP8Matrix;   // forward declaration
+typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16],
+                                const struct VP8Matrix* const mtx);
+// Same as VP8QuantizeBlock, but quantizes two consecutive blocks.
+typedef int (*VP8Quantize2Blocks)(int16_t in[32], int16_t out[32],
+                                  const struct VP8Matrix* const mtx);
+
+extern VP8QuantizeBlock VP8EncQuantizeBlock;
+extern VP8Quantize2Blocks VP8EncQuantize2Blocks;
+
+// specific to 2nd transform:
+typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16],
+                                   const struct VP8Matrix* const mtx);
+extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
+
+extern const int VP8DspScan[16 + 4 + 4];
+
+// Collect histogram for susceptibility calculation.
+#define MAX_COEFF_THRESH   31   // size of histogram used by CollectHistogram.
+typedef struct {
+  // We only need to store max_value and last_non_zero, not the distribution.
+  int max_value;
+  int last_non_zero;
+} VP8Histogram;
+typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
+                          int start_block, int end_block,
+                          VP8Histogram* const histo);
+extern VP8CHisto VP8CollectHistogram;
+// General-purpose util function to help VP8CollectHistogram().
+void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
+                         VP8Histogram* const histo);
+
+// must be called before using any of the above
+void VP8EncDspInit(void);
+
+//------------------------------------------------------------------------------
+// cost functions (encoding)
+
+extern const uint16_t VP8EntropyCost[256];        // 8bit fixed-point log(p)
+// approximate cost per level:
+extern const uint16_t VP8LevelFixedCosts[2047 /*MAX_LEVEL*/ + 1];
+extern const uint8_t VP8EncBands[16 + 1];
+
+struct VP8Residual;
+typedef void (*VP8SetResidualCoeffsFunc)(const int16_t* const coeffs,
+                                         struct VP8Residual* const res);
+extern VP8SetResidualCoeffsFunc VP8SetResidualCoeffs;
+
+// Cost calculation function.
+typedef int (*VP8GetResidualCostFunc)(int ctx0,
+                                      const struct VP8Residual* const res);
+extern VP8GetResidualCostFunc VP8GetResidualCost;
+
+// must be called before anything using the above
+void VP8EncDspCostInit(void);
+
+//------------------------------------------------------------------------------
+// SSIM / PSNR utils
+
+// struct for accumulating statistical moments
+typedef struct {
+  uint32_t w;              // sum(w_i) : sum of weights
+  uint32_t xm, ym;         // sum(w_i * x_i), sum(w_i * y_i)
+  uint32_t xxm, xym, yym;  // sum(w_i * x_i * x_i), etc.
+} VP8DistoStats;
+
+// Compute the final SSIM value
+// The non-clipped version assumes stats->w = (2 * VP8_SSIM_KERNEL + 1)^2.
+double VP8SSIMFromStats(const VP8DistoStats* const stats);
+double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats);
+
+#define VP8_SSIM_KERNEL 3   // total size of the kernel: 2 * VP8_SSIM_KERNEL + 1
+typedef double (*VP8SSIMGetClippedFunc)(const uint8_t* src1, int stride1,
+                                        const uint8_t* src2, int stride2,
+                                        int xo, int yo,  // center position
+                                        int W, int H);   // plane dimension
+
+#if !defined(WEBP_REDUCE_SIZE)
+// This version is called with the guarantee that you can load 8 bytes and
+// 8 rows at offset src1 and src2
+typedef double (*VP8SSIMGetFunc)(const uint8_t* src1, int stride1,
+                                 const uint8_t* src2, int stride2);
+
+extern VP8SSIMGetFunc VP8SSIMGet;         // unclipped / unchecked
+extern VP8SSIMGetClippedFunc VP8SSIMGetClipped;   // with clipping
+#endif
+
+#if !defined(WEBP_DISABLE_STATS)
+typedef uint32_t (*VP8AccumulateSSEFunc)(const uint8_t* src1,
+                                         const uint8_t* src2, int len);
+extern VP8AccumulateSSEFunc VP8AccumulateSSE;
+#endif
+
+// must be called before using any of the above directly
+void VP8SSIMDspInit(void);
+
+//------------------------------------------------------------------------------
+// Decoding
+
+typedef void (*VP8DecIdct)(const int16_t* coeffs, uint8_t* dst);
+// when doing two transforms, coeffs is actually int16_t[2][16].
+typedef void (*VP8DecIdct2)(const int16_t* coeffs, uint8_t* dst, int do_two);
+extern VP8DecIdct2 VP8Transform;
+extern VP8DecIdct VP8TransformAC3;
+extern VP8DecIdct VP8TransformUV;
+extern VP8DecIdct VP8TransformDC;
+extern VP8DecIdct VP8TransformDCUV;
+extern VP8WHT VP8TransformWHT;
+
+// *dst is the destination block, with stride BPS. Boundary samples are
+// assumed accessible when needed.
+typedef void (*VP8PredFunc)(uint8_t* dst);
+extern VP8PredFunc VP8PredLuma16[/* NUM_B_DC_MODES */];
+extern VP8PredFunc VP8PredChroma8[/* NUM_B_DC_MODES */];
+extern VP8PredFunc VP8PredLuma4[/* NUM_BMODES */];
+
+// clipping tables (for filtering)
+extern const int8_t* const VP8ksclip1;  // clips [-1020, 1020] to [-128, 127]
+extern const int8_t* const VP8ksclip2;  // clips [-112, 112] to [-16, 15]
+extern const uint8_t* const VP8kclip1;  // clips [-255,511] to [0,255]
+extern const uint8_t* const VP8kabs0;   // abs(x) for x in [-255,255]
+// must be called first
+void VP8InitClipTables(void);
+
+// simple filter (only for luma)
+typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh);
+extern VP8SimpleFilterFunc VP8SimpleVFilter16;
+extern VP8SimpleFilterFunc VP8SimpleHFilter16;
+extern VP8SimpleFilterFunc VP8SimpleVFilter16i;  // filter 3 inner edges
+extern VP8SimpleFilterFunc VP8SimpleHFilter16i;
+
+// regular filter (on both macroblock edges and inner edges)
+typedef void (*VP8LumaFilterFunc)(uint8_t* luma, int stride,
+                                  int thresh, int ithresh, int hev_t);
+typedef void (*VP8ChromaFilterFunc)(uint8_t* u, uint8_t* v, int stride,
+                                    int thresh, int ithresh, int hev_t);
+// on outer edge
+extern VP8LumaFilterFunc VP8VFilter16;
+extern VP8LumaFilterFunc VP8HFilter16;
+extern VP8ChromaFilterFunc VP8VFilter8;
+extern VP8ChromaFilterFunc VP8HFilter8;
+
+// on inner edge
+extern VP8LumaFilterFunc VP8VFilter16i;   // filtering 3 inner edges altogether
+extern VP8LumaFilterFunc VP8HFilter16i;
+extern VP8ChromaFilterFunc VP8VFilter8i;  // filtering u and v altogether
+extern VP8ChromaFilterFunc VP8HFilter8i;
+
+// Dithering. Combines dithering values (centered around 128) with dst[],
+// according to: dst[] = clip(dst[] + (((dither[]-128) + 8) >> 4)
+#define VP8_DITHER_DESCALE 4
+#define VP8_DITHER_DESCALE_ROUNDER (1 << (VP8_DITHER_DESCALE - 1))
+#define VP8_DITHER_AMP_BITS 7
+#define VP8_DITHER_AMP_CENTER (1 << VP8_DITHER_AMP_BITS)
+extern void (*VP8DitherCombine8x8)(const uint8_t* dither, uint8_t* dst,
+                                   int dst_stride);
+
+// must be called before anything using the above
+void VP8DspInit(void);
+
+//------------------------------------------------------------------------------
+// WebP I/O
+
+#define FANCY_UPSAMPLING   // undefined to remove fancy upsampling support
+
+// Convert a pair of y/u/v lines together to the output rgb/a colorspace.
+// bottom_y can be NULL if only one line of output is needed (at top/bottom).
+typedef void (*WebPUpsampleLinePairFunc)(
+    const uint8_t* top_y, const uint8_t* bottom_y,
+    const uint8_t* top_u, const uint8_t* top_v,
+    const uint8_t* cur_u, const uint8_t* cur_v,
+    uint8_t* top_dst, uint8_t* bottom_dst, int len);
+
+#ifdef FANCY_UPSAMPLING
+
+// Fancy upsampling functions to convert YUV to RGB(A) modes
+extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
+
+#endif    // FANCY_UPSAMPLING
+
+// Per-row point-sampling methods.
+typedef void (*WebPSamplerRowFunc)(const uint8_t* y,
+                                   const uint8_t* u, const uint8_t* v,
+                                   uint8_t* dst, int len);
+// Generic function to apply 'WebPSamplerRowFunc' to the whole plane:
+void WebPSamplerProcessPlane(const uint8_t* y, int y_stride,
+                             const uint8_t* u, const uint8_t* v, int uv_stride,
+                             uint8_t* dst, int dst_stride,
+                             int width, int height, WebPSamplerRowFunc func);
+
+// Sampling functions to convert rows of YUV to RGB(A)
+extern WebPSamplerRowFunc WebPSamplers[/* MODE_LAST */];
+
+// General function for converting two lines of ARGB or RGBA.
+// 'alpha_is_last' should be true if 0xff000000 is stored in memory as
+// as 0x00, 0x00, 0x00, 0xff (little endian).
+WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last);
+
+// YUV444->RGB converters
+typedef void (*WebPYUV444Converter)(const uint8_t* y,
+                                    const uint8_t* u, const uint8_t* v,
+                                    uint8_t* dst, int len);
+
+extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */];
+
+// Must be called before using the WebPUpsamplers[] (and for premultiplied
+// colorspaces like rgbA, rgbA4444, etc)
+void WebPInitUpsamplers(void);
+// Must be called before using WebPSamplers[]
+void WebPInitSamplers(void);
+// Must be called before using WebPYUV444Converters[]
+void WebPInitYUV444Converters(void);
+
+//------------------------------------------------------------------------------
+// ARGB -> YUV converters
+
+// Convert ARGB samples to luma Y.
+extern void (*WebPConvertARGBToY)(const uint32_t* argb, uint8_t* y, int width);
+// Convert ARGB samples to U/V with downsampling. do_store should be '1' for
+// even lines and '0' for odd ones. 'src_width' is the original width, not
+// the U/V one.
+extern void (*WebPConvertARGBToUV)(const uint32_t* argb, uint8_t* u, uint8_t* v,
+                                   int src_width, int do_store);
+
+// Convert a row of accumulated (four-values) of rgba32 toward U/V
+extern void (*WebPConvertRGBA32ToUV)(const uint16_t* rgb,
+                                     uint8_t* u, uint8_t* v, int width);
+
+// Convert RGB or BGR to Y
+extern void (*WebPConvertRGB24ToY)(const uint8_t* rgb, uint8_t* y, int width);
+extern void (*WebPConvertBGR24ToY)(const uint8_t* bgr, uint8_t* y, int width);
+
+// used for plain-C fallback.
+extern void WebPConvertARGBToUV_C(const uint32_t* argb, uint8_t* u, uint8_t* v,
+                                  int src_width, int do_store);
+extern void WebPConvertRGBA32ToUV_C(const uint16_t* rgb,
+                                    uint8_t* u, uint8_t* v, int width);
+
+// utilities for accurate RGB->YUV conversion
+extern uint64_t (*WebPSharpYUVUpdateY)(const uint16_t* src, const uint16_t* ref,
+                                       uint16_t* dst, int len);
+extern void (*WebPSharpYUVUpdateRGB)(const int16_t* src, const int16_t* ref,
+                                     int16_t* dst, int len);
+extern void (*WebPSharpYUVFilterRow)(const int16_t* A, const int16_t* B,
+                                     int len,
+                                     const uint16_t* best_y, uint16_t* out);
+
+// Must be called before using the above.
+void WebPInitConvertARGBToYUV(void);
+
+//------------------------------------------------------------------------------
+// Rescaler
+
+struct WebPRescaler;
+
+// Import a row of data and save its contribution in the rescaler.
+// 'channel' denotes the channel number to be imported. 'Expand' corresponds to
+// the wrk->x_expand case. Otherwise, 'Shrink' is to be used.
+typedef void (*WebPRescalerImportRowFunc)(struct WebPRescaler* const wrk,
+                                          const uint8_t* src);
+
+extern WebPRescalerImportRowFunc WebPRescalerImportRowExpand;
+extern WebPRescalerImportRowFunc WebPRescalerImportRowShrink;
+
+// Export one row (starting at x_out position) from rescaler.
+// 'Expand' corresponds to the wrk->y_expand case.
+// Otherwise 'Shrink' is to be used
+typedef void (*WebPRescalerExportRowFunc)(struct WebPRescaler* const wrk);
+extern WebPRescalerExportRowFunc WebPRescalerExportRowExpand;
+extern WebPRescalerExportRowFunc WebPRescalerExportRowShrink;
+
+// Plain-C implementation, as fall-back.
+extern void WebPRescalerImportRowExpand_C(struct WebPRescaler* const wrk,
+                                          const uint8_t* src);
+extern void WebPRescalerImportRowShrink_C(struct WebPRescaler* const wrk,
+                                          const uint8_t* src);
+extern void WebPRescalerExportRowExpand_C(struct WebPRescaler* const wrk);
+extern void WebPRescalerExportRowShrink_C(struct WebPRescaler* const wrk);
+
+// Main entry calls:
+extern void WebPRescalerImportRow(struct WebPRescaler* const wrk,
+                                  const uint8_t* src);
+// Export one row (starting at x_out position) from rescaler.
+extern void WebPRescalerExportRow(struct WebPRescaler* const wrk);
+
+// Must be called first before using the above.
+void WebPRescalerDspInit(void);
+
+//------------------------------------------------------------------------------
+// Utilities for processing transparent channel.
+
+// Apply alpha pre-multiply on an rgba, bgra or argb plane of size w * h.
+// alpha_first should be 0 for argb, 1 for rgba or bgra (where alpha is last).
+extern void (*WebPApplyAlphaMultiply)(
+    uint8_t* rgba, int alpha_first, int w, int h, int stride);
+
+// Same, buf specifically for RGBA4444 format
+extern void (*WebPApplyAlphaMultiply4444)(
+    uint8_t* rgba4444, int w, int h, int stride);
+
+// Dispatch the values from alpha[] plane to the ARGB destination 'dst'.
+// Returns true if alpha[] plane has non-trivial values different from 0xff.
+extern int (*WebPDispatchAlpha)(const uint8_t* alpha, int alpha_stride,
+                                int width, int height,
+                                uint8_t* dst, int dst_stride);
+
+// Transfer packed 8b alpha[] values to green channel in dst[], zero'ing the
+// A/R/B values. 'dst_stride' is the stride for dst[] in uint32_t units.
+extern void (*WebPDispatchAlphaToGreen)(const uint8_t* alpha, int alpha_stride,
+                                        int width, int height,
+                                        uint32_t* dst, int dst_stride);
+
+// Extract the alpha values from 32b values in argb[] and pack them into alpha[]
+// (this is the opposite of WebPDispatchAlpha).
+// Returns true if there's only trivial 0xff alpha values.
+extern int (*WebPExtractAlpha)(const uint8_t* argb, int argb_stride,
+                               int width, int height,
+                               uint8_t* alpha, int alpha_stride);
+
+// Extract the green values from 32b values in argb[] and pack them into alpha[]
+// (this is the opposite of WebPDispatchAlphaToGreen).
+extern void (*WebPExtractGreen)(const uint32_t* argb, uint8_t* alpha, int size);
+
+// Pre-Multiply operation transforms x into x * A / 255  (where x=Y,R,G or B).
+// Un-Multiply operation transforms x into x * 255 / A.
+
+// Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row.
+extern void (*WebPMultARGBRow)(uint32_t* const ptr, int width, int inverse);
+
+// Same a WebPMultARGBRow(), but for several rows.
+void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows,
+                      int inverse);
+
+// Same for a row of single values, with side alpha values.
+extern void (*WebPMultRow)(uint8_t* const ptr, const uint8_t* const alpha,
+                           int width, int inverse);
+
+// Same a WebPMultRow(), but for several 'num_rows' rows.
+void WebPMultRows(uint8_t* ptr, int stride,
+                  const uint8_t* alpha, int alpha_stride,
+                  int width, int num_rows, int inverse);
+
+// Plain-C versions, used as fallback by some implementations.
+void WebPMultRow_C(uint8_t* const ptr, const uint8_t* const alpha,
+                   int width, int inverse);
+void WebPMultARGBRow_C(uint32_t* const ptr, int width, int inverse);
+
+#ifdef WORDS_BIGENDIAN
+// ARGB packing function: a/r/g/b input is rgba or bgra order.
+extern void (*WebPPackARGB)(const uint8_t* a, const uint8_t* r,
+                            const uint8_t* g, const uint8_t* b, int len,
+                            uint32_t* out);
+#endif
+
+// RGB packing function. 'step' can be 3 or 4. r/g/b input is rgb or bgr order.
+extern void (*WebPPackRGB)(const uint8_t* r, const uint8_t* g, const uint8_t* b,
+                           int len, int step, uint32_t* out);
+
+// This function returns true if src[i] contains a value different from 0xff.
+extern int (*WebPHasAlpha8b)(const uint8_t* src, int length);
+// This function returns true if src[4*i] contains a value different from 0xff.
+extern int (*WebPHasAlpha32b)(const uint8_t* src, int length);
+// replaces transparent values in src[] by 'color'.
+extern void (*WebPAlphaReplace)(uint32_t* src, int length, uint32_t color);
+
+// To be called first before using the above.
+void WebPInitAlphaProcessing(void);
+
+//------------------------------------------------------------------------------
+// Filter functions
+
+typedef enum {     // Filter types.
+  WEBP_FILTER_NONE = 0,
+  WEBP_FILTER_HORIZONTAL,
+  WEBP_FILTER_VERTICAL,
+  WEBP_FILTER_GRADIENT,
+  WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
+  WEBP_FILTER_BEST,    // meta-types
+  WEBP_FILTER_FAST
+} WEBP_FILTER_TYPE;
+
+typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
+                               int stride, uint8_t* out);
+// In-place un-filtering.
+// Warning! 'prev_line' pointer can be equal to 'cur_line' or 'preds'.
+typedef void (*WebPUnfilterFunc)(const uint8_t* prev_line, const uint8_t* preds,
+                                 uint8_t* cur_line, int width);
+
+// Filter the given data using the given predictor.
+// 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
+// in raster order.
+// 'stride' is number of bytes per scan line (with possible padding).
+// 'out' should be pre-allocated.
+extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
+
+// In-place reconstruct the original data from the given filtered data.
+// The reconstruction will be done for 'num_rows' rows starting from 'row'
+// (assuming rows upto 'row - 1' are already reconstructed).
+extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
+
+// To be called first before using the above.
+void VP8FiltersInit(void);
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  // WEBP_DSP_DSP_H_