WebP encoder: extract out some methods into a separate helper library.

This is the 2nd patch in preparation for using WebPAnimEncoder API for encoding
and muxing WebP images.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

4 files changed, 360 insertions, 271 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index cb88fd165a..789a6d0fa5 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -783,7 +783,7 @@ OBJS-$(CONFIG_LIBVPX_VP8_ENCODER)         += libvpxenc.o
 OBJS-$(CONFIG_LIBVPX_VP9_DECODER)         += libvpxdec.o libvpx.o
 OBJS-$(CONFIG_LIBVPX_VP9_ENCODER)         += libvpxenc.o libvpx.o
 OBJS-$(CONFIG_LIBWAVPACK_ENCODER)         += libwavpackenc.o
-OBJS-$(CONFIG_LIBWEBP_ENCODER)            += libwebpenc.o
+OBJS-$(CONFIG_LIBWEBP_ENCODER)            += libwebpenc_common.o libwebpenc.o
 OBJS-$(CONFIG_LIBX264_ENCODER)            += libx264.o
 OBJS-$(CONFIG_LIBX265_ENCODER)            += libx265.o
 OBJS-$(CONFIG_LIBXAVS_ENCODER)            += libxavs.o
diff --git a/libavcodec/libwebpenc.c b/libavcodec/libwebpenc.c
index 95d56acd0b..6896742607 100644
--- a/libavcodec/libwebpenc.c
+++ b/libavcodec/libwebpenc.c
@@ -21,254 +21,29 @@
 
 /**
  * @file
- * WebP encoder using libwebp
+ * WebP encoder using libwebp (WebPEncode API)
  */
 
-#include <webp/encode.h>
+#include "libwebpenc_common.h"
 
-#include "libavutil/common.h"
-#include "libavutil/frame.h"
-#include "libavutil/imgutils.h"
-#include "libavutil/opt.h"
-#include "avcodec.h"
-#include "internal.h"
-
-typedef struct LibWebPContext {
-    AVClass *class;         // class for AVOptions
-    float quality;          // lossy quality 0 - 100
-    int lossless;           // use lossless encoding
-    int preset;             // configuration preset
-    int chroma_warning;     // chroma linesize mismatch warning has been printed
-    int conversion_warning; // pixel format conversion warning has been printed
-    WebPConfig config;      // libwebp configuration
-    AVFrame *ref;
-    int cr_size;
-    int cr_threshold;
-} LibWebPContext;
-
-static int libwebp_error_to_averror(int err)
-{
-    switch (err) {
-    case VP8_ENC_ERROR_OUT_OF_MEMORY:
-    case VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY:
-        return AVERROR(ENOMEM);
-    case VP8_ENC_ERROR_NULL_PARAMETER:
-    case VP8_ENC_ERROR_INVALID_CONFIGURATION:
-    case VP8_ENC_ERROR_BAD_DIMENSION:
-        return AVERROR(EINVAL);
-    }
-    return AVERROR_UNKNOWN;
-}
+typedef LibWebPContextCommon LibWebPContext;
 
 static av_cold int libwebp_encode_init(AVCodecContext *avctx)
 {
-    LibWebPContext *s = avctx->priv_data;
-    int ret;
-
-    if (avctx->global_quality >= 0)
-        s->quality = av_clipf(avctx->global_quality / (float)FF_QP2LAMBDA,
-                              0.0f, 100.0f);
-
-    if (avctx->compression_level < 0 || avctx->compression_level > 6) {
-        av_log(avctx, AV_LOG_WARNING, "invalid compression level: %d\n",
-               avctx->compression_level);
-        avctx->compression_level = av_clip(avctx->compression_level, 0, 6);
-    }
-
-    if (s->preset >= WEBP_PRESET_DEFAULT) {
-        ret = WebPConfigPreset(&s->config, s->preset, s->quality);
-        if (!ret)
-            return AVERROR_UNKNOWN;
-        s->lossless              = s->config.lossless;
-        s->quality               = s->config.quality;
-        avctx->compression_level = s->config.method;
-    } else {
-        ret = WebPConfigInit(&s->config);
-        if (!ret)
-            return AVERROR_UNKNOWN;
-
-        s->config.lossless = s->lossless;
-        s->config.quality  = s->quality;
-        s->config.method   = avctx->compression_level;
-
-        ret = WebPValidateConfig(&s->config);
-        if (!ret)
-            return AVERROR(EINVAL);
-    }
-
-    av_log(avctx, AV_LOG_DEBUG, "%s - quality=%.1f method=%d\n",
-           s->lossless ? "Lossless" : "Lossy", s->quality,
-           avctx->compression_level);
-
-    return 0;
+    return ff_libwebp_encode_init_common(avctx);
 }
 
 static int libwebp_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                                 const AVFrame *frame, int *got_packet)
 {
     LibWebPContext *s  = avctx->priv_data;
-    AVFrame *alt_frame = NULL;
     WebPPicture *pic = NULL;
+    AVFrame *alt_frame = NULL;
     WebPMemoryWriter mw = { 0 };
-    int ret;
-
-    if (avctx->width > WEBP_MAX_DIMENSION || avctx->height > WEBP_MAX_DIMENSION) {
-        av_log(avctx, AV_LOG_ERROR, "Picture size is too large. Max is %dx%d.\n",
-               WEBP_MAX_DIMENSION, WEBP_MAX_DIMENSION);
-        return AVERROR(EINVAL);
-    }
 
-    pic = av_malloc(sizeof(*pic));
-    if (!pic)
-        return AVERROR(ENOMEM);
-
-    ret = WebPPictureInit(pic);
-    if (!ret) {
-        ret = AVERROR_UNKNOWN;
+    int ret = ff_libwebp_get_frame(avctx, s, frame, &alt_frame, &pic);
+    if (ret < 0)
         goto end;
-    }
-    pic->width  = avctx->width;
-    pic->height = avctx->height;
-
-    if (avctx->pix_fmt == AV_PIX_FMT_RGB32) {
-        if (!s->lossless) {
-            /* libwebp will automatically convert RGB input to YUV when
-               encoding lossy. */
-            if (!s->conversion_warning) {
-                av_log(avctx, AV_LOG_WARNING,
-                       "Using libwebp for RGB-to-YUV conversion. You may want "
-                       "to consider passing in YUV instead for lossy "
-                       "encoding.\n");
-                s->conversion_warning = 1;
-            }
-        }
-        pic->use_argb    = 1;
-        pic->argb        = (uint32_t *)frame->data[0];
-        pic->argb_stride = frame->linesize[0] / 4;
-    } else {
-        if (frame->linesize[1] != frame->linesize[2] || s->cr_threshold) {
-            if (!s->chroma_warning && !s->cr_threshold) {
-                av_log(avctx, AV_LOG_WARNING,
-                       "Copying frame due to differing chroma linesizes.\n");
-                s->chroma_warning = 1;
-            }
-            alt_frame = av_frame_alloc();
-            if (!alt_frame) {
-                ret = AVERROR(ENOMEM);
-                goto end;
-            }
-            alt_frame->width  = frame->width;
-            alt_frame->height = frame->height;
-            alt_frame->format = frame->format;
-            if (s->cr_threshold)
-                alt_frame->format = AV_PIX_FMT_YUVA420P;
-            ret = av_frame_get_buffer(alt_frame, 32);
-            if (ret < 0)
-                goto end;
-            alt_frame->format = frame->format;
-            av_frame_copy(alt_frame, frame);
-            frame = alt_frame;
-            if (s->cr_threshold) {
-                int x,y, x2, y2, p;
-                int bs = s->cr_size;
-
-                if (!s->ref) {
-                    s->ref = av_frame_clone(frame);
-                    if (!s->ref) {
-                        ret = AVERROR(ENOMEM);
-                        goto end;
-                    }
-                }
-
-                alt_frame->format = AV_PIX_FMT_YUVA420P;
-                for (y = 0; y < frame->height; y+= bs) {
-                    for (x = 0; x < frame->width; x+= bs) {
-                        int skip;
-                        int sse = 0;
-                        for (p = 0; p < 3; p++) {
-                            int bs2 = bs >> !!p;
-                            int w = FF_CEIL_RSHIFT(frame->width , !!p);
-                            int h = FF_CEIL_RSHIFT(frame->height, !!p);
-                            int xs = x >> !!p;
-                            int ys = y >> !!p;
-                            for (y2 = ys; y2 < FFMIN(ys + bs2, h); y2++) {
-                                for (x2 = xs; x2 < FFMIN(xs + bs2, w); x2++) {
-                                    int diff =  frame->data[p][frame->linesize[p] * y2 + x2]
-                                              -s->ref->data[p][frame->linesize[p] * y2 + x2];
-                                    sse += diff*diff;
-                                }
-                            }
-                        }
-                        skip = sse < s->cr_threshold && frame->data[3] != s->ref->data[3];
-                        if (!skip)
-                            for (p = 0; p < 3; p++) {
-                                int bs2 = bs >> !!p;
-                                int w = FF_CEIL_RSHIFT(frame->width , !!p);
-                                int h = FF_CEIL_RSHIFT(frame->height, !!p);
-                                int xs = x >> !!p;
-                                int ys = y >> !!p;
-                                for (y2 = ys; y2 < FFMIN(ys + bs2, h); y2++) {
-                                    memcpy(&s->ref->data[p][frame->linesize[p] * y2 + xs],
-                                            & frame->data[p][frame->linesize[p] * y2 + xs], FFMIN(bs2, w-xs));
-                                }
-                            }
-                        for (y2 = y; y2 < FFMIN(y+bs, frame->height); y2++) {
-                            memset(&frame->data[3][frame->linesize[3] * y2 + x],
-                                    skip ? 0 : 255,
-                                    FFMIN(bs, frame->width-x));
-                        }
-                    }
-                }
-            }
-        }
-
-        pic->use_argb  = 0;
-        pic->y         = frame->data[0];
-        pic->u         = frame->data[1];
-        pic->v         = frame->data[2];
-        pic->y_stride  = frame->linesize[0];
-        pic->uv_stride = frame->linesize[1];
-        if (frame->format == AV_PIX_FMT_YUVA420P) {
-            pic->colorspace = WEBP_YUV420A;
-            pic->a          = frame->data[3];
-            pic->a_stride   = frame->linesize[3];
-            if (alt_frame)
-                WebPCleanupTransparentArea(pic);
-        } else {
-            pic->colorspace = WEBP_YUV420;
-        }
-
-        if (s->lossless) {
-            /* We do not have a way to automatically prioritize RGB over YUV
-               in automatic pixel format conversion based on whether we're
-               encoding lossless or lossy, so we do conversion with libwebp as
-               a convenience. */
-            if (!s->conversion_warning) {
-                av_log(avctx, AV_LOG_WARNING,
-                       "Using libwebp for YUV-to-RGB conversion. You may want "
-                       "to consider passing in RGB instead for lossless "
-                       "encoding.\n");
-                s->conversion_warning = 1;
-            }
-
-#if (WEBP_ENCODER_ABI_VERSION <= 0x201)
-            /* libwebp should do the conversion automatically, but there is a
-               bug that causes it to return an error instead, so a work-around
-               is required.
-               See https://code.google.com/p/webp/issues/detail?id=178 */
-            pic->memory_ = (void*)1;  /* something non-null */
-            ret = WebPPictureYUVAToARGB(pic);
-            if (!ret) {
-                av_log(avctx, AV_LOG_ERROR,
-                       "WebPPictureYUVAToARGB() failed with error: %d\n",
-                       pic->error_code);
-                ret = libwebp_error_to_averror(pic->error_code);
-                goto end;
-            }
-            pic->memory_ = NULL;  /* restore pointer */
-#endif
-        }
-    }
 
     WebPMemoryWriterInit(&mw);
     pic->custom_ptr = &mw;
@@ -278,7 +53,7 @@ static int libwebp_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     if (!ret) {
         av_log(avctx, AV_LOG_ERROR, "WebPEncode() failed with error: %d\n",
                pic->error_code);
-        ret = libwebp_error_to_averror(pic->error_code);
+        ret = ff_libwebp_error_to_averror(pic->error_code);
         goto end;
     }
 
@@ -305,45 +80,9 @@ end:
 
 static int libwebp_encode_close(AVCodecContext *avctx)
 {
-    LibWebPContext *s  = avctx->priv_data;
-
-    av_frame_free(&s->ref);
-
-    return 0;
+    return ff_libwebp_encode_close_common(avctx);
 }
 
-#define OFFSET(x) offsetof(LibWebPContext, x)
-#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
-static const AVOption options[] = {
-    { "lossless",   "Use lossless mode",       OFFSET(lossless), AV_OPT_TYPE_INT,   { .i64 =  0 },  0, 1,                           VE           },
-    { "preset",     "Configuration preset",    OFFSET(preset),   AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, WEBP_PRESET_TEXT,            VE, "preset" },
-    { "none",       "do not use a preset",                              0, AV_OPT_TYPE_CONST, { .i64 = -1                  }, 0, 0, VE, "preset" },
-    { "default",    "default preset",                                   0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_DEFAULT }, 0, 0, VE, "preset" },
-    { "picture",    "digital picture, like portrait, inner shot",       0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_PICTURE }, 0, 0, VE, "preset" },
-    { "photo",      "outdoor photograph, with natural lighting",        0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_PHOTO   }, 0, 0, VE, "preset" },
-    { "drawing",    "hand or line drawing, with high-contrast details", 0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_DRAWING }, 0, 0, VE, "preset" },
-    { "icon",       "small-sized colorful images",                      0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_ICON    }, 0, 0, VE, "preset" },
-    { "text",       "text-like",                                        0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_TEXT    }, 0, 0, VE, "preset" },
-    { "cr_threshold","Conditional replenishment threshold",     OFFSET(cr_threshold), AV_OPT_TYPE_INT, { .i64 =  0  },  0, INT_MAX, VE           },
-    { "cr_size"     ,"Conditional replenishment block size",    OFFSET(cr_size)     , AV_OPT_TYPE_INT, { .i64 =  16 },  0, 256,     VE           },
-    { "quality"     ,"Quality",                OFFSET(quality),  AV_OPT_TYPE_FLOAT, { .dbl =  75 }, 0, 100,                         VE           },
-    { NULL },
-};
-
-
-static const AVClass class = {
-    .class_name = "libwebp",
-    .item_name  = av_default_item_name,
-    .option     = options,
-    .version    = LIBAVUTIL_VERSION_INT,
-};
-
-static const AVCodecDefault libwebp_defaults[] = {
-    { "compression_level",  "4"  },
-    { "global_quality",     "-1" },
-    { NULL },
-};
-
 AVCodec ff_libwebp_encoder = {
     .name           = "libwebp",
     .long_name      = NULL_IF_CONFIG_SMALL("libwebp WebP image"),
diff --git a/libavcodec/libwebpenc_common.c b/libavcodec/libwebpenc_common.c
new file mode 100644
index 0000000000..373adca756
--- /dev/null
+++ b/libavcodec/libwebpenc_common.c
@@ -0,0 +1,261 @@
+/*
+ * WebP encoding support via libwebp
+ * Copyright (c) 2013 Justin Ruggles <justin.ruggles@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * WebP encoder using libwebp: common structs and methods.
+ */
+
+#include "libwebpenc_common.h"
+
+int ff_libwebp_error_to_averror(int err)
+{
+    switch (err) {
+    case VP8_ENC_ERROR_OUT_OF_MEMORY:
+    case VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY:
+        return AVERROR(ENOMEM);
+    case VP8_ENC_ERROR_NULL_PARAMETER:
+    case VP8_ENC_ERROR_INVALID_CONFIGURATION:
+    case VP8_ENC_ERROR_BAD_DIMENSION:
+        return AVERROR(EINVAL);
+    }
+    return AVERROR_UNKNOWN;
+}
+
+av_cold int ff_libwebp_encode_init_common(AVCodecContext *avctx)
+{
+    LibWebPContextCommon *s = avctx->priv_data;
+    int ret;
+
+    if (avctx->global_quality >= 0)
+        s->quality = av_clipf(avctx->global_quality / (float)FF_QP2LAMBDA,
+                              0.0f, 100.0f);
+
+    if (avctx->compression_level < 0 || avctx->compression_level > 6) {
+        av_log(avctx, AV_LOG_WARNING, "invalid compression level: %d\n",
+               avctx->compression_level);
+        avctx->compression_level = av_clip(avctx->compression_level, 0, 6);
+    }
+
+    if (s->preset >= WEBP_PRESET_DEFAULT) {
+        ret = WebPConfigPreset(&s->config, s->preset, s->quality);
+        if (!ret)
+            return AVERROR_UNKNOWN;
+        s->lossless              = s->config.lossless;
+        s->quality               = s->config.quality;
+        avctx->compression_level = s->config.method;
+    } else {
+        ret = WebPConfigInit(&s->config);
+        if (!ret)
+            return AVERROR_UNKNOWN;
+
+        s->config.lossless = s->lossless;
+        s->config.quality  = s->quality;
+        s->config.method   = avctx->compression_level;
+
+        ret = WebPValidateConfig(&s->config);
+        if (!ret)
+            return AVERROR(EINVAL);
+    }
+
+    av_log(avctx, AV_LOG_DEBUG, "%s - quality=%.1f method=%d\n",
+           s->lossless ? "Lossless" : "Lossy", s->quality,
+           avctx->compression_level);
+
+    return 0;
+}
+
+int ff_libwebp_get_frame(AVCodecContext *avctx, LibWebPContextCommon *s,
+                         const AVFrame *frame, AVFrame **alt_frame_ptr,
+                         WebPPicture **pic_ptr) {
+    int ret;
+    WebPPicture *pic = NULL;
+    AVFrame *alt_frame = NULL;
+
+    if (avctx->width > WEBP_MAX_DIMENSION || avctx->height > WEBP_MAX_DIMENSION) {
+        av_log(avctx, AV_LOG_ERROR, "Picture size is too large. Max is %dx%d.\n",
+               WEBP_MAX_DIMENSION, WEBP_MAX_DIMENSION);
+        return AVERROR(EINVAL);
+    }
+
+    *pic_ptr = av_malloc(sizeof(*pic));
+    pic = *pic_ptr;
+    if (!pic)
+        return AVERROR(ENOMEM);
+
+    ret = WebPPictureInit(pic);
+    if (!ret) {
+        ret = AVERROR_UNKNOWN;
+        goto end;
+    }
+    pic->width  = avctx->width;
+    pic->height = avctx->height;
+
+    if (avctx->pix_fmt == AV_PIX_FMT_RGB32) {
+        if (!s->lossless) {
+            /* libwebp will automatically convert RGB input to YUV when
+               encoding lossy. */
+            if (!s->conversion_warning) {
+                av_log(avctx, AV_LOG_WARNING,
+                       "Using libwebp for RGB-to-YUV conversion. You may want "
+                       "to consider passing in YUV instead for lossy "
+                       "encoding.\n");
+                s->conversion_warning = 1;
+            }
+        }
+        pic->use_argb    = 1;
+        pic->argb        = (uint32_t *)frame->data[0];
+        pic->argb_stride = frame->linesize[0] / 4;
+    } else {
+        if (frame->linesize[1] != frame->linesize[2] || s->cr_threshold) {
+            if (!s->chroma_warning && !s->cr_threshold) {
+                av_log(avctx, AV_LOG_WARNING,
+                       "Copying frame due to differing chroma linesizes.\n");
+                s->chroma_warning = 1;
+            }
+            *alt_frame_ptr = av_frame_alloc();
+            alt_frame = *alt_frame_ptr;
+            if (!alt_frame) {
+                ret = AVERROR(ENOMEM);
+                goto end;
+            }
+            alt_frame->width  = frame->width;
+            alt_frame->height = frame->height;
+            alt_frame->format = frame->format;
+            if (s->cr_threshold)
+                alt_frame->format = AV_PIX_FMT_YUVA420P;
+            ret = av_frame_get_buffer(alt_frame, 32);
+            if (ret < 0)
+                goto end;
+            alt_frame->format = frame->format;
+            av_frame_copy(alt_frame, frame);
+            frame = alt_frame;
+            if (s->cr_threshold) {
+                int x,y, x2, y2, p;
+                int bs = s->cr_size;
+
+                if (!s->ref) {
+                    s->ref = av_frame_clone(frame);
+                    if (!s->ref) {
+                        ret = AVERROR(ENOMEM);
+                        goto end;
+                    }
+                }
+
+                alt_frame->format = AV_PIX_FMT_YUVA420P;
+                for (y = 0; y < frame->height; y+= bs) {
+                    for (x = 0; x < frame->width; x+= bs) {
+                        int skip;
+                        int sse = 0;
+                        for (p = 0; p < 3; p++) {
+                            int bs2 = bs >> !!p;
+                            int w = FF_CEIL_RSHIFT(frame->width , !!p);
+                            int h = FF_CEIL_RSHIFT(frame->height, !!p);
+                            int xs = x >> !!p;
+                            int ys = y >> !!p;
+                            for (y2 = ys; y2 < FFMIN(ys + bs2, h); y2++) {
+                                for (x2 = xs; x2 < FFMIN(xs + bs2, w); x2++) {
+                                    int diff =  frame->data[p][frame->linesize[p] * y2 + x2]
+                                              -s->ref->data[p][frame->linesize[p] * y2 + x2];
+                                    sse += diff*diff;
+                                }
+                            }
+                        }
+                        skip = sse < s->cr_threshold && frame->data[3] != s->ref->data[3];
+                        if (!skip)
+                            for (p = 0; p < 3; p++) {
+                                int bs2 = bs >> !!p;
+                                int w = FF_CEIL_RSHIFT(frame->width , !!p);
+                                int h = FF_CEIL_RSHIFT(frame->height, !!p);
+                                int xs = x >> !!p;
+                                int ys = y >> !!p;
+                                for (y2 = ys; y2 < FFMIN(ys + bs2, h); y2++) {
+                                    memcpy(&s->ref->data[p][frame->linesize[p] * y2 + xs],
+                                            & frame->data[p][frame->linesize[p] * y2 + xs], FFMIN(bs2, w-xs));
+                                }
+                            }
+                        for (y2 = y; y2 < FFMIN(y+bs, frame->height); y2++) {
+                            memset(&frame->data[3][frame->linesize[3] * y2 + x],
+                                    skip ? 0 : 255,
+                                    FFMIN(bs, frame->width-x));
+                        }
+                    }
+                }
+            }
+        }
+
+        pic->use_argb  = 0;
+        pic->y         = frame->data[0];
+        pic->u         = frame->data[1];
+        pic->v         = frame->data[2];
+        pic->y_stride  = frame->linesize[0];
+        pic->uv_stride = frame->linesize[1];
+        if (frame->format == AV_PIX_FMT_YUVA420P) {
+            pic->colorspace = WEBP_YUV420A;
+            pic->a          = frame->data[3];
+            pic->a_stride   = frame->linesize[3];
+            if (alt_frame)
+                WebPCleanupTransparentArea(pic);
+        } else {
+            pic->colorspace = WEBP_YUV420;
+        }
+
+        if (s->lossless) {
+            /* We do not have a way to automatically prioritize RGB over YUV
+               in automatic pixel format conversion based on whether we're
+               encoding lossless or lossy, so we do conversion with libwebp as
+               a convenience. */
+            if (!s->conversion_warning) {
+                av_log(avctx, AV_LOG_WARNING,
+                       "Using libwebp for YUV-to-RGB conversion. You may want "
+                       "to consider passing in RGB instead for lossless "
+                       "encoding.\n");
+                s->conversion_warning = 1;
+            }
+
+#if (WEBP_ENCODER_ABI_VERSION <= 0x201)
+            /* libwebp should do the conversion automatically, but there is a
+               bug that causes it to return an error instead, so a work-around
+               is required.
+               See https://code.google.com/p/webp/issues/detail?id=178 */
+            pic->memory_ = (void*)1;  /* something non-null */
+            ret = WebPPictureYUVAToARGB(pic);
+            if (!ret) {
+                av_log(avctx, AV_LOG_ERROR,
+                       "WebPPictureYUVAToARGB() failed with error: %d\n",
+                       pic->error_code);
+                ret = libwebp_error_to_averror(pic->error_code);
+                goto end;
+            }
+            pic->memory_ = NULL;  /* restore pointer */
+#endif
+        }
+    }
+end:
+    return ret;
+}
+
+int ff_libwebp_encode_close_common(AVCodecContext *avctx)
+{
+    LibWebPContextCommon *s  = avctx->priv_data;
+    av_frame_free(&s->ref);
+    return 0;
+}
diff --git a/libavcodec/libwebpenc_common.h b/libavcodec/libwebpenc_common.h
new file mode 100644
index 0000000000..ea2410ceac
--- /dev/null
+++ b/libavcodec/libwebpenc_common.h
@@ -0,0 +1,89 @@
+/*
+ * WebP encoding support via libwebp
+ * Copyright (c) 2013 Justin Ruggles <justin.ruggles@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * WebP encoder using libwebp: common structs and methods.
+ */
+
+#include <webp/encode.h>
+
+#include "libavutil/common.h"
+#include "libavutil/frame.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "avcodec.h"
+#include "internal.h"
+
+typedef struct LibWebPContextCommon {
+    AVClass *class;         // class for AVOptions
+    float quality;          // lossy quality 0 - 100
+    int lossless;           // use lossless encoding
+    int preset;             // configuration preset
+    int chroma_warning;     // chroma linesize mismatch warning has been printed
+    int conversion_warning; // pixel format conversion warning has been printed
+    WebPConfig config;      // libwebp configuration
+    AVFrame *ref;
+    int cr_size;
+    int cr_threshold;
+} LibWebPContextCommon;
+
+int ff_libwebp_error_to_averror(int err);
+
+av_cold int ff_libwebp_encode_init_common(AVCodecContext *avctx);
+
+int ff_libwebp_get_frame(AVCodecContext *avctx, LibWebPContextCommon *s,
+                         const AVFrame *frame, AVFrame **alt_frame_ptr,
+                         WebPPicture **pic_ptr);
+
+int ff_libwebp_encode_close_common(AVCodecContext *avctx);
+
+#define OFFSET(x) offsetof(LibWebPContextCommon, x)
+#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
+static const AVOption options[] = {
+    { "lossless",   "Use lossless mode",       OFFSET(lossless), AV_OPT_TYPE_INT,   { .i64 =  0 },  0, 1,                           VE           },
+    { "preset",     "Configuration preset",    OFFSET(preset),   AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, WEBP_PRESET_TEXT,            VE, "preset" },
+    { "none",       "do not use a preset",                              0, AV_OPT_TYPE_CONST, { .i64 = -1                  }, 0, 0, VE, "preset" },
+    { "default",    "default preset",                                   0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_DEFAULT }, 0, 0, VE, "preset" },
+    { "picture",    "digital picture, like portrait, inner shot",       0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_PICTURE }, 0, 0, VE, "preset" },
+    { "photo",      "outdoor photograph, with natural lighting",        0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_PHOTO   }, 0, 0, VE, "preset" },
+    { "drawing",    "hand or line drawing, with high-contrast details", 0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_DRAWING }, 0, 0, VE, "preset" },
+    { "icon",       "small-sized colorful images",                      0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_ICON    }, 0, 0, VE, "preset" },
+    { "text",       "text-like",                                        0, AV_OPT_TYPE_CONST, { .i64 = WEBP_PRESET_TEXT    }, 0, 0, VE, "preset" },
+    { "cr_threshold","Conditional replenishment threshold",     OFFSET(cr_threshold), AV_OPT_TYPE_INT, { .i64 =  0  },  0, INT_MAX, VE           },
+    { "cr_size"     ,"Conditional replenishment block size",    OFFSET(cr_size)     , AV_OPT_TYPE_INT, { .i64 =  16 },  0, 256,     VE           },
+    { "quality"     ,"Quality",                OFFSET(quality),  AV_OPT_TYPE_FLOAT, { .dbl =  75 }, 0, 100,                         VE           },
+    { NULL },
+};
+
+
+static const AVClass class = {
+    .class_name = "libwebp",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static const AVCodecDefault libwebp_defaults[] = {
+    { "compression_level",  "4"  },
+    { "global_quality",     "-1" },
+    { NULL },
+};