avcodec/libwebpenc: support "P" frames in webp animations

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

libavcodec/libwebpenc.c

@@ -41,6 +41,9 @@ typedef struct LibWebPContext {
     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)
@@ -144,8 +147,8 @@ static int libwebp_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         pic->argb        = (uint32_t *)frame->data[0];
         pic->argb_stride = frame->linesize[0] / 4;
     } else {
-        if (frame->linesize[1] != frame->linesize[2]) {
-            if (!s->chroma_warning) {
+        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;
@@ -158,22 +161,80 @@ static int libwebp_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
             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 (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) {
+        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;
         }
@@ -243,6 +304,15 @@ end:
     return ret;
 }
 
+static int libwebp_encode_close(AVCodecContext *avctx)
+{
+    LibWebPContext *s  = avctx->priv_data;
+
+    av_frame_free(&s->ref);
+
+    return 0;
+}
+
 #define OFFSET(x) offsetof(LibWebPContext, x)
 #define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
@@ -255,9 +325,12 @@ static const AVOption options[] = {
     { "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           },
     { NULL },
 };
 
+
 static const AVClass class = {
     .class_name = "libwebp",
     .item_name  = av_default_item_name,
@@ -279,6 +352,7 @@ AVCodec ff_libwebp_encoder = {
     .priv_data_size = sizeof(LibWebPContext),
     .init           = libwebp_encode_init,
     .encode2        = libwebp_encode_frame,
+    .close          = libwebp_encode_close,
     .pix_fmts       = (const enum AVPixelFormat[]) {
         AV_PIX_FMT_RGB32,
         AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUVA420P,

libavcodec/version.h

@@ -30,7 +30,7 @@
 
 #define LIBAVCODEC_VERSION_MAJOR 56
 #define LIBAVCODEC_VERSION_MINOR  10
-#define LIBAVCODEC_VERSION_MICRO 100
+#define LIBAVCODEC_VERSION_MICRO 101
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \