diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
index 50ba8fbcf8..af06a9172f 100644
--- a/libavfilter/avfiltergraph.c
+++ b/libavfilter/avfiltergraph.c
@@ -28,9 +28,23 @@
 #include "avfiltergraph.h"
 #include "internal.h"
 
+#include "libavutil/log.h"
+
+static const AVClass filtergraph_class = {
+    .class_name = "AVFilterGraph",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 AVFilterGraph *avfilter_graph_alloc(void)
 {
-    return av_mallocz(sizeof(AVFilterGraph));
+    AVFilterGraph *ret = av_mallocz(sizeof(AVFilterGraph));
+    if (!ret)
+        return NULL;
+#if FF_API_GRAPH_AVCLASS
+    ret->av_class = &filtergraph_class;
+#endif
+    return ret;
 }
 
 void avfilter_graph_free(AVFilterGraph **graph)
@@ -261,6 +275,49 @@ static void pick_format(AVFilterLink *link)
     }
 }
 
+static int reduce_formats_on_filter(AVFilterContext *filter)
+{
+    int i, j, k, ret = 0;
+
+    for (i = 0; i < filter->input_count; i++) {
+        AVFilterLink *link = filter->inputs[i];
+        int         format = link->out_formats->formats[0];
+
+        if (link->out_formats->format_count != 1)
+            continue;
+
+        for (j = 0; j < filter->output_count; j++) {
+            AVFilterLink *out_link = filter->outputs[j];
+            AVFilterFormats  *fmts = out_link->in_formats;
+
+            if (link->type != out_link->type ||
+                out_link->in_formats->format_count == 1)
+                continue;
+
+            for (k = 0; k < out_link->in_formats->format_count; k++)
+                if (fmts->formats[k] == format) {
+                    fmts->formats[0]   = format;
+                    fmts->format_count = 1;
+                    ret = 1;
+                    break;
+                }
+        }
+    }
+    return ret;
+}
+
+static void reduce_formats(AVFilterGraph *graph)
+{
+    int i, reduced;
+
+    do {
+        reduced = 0;
+
+        for (i = 0; i < graph->filter_count; i++)
+            reduced |= reduce_formats_on_filter(graph->filters[i]);
+    } while (reduced);
+}
+
 static void pick_formats(AVFilterGraph *graph)
 {
     int i, j;
@@ -284,7 +341,10 @@ int ff_avfilter_graph_config_formats(AVFilterGraph *graph, AVClass *log_ctx)
         return ret;
 
     /* Once everything is merged, it's possible that we'll still have
-     * multiple valid media format choices. We pick the first one. */
+     * multiple valid media format choices. We try to minimize the amount
+     * of format conversion inside filters */
+    reduce_formats(graph);
+
     pick_formats(graph);
 
     return 0;
diff --git a/libavfilter/avfiltergraph.h b/libavfilter/avfiltergraph.h
index 375ab8efbc..cca9488f87 100644
--- a/libavfilter/avfiltergraph.h
+++ b/libavfilter/avfiltergraph.h
@@ -23,8 +23,12 @@
 #define AVFILTER_AVFILTERGRAPH_H
 
 #include "avfilter.h"
+#include "libavutil/log.h"
 
 typedef struct AVFilterGraph {
+#if FF_API_GRAPH_AVCLASS
+    const AVClass *av_class;
+#endif
     unsigned filter_count;
     AVFilterContext **filters;
 
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 6269bf88f0..c169ed25fc 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -40,4 +40,12 @@
                                            LIBAVFILTER_VERSION_MICRO)
 #define LIBAVFILTER_BUILD       LIBAVFILTER_VERSION_INT
 
+/**
+ * Those FF_API_* defines are not part of public API.
+ * They may change, break or disappear at any time.
+ */
+#ifndef FF_API_GRAPH_AVCLASS
+#define FF_API_GRAPH_AVCLASS            (LIBAVFILTER_VERSION_MAJOR > 2)
+#endif
+
 #endif // AVFILTER_VERSION_H
diff --git a/libavfilter/vf_scale.c b/libavfilter/vf_scale.c
index 692e2c5a14..deb7009fa1 100644
--- a/libavfilter/vf_scale.c
+++ b/libavfilter/vf_scale.c
@@ -214,21 +214,26 @@ static int config_props(AVFilterLink *outlink)
 
     if (scale->sws)
         sws_freeContext(scale->sws);
-    scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
-                                outlink->w, outlink->h, outfmt,
-                                scale->flags, NULL, NULL, NULL);
-    if (scale->isws[0])
-        sws_freeContext(scale->isws[0]);
-    scale->isws[0] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,
-                                    outlink->w, outlink->h/2, outfmt,
+    if (inlink->w == outlink->w && inlink->h == outlink->h &&
+        inlink->format == outlink->format)
+        scale->sws = NULL;
+    else {
+        scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
+                                    outlink->w, outlink->h, outfmt,
                                     scale->flags, NULL, NULL, NULL);
-    if (scale->isws[1])
-        sws_freeContext(scale->isws[1]);
-    scale->isws[1] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,
-                                    outlink->w, outlink->h/2, outfmt,
-                                    scale->flags, NULL, NULL, NULL);
-    if (!scale->sws || !scale->isws[0] || !scale->isws[1])
-        return AVERROR(EINVAL);
+        if (scale->isws[0])
+            sws_freeContext(scale->isws[0]);
+        scale->isws[0] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,
+                                        outlink->w, outlink->h/2, outfmt,
+                                        scale->flags, NULL, NULL, NULL);
+        if (scale->isws[1])
+            sws_freeContext(scale->isws[1]);
+        scale->isws[1] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,
+                                        outlink->w, outlink->h/2, outfmt,
+                                        scale->flags, NULL, NULL, NULL);
+        if (!scale->sws || !scale->isws[0] || !scale->isws[1])
+            return AVERROR(EINVAL);
+    }
 
     if (inlink->sample_aspect_ratio.num){
         outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h * inlink->w, outlink->w * inlink->h}, inlink->sample_aspect_ratio);
@@ -257,6 +262,11 @@ static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
     AVFilterLink *outlink = link->dst->outputs[0];
     AVFilterBufferRef *outpicref;
 
+    if (!scale->sws) {
+        avfilter_start_frame(outlink, avfilter_ref_buffer(picref, ~0));
+        return;
+    }
+
     scale->hsub = av_pix_fmt_descriptors[link->format].log2_chroma_w;
     scale->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;
 
@@ -307,6 +317,11 @@ static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
     ScaleContext *scale = link->dst->priv;
     int out_h;
 
+    if (!scale->sws) {
+        avfilter_draw_slice(link->dst->outputs[0], y, h, slice_dir);
+        return;
+    }
+
     if (scale->slice_y == 0 && slice_dir == -1)
         scale->slice_y = link->dst->outputs[0]->h;
 
diff --git a/libavfilter/vsrc_buffer.c b/libavfilter/vsrc_buffer.c
index dbccbe07fb..61d66468d5 100644
--- a/libavfilter/vsrc_buffer.c
+++ b/libavfilter/vsrc_buffer.c
@@ -28,11 +28,12 @@
 #include "avcodec.h"
 #include "buffersrc.h"
 #include "vsrc_buffer.h"
+#include "libavutil/fifo.h"
 #include "libavutil/imgutils.h"
 
 typedef struct {
-    AVFilterBufferRef *picref;
-    AVFilterContext   *scale;
+    AVFilterContext  *scale;
+    AVFifoBuffer     *fifo;
     int               h, w;
     enum PixelFormat  pix_fmt;
     AVRational        time_base;     ///< time_base to set in the output link
@@ -51,19 +52,18 @@ int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_filter,
 {
     BufferSourceContext *c = buffer_filter->priv;
     AVFilterLink *outlink = buffer_filter->outputs[0];
+    AVFilterBufferRef *buf;
     int ret;
 
-    if (c->picref) {
+    if (av_fifo_size(c->fifo)) {
         if (flags & AV_VSRC_BUF_FLAG_OVERWRITE) {
-            avfilter_unref_buffer(c->picref);
-            c->picref = NULL;
-        } else {
-            av_log(buffer_filter, AV_LOG_ERROR,
-                   "Buffering several frames is not supported. "
-                   "Please consume all available frames before adding a new one.\n");
-            return AVERROR(EINVAL);
+            //FIXME not implemented
         }
     }
+    if (!av_fifo_space(c->fifo) &&
+        (ret = av_fifo_realloc2(c->fifo, av_fifo_size(c->fifo) +
+                                         sizeof(buf))) < 0)
+        return ret;
 
     if (picref->video->w != c->w || picref->video->h != c->h || picref->format != c->pix_fmt) {
         AVFilterContext *scale = buffer_filter->outputs[0]->dst;
@@ -110,12 +110,17 @@ int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_filter,
             return ret;
     }
 
-    c->picref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE,
-                                          picref->video->w, picref->video->h);
-    av_image_copy(c->picref->data, c->picref->linesize,
+    buf = avfilter_get_video_buffer(outlink, AV_PERM_WRITE,
+                                    picref->video->w, picref->video->h);
+    av_image_copy(buf->data, buf->linesize,
                   (void*)picref->data, picref->linesize,
                   picref->format, picref->video->w, picref->video->h);
-    avfilter_copy_buffer_ref_props(c->picref, picref);
+    avfilter_copy_buffer_ref_props(buf, picref);
+
+    if ((ret = av_fifo_generic_write(c->fifo, &buf, sizeof(buf), NULL)) < 0) {
+        avfilter_unref_buffer(buf);
+        return ret;
+    }
 
     return 0;
 }
@@ -123,18 +128,17 @@ int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_filter,
 int av_buffersrc_buffer(AVFilterContext *s, AVFilterBufferRef *buf)
 {
     BufferSourceContext *c = s->priv;
+    int ret;
 
-    if (c->picref) {
-        av_log(s, AV_LOG_ERROR,
-               "Buffering several frames is not supported. "
-               "Please consume all available frames before adding a new one.\n"
-            );
-        return AVERROR(EINVAL);
-    }
+    if (!av_fifo_space(c->fifo) &&
+        (ret = av_fifo_realloc2(c->fifo, av_fifo_size(c->fifo) +
+                                         sizeof(buf))) < 0)
+        return ret;
 
 //     CHECK_PARAM_CHANGE(s, c, buf->video->w, buf->video->h, buf->format);
 
-    c->picref = buf;
+    if ((ret = av_fifo_generic_write(c->fifo, &buf, sizeof(buf), NULL)) < 0)
+        return ret;
 
     return 0;
 }
@@ -176,6 +180,9 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
     if ((ret = ff_parse_pixel_format(&c->pix_fmt, pix_fmt_str, ctx)) < 0)
         return ret;
 
+    if (!(c->fifo = av_fifo_alloc(sizeof(AVFilterBufferRef*))))
+        return AVERROR(ENOMEM);
+
     av_log(ctx, AV_LOG_INFO, "w:%d h:%d pixfmt:%s tb:%d/%d sar:%d/%d sws_param:%s\n",
            c->w, c->h, av_pix_fmt_descriptors[c->pix_fmt].name,
            c->time_base.num, c->time_base.den,
@@ -186,9 +193,13 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 static av_cold void uninit(AVFilterContext *ctx)
 {
     BufferSourceContext *s = ctx->priv;
-    if (s->picref)
-        avfilter_unref_buffer(s->picref);
-    s->picref = NULL;
+    while (av_fifo_size(s->fifo)) {
+        AVFilterBufferRef *buf;
+        av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);
+        avfilter_unref_buffer(buf);
+    }
+    av_fifo_free(s->fifo);
+    s->fifo = NULL;
     avfilter_free(s->scale);
     s->scale = NULL;
 }
@@ -217,18 +228,19 @@ static int config_props(AVFilterLink *link)
 static int request_frame(AVFilterLink *link)
 {
     BufferSourceContext *c = link->src->priv;
+    AVFilterBufferRef *buf;
 
-    if (!c->picref) {
+    if (!av_fifo_size(c->fifo)) {
         av_log(link->src, AV_LOG_WARNING,
                "request_frame() called with no available frame!\n");
         return AVERROR(EINVAL);
     }
+    av_fifo_generic_read(c->fifo, &buf, sizeof(buf), NULL);
 
-    avfilter_start_frame(link, avfilter_ref_buffer(c->picref, ~0));
+    avfilter_start_frame(link, avfilter_ref_buffer(buf, ~0));
     avfilter_draw_slice(link, 0, link->h, 1);
     avfilter_end_frame(link);
-    avfilter_unref_buffer(c->picref);
-    c->picref = NULL;
+    avfilter_unref_buffer(buf);
 
     return 0;
 }
@@ -236,7 +248,7 @@ static int request_frame(AVFilterLink *link)
 static int poll_frame(AVFilterLink *link)
 {
     BufferSourceContext *c = link->src->priv;
-    return !!c->picref;
+    return !!av_fifo_size(c->fifo);
 }
 
 AVFilter avfilter_vsrc_buffer = {
diff --git a/libavformat/id3v2.c b/libavformat/id3v2.c
index 16eff7e27d..1352b57b63 100644
--- a/libavformat/id3v2.c
+++ b/libavformat/id3v2.c
@@ -577,21 +577,21 @@ static void ff_id3v2_parse(AVFormatContext *s, int len, uint8_t version, uint8_t
 
     unsync = flags & 0x80;
 
-    /* Extended header present, just skip over it */
-    if (isv34 && flags & 0x40) {
-        int size = get_size(s->pb, 4);
-        if (size < 6) {
-            reason = "extended header too short.";
+    if (isv34 && flags & 0x40) { /* Extended header present, just skip over it */
+        int extlen = get_size(s->pb, 4);
+        if (version == 4)
+            extlen -= 4;     // in v2.4 the length includes the length field we just read
+
+        if (extlen < 0) {
+            reason = "invalid extended header length";
             goto error;
         }
-        len -= size;
+        avio_skip(s->pb, extlen);
+        len -= extlen + 4;
         if (len < 0) {
             reason = "extended header too long.";
             goto error;
         }
-        /* already seeked past size, skip the reset */
-        size -= 4;
-        avio_skip(s->pb, size);
     }
 
     while (len >= taghdrlen) {