lavfi: add video buffer sink, and use it in avtools

Also add the public interface libavfilter/buffersink.h.

Based on a commit by Stefano Sabatini.

1 files changed, 114 insertions, 0 deletions

diff --git a/libavfilter/buffersink.c b/libavfilter/buffersink.c
new file mode 100644
index 0000000000..e4cbe3be42
--- /dev/null
+++ b/libavfilter/buffersink.c
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2011 Stefano Sabatini
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * buffer sink
+ */
+
+#include "libavutil/fifo.h"
+
+#include "avfilter.h"
+#include "buffersink.h"
+
+typedef struct {
+    AVFifoBuffer *fifo;          ///< FIFO buffer of video frame references
+} BufferSinkContext;
+
+#define FIFO_INIT_SIZE 8
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    BufferSinkContext *sink = ctx->priv;
+
+    while (sink->fifo && av_fifo_size(sink->fifo)) {
+        AVFilterBufferRef *buf;
+        av_fifo_generic_read(sink->fifo, &buf, sizeof(buf), NULL);
+        avfilter_unref_buffer(buf);
+    }
+    av_fifo_free(sink->fifo);
+}
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    BufferSinkContext *sink = ctx->priv;
+
+    if (!(sink->fifo = av_fifo_alloc(FIFO_INIT_SIZE*sizeof(AVFilterBufferRef*)))) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to allocate fifo\n");
+        return AVERROR(ENOMEM);
+    }
+
+    return 0;
+}
+
+static void end_frame(AVFilterLink *link)
+{
+    AVFilterContext   *ctx = link->dst;
+    BufferSinkContext *sink = ctx->priv;
+
+    if (av_fifo_space(sink->fifo) < sizeof(AVFilterBufferRef *) &&
+        (av_fifo_realloc2(sink->fifo, av_fifo_size(sink->fifo) * 2) < 0)) {
+            av_log(ctx, AV_LOG_ERROR, "Error reallocating the FIFO.\n");
+            return;
+    }
+
+    av_fifo_generic_write(sink->fifo, &link->cur_buf, sizeof(link->cur_buf), NULL);
+    link->cur_buf = NULL;
+}
+
+int av_buffersink_read(AVFilterContext *ctx, AVFilterBufferRef **buf)
+{
+    BufferSinkContext *sink = ctx->priv;
+    AVFilterLink      *link = ctx->inputs[0];
+    int ret;
+
+    if (!buf) {
+        if (av_fifo_size(sink->fifo))
+            return av_fifo_size(sink->fifo)/sizeof(*buf);
+        else
+            return avfilter_poll_frame(ctx->inputs[0]);
+    }
+
+    if (!av_fifo_size(sink->fifo) &&
+        (ret = avfilter_request_frame(link)) < 0)
+        return ret;
+
+    if (!av_fifo_size(sink->fifo))
+        return AVERROR(EINVAL);
+
+    av_fifo_generic_read(sink->fifo, buf, sizeof(*buf), NULL);
+
+    return 0;
+}
+
+AVFilter avfilter_vsink_buffer = {
+    .name      = "buffersink",
+    .description = NULL_IF_CONFIG_SMALL("Buffer video frames, and make them available to the end of the filter graph."),
+    .priv_size = sizeof(BufferSinkContext),
+    .init      = init,
+    .uninit    = uninit,
+
+    .inputs    = (AVFilterPad[]) {{ .name          = "default",
+                                    .type          = AVMEDIA_TYPE_VIDEO,
+                                    .end_frame     = end_frame,
+                                    .min_perms     = AV_PERM_READ, },
+                                  { .name = NULL }},
+    .outputs   = (AVFilterPad[]) {{ .name = NULL }},
+};