1 files changed, 157 insertions, 0 deletions
diff --git a/vp8/encoder/lookahead.c b/vp8/encoder/lookahead.c
new file mode 100644
index 000000000..3b86d4094
--- /dev/null
+++ b/vp8/encoder/lookahead.c
@@ -0,0 +1,157 @@
+/*
+ *  Copyright (c) 2011 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE 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.
+ */
+#include <assert.h>
+#include <stdlib.h>
+#include "vpx_config.h"
+#include "lookahead.h"
+#include "vp8/common/extend.h"
+
+#define MAX_LAG_BUFFERS (CONFIG_REALTIME_ONLY? 1 : 25)
+
+struct lookahead_ctx
+{
+    unsigned int max_sz;         /* Absolute size of the queue */
+    unsigned int sz;             /* Number of buffers currently in the queue */
+    unsigned int read_idx;       /* Read index */
+    unsigned int write_idx;      /* Write index */
+    struct lookahead_entry *buf; /* Buffer list */
+};
+
+
+/* Return the buffer at the given absolute index and increment the index */
+static struct lookahead_entry *
+pop(struct lookahead_ctx *ctx,
+    unsigned int         *idx)
+{
+    unsigned int            index = *idx;
+    struct lookahead_entry *buf = ctx->buf + index;
+
+    assert(index < ctx->max_sz);
+    if(++index >= ctx->max_sz)
+        index -= ctx->max_sz;
+    *idx = index;
+    return buf;
+}
+
+
+void
+vp8_lookahead_destroy(struct lookahead_ctx *ctx)
+{
+    if(ctx)
+    {
+        if(ctx->buf)
+        {
+            int i;
+
+            for(i = 0; i < ctx->max_sz; i++)
+                vp8_yv12_de_alloc_frame_buffer(&ctx->buf[i].img);
+            free(ctx->buf);
+        }
+        free(ctx);
+    }
+}
+
+
+struct lookahead_ctx*
+vp8_lookahead_init(unsigned int width,
+                   unsigned int height,
+                   unsigned int depth)
+{
+    struct lookahead_ctx *ctx = NULL;
+    int i;
+
+    /* Clamp the lookahead queue depth */
+    if(depth < 1)
+        depth = 1;
+    else if(depth > MAX_LAG_BUFFERS)
+        depth = MAX_LAG_BUFFERS;
+
+    /* Align the buffer dimensions */
+    width = (width + 15) & ~15;
+    height = (height + 15) & ~15;
+
+    /* Allocate the lookahead structures */
+    ctx = calloc(1, sizeof(*ctx));
+    if(ctx)
+    {
+        ctx->max_sz = depth;
+        ctx->buf = calloc(depth, sizeof(*ctx->buf));
+        if(!ctx->buf)
+            goto bail;
+        for(i=0; i<depth; i++)
+            if (vp8_yv12_alloc_frame_buffer(&ctx->buf[i].img, width, height, 16))
+                goto bail;
+    }
+    return ctx;
+bail:
+    vp8_lookahead_destroy(ctx);
+    return NULL;
+}
+
+
+int
+vp8_lookahead_push(struct lookahead_ctx *ctx,
+                   YV12_BUFFER_CONFIG   *src,
+                   int64_t               ts_start,
+                   int64_t               ts_end,
+                   unsigned int          flags)
+{
+    struct lookahead_entry* buf;
+
+    if(ctx->sz + 1 > ctx->max_sz)
+        return 1;
+    ctx->sz++;
+    buf = pop(ctx, &ctx->write_idx);
+    vp8_copy_and_extend_frame(src, &buf->img);
+    buf->ts_start = ts_start;
+    buf->ts_end = ts_end;
+    buf->flags = flags;
+    return 0;
+}
+
+
+struct lookahead_entry*
+vp8_lookahead_pop(struct lookahead_ctx *ctx,
+                  int                   drain)
+{
+    struct lookahead_entry* buf = NULL;
+
+    if(ctx->sz && (drain || ctx->sz == ctx->max_sz))
+    {
+        buf = pop(ctx, &ctx->read_idx);
+        ctx->sz--;
+    }
+    return buf;
+}
+
+
+struct lookahead_entry*
+vp8_lookahead_peek(struct lookahead_ctx *ctx,
+                   int                   index)
+{
+    struct lookahead_entry* buf = NULL;
+
+    assert(index < ctx->max_sz);
+    if(index < ctx->sz)
+    {
+        index += ctx->read_idx;
+        if(index >= ctx->max_sz)
+            index -= ctx->max_sz;
+        buf = ctx->buf + index;
+    }
+    return buf;
+}
+
+
+unsigned int
+vp8_lookahead_depth(struct lookahead_ctx *ctx)
+{
+    return ctx->sz;
+}