libvpx: Add VP9 decoder.

source/libvpx/vp9/encoder/vp9_lookahead.c

+/*
+ *  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 "vp9/encoder/vp9_lookahead.h"
+#include "vp9/common/vp9_extend.h"
+
+#define MAX_LAG_BUFFERS 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
+vp9_lookahead_destroy(struct lookahead_ctx *ctx) {
+  if (ctx) {
+    if (ctx->buf) {
+      unsigned 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 *
+vp9_lookahead_init(unsigned int width,
+                   unsigned int height,
+                   unsigned int depth) {
+  struct lookahead_ctx *ctx = NULL;
+
+  /* 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) {
+    unsigned int i;
+    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, VP9BORDERINPIXELS))
+        goto bail;
+  }
+  return ctx;
+bail:
+  vp9_lookahead_destroy(ctx);
+  return NULL;
+}
+
+
+int
+vp9_lookahead_push(struct lookahead_ctx *ctx,
+                   YV12_BUFFER_CONFIG   *src,
+                   int64_t               ts_start,
+                   int64_t               ts_end,
+                   unsigned int          flags,
+                   unsigned char        *active_map) {
+  struct lookahead_entry *buf;
+  int row, col, active_end;
+  int mb_rows = (src->y_height + 15) >> 4;
+  int mb_cols = (src->y_width + 15) >> 4;
+
+  if (ctx->sz + 1 > ctx->max_sz)
+    return 1;
+  ctx->sz++;
+  buf = pop(ctx, &ctx->write_idx);
+
+  // Only do this partial copy if the following conditions are all met:
+  // 1. Lookahead queue has has size of 1.
+  // 2. Active map is provided.
+  // 3. This is not a key frame, golden nor altref frame.
+  if (ctx->max_sz == 1 && active_map && !flags) {
+    for (row = 0; row < mb_rows; ++row) {
+      col = 0;
+
+      while (1) {
+        // Find the first active macroblock in this row.
+        for (; col < mb_cols; ++col) {
+          if (active_map[col])
+            break;
+        }
+
+        // No more active macroblock in this row.
+        if (col == mb_cols)
+          break;
+
+        // Find the end of active region in this row.
+        active_end = col;
+
+        for (; active_end < mb_cols; ++active_end) {
+          if (!active_map[active_end])
+            break;
+        }
+
+        // Only copy this active region.
+        vp9_copy_and_extend_frame_with_rect(src, &buf->img,
+                                            row << 4,
+                                            col << 4, 16,
+                                            (active_end - col) << 4);
+
+        // Start again from the end of this active region.
+        col = active_end;
+      }
+
+      active_map += mb_cols;
+    }
+  } else {
+    vp9_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 *
+vp9_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 *
+vp9_lookahead_peek(struct lookahead_ctx *ctx,
+                   int                   index) {
+  struct lookahead_entry *buf = NULL;
+
+  assert(index < ctx->max_sz);
+  if (index < (int)ctx->sz) {
+    index += ctx->read_idx;
+    if (index >= (int)ctx->max_sz)
+      index -= ctx->max_sz;
+    buf = ctx->buf + index;
+  }
+  return buf;
+}
+
+
+unsigned int
+vp9_lookahead_depth(struct lookahead_ctx *ctx) {
+  return ctx->sz;
+}