vpx_scale/generic/yv12config.c

/*
 *  Copyright (c) 2010 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 "vpx_scale/yv12config.h"
#include "vpx_mem/vpx_mem.h"

/****************************************************************************
*  Exports
****************************************************************************/

/****************************************************************************
 *
 ****************************************************************************/
int
vp8_yv12_de_alloc_frame_buffer(YV12_BUFFER_CONFIG *ybf) {
  if (ybf) {
    vpx_free(ybf->buffer_alloc);

    /* buffer_alloc isn't accessed by most functions.  Rather y_buffer,
      u_buffer and v_buffer point to buffer_alloc and are used.  Clear out
      all of this so that a freed pointer isn't inadvertently used */
    vpx_memset(ybf, 0, sizeof(YV12_BUFFER_CONFIG));
  } else {
    return -1;
  }

  return 0;
}

int vp8_yv12_realloc_frame_buffer(YV12_BUFFER_CONFIG *ybf,
                                  int width, int height, int border) {
  if (ybf) {
    int aligned_width = (width + 15) & ~15;
    int aligned_height = (height + 15) & ~15;
    int y_stride = ((aligned_width + 2 * border) + 31) & ~31;
    int yplane_size = (aligned_height + 2 * border) * y_stride;
    int uv_width = aligned_width >> 1;
    int uv_height = aligned_height >> 1;
    /** There is currently a bunch of code which assumes
      *  uv_stride == y_stride/2, so enforce this here. */
    int uv_stride = y_stride >> 1;
    int uvplane_size = (uv_height + border) * uv_stride;
    const int frame_size = yplane_size + 2 * uvplane_size;

    if (!ybf->buffer_alloc) {
      ybf->buffer_alloc = vpx_memalign(32, frame_size);
      ybf->buffer_alloc_sz = frame_size;
    }

    if (!ybf->buffer_alloc || ybf->buffer_alloc_sz < frame_size)
      return -1;

    /* Only support allocating buffers that have a border that's a multiple
     * of 32. The border restriction is required to get 16-byte alignment of
     * the start of the chroma rows without intoducing an arbitrary gap
     * between planes, which would break the semantics of things like
     * vpx_img_set_rect(). */
    if (border & 0x1f)
      return -3;

    ybf->y_crop_width = width;
    ybf->y_crop_height = height;
    ybf->y_width  = aligned_width;
    ybf->y_height = aligned_height;
    ybf->y_stride = y_stride;

    ybf->uv_width = uv_width;
    ybf->uv_height = uv_height;
    ybf->uv_stride = uv_stride;

    ybf->border = border;
    ybf->frame_size = frame_size;

    ybf->y_buffer = ybf->buffer_alloc + (border * y_stride) + border;
    ybf->u_buffer = ybf->buffer_alloc + yplane_size + (border / 2  * uv_stride) + border / 2;
    ybf->v_buffer = ybf->buffer_alloc + yplane_size + uvplane_size + (border / 2  * uv_stride) + border / 2;

    ybf->corrupted = 0; /* assume not currupted by errors */
    return 0;
  }
  return -2;
}

int vp8_yv12_alloc_frame_buffer(YV12_BUFFER_CONFIG *ybf,
                                int width, int height, int border) {
  if (ybf) {
    vp8_yv12_de_alloc_frame_buffer(ybf);
    return vp8_yv12_realloc_frame_buffer(ybf, width, height, border);
  }
  return -2;
}