/*
 *  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 <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <limits.h>

#include "./vpx_config.h"

#if CONFIG_LIBYUV
#include "third_party/libyuv/include/libyuv/scale.h"
#endif

#include "./args.h"
#include "./ivfdec.h"

#include "vpx/vpx_decoder.h"
#include "vpx_ports/mem_ops.h"
#include "vpx_ports/vpx_timer.h"

#if CONFIG_VP8_DECODER || CONFIG_VP9_DECODER
#include "vpx/vp8dx.h"
#endif

#include "./md5_utils.h"

#include "./tools_common.h"
#if CONFIG_WEBM_IO
#include "./webmdec.h"
#endif
#include "./y4menc.h"

static const char *exec_name;

struct VpxDecInputContext {
  struct VpxInputContext *vpx_input_ctx;
  struct WebmInputContext *webm_ctx;
};

static const arg_def_t looparg = ARG_DEF(NULL, "loops", 1,
                                          "Number of times to decode the file");
static const arg_def_t codecarg = ARG_DEF(NULL, "codec", 1,
                                          "Codec to use");
static const arg_def_t use_yv12 = ARG_DEF(NULL, "yv12", 0,
                                          "Output raw YV12 frames");
static const arg_def_t use_i420 = ARG_DEF(NULL, "i420", 0,
                                          "Output raw I420 frames");
static const arg_def_t flipuvarg = ARG_DEF(NULL, "flipuv", 0,
                                           "Flip the chroma planes in the output");
static const arg_def_t rawvideo = ARG_DEF(NULL, "rawvideo", 0,
                                          "Output raw YUV frames");
static const arg_def_t noblitarg = ARG_DEF(NULL, "noblit", 0,
                                           "Don't process the decoded frames");
static const arg_def_t progressarg = ARG_DEF(NULL, "progress", 0,
                                             "Show progress after each frame decodes");
static const arg_def_t limitarg = ARG_DEF(NULL, "limit", 1,
                                          "Stop decoding after n frames");
static const arg_def_t skiparg = ARG_DEF(NULL, "skip", 1,
                                         "Skip the first n input frames");
static const arg_def_t postprocarg = ARG_DEF(NULL, "postproc", 0,
                                             "Postprocess decoded frames");
static const arg_def_t summaryarg = ARG_DEF(NULL, "summary", 0,
                                            "Show timing summary");
static const arg_def_t outputfile = ARG_DEF("o", "output", 1,
                                            "Output file name pattern (see below)");
static const arg_def_t threadsarg = ARG_DEF("t", "threads", 1,
                                            "Max threads to use");
static const arg_def_t verbosearg = ARG_DEF("v", "verbose", 0,
                                            "Show version string");
static const arg_def_t error_concealment = ARG_DEF(NULL, "error-concealment", 0,
                                                   "Enable decoder error-concealment");
static const arg_def_t scalearg = ARG_DEF("S", "scale", 0,
                                            "Scale output frames uniformly");
static const arg_def_t continuearg =
    ARG_DEF("k", "keep-going", 0, "(debug) Continue decoding after error");

static const arg_def_t fb_arg =
    ARG_DEF(NULL, "frame-buffers", 1, "Number of frame buffers to use");

static const arg_def_t md5arg = ARG_DEF(NULL, "md5", 0,
                                        "Compute the MD5 sum of the decoded frame");
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
static const arg_def_t outbitdeptharg = ARG_DEF(
    NULL, "output-bit-depth", 1,
    "Output bit-depth for decoded frames");
#endif

static const arg_def_t *all_args[] = {
  &codecarg, &use_yv12, &use_i420, &flipuvarg, &rawvideo, &noblitarg,
  &progressarg, &limitarg, &skiparg, &postprocarg, &summaryarg, &outputfile,
  &threadsarg, &verbosearg, &scalearg, &fb_arg,
  &md5arg, &error_concealment, &continuearg,
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
  &outbitdeptharg,
#endif
  NULL
};

#if CONFIG_VP8_DECODER
static const arg_def_t addnoise_level = ARG_DEF(NULL, "noise-level", 1,
                                                "Enable VP8 postproc add noise");
static const arg_def_t deblock = ARG_DEF(NULL, "deblock", 0,
                                         "Enable VP8 deblocking");
static const arg_def_t demacroblock_level = ARG_DEF(NULL, "demacroblock-level", 1,
                                                    "Enable VP8 demacroblocking, w/ level");
static const arg_def_t pp_debug_info = ARG_DEF(NULL, "pp-debug-info", 1,
                                               "Enable VP8 visible debug info");
static const arg_def_t pp_disp_ref_frame = ARG_DEF(NULL, "pp-dbg-ref-frame", 1,
                                                   "Display only selected reference frame per macro block");
static const arg_def_t pp_disp_mb_modes = ARG_DEF(NULL, "pp-dbg-mb-modes", 1,
                                                  "Display only selected macro block modes");
static const arg_def_t pp_disp_b_modes = ARG_DEF(NULL, "pp-dbg-b-modes", 1,
                                                 "Display only selected block modes");
static const arg_def_t pp_disp_mvs = ARG_DEF(NULL, "pp-dbg-mvs", 1,
                                             "Draw only selected motion vectors");
static const arg_def_t mfqe = ARG_DEF(NULL, "mfqe", 0,
                                      "Enable multiframe quality enhancement");

static const arg_def_t *vp8_pp_args[] = {
  &addnoise_level, &deblock, &demacroblock_level, &pp_debug_info,
  &pp_disp_ref_frame, &pp_disp_mb_modes, &pp_disp_b_modes, &pp_disp_mvs, &mfqe,
  NULL
};
#endif

#if CONFIG_LIBYUV
static INLINE int vpx_image_scale(vpx_image_t *src, vpx_image_t *dst,
                                  FilterModeEnum mode) {
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
  if (src->fmt == VPX_IMG_FMT_I42016) {
    assert(dst->fmt == VPX_IMG_FMT_I42016);
    return I420Scale_16((uint16_t*)src->planes[VPX_PLANE_Y],
                        src->stride[VPX_PLANE_Y]/2,
                        (uint16_t*)src->planes[VPX_PLANE_U],
                        src->stride[VPX_PLANE_U]/2,
                        (uint16_t*)src->planes[VPX_PLANE_V],
                        src->stride[VPX_PLANE_V]/2,
                        src->d_w, src->d_h,
                        (uint16_t*)dst->planes[VPX_PLANE_Y],
                        dst->stride[VPX_PLANE_Y]/2,
                        (uint16_t*)dst->planes[VPX_PLANE_U],
                        dst->stride[VPX_PLANE_U]/2,
                        (uint16_t*)dst->planes[VPX_PLANE_V],
                        dst->stride[VPX_PLANE_V]/2,
                        dst->d_w, dst->d_h,
                        mode);
  }
#endif
  assert(src->fmt == VPX_IMG_FMT_I420);
  assert(dst->fmt == VPX_IMG_FMT_I420);
  return I420Scale(src->planes[VPX_PLANE_Y], src->stride[VPX_PLANE_Y],
                   src->planes[VPX_PLANE_U], src->stride[VPX_PLANE_U],
                   src->planes[VPX_PLANE_V], src->stride[VPX_PLANE_V],
                   src->d_w, src->d_h,
                   dst->planes[VPX_PLANE_Y], dst->stride[VPX_PLANE_Y],
                   dst->planes[VPX_PLANE_U], dst->stride[VPX_PLANE_U],
                   dst->planes[VPX_PLANE_V], dst->stride[VPX_PLANE_V],
                   dst->d_w, dst->d_h,
                   mode);
}
#endif

void usage_exit() {
  int i;

  fprintf(stderr, "Usage: %s <options> filename\n\n"
          "Options:\n", exec_name);
  arg_show_usage(stderr, all_args);
#if CONFIG_VP8_DECODER
  fprintf(stderr, "\nVP8 Postprocessing Options:\n");
  arg_show_usage(stderr, vp8_pp_args);
#endif
  fprintf(stderr,
          "\nOutput File Patterns:\n\n"
          "  The -o argument specifies the name of the file(s) to "
          "write to. If the\n  argument does not include any escape "
          "characters, the output will be\n  written to a single file. "
          "Otherwise, the filename will be calculated by\n  expanding "
          "the following escape characters:\n");
  fprintf(stderr,
          "\n\t%%w   - Frame width"
          "\n\t%%h   - Frame height"
          "\n\t%%<n> - Frame number, zero padded to <n> places (1..9)"
          "\n\n  Pattern arguments are only supported in conjunction "
          "with the --yv12 and\n  --i420 options. If the -o option is "
          "not specified, the output will be\n  directed to stdout.\n"
         );
  fprintf(stderr, "\nIncluded decoders:\n\n");

  for (i = 0; i < get_vpx_decoder_count(); ++i) {
    const VpxInterface *const decoder = get_vpx_decoder_by_index(i);
    fprintf(stderr, "    %-6s - %s\n",
            decoder->name, vpx_codec_iface_name(decoder->codec_interface()));
  }

  exit(EXIT_FAILURE);
}

static int raw_read_frame(FILE *infile, uint8_t **buffer,
                          size_t *bytes_read, size_t *buffer_size) {
  char raw_hdr[RAW_FRAME_HDR_SZ];
  size_t frame_size = 0;

  if (fread(raw_hdr, RAW_FRAME_HDR_SZ, 1, infile) != 1) {
    if (!feof(infile))
      warn("Failed to read RAW frame size\n");
  } else {
    const size_t kCorruptFrameThreshold = 256 * 1024 * 1024;
    const size_t kFrameTooSmallThreshold = 256 * 1024;
    frame_size = mem_get_le32(raw_hdr);

    if (frame_size > kCorruptFrameThreshold) {
      warn("Read invalid frame size (%u)\n", (unsigned int)frame_size);
      frame_size = 0;
    }

    if (frame_size < kFrameTooSmallThreshold) {
      warn("Warning: Read invalid frame size (%u) - not a raw file?\n",
           (unsigned int)frame_size);
    }

    if (frame_size > *buffer_size) {
      uint8_t *new_buf = realloc(*buffer, 2 * frame_size);
      if (new_buf) {
        *buffer = new_buf;
        *buffer_size = 2 * frame_size;
      } else {
        warn("Failed to allocate compressed data buffer\n");
        frame_size = 0;
      }
    }
  }

  if (!feof(infile)) {
    if (fread(*buffer, 1, frame_size, infile) != frame_size) {
      warn("Failed to read full frame\n");
      return 1;
    }
    *bytes_read = frame_size;
  }

  return 0;
}

static int read_frame(struct VpxDecInputContext *input, uint8_t **buf,
                      size_t *bytes_in_buffer, size_t *buffer_size) {
  switch (input->vpx_input_ctx->file_type) {
#if CONFIG_WEBM_IO
    case FILE_TYPE_WEBM:
      return webm_read_frame(input->webm_ctx,
                             buf, bytes_in_buffer, buffer_size);
#endif
    case FILE_TYPE_RAW:
      return raw_read_frame(input->vpx_input_ctx->file,
                            buf, bytes_in_buffer, buffer_size);
    case FILE_TYPE_IVF:
      return ivf_read_frame(input->vpx_input_ctx->file,
                            buf, bytes_in_buffer, buffer_size);
    default:
      return 1;
  }
}

static void update_image_md5(const vpx_image_t *img, const int planes[3],
                             MD5Context *md5) {
  int i, y;

  for (i = 0; i < 3; ++i) {
    const int plane = planes[i];
    const unsigned char *buf = img->planes[plane];
    const int stride = img->stride[plane];
    const int w = vpx_img_plane_width(img, plane);
    const int h = vpx_img_plane_height(img, plane);

    for (y = 0; y < h; ++y) {
      MD5Update(md5, buf, w);
      buf += stride;
    }
  }
}

static void write_image_file(const vpx_image_t *img, const int planes[3],
                             FILE *file) {
  int i, y;
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
  const int bytes_per_sample = ((img->fmt & VPX_IMG_FMT_HIGHBITDEPTH) ? 2 : 1);
#else
  const int bytes_per_sample = 1;
#endif

  for (i = 0; i < 3; ++i) {
    const int plane = planes[i];
    const unsigned char *buf = img->planes[plane];
    const int stride = img->stride[plane];
    const int w = vpx_img_plane_width(img, plane);
    const int h = vpx_img_plane_height(img, plane);

    for (y = 0; y < h; ++y) {
      fwrite(buf, bytes_per_sample, w, file);
      buf += stride;
    }
  }
}

int file_is_raw(struct VpxInputContext *input) {
  uint8_t buf[32];
  int is_raw = 0;
  vpx_codec_stream_info_t si;

  si.sz = sizeof(si);

  if (fread(buf, 1, 32, input->file) == 32) {
    int i;

    if (mem_get_le32(buf) < 256 * 1024 * 1024) {
      for (i = 0; i < get_vpx_decoder_count(); ++i) {
        const VpxInterface *const decoder = get_vpx_decoder_by_index(i);
        if (!vpx_codec_peek_stream_info(decoder->codec_interface(),
                                        buf + 4, 32 - 4, &si)) {
          is_raw = 1;
          input->fourcc = decoder->fourcc;
          input->width = si.w;
          input->height = si.h;
          input->framerate.numerator = 30;
          input->framerate.denominator = 1;
          break;
        }
      }
    }
  }

  rewind(input->file);
  return is_raw;
}

void show_progress(int frame_in, int frame_out, uint64_t dx_time) {
  fprintf(stderr,
          "%d decoded frames/%d showed frames in %"PRId64" us (%.2f fps)\r",
          frame_in, frame_out, dx_time,
          (double)frame_out * 1000000.0 / (double)dx_time);
}

struct ExternalFrameBuffer {
  uint8_t* data;
  size_t size;
  int in_use;
};

struct ExternalFrameBufferList {
  int num_external_frame_buffers;
  struct ExternalFrameBuffer *ext_fb;
};

// Callback used by libvpx to request an external frame buffer. |cb_priv|
// Application private data passed into the set function. |min_size| is the
// minimum size in bytes needed to decode the next frame. |fb| pointer to the
// frame buffer.
int get_vp9_frame_buffer(void *cb_priv, size_t min_size,
                         vpx_codec_frame_buffer_t *fb) {
  int i;
  struct ExternalFrameBufferList *const ext_fb_list =
      (struct ExternalFrameBufferList *)cb_priv;
  if (ext_fb_list == NULL)
    return -1;

  // Find a free frame buffer.
  for (i = 0; i < ext_fb_list->num_external_frame_buffers; ++i) {
    if (!ext_fb_list->ext_fb[i].in_use)
      break;
  }

  if (i == ext_fb_list->num_external_frame_buffers)
    return -1;

  if (ext_fb_list->ext_fb[i].size < min_size) {
    free(ext_fb_list->ext_fb[i].data);
    ext_fb_list->ext_fb[i].data = (uint8_t *)calloc(min_size, sizeof(uint8_t));
    if (!ext_fb_list->ext_fb[i].data)
      return -1;

    ext_fb_list->ext_fb[i].size = min_size;
  }

  fb->data = ext_fb_list->ext_fb[i].data;
  fb->size = ext_fb_list->ext_fb[i].size;
  ext_fb_list->ext_fb[i].in_use = 1;

  // Set the frame buffer's private data to point at the external frame buffer.
  fb->priv = &ext_fb_list->ext_fb[i];
  return 0;
}

// Callback used by libvpx when there are no references to the frame buffer.
// |cb_priv| user private data passed into the set function. |fb| pointer
// to the frame buffer.
int release_vp9_frame_buffer(void *cb_priv,
                             vpx_codec_frame_buffer_t *fb) {
  struct ExternalFrameBuffer *const ext_fb =
      (struct ExternalFrameBuffer *)fb->priv;
  (void)cb_priv;
  ext_fb->in_use = 0;
  return 0;
}

void generate_filename(const char *pattern, char *out, size_t q_len,
                       unsigned int d_w, unsigned int d_h,
                       unsigned int frame_in) {
  const char *p = pattern;
  char *q = out;

  do {
    char *next_pat = strchr(p, '%');

    if (p == next_pat) {
      size_t pat_len;

      /* parse the pattern */
      q[q_len - 1] = '\0';
      switch (p[1]) {
        case 'w':
          snprintf(q, q_len - 1, "%d", d_w);
          break;
        case 'h':
          snprintf(q, q_len - 1, "%d", d_h);
          break;
        case '1':
          snprintf(q, q_len - 1, "%d", frame_in);
          break;
        case '2':
          snprintf(q, q_len - 1, "%02d", frame_in);
          break;
        case '3':
          snprintf(q, q_len - 1, "%03d", frame_in);
          break;
        case '4':
          snprintf(q, q_len - 1, "%04d", frame_in);
          break;
        case '5':
          snprintf(q, q_len - 1, "%05d", frame_in);
          break;
        case '6':
          snprintf(q, q_len - 1, "%06d", frame_in);
          break;
        case '7':
          snprintf(q, q_len - 1, "%07d", frame_in);
          break;
        case '8':
          snprintf(q, q_len - 1, "%08d", frame_in);
          break;
        case '9':
          snprintf(q, q_len - 1, "%09d", frame_in);
          break;
        default:
          die("Unrecognized pattern %%%c\n", p[1]);
          break;
      }

      pat_len = strlen(q);
      if (pat_len >= q_len - 1)
        die("Output filename too long.\n");
      q += pat_len;
      p += 2;
      q_len -= pat_len;
    } else {
      size_t copy_len;

      /* copy the next segment */
      if (!next_pat)
        copy_len = strlen(p);
      else
        copy_len = next_pat - p;

      if (copy_len >= q_len - 1)
        die("Output filename too long.\n");

      memcpy(q, p, copy_len);
      q[copy_len] = '\0';
      q += copy_len;
      p += copy_len;
      q_len -= copy_len;
    }
  } while (*p);
}

static int is_single_file(const char *outfile_pattern) {
  const char *p = outfile_pattern;

  do {
    p = strchr(p, '%');
    if (p && p[1] >= '1' && p[1] <= '9')
      return 0;  // pattern contains sequence number, so it's not unique
    if (p)
      p++;
  } while (p);

  return 1;
}

static void print_md5(unsigned char digest[16], const char *filename) {
  int i;

  for (i = 0; i < 16; ++i)
    printf("%02x", digest[i]);
  printf("  %s\n", filename);
}

static FILE *open_outfile(const char *name) {
  if (strcmp("-", name) == 0) {
    set_binary_mode(stdout);
    return stdout;
  } else {
    FILE *file = fopen(name, "wb");
    if (!file)
      fatal("Failed to output file %s", name);
    return file;
  }
}

#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
static void high_img_upshift(vpx_image_t *dst, vpx_image_t *src,
                             int input_shift) {
  const int offset = input_shift > 0 ? (1 << (input_shift - 1)) : 0;
  int plane;
  if (dst->d_w != src->d_w || dst->d_h != src->d_h ||
      dst->x_chroma_shift != src->x_chroma_shift ||
      dst->y_chroma_shift != src->y_chroma_shift ||
      dst->fmt != src->fmt || input_shift < 0) {
    fatal("Unsupported image conversion");
  }
  switch (src->fmt) {
    case VPX_IMG_FMT_I42016:
    case VPX_IMG_FMT_I42216:
    case VPX_IMG_FMT_I44416:
    case VPX_IMG_FMT_I44016:
      break;
    default:
      fatal("Unsupported image conversion");
      break;
  }
  for (plane = 0; plane < 3; plane++) {
    int w = src->d_w;
    int h = src->d_h;
    int x, y;
    if (plane) {
      w = (w + src->x_chroma_shift) >> src->x_chroma_shift;
      h = (h + src->y_chroma_shift) >> src->y_chroma_shift;
    }
    for (y = 0; y < h; y++) {
      uint16_t *p_src = (uint16_t *)(src->planes[plane] +
                                     y * src->stride[plane]);
      uint16_t *p_dst = (uint16_t *)(dst->planes[plane] +
                                     y * dst->stride[plane]);
      for (x = 0; x < w; x++)
        *p_dst++ = (*p_src++ << input_shift) + offset;
    }
  }
}

static void low_img_upshift(vpx_image_t *dst, vpx_image_t *src,
                            int input_shift) {
  const int offset = input_shift > 0 ? (1 << (input_shift - 1)) : 0;
  int plane;
  if (dst->d_w != src->d_w || dst->d_h != src->d_h ||
      dst->x_chroma_shift != src->x_chroma_shift ||
      dst->y_chroma_shift != src->y_chroma_shift ||
      dst->fmt != src->fmt + VPX_IMG_FMT_HIGHBITDEPTH ||
      input_shift < 0) {
    fatal("Unsupported image conversion");
  }
  switch (src->fmt) {
    case VPX_IMG_FMT_I420:
    case VPX_IMG_FMT_I422:
    case VPX_IMG_FMT_I444:
    case VPX_IMG_FMT_I440:
      break;
    default:
      fatal("Unsupported image conversion");
      break;
  }
  for (plane = 0; plane < 3; plane++) {
    int w = src->d_w;
    int h = src->d_h;
    int x, y;
    if (plane) {
      w = (w + src->x_chroma_shift) >> src->x_chroma_shift;
      h = (h + src->y_chroma_shift) >> src->y_chroma_shift;
    }
    for (y = 0; y < h; y++) {
      uint8_t *p_src = src->planes[plane] + y * src->stride[plane];
      uint16_t *p_dst = (uint16_t *)(dst->planes[plane] +
                                     y * dst->stride[plane]);
      for (x = 0; x < w; x++) {
        *p_dst++ = (*p_src++ << input_shift) + offset;
      }
    }
  }
}

static void img_upshift(vpx_image_t *dst, vpx_image_t *src,
                        int input_shift) {
  if (src->fmt & VPX_IMG_FMT_HIGHBITDEPTH) {
    high_img_upshift(dst, src, input_shift);
  } else {
    low_img_upshift(dst, src, input_shift);
  }
}

static void high_img_downshift(vpx_image_t *dst, vpx_image_t *src,
                               int down_shift) {
  int plane;
  if (dst->d_w != src->d_w || dst->d_h != src->d_h ||
      dst->x_chroma_shift != src->x_chroma_shift ||
      dst->y_chroma_shift != src->y_chroma_shift ||
      dst->fmt != src->fmt || down_shift < 0) {
    fatal("Unsupported image conversion");
  }
  switch (src->fmt) {
    case VPX_IMG_FMT_I42016:
    case VPX_IMG_FMT_I42216:
    case VPX_IMG_FMT_I44416:
    case VPX_IMG_FMT_I44016:
      break;
    default:
      fatal("Unsupported image conversion");
      break;
  }
  for (plane = 0; plane < 3; plane++) {
    int w = src->d_w;
    int h = src->d_h;
    int x, y;
    if (plane) {
      w = (w + src->x_chroma_shift) >> src->x_chroma_shift;
      h = (h + src->y_chroma_shift) >> src->y_chroma_shift;
    }
    for (y = 0; y < h; y++) {
      uint16_t *p_src = (uint16_t *)(src->planes[plane] +
                                     y * src->stride[plane]);
      uint16_t *p_dst = (uint16_t *)(dst->planes[plane] +
                                     y * dst->stride[plane]);
      for (x = 0; x < w; x++)
        *p_dst++ = *p_src++ >> down_shift;
    }
  }
}

static void low_img_downshift(vpx_image_t *dst, vpx_image_t *src,
                            int down_shift) {
  int plane;
  if (dst->d_w != src->d_w || dst->d_h != src->d_h ||
      dst->x_chroma_shift != src->x_chroma_shift ||
      dst->y_chroma_shift != src->y_chroma_shift ||
      src->fmt != dst->fmt + VPX_IMG_FMT_HIGHBITDEPTH ||
      down_shift < 0) {
    fatal("Unsupported image conversion");
  }
  switch (dst->fmt) {
    case VPX_IMG_FMT_I420:
    case VPX_IMG_FMT_I422:
    case VPX_IMG_FMT_I444:
    case VPX_IMG_FMT_I440:
      break;
    default:
      fatal("Unsupported image conversion");
      break;
  }
  for (plane = 0; plane < 3; plane++) {
    int w = src->d_w;
    int h = src->d_h;
    int x, y;
    if (plane) {
      w = (w + src->x_chroma_shift) >> src->x_chroma_shift;
      h = (h + src->y_chroma_shift) >> src->y_chroma_shift;
    }
    for (y = 0; y < h; y++) {
      uint16_t *p_src = (uint16_t *)(src->planes[plane] +
                                     y * src->stride[plane]);
      uint8_t *p_dst = dst->planes[plane] + y * dst->stride[plane];
      for (x = 0; x < w; x++) {
        *p_dst++ = *p_src++ >> down_shift;
      }
    }
  }
}

static void img_downshift(vpx_image_t *dst, vpx_image_t *src,
                          int down_shift) {
  if (dst->fmt & VPX_IMG_FMT_HIGHBITDEPTH) {
    high_img_downshift(dst, src, down_shift);
  } else {
    low_img_downshift(dst, src, down_shift);
  }
}

static int img_shifted_realloc_required(const vpx_image_t *img,
                                        const vpx_image_t *shifted,
                                        vpx_img_fmt_t required_fmt) {
  return img->d_w != shifted->d_w ||
         img->d_h != shifted->d_h ||
         required_fmt != shifted->fmt;
}
#endif

int main_loop(int argc, const char **argv_) {
  vpx_codec_ctx_t       decoder;
  char                  *fn = NULL;
  int                    i;
  uint8_t               *buf = NULL;
  size_t                 bytes_in_buffer = 0, buffer_size = 0;
  FILE                  *infile;
  int                    frame_in = 0, frame_out = 0, flipuv = 0, noblit = 0;
  int                    do_md5 = 0, progress = 0;
  int                    stop_after = 0, postproc = 0, summary = 0, quiet = 1;
  int                    arg_skip = 0;
  int                    ec_enabled = 0;
  int                    keep_going = 0;
  const VpxInterface *interface = NULL;
  const VpxInterface *fourcc_interface = NULL;
  uint64_t dx_time = 0;
  struct arg               arg;
  char                   **argv, **argi, **argj;

  int                     single_file;
  int                     use_y4m = 1;
  int                     opt_yv12 = 0;
  int                     opt_i420 = 0;
  vpx_codec_dec_cfg_t     cfg = {0, 0, 0};
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
  int                     output_bit_depth = 0;
#endif
#if CONFIG_VP8_DECODER
  vp8_postproc_cfg_t      vp8_pp_cfg = {0};
  int                     vp8_dbg_color_ref_frame = 0;
  int                     vp8_dbg_color_mb_modes = 0;
  int                     vp8_dbg_color_b_modes = 0;
  int                     vp8_dbg_display_mv = 0;
#endif
  int                     frames_corrupted = 0;
  int                     dec_flags = 0;
  int                     do_scale = 0;
  vpx_image_t             *scaled_img = NULL;
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
  vpx_image_t             *img_shifted = NULL;
#endif
  int                     frame_avail, got_data;
  int                     num_external_frame_buffers = 0;
  struct ExternalFrameBufferList ext_fb_list = {0, NULL};

  const char *outfile_pattern = NULL;
  char outfile_name[PATH_MAX] = {0};
  FILE *outfile = NULL;

  MD5Context md5_ctx;
  unsigned char md5_digest[16];

  struct VpxDecInputContext input = {NULL, NULL};
  struct VpxInputContext vpx_input_ctx;
#if CONFIG_WEBM_IO
  struct WebmInputContext webm_ctx;
  memset(&(webm_ctx), 0, sizeof(webm_ctx));
  input.webm_ctx = &webm_ctx;
#endif
  input.vpx_input_ctx = &vpx_input_ctx;

  /* Parse command line */
  exec_name = argv_[0];
  argv = argv_dup(argc - 1, argv_ + 1);

  for (argi = argj = argv; (*argj = *argi); argi += arg.argv_step) {
    memset(&arg, 0, sizeof(arg));
    arg.argv_step = 1;

    if (arg_match(&arg, &codecarg, argi)) {
      interface = get_vpx_decoder_by_name(arg.val);
      if (!interface)
        die("Error: Unrecognized argument (%s) to --codec\n", arg.val);
    } else if (arg_match(&arg, &looparg, argi)) {
      // no-op
    } else if (arg_match(&arg, &outputfile, argi))
      outfile_pattern = arg.val;
    else if (arg_match(&arg, &use_yv12, argi)) {
      use_y4m = 0;
      flipuv = 1;
      opt_yv12 = 1;
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
      output_bit_depth = 8;  // For yv12 8-bit depth output is assumed
#endif
    } else if (arg_match(&arg, &use_i420, argi)) {
      use_y4m = 0;
      flipuv = 0;
      opt_i420 = 1;
    } else if (arg_match(&arg, &rawvideo, argi)) {
      use_y4m = 0;
    } else if (arg_match(&arg, &flipuvarg, argi))
      flipuv = 1;
    else if (arg_match(&arg, &noblitarg, argi))
      noblit = 1;
    else if (arg_match(&arg, &progressarg, argi))
      progress = 1;
    else if (arg_match(&arg, &limitarg, argi))
      stop_after = arg_parse_uint(&arg);
    else if (arg_match(&arg, &skiparg, argi))
      arg_skip = arg_parse_uint(&arg);
    else if (arg_match(&arg, &postprocarg, argi))
      postproc = 1;
    else if (arg_match(&arg, &md5arg, argi))
      do_md5 = 1;
    else if (arg_match(&arg, &summaryarg, argi))
      summary = 1;
    else if (arg_match(&arg, &threadsarg, argi))
      cfg.threads = arg_parse_uint(&arg);
    else if (arg_match(&arg, &verbosearg, argi))
      quiet = 0;
    else if (arg_match(&arg, &scalearg, argi))
      do_scale = 1;
    else if (arg_match(&arg, &fb_arg, argi))
      num_external_frame_buffers = arg_parse_uint(&arg);
    else if (arg_match(&arg, &continuearg, argi))
      keep_going = 1;
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
    else if (arg_match(&arg, &outbitdeptharg, argi)) {
      output_bit_depth = arg_parse_uint(&arg);
    }
#endif
#if CONFIG_VP8_DECODER
    else if (arg_match(&arg, &addnoise_level, argi)) {
      postproc = 1;
      vp8_pp_cfg.post_proc_flag |= VP8_ADDNOISE;
      vp8_pp_cfg.noise_level = arg_parse_uint(&arg);
    } else if (arg_match(&arg, &demacroblock_level, argi)) {
      postproc = 1;
      vp8_pp_cfg.post_proc_flag |= VP8_DEMACROBLOCK;
      vp8_pp_cfg.deblocking_level = arg_parse_uint(&arg);
    } else if (arg_match(&arg, &deblock, argi)) {
      postproc = 1;
      vp8_pp_cfg.post_proc_flag |= VP8_DEBLOCK;
    } else if (arg_match(&arg, &mfqe, argi)) {
      postproc = 1;
      vp8_pp_cfg.post_proc_flag |= VP8_MFQE;
    } else if (arg_match(&arg, &pp_debug_info, argi)) {
      unsigned int level = arg_parse_uint(&arg);

      postproc = 1;
      vp8_pp_cfg.post_proc_flag &= ~0x7;

      if (level)
        vp8_pp_cfg.post_proc_flag |= level;
    } else if (arg_match(&arg, &pp_disp_ref_frame, argi)) {
      unsigned int flags = arg_parse_int(&arg);
      if (flags) {
        postproc = 1;
        vp8_dbg_color_ref_frame = flags;
      }
    } else if (arg_match(&arg, &pp_disp_mb_modes, argi)) {
      unsigned int flags = arg_parse_int(&arg);
      if (flags) {
        postproc = 1;
        vp8_dbg_color_mb_modes = flags;
      }
    } else if (arg_match(&arg, &pp_disp_b_modes, argi)) {
      unsigned int flags = arg_parse_int(&arg);
      if (flags) {
        postproc = 1;
        vp8_dbg_color_b_modes = flags;
      }
    } else if (arg_match(&arg, &pp_disp_mvs, argi)) {
      unsigned int flags = arg_parse_int(&arg);
      if (flags) {
        postproc = 1;
        vp8_dbg_display_mv = flags;
      }
    } else if (arg_match(&arg, &error_concealment, argi)) {
      ec_enabled = 1;
    }
#endif  // CONFIG_VP8_DECODER
    else
      argj++;
  }

  /* Check for unrecognized options */
  for (argi = argv; *argi; argi++)
    if (argi[0][0] == '-' && strlen(argi[0]) > 1)
      die("Error: Unrecognized option %s\n", *argi);

  /* Handle non-option arguments */
  fn = argv[0];

  if (!fn)
    usage_exit();

  /* Open file */
  infile = strcmp(fn, "-") ? fopen(fn, "rb") : set_binary_mode(stdin);

  if (!infile) {
    fprintf(stderr, "Failed to open file '%s'", strcmp(fn, "-") ? fn : "stdin");
    return EXIT_FAILURE;
  }
#if CONFIG_OS_SUPPORT
  /* Make sure we don't dump to the terminal, unless forced to with -o - */
  if (!outfile_pattern && isatty(fileno(stdout)) && !do_md5 && !noblit) {
    fprintf(stderr,
            "Not dumping raw video to your terminal. Use '-o -' to "
            "override.\n");
    return EXIT_FAILURE;
  }
#endif
  input.vpx_input_ctx->file = infile;
  if (file_is_ivf(input.vpx_input_ctx))
    input.vpx_input_ctx->file_type = FILE_TYPE_IVF;
#if CONFIG_WEBM_IO
  else if (file_is_webm(input.webm_ctx, input.vpx_input_ctx))
    input.vpx_input_ctx->file_type = FILE_TYPE_WEBM;
#endif
  else if (file_is_raw(input.vpx_input_ctx))
    input.vpx_input_ctx->file_type = FILE_TYPE_RAW;
  else {
    fprintf(stderr, "Unrecognized input file type.\n");
#if !CONFIG_WEBM_IO
    fprintf(stderr, "vpxdec was built without WebM container support.\n");
#endif
    return EXIT_FAILURE;
  }

  outfile_pattern = outfile_pattern ? outfile_pattern : "-";
  single_file = is_single_file(outfile_pattern);

  if (!noblit && single_file) {
    generate_filename(outfile_pattern, outfile_name, PATH_MAX,
                      vpx_input_ctx.width, vpx_input_ctx.height, 0);
    if (do_md5)
      MD5Init(&md5_ctx);
    else
      outfile = open_outfile(outfile_name);
  }

  if (use_y4m && !noblit) {
    if (!single_file) {
      fprintf(stderr, "YUV4MPEG2 not supported with output patterns,"
              " try --i420 or --yv12 or --rawvideo.\n");
      return EXIT_FAILURE;
    }

#if CONFIG_WEBM_IO
    if (vpx_input_ctx.file_type == FILE_TYPE_WEBM) {
      if (webm_guess_framerate(input.webm_ctx, input.vpx_input_ctx)) {
        fprintf(stderr, "Failed to guess framerate -- error parsing "
                "webm file?\n");
        return EXIT_FAILURE;
      }
    }
#endif
  }

  fourcc_interface = get_vpx_decoder_by_fourcc(vpx_input_ctx.fourcc);
  if (interface && fourcc_interface && interface != fourcc_interface)
    warn("Header indicates codec: %s\n", fourcc_interface->name);
  else
    interface = fourcc_interface;

  if (!interface)
    interface = get_vpx_decoder_by_index(0);

  dec_flags = (postproc ? VPX_CODEC_USE_POSTPROC : 0) |
              (ec_enabled ? VPX_CODEC_USE_ERROR_CONCEALMENT : 0);
  if (vpx_codec_dec_init(&decoder, interface->codec_interface(),
                         &cfg, dec_flags)) {
    fprintf(stderr, "Failed to initialize decoder: %s\n",
            vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }

  if (!quiet)
    fprintf(stderr, "%s\n", decoder.name);

#if CONFIG_VP8_DECODER

  if (vp8_pp_cfg.post_proc_flag
      && vpx_codec_control(&decoder, VP8_SET_POSTPROC, &vp8_pp_cfg)) {
    fprintf(stderr, "Failed to configure postproc: %s\n", vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }

  if (vp8_dbg_color_ref_frame
      && vpx_codec_control(&decoder, VP8_SET_DBG_COLOR_REF_FRAME, vp8_dbg_color_ref_frame)) {
    fprintf(stderr, "Failed to configure reference block visualizer: %s\n", vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }

  if (vp8_dbg_color_mb_modes
      && vpx_codec_control(&decoder, VP8_SET_DBG_COLOR_MB_MODES, vp8_dbg_color_mb_modes)) {
    fprintf(stderr, "Failed to configure macro block visualizer: %s\n", vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }

  if (vp8_dbg_color_b_modes
      && vpx_codec_control(&decoder, VP8_SET_DBG_COLOR_B_MODES, vp8_dbg_color_b_modes)) {
    fprintf(stderr, "Failed to configure block visualizer: %s\n", vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }

  if (vp8_dbg_display_mv
      && vpx_codec_control(&decoder, VP8_SET_DBG_DISPLAY_MV, vp8_dbg_display_mv)) {
    fprintf(stderr, "Failed to configure motion vector visualizer: %s\n", vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }
#endif


  if (arg_skip)
    fprintf(stderr, "Skipping first %d frames.\n", arg_skip);
  while (arg_skip) {
    if (read_frame(&input, &buf, &bytes_in_buffer, &buffer_size))
      break;
    arg_skip--;
  }

  if (num_external_frame_buffers > 0) {
    ext_fb_list.num_external_frame_buffers = num_external_frame_buffers;
    ext_fb_list.ext_fb = (struct ExternalFrameBuffer *)calloc(
        num_external_frame_buffers, sizeof(*ext_fb_list.ext_fb));
    if (vpx_codec_set_frame_buffer_functions(
            &decoder, get_vp9_frame_buffer, release_vp9_frame_buffer,
            &ext_fb_list)) {
      fprintf(stderr, "Failed to configure external frame buffers: %s\n",
              vpx_codec_error(&decoder));
      return EXIT_FAILURE;
    }
  }

  frame_avail = 1;
  got_data = 0;

  /* Decode file */
  while (frame_avail || got_data) {
    vpx_codec_iter_t  iter = NULL;
    vpx_image_t    *img;
    struct vpx_usec_timer timer;
    int                   corrupted;

    frame_avail = 0;
    if (!stop_after || frame_in < stop_after) {
      if (!read_frame(&input, &buf, &bytes_in_buffer, &buffer_size)) {
        frame_avail = 1;
        frame_in++;

        vpx_usec_timer_start(&timer);

        if (vpx_codec_decode(&decoder, buf, (unsigned int)bytes_in_buffer,
                             NULL, 0)) {
          const char *detail = vpx_codec_error_detail(&decoder);
          warn("Failed to decode frame %d: %s",
               frame_in, vpx_codec_error(&decoder));

          if (detail)
            warn("Additional information: %s", detail);
          if (!keep_going)
            goto fail;
        }

        vpx_usec_timer_mark(&timer);
        dx_time += vpx_usec_timer_elapsed(&timer);
      }
    }

    vpx_usec_timer_start(&timer);

    got_data = 0;
    if ((img = vpx_codec_get_frame(&decoder, &iter))) {
      ++frame_out;
      got_data = 1;
    }

    vpx_usec_timer_mark(&timer);
    dx_time += (unsigned int)vpx_usec_timer_elapsed(&timer);

    if (vpx_codec_control(&decoder, VP8D_GET_FRAME_CORRUPTED, &corrupted)) {
      warn("Failed VP8_GET_FRAME_CORRUPTED: %s", vpx_codec_error(&decoder));
      goto fail;
    }
    frames_corrupted += corrupted;

    if (progress)
      show_progress(frame_in, frame_out, dx_time);

    if (!noblit && img) {
      const int PLANES_YUV[] = {VPX_PLANE_Y, VPX_PLANE_U, VPX_PLANE_V};
      const int PLANES_YVU[] = {VPX_PLANE_Y, VPX_PLANE_V, VPX_PLANE_U};
      const int *planes = flipuv ? PLANES_YVU : PLANES_YUV;

      if (do_scale) {
        if (frame_out == 1) {
          // If the output frames are to be scaled to a fixed display size then
          // use the width and height specified in the container. If either of
          // these is set to 0, use the display size set in the first frame
          // header. If that is unavailable, use the raw decoded size of the
          // first decoded frame.
          int display_width = vpx_input_ctx.width;
          int display_height = vpx_input_ctx.height;
          if (!display_width || !display_height) {
            int display_size[2];
            if (vpx_codec_control(&decoder, VP9D_GET_DISPLAY_SIZE,
                                  display_size)) {
              // As last resort use size of first frame as display size.
              display_width = img->d_w;
              display_height = img->d_h;
            } else {
              display_width = display_size[0];
              display_height = display_size[1];
            }
          }
          scaled_img = vpx_img_alloc(NULL, img->fmt, display_width,
                                     display_height, 16);
          scaled_img->bit_depth = img->bit_depth;
        }

        if (img->d_w != scaled_img->d_w || img->d_h != scaled_img->d_h) {
#if CONFIG_LIBYUV
          vpx_image_scale(img, scaled_img, kFilterBox);
          img = scaled_img;
#else
          fprintf(stderr, "Failed  to scale output frame: %s.\n"
                  "Scaling is disabled in this configuration. "
                  "To enable scaling, configure with --enable-libyuv\n",
                  vpx_codec_error(&decoder));
          return EXIT_FAILURE;
#endif
        }
      }
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
      // Default to codec bit depth if output bit depth not set
      if (!output_bit_depth) {
        output_bit_depth = img->bit_depth;
      }
      // Shift up or down if necessary
      if (output_bit_depth != img->bit_depth) {
        const vpx_img_fmt_t shifted_fmt = output_bit_depth == 8 ?
            img->fmt ^ (img->fmt & VPX_IMG_FMT_HIGHBITDEPTH) :
            img->fmt | VPX_IMG_FMT_HIGHBITDEPTH;
        if (img_shifted &&
            img_shifted_realloc_required(img, img_shifted, shifted_fmt)) {
          vpx_img_free(img_shifted);
          img_shifted = NULL;
        }
        if (!img_shifted) {
          img_shifted = vpx_img_alloc(NULL, shifted_fmt,
                                      img->d_w, img->d_h, 16);
          img_shifted->bit_depth = output_bit_depth;
        }
        if (output_bit_depth > img->bit_depth) {
          img_upshift(img_shifted, img, output_bit_depth - img->bit_depth);
        } else {
          img_downshift(img_shifted, img, img->bit_depth - output_bit_depth);
        }
        img = img_shifted;
      }
#endif

      if (single_file) {
        if (use_y4m) {
          char buf[Y4M_BUFFER_SIZE] = {0};
          size_t len = 0;
          if (img->fmt == VPX_IMG_FMT_I440 || img->fmt == VPX_IMG_FMT_I44016) {
            fprintf(stderr, "Cannot produce y4m output for 440 sampling.\n");
            goto fail;
          }
          if (frame_out == 1) {
            // Y4M file header
            len = y4m_write_file_header(buf, sizeof(buf),
                                        vpx_input_ctx.width,
                                        vpx_input_ctx.height,
                                        &vpx_input_ctx.framerate,
                                        img->fmt, img->bit_depth);
            if (do_md5) {
              MD5Update(&md5_ctx, (md5byte *)buf, (unsigned int)len);
            } else {
              fputs(buf, outfile);
            }
          }

          // Y4M frame header
          len = y4m_write_frame_header(buf, sizeof(buf));
          if (do_md5) {
            MD5Update(&md5_ctx, (md5byte *)buf, (unsigned int)len);
          } else {
            fputs(buf, outfile);
          }
        } else {
          if (frame_out == 1) {
            // Check if --yv12 or --i420 options are consistent with the
            // bit-stream decoded
            if (opt_i420) {
              if (img->fmt != VPX_IMG_FMT_I420 &&
                  img->fmt != VPX_IMG_FMT_I42016) {
                fprintf(stderr, "Cannot produce i420 output for bit-stream.\n");
                goto fail;
              }
            }
            if (opt_yv12) {
              if ((img->fmt != VPX_IMG_FMT_I420 &&
                   img->fmt != VPX_IMG_FMT_YV12) || img->bit_depth != 8) {
                fprintf(stderr, "Cannot produce yv12 output for bit-stream.\n");
                goto fail;
              }
            }
          }
        }

        if (do_md5) {
          update_image_md5(img, planes, &md5_ctx);
        } else {
          write_image_file(img, planes, outfile);
        }
      } else {
        generate_filename(outfile_pattern, outfile_name, PATH_MAX,
                          img->d_w, img->d_h, frame_in);
        if (do_md5) {
          MD5Init(&md5_ctx);
          update_image_md5(img, planes, &md5_ctx);
          MD5Final(md5_digest, &md5_ctx);
          print_md5(md5_digest, outfile_name);
        } else {
          outfile = open_outfile(outfile_name);
          write_image_file(img, planes, outfile);
          fclose(outfile);
        }
      }
    }

    if (stop_after && frame_in >= stop_after)
      break;
  }

  if (summary || progress) {
    show_progress(frame_in, frame_out, dx_time);
    fprintf(stderr, "\n");
  }

  if (frames_corrupted)
    fprintf(stderr, "WARNING: %d frames corrupted.\n", frames_corrupted);

fail:

  if (vpx_codec_destroy(&decoder)) {
    fprintf(stderr, "Failed to destroy decoder: %s\n",
            vpx_codec_error(&decoder));
    return EXIT_FAILURE;
  }

  if (!noblit && single_file) {
    if (do_md5) {
      MD5Final(md5_digest, &md5_ctx);
      print_md5(md5_digest, outfile_name);
    } else {
      fclose(outfile);
    }
  }

#if CONFIG_WEBM_IO
  if (input.vpx_input_ctx->file_type == FILE_TYPE_WEBM)
    webm_free(input.webm_ctx);
#endif

  if (input.vpx_input_ctx->file_type != FILE_TYPE_WEBM)
    free(buf);

  if (scaled_img) vpx_img_free(scaled_img);
#if CONFIG_VP9 && CONFIG_VP9_HIGHBITDEPTH
  if (img_shifted) vpx_img_free(img_shifted);
#endif

  for (i = 0; i < ext_fb_list.num_external_frame_buffers; ++i) {
    free(ext_fb_list.ext_fb[i].data);
  }
  free(ext_fb_list.ext_fb);

  fclose(infile);
  free(argv);

  return frames_corrupted ? EXIT_FAILURE : EXIT_SUCCESS;
}

int main(int argc, const char **argv_) {
  unsigned int loops = 1, i;
  char **argv, **argi, **argj;
  struct arg arg;
  int error = 0;

  argv = argv_dup(argc - 1, argv_ + 1);
  for (argi = argj = argv; (*argj = *argi); argi += arg.argv_step) {
    memset(&arg, 0, sizeof(arg));
    arg.argv_step = 1;

    if (arg_match(&arg, &looparg, argi)) {
      loops = arg_parse_uint(&arg);
      break;
    }
  }
  free(argv);
  for (i = 0; !error && i < loops; i++)
    error = main_loop(argc, argv_);
  return error;
}