/*
 *  Copyright (c) 2013 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.
 */

/**
 * @file
 * VP9 SVC encoding support via libvpx
 */

#include <math.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define VPX_DISABLE_CTRL_TYPECHECKS 1
#define VPX_CODEC_DISABLE_COMPAT 1
#include "vpx/svc_context.h"
#include "vpx/vp8cx.h"
#include "vpx/vpx_encoder.h"

#ifdef __MINGW32__
#define strtok_r strtok_s
#ifndef MINGW_HAS_SECURE_API
// proto from /usr/x86_64-w64-mingw32/include/sec_api/string_s.h
_CRTIMP char *__cdecl strtok_s(char *str, const char *delim, char **context);
#endif  /* MINGW_HAS_SECURE_API */
#endif  /* __MINGW32__ */

#ifdef _MSC_VER
#define strdup _strdup
#define strtok_r strtok_s
#endif

#define SVC_REFERENCE_FRAMES 8
#define SUPERFRAME_SLOTS (8)
#define SUPERFRAME_BUFFER_SIZE (SUPERFRAME_SLOTS * sizeof(uint32_t) + 2)
#define OPTION_BUFFER_SIZE 256
#define COMPONENTS 4  // psnr & sse statistics maintained for total, y, u, v

static const char *DEFAULT_QUANTIZER_VALUES = "60,53,39,33,27";
static const char *DEFAULT_SCALE_FACTORS = "4/16,5/16,7/16,11/16,16/16";

typedef struct SvcInternal {
  char options[OPTION_BUFFER_SIZE];        // set by vpx_svc_set_options
  char quantizers[OPTION_BUFFER_SIZE];     // set by vpx_svc_set_quantizers
  char quantizers_keyframe[OPTION_BUFFER_SIZE];  // set by
                                                 // vpx_svc_set_quantizers
  char scale_factors[OPTION_BUFFER_SIZE];  // set by vpx_svc_set_scale_factors

  // values extracted from option, quantizers
  int scaling_factor_num[VPX_SS_MAX_LAYERS];
  int scaling_factor_den[VPX_SS_MAX_LAYERS];
  int quantizer_keyframe[VPX_SS_MAX_LAYERS];
  int quantizer[VPX_SS_MAX_LAYERS];

  // accumulated statistics
  double psnr_sum[VPX_SS_MAX_LAYERS][COMPONENTS];   // total/Y/U/V
  uint64_t sse_sum[VPX_SS_MAX_LAYERS][COMPONENTS];
  uint32_t bytes_sum[VPX_SS_MAX_LAYERS];

  // codec encoding values
  int width;    // width of highest layer
  int height;   // height of highest layer
  int kf_dist;  // distance between keyframes

  // state variables
  int encode_frame_count;
  int frame_within_gop;
  vpx_enc_frame_flags_t enc_frame_flags;
  int layers;
  int layer;
  int is_keyframe;

  size_t frame_size;
  size_t buffer_size;
  void *buffer;

  char *rc_stats_buf;
  size_t rc_stats_buf_size;
  size_t rc_stats_buf_used;

  char message_buffer[2048];
  vpx_codec_ctx_t *codec_ctx;
} SvcInternal;

// Superframe is used to generate an index of individual frames (i.e., layers)
struct Superframe {
  int count;
  uint32_t sizes[SUPERFRAME_SLOTS];
  uint32_t magnitude;
  uint8_t buffer[SUPERFRAME_BUFFER_SIZE];
  size_t index_size;
};

// One encoded frame layer
struct LayerData {
  void *buf;    // compressed data buffer
  size_t size;  // length of compressed data
  struct LayerData *next;
};

// create LayerData from encoder output
static struct LayerData *ld_create(void *buf, size_t size) {
  struct LayerData *const layer_data =
      (struct LayerData *)malloc(sizeof(*layer_data));
  if (layer_data == NULL) {
    return NULL;
  }
  layer_data->buf = malloc(size);
  if (layer_data->buf == NULL) {
    free(layer_data);
    return NULL;
  }
  memcpy(layer_data->buf, buf, size);
  layer_data->size = size;
  return layer_data;
}

// free LayerData
static void ld_free(struct LayerData *layer_data) {
  if (layer_data) {
    if (layer_data->buf) {
      free(layer_data->buf);
      layer_data->buf = NULL;
    }
    free(layer_data);
  }
}

// add layer data to list
static void ld_list_add(struct LayerData **list, struct LayerData *layer_data) {
  struct LayerData **p = list;

  while (*p != NULL) p = &(*p)->next;
  *p = layer_data;
  layer_data->next = NULL;
}

// get accumulated size of layer data
static size_t ld_list_get_buffer_size(struct LayerData *list) {
  struct LayerData *p;
  size_t size = 0;

  for (p = list; p != NULL; p = p->next) {
    size += p->size;
  }
  return size;
}

// copy layer data to buffer
static void ld_list_copy_to_buffer(struct LayerData *list, uint8_t *buffer) {
  struct LayerData *p;

  for (p = list; p != NULL; p = p->next) {
    buffer[0] = 1;
    memcpy(buffer, p->buf, p->size);
    buffer += p->size;
  }
}

// free layer data list
static void ld_list_free(struct LayerData *list) {
  struct LayerData *p = list;

  while (p) {
    list = list->next;
    ld_free(p);
    p = list;
  }
}

static void sf_create_index(struct Superframe *sf) {
  uint8_t marker = 0xc0;
  int i;
  uint32_t mag, mask;
  uint8_t *bufp;

  if (sf->count == 0 || sf->count >= 8) return;

  // Add the number of frames to the marker byte
  marker |= sf->count - 1;

  // Choose the magnitude
  for (mag = 0, mask = 0xff; mag < 4; ++mag) {
    if (sf->magnitude < mask) break;
    mask <<= 8;
    mask |= 0xff;
  }
  marker |= mag << 3;

  // Write the index
  sf->index_size = 2 + (mag + 1) * sf->count;
  bufp = sf->buffer;

  *bufp++ = marker;
  for (i = 0; i < sf->count; ++i) {
    int this_sz = sf->sizes[i];
    uint32_t j;

    for (j = 0; j <= mag; ++j) {
      *bufp++ = this_sz & 0xff;
      this_sz >>= 8;
    }
  }
  *bufp++ = marker;
}

static SvcInternal *get_svc_internal(SvcContext *svc_ctx) {
  if (svc_ctx == NULL) return NULL;
  if (svc_ctx->internal == NULL) {
    SvcInternal *const si = (SvcInternal *)malloc(sizeof(*si));
    if (si != NULL) {
      memset(si, 0, sizeof(*si));
    }
    svc_ctx->internal = si;
  }
  return (SvcInternal *)svc_ctx->internal;
}

static const SvcInternal *get_const_svc_internal(const SvcContext *svc_ctx) {
  if (svc_ctx == NULL) return NULL;
  return (const SvcInternal *)svc_ctx->internal;
}

static void svc_log_reset(SvcContext *svc_ctx) {
  SvcInternal *const si = (SvcInternal *)svc_ctx->internal;
  si->message_buffer[0] = '\0';
}

static int svc_log(SvcContext *svc_ctx, int level, const char *fmt, ...) {
  char buf[512];
  int retval = 0;
  va_list ap;
  SvcInternal *const si = get_svc_internal(svc_ctx);

  if (level > svc_ctx->log_level) {
    return retval;
  }

  va_start(ap, fmt);
  retval = vsnprintf(buf, sizeof(buf), fmt, ap);
  va_end(ap);

  if (svc_ctx->log_print) {
    printf("%s", buf);
  } else {
    strncat(si->message_buffer, buf,
            sizeof(si->message_buffer) - strlen(si->message_buffer) - 1);
  }

  if (level == SVC_LOG_ERROR) {
    si->codec_ctx->err_detail = si->message_buffer;
  }
  return retval;
}

static vpx_codec_err_t set_option_encoding_mode(SvcContext *svc_ctx,
                                                const char *value_str) {
  if (strcmp(value_str, "i") == 0) {
    svc_ctx->encoding_mode = INTER_LAYER_PREDICTION_I;
  } else if (strcmp(value_str, "alt-ip") == 0) {
    svc_ctx->encoding_mode = ALT_INTER_LAYER_PREDICTION_IP;
  } else if (strcmp(value_str, "ip") == 0) {
    svc_ctx->encoding_mode = INTER_LAYER_PREDICTION_IP;
  } else if (strcmp(value_str, "gf") == 0) {
    svc_ctx->encoding_mode = USE_GOLDEN_FRAME;
  } else {
    svc_log(svc_ctx, SVC_LOG_ERROR, "invalid encoding mode: %s", value_str);
    return VPX_CODEC_INVALID_PARAM;
  }
  return VPX_CODEC_OK;
}

static vpx_codec_err_t parse_quantizer_values(SvcContext *svc_ctx,
                                              const char *quantizer_values,
                                              const int is_keyframe) {
  char *input_string;
  char *token;
  const char *delim = ",";
  char *save_ptr;
  int found = 0;
  int i, q;
  vpx_codec_err_t res = VPX_CODEC_OK;
  SvcInternal *const si = get_svc_internal(svc_ctx);

  if (quantizer_values == NULL || strlen(quantizer_values) == 0) {
    if (is_keyframe) {
      // If there non settings for key frame, we will apply settings from
      // non key frame. So just simply return here.
      return VPX_CODEC_INVALID_PARAM;
    }
    input_string = strdup(DEFAULT_QUANTIZER_VALUES);
  } else {
    input_string = strdup(quantizer_values);
  }

  token = strtok_r(input_string, delim, &save_ptr);
  for (i = 0; i < svc_ctx->spatial_layers; ++i) {
    if (token != NULL) {
      q = atoi(token);
      if (q <= 0 || q > 100) {
        svc_log(svc_ctx, SVC_LOG_ERROR,
                "svc-quantizer-values: invalid value %s\n", token);
        res = VPX_CODEC_INVALID_PARAM;
        break;
      }
      token = strtok_r(NULL, delim, &save_ptr);
      found = i + 1;
    } else {
      q = 0;
    }
    if (is_keyframe) {
      si->quantizer_keyframe[i + VPX_SS_MAX_LAYERS - svc_ctx->spatial_layers]
      = q;
    } else {
      si->quantizer[i + VPX_SS_MAX_LAYERS - svc_ctx->spatial_layers] = q;
    }
  }
  if (res == VPX_CODEC_OK && found != svc_ctx->spatial_layers) {
    svc_log(svc_ctx, SVC_LOG_ERROR,
            "svc: quantizers: %d values required, but only %d specified\n",
            svc_ctx->spatial_layers, found);
    res = VPX_CODEC_INVALID_PARAM;
  }
  free(input_string);
  return res;
}

static void log_invalid_scale_factor(SvcContext *svc_ctx, const char *value) {
  svc_log(svc_ctx, SVC_LOG_ERROR, "svc scale-factors: invalid value %s\n",
          value);
}

static vpx_codec_err_t parse_scale_factors(SvcContext *svc_ctx,
                                           const char *scale_factors) {
  char *input_string;
  char *token;
  const char *delim = ",";
  char *save_ptr;
  int found = 0;
  int i;
  int64_t num, den;
  vpx_codec_err_t res = VPX_CODEC_OK;
  SvcInternal *const si = get_svc_internal(svc_ctx);

  if (scale_factors == NULL || strlen(scale_factors) == 0) {
    input_string = strdup(DEFAULT_SCALE_FACTORS);
  } else {
    input_string = strdup(scale_factors);
  }
  token = strtok_r(input_string, delim, &save_ptr);
  for (i = 0; i < svc_ctx->spatial_layers; ++i) {
    num = den = 0;
    if (token != NULL) {
      num = strtol(token, &token, 10);
      if (num <= 0) {
        log_invalid_scale_factor(svc_ctx, token);
        res = VPX_CODEC_INVALID_PARAM;
        break;
      }
      if (*token++ != '/') {
        log_invalid_scale_factor(svc_ctx, token);
        res = VPX_CODEC_INVALID_PARAM;
        break;
      }
      den = strtol(token, &token, 10);
      if (den <= 0) {
        log_invalid_scale_factor(svc_ctx, token);
        res = VPX_CODEC_INVALID_PARAM;
        break;
      }
      token = strtok_r(NULL, delim, &save_ptr);
      found = i + 1;
    }
    si->scaling_factor_num[i + VPX_SS_MAX_LAYERS - svc_ctx->spatial_layers] =
        (int)num;
    si->scaling_factor_den[i + VPX_SS_MAX_LAYERS - svc_ctx->spatial_layers] =
        (int)den;
  }
  if (res == VPX_CODEC_OK && found != svc_ctx->spatial_layers) {
    svc_log(svc_ctx, SVC_LOG_ERROR,
            "svc: scale-factors: %d values required, but only %d specified\n",
            svc_ctx->spatial_layers, found);
    res = VPX_CODEC_INVALID_PARAM;
  }
  free(input_string);
  return res;
}

/**
 * Parse SVC encoding options
 * Format: encoding-mode=<svc_mode>,layers=<layer_count>
 *         scale-factors=<n1>/<d1>,<n2>/<d2>,...
 *         quantizers=<q1>,<q2>,...
 * svc_mode = [i|ip|alt_ip|gf]
 */
static vpx_codec_err_t parse_options(SvcContext *svc_ctx, const char *options) {
  char *input_string;
  char *option_name;
  char *option_value;
  char *input_ptr;
  int is_keyframe_qaunt_set = 0;
  vpx_codec_err_t res = VPX_CODEC_OK;

  if (options == NULL) return VPX_CODEC_OK;
  input_string = strdup(options);

  // parse option name
  option_name = strtok_r(input_string, "=", &input_ptr);
  while (option_name != NULL) {
    // parse option value
    option_value = strtok_r(NULL, " ", &input_ptr);
    if (option_value == NULL) {
      svc_log(svc_ctx, SVC_LOG_ERROR, "option missing value: %s\n",
              option_name);
      res = VPX_CODEC_INVALID_PARAM;
      break;
    }
    if (strcmp("encoding-mode", option_name) == 0) {
      res = set_option_encoding_mode(svc_ctx, option_value);
      if (res != VPX_CODEC_OK) break;
    } else if (strcmp("layers", option_name) == 0) {
      svc_ctx->spatial_layers = atoi(option_value);
    } else if (strcmp("scale-factors", option_name) == 0) {
      res = parse_scale_factors(svc_ctx, option_value);
      if (res != VPX_CODEC_OK) break;
    } else if (strcmp("quantizers", option_name) == 0) {
      res = parse_quantizer_values(svc_ctx, option_value, 0);
      if (res != VPX_CODEC_OK) break;
      if (!is_keyframe_qaunt_set) {
        SvcInternal *const si = get_svc_internal(svc_ctx);
        memcpy(get_svc_internal(svc_ctx)->quantizer_keyframe, si->quantizer,
               sizeof(si->quantizer));
      }
    } else if (strcmp("quantizers-keyframe", option_name) == 0) {
      res = parse_quantizer_values(svc_ctx, option_value, 1);
      if (res != VPX_CODEC_OK) break;
      is_keyframe_qaunt_set = 1;
    } else {
      svc_log(svc_ctx, SVC_LOG_ERROR, "invalid option: %s\n", option_name);
      res = VPX_CODEC_INVALID_PARAM;
      break;
    }
    option_name = strtok_r(NULL, "=", &input_ptr);
  }
  free(input_string);
  return res;
}

vpx_codec_err_t vpx_svc_set_options(SvcContext *svc_ctx, const char *options) {
  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || options == NULL || si == NULL) {
    return VPX_CODEC_INVALID_PARAM;
  }
  strncpy(si->options, options, sizeof(si->options));
  si->options[sizeof(si->options) - 1] = '\0';
  return VPX_CODEC_OK;
}

vpx_codec_err_t vpx_svc_set_quantizers(SvcContext *svc_ctx,
                                       const char *quantizers,
                                       const int is_for_keyframe) {
  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || quantizers == NULL || si == NULL) {
    return VPX_CODEC_INVALID_PARAM;
  }
  if (is_for_keyframe) {
    strncpy(si->quantizers_keyframe, quantizers, sizeof(si->quantizers));
    si->quantizers_keyframe[sizeof(si->quantizers_keyframe) - 1] = '\0';
  } else {
    strncpy(si->quantizers, quantizers, sizeof(si->quantizers));
    si->quantizers[sizeof(si->quantizers) - 1] = '\0';
  }
  return VPX_CODEC_OK;
}

vpx_codec_err_t vpx_svc_set_scale_factors(SvcContext *svc_ctx,
                                          const char *scale_factors) {
  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || scale_factors == NULL || si == NULL) {
    return VPX_CODEC_INVALID_PARAM;
  }
  strncpy(si->scale_factors, scale_factors, sizeof(si->scale_factors));
  si->scale_factors[sizeof(si->scale_factors) - 1] = '\0';
  return VPX_CODEC_OK;
}

vpx_codec_err_t vpx_svc_init(SvcContext *svc_ctx, vpx_codec_ctx_t *codec_ctx,
                             vpx_codec_iface_t *iface,
                             vpx_codec_enc_cfg_t *enc_cfg) {
  int max_intra_size_pct;
  vpx_codec_err_t res;
  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || codec_ctx == NULL || iface == NULL ||
      enc_cfg == NULL) {
    return VPX_CODEC_INVALID_PARAM;
  }
  if (si == NULL) return VPX_CODEC_MEM_ERROR;

  si->codec_ctx = codec_ctx;

  si->width = enc_cfg->g_w;
  si->height = enc_cfg->g_h;

  if (enc_cfg->kf_max_dist < 2) {
    svc_log(svc_ctx, SVC_LOG_ERROR, "key frame distance too small: %d\n",
            enc_cfg->kf_max_dist);
    return VPX_CODEC_INVALID_PARAM;
  }
  si->kf_dist = enc_cfg->kf_max_dist;

  if (svc_ctx->spatial_layers == 0)
    svc_ctx->spatial_layers = VPX_SS_DEFAULT_LAYERS;
  if (svc_ctx->spatial_layers < 1 ||
      svc_ctx->spatial_layers > VPX_SS_MAX_LAYERS) {
    svc_log(svc_ctx, SVC_LOG_ERROR, "spatial layers: invalid value: %d\n",
            svc_ctx->spatial_layers);
    return VPX_CODEC_INVALID_PARAM;
  }
  // use SvcInternal value for number of layers to enable forcing single layer
  // for first frame
  si->layers = svc_ctx->spatial_layers;

  res = parse_quantizer_values(svc_ctx, si->quantizers, 0);
  if (res != VPX_CODEC_OK) return res;

  res = parse_quantizer_values(svc_ctx, si->quantizers_keyframe, 1);
  if (res != VPX_CODEC_OK)
    memcpy(si->quantizer_keyframe, si->quantizer, sizeof(si->quantizer));

  res = parse_scale_factors(svc_ctx, si->scale_factors);
  if (res != VPX_CODEC_OK) return res;

  // parse aggregate command line options
  res = parse_options(svc_ctx, si->options);
  if (res != VPX_CODEC_OK) return res;

  // Assign target bitrate for each layer. We calculate the ratio
  // from the resolution for now.
  // TODO(Minghai): Optimize the mechanism of allocating bits after
  // implementing svc two pass rate control.
  if (si->layers > 1) {
    int i;
    float total = 0;
    float alloc_ratio[VPX_SS_MAX_LAYERS] = {0};

    for (i = 0; i < si->layers; ++i) {
      int pos = i + VPX_SS_MAX_LAYERS - svc_ctx->spatial_layers;
      if (pos < VPX_SS_MAX_LAYERS && si->scaling_factor_den[pos] > 0) {
        alloc_ratio[i] = (float)(si->scaling_factor_num[pos] * 1.0 /
            si->scaling_factor_den[pos]);

        alloc_ratio[i] *= alloc_ratio[i];
        total += alloc_ratio[i];
      }
    }

    for (i = 0; i < si->layers; ++i) {
      if (total > 0) {
        enc_cfg->ss_target_bitrate[i] = (unsigned int)
            (enc_cfg->rc_target_bitrate * alloc_ratio[i] / total);
      }
    }
  }

  // modify encoder configuration
  enc_cfg->ss_number_layers = si->layers;
  enc_cfg->ts_number_layers = 1;  // Temporal layers not used in this encoder.
  enc_cfg->kf_mode = VPX_KF_DISABLED;
  // Lag in frames not currently supported
  enc_cfg->g_lag_in_frames = 0;

  // TODO(ivanmaltz): determine if these values need to be set explicitly for
  // svc, or if the normal default/override mechanism can be used
  enc_cfg->rc_dropframe_thresh = 0;
  enc_cfg->rc_end_usage = VPX_CBR;
  enc_cfg->rc_resize_allowed = 0;
  enc_cfg->rc_min_quantizer = 33;
  enc_cfg->rc_max_quantizer = 33;
  enc_cfg->rc_undershoot_pct = 100;
  enc_cfg->rc_overshoot_pct = 15;
  enc_cfg->rc_buf_initial_sz = 500;
  enc_cfg->rc_buf_optimal_sz = 600;
  enc_cfg->rc_buf_sz = 1000;
  enc_cfg->g_error_resilient = 1;

  // Initialize codec
  res = vpx_codec_enc_init(codec_ctx, iface, enc_cfg, VPX_CODEC_USE_PSNR);
  if (res != VPX_CODEC_OK) {
    svc_log(svc_ctx, SVC_LOG_ERROR, "svc_enc_init error\n");
    return res;
  }

  vpx_codec_control(codec_ctx, VP9E_SET_SVC, 1);
  vpx_codec_control(codec_ctx, VP8E_SET_CPUUSED, 1);
  vpx_codec_control(codec_ctx, VP8E_SET_STATIC_THRESHOLD, 1);
  vpx_codec_control(codec_ctx, VP8E_SET_NOISE_SENSITIVITY, 1);
  vpx_codec_control(codec_ctx, VP8E_SET_TOKEN_PARTITIONS, 1);

  max_intra_size_pct =
      (int)(((double)enc_cfg->rc_buf_optimal_sz * 0.5) *
            ((double)enc_cfg->g_timebase.den / enc_cfg->g_timebase.num) / 10.0);
  vpx_codec_control(codec_ctx, VP8E_SET_MAX_INTRA_BITRATE_PCT,
                    max_intra_size_pct);
  return VPX_CODEC_OK;
}

// SVC Algorithm flags - these get mapped to VP8_EFLAG_* defined in vp8cx.h

// encoder should reference the last frame
#define USE_LAST (1 << 0)

// encoder should reference the alt ref frame
#define USE_ARF (1 << 1)

// encoder should reference the golden frame
#define USE_GF (1 << 2)

// encoder should copy current frame to the last frame buffer
#define UPDATE_LAST (1 << 3)

// encoder should copy current frame to the alt ref frame buffer
#define UPDATE_ARF (1 << 4)

// encoder should copy current frame to the golden frame
#define UPDATE_GF (1 << 5)

static int map_vp8_flags(int svc_flags) {
  int flags = 0;

  if (!(svc_flags & USE_LAST)) flags |= VP8_EFLAG_NO_REF_LAST;
  if (!(svc_flags & USE_ARF)) flags |= VP8_EFLAG_NO_REF_ARF;
  if (!(svc_flags & USE_GF)) flags |= VP8_EFLAG_NO_REF_GF;

  if (svc_flags & UPDATE_LAST) {
    // last is updated automatically
  } else {
    flags |= VP8_EFLAG_NO_UPD_LAST;
  }
  if (svc_flags & UPDATE_ARF) {
    flags |= VP8_EFLAG_FORCE_ARF;
  } else {
    flags |= VP8_EFLAG_NO_UPD_ARF;
  }
  if (svc_flags & UPDATE_GF) {
    flags |= VP8_EFLAG_FORCE_GF;
  } else {
    flags |= VP8_EFLAG_NO_UPD_GF;
  }
  return flags;
}

static void calculate_enc_frame_flags(SvcContext *svc_ctx) {
  vpx_enc_frame_flags_t flags = VPX_EFLAG_FORCE_KF;
  SvcInternal *const si = get_svc_internal(svc_ctx);
  const int is_keyframe = (si->frame_within_gop == 0);

  // keyframe layer zero is identical for all modes
  if (is_keyframe && si->layer == 0) {
    si->enc_frame_flags = VPX_EFLAG_FORCE_KF;
    return;
  }

  switch (svc_ctx->encoding_mode) {
    case ALT_INTER_LAYER_PREDICTION_IP:
      if (si->layer == 0) {
        flags = map_vp8_flags(USE_LAST | UPDATE_LAST);
      } else if (is_keyframe) {
        if (si->layer == si->layers - 1) {
          flags = map_vp8_flags(USE_ARF | UPDATE_LAST);
        } else {
          flags = map_vp8_flags(USE_ARF | UPDATE_LAST | UPDATE_GF);
        }
      } else {
        flags = map_vp8_flags(USE_LAST | USE_ARF | UPDATE_LAST);
      }
      break;
    case INTER_LAYER_PREDICTION_I:
      if (si->layer == 0) {
        flags = map_vp8_flags(USE_LAST | UPDATE_LAST);
      } else if (is_keyframe) {
        flags = map_vp8_flags(USE_ARF | UPDATE_LAST);
      } else {
        flags = map_vp8_flags(USE_LAST | UPDATE_LAST);
      }
      break;
    case INTER_LAYER_PREDICTION_IP:
      if (si->layer == 0) {
        flags = map_vp8_flags(USE_LAST | UPDATE_LAST);
      } else if (is_keyframe) {
        flags = map_vp8_flags(USE_ARF | UPDATE_LAST);
      } else {
        flags = map_vp8_flags(USE_LAST | USE_ARF | UPDATE_LAST);
      }
      break;
    case USE_GOLDEN_FRAME:
      if (2 * si->layers - SVC_REFERENCE_FRAMES <= si->layer) {
        if (si->layer == 0) {
          flags = map_vp8_flags(USE_LAST | USE_GF | UPDATE_LAST);
        } else if (is_keyframe) {
          flags = map_vp8_flags(USE_ARF | UPDATE_LAST | UPDATE_GF);
        } else {
          flags = map_vp8_flags(USE_LAST | USE_ARF | USE_GF | UPDATE_LAST);
        }
      } else {
        if (si->layer == 0) {
          flags = map_vp8_flags(USE_LAST | UPDATE_LAST);
        } else if (is_keyframe) {
          flags = map_vp8_flags(USE_ARF | UPDATE_LAST);
        } else {
          flags = map_vp8_flags(USE_LAST | UPDATE_LAST);
        }
      }
      break;
    default:
      svc_log(svc_ctx, SVC_LOG_ERROR, "unexpected encoding mode: %d\n",
              svc_ctx->encoding_mode);
      break;
  }
  si->enc_frame_flags = flags;
}

vpx_codec_err_t vpx_svc_get_layer_resolution(const SvcContext *svc_ctx,
                                             int layer,
                                             unsigned int *width,
                                             unsigned int *height) {
  int w, h, index, num, den;
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);

  if (svc_ctx == NULL || si == NULL || width == NULL || height == NULL) {
    return VPX_CODEC_INVALID_PARAM;
  }
  if (layer < 0 || layer >= si->layers) return VPX_CODEC_INVALID_PARAM;

  index = layer + VPX_SS_MAX_LAYERS - si->layers;
  num = si->scaling_factor_num[index];
  den = si->scaling_factor_den[index];
  if (num == 0 || den == 0) return VPX_CODEC_INVALID_PARAM;

  w = si->width * num / den;
  h = si->height * num / den;

  // make height and width even to make chrome player happy
  w += w % 2;
  h += h % 2;

  *width = w;
  *height = h;

  return VPX_CODEC_OK;
}

static void set_svc_parameters(SvcContext *svc_ctx,
                               vpx_codec_ctx_t *codec_ctx) {
  int layer, layer_index;
  vpx_svc_parameters_t svc_params;
  SvcInternal *const si = get_svc_internal(svc_ctx);

  memset(&svc_params, 0, sizeof(svc_params));
  svc_params.temporal_layer = 0;
  svc_params.spatial_layer = si->layer;
  svc_params.flags = si->enc_frame_flags;

  layer = si->layer;
  if (svc_ctx->encoding_mode == ALT_INTER_LAYER_PREDICTION_IP &&
      si->frame_within_gop == 0) {
    // layers 1 & 3 don't exist in this mode, use the higher one
    if (layer == 0 || layer == 2) {
      layer += 1;
    }
  }
  if (VPX_CODEC_OK != vpx_svc_get_layer_resolution(svc_ctx, layer,
                                                   &svc_params.width,
                                                   &svc_params.height)) {
    svc_log(svc_ctx, SVC_LOG_ERROR, "vpx_svc_get_layer_resolution failed\n");
  }
  layer_index = layer + VPX_SS_MAX_LAYERS - si->layers;

  if (vpx_svc_is_keyframe(svc_ctx)) {
    svc_params.min_quantizer = si->quantizer_keyframe[layer_index];
    svc_params.max_quantizer = si->quantizer_keyframe[layer_index];
  } else {
    svc_params.min_quantizer = si->quantizer[layer_index];
    svc_params.max_quantizer = si->quantizer[layer_index];
  }

  svc_params.distance_from_i_frame = si->frame_within_gop;

  // Use buffer i for layer i LST
  svc_params.lst_fb_idx = si->layer;

  // Use buffer i-1 for layer i Alt (Inter-layer prediction)
  if (si->layer != 0) {
    const int use_higher_layer =
        svc_ctx->encoding_mode == ALT_INTER_LAYER_PREDICTION_IP &&
        si->frame_within_gop == 0;
    svc_params.alt_fb_idx = use_higher_layer ? si->layer - 2 : si->layer - 1;
  }

  if (svc_ctx->encoding_mode == ALT_INTER_LAYER_PREDICTION_IP) {
    svc_params.gld_fb_idx = si->layer + 1;
  } else {
    if (si->layer < 2 * si->layers - SVC_REFERENCE_FRAMES)
      svc_params.gld_fb_idx = svc_params.lst_fb_idx;
    else
      svc_params.gld_fb_idx = 2 * si->layers - 1 - si->layer;
  }

  svc_log(svc_ctx, SVC_LOG_DEBUG, "SVC frame: %d, layer: %d, %dx%d, q: %d\n",
          si->encode_frame_count, si->layer, svc_params.width,
          svc_params.height, svc_params.min_quantizer);

  if (svc_params.flags == VPX_EFLAG_FORCE_KF) {
    svc_log(svc_ctx, SVC_LOG_DEBUG, "flags == VPX_EFLAG_FORCE_KF\n");
  } else {
    svc_log(
        svc_ctx, SVC_LOG_DEBUG, "Using:    LST/GLD/ALT [%2d|%2d|%2d]\n",
        svc_params.flags & VP8_EFLAG_NO_REF_LAST ? -1 : svc_params.lst_fb_idx,
        svc_params.flags & VP8_EFLAG_NO_REF_GF ? -1 : svc_params.gld_fb_idx,
        svc_params.flags & VP8_EFLAG_NO_REF_ARF ? -1 : svc_params.alt_fb_idx);
    svc_log(
        svc_ctx, SVC_LOG_DEBUG, "Updating: LST/GLD/ALT [%2d|%2d|%2d]\n",
        svc_params.flags & VP8_EFLAG_NO_UPD_LAST ? -1 : svc_params.lst_fb_idx,
        svc_params.flags & VP8_EFLAG_NO_UPD_GF ? -1 : svc_params.gld_fb_idx,
        svc_params.flags & VP8_EFLAG_NO_UPD_ARF ? -1 : svc_params.alt_fb_idx);
  }

  vpx_codec_control(codec_ctx, VP9E_SET_SVC_PARAMETERS, &svc_params);
}

/**
 * Encode a frame into multiple layers
 * Create a superframe containing the individual layers
 */
vpx_codec_err_t vpx_svc_encode(SvcContext *svc_ctx, vpx_codec_ctx_t *codec_ctx,
                               struct vpx_image *rawimg, vpx_codec_pts_t pts,
                               int64_t duration, int deadline) {
  vpx_codec_err_t res;
  vpx_codec_iter_t iter;
  const vpx_codec_cx_pkt_t *cx_pkt;
  struct LayerData *cx_layer_list = NULL;
  struct LayerData *layer_data;
  struct Superframe superframe;
  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || codec_ctx == NULL || rawimg == NULL || si == NULL) {
    return VPX_CODEC_INVALID_PARAM;
  }

  memset(&superframe, 0, sizeof(superframe));
  svc_log_reset(svc_ctx);
  si->rc_stats_buf_used = 0;

  si->layers = svc_ctx->spatial_layers;
  if (si->frame_within_gop >= si->kf_dist ||
      si->encode_frame_count == 0) {
    si->frame_within_gop = 0;
  }
  si->is_keyframe = (si->frame_within_gop == 0);
  si->frame_size = 0;

  svc_log(svc_ctx, SVC_LOG_DEBUG,
          "vpx_svc_encode  layers: %d, frame_count: %d, frame_within_gop: %d\n",
          si->layers, si->encode_frame_count, si->frame_within_gop);

  // encode each layer
  for (si->layer = 0; si->layer < si->layers; ++si->layer) {
    if (svc_ctx->encoding_mode == ALT_INTER_LAYER_PREDICTION_IP &&
        si->is_keyframe && (si->layer == 1 || si->layer == 3)) {
      svc_log(svc_ctx, SVC_LOG_DEBUG, "Skip encoding layer %d\n", si->layer);
      continue;
    }
    calculate_enc_frame_flags(svc_ctx);

    set_svc_parameters(svc_ctx, codec_ctx);

    res = vpx_codec_encode(codec_ctx, rawimg, pts, (uint32_t)duration,
                           si->enc_frame_flags, deadline);
    if (res != VPX_CODEC_OK) {
      return res;
    }
    // save compressed data
    iter = NULL;
    while ((cx_pkt = vpx_codec_get_cx_data(codec_ctx, &iter))) {
      switch (cx_pkt->kind) {
        case VPX_CODEC_CX_FRAME_PKT: {
          const uint32_t frame_pkt_size = (uint32_t)(cx_pkt->data.frame.sz);
          si->bytes_sum[si->layer] += frame_pkt_size;
          svc_log(svc_ctx, SVC_LOG_DEBUG,
                  "SVC frame: %d, layer: %d, size: %u\n",
                  si->encode_frame_count, si->layer, frame_pkt_size);
          layer_data =
              ld_create(cx_pkt->data.frame.buf, (size_t)frame_pkt_size);
          if (layer_data == NULL) {
            svc_log(svc_ctx, SVC_LOG_ERROR, "Error allocating LayerData\n");
            return VPX_CODEC_OK;
          }
          ld_list_add(&cx_layer_list, layer_data);

          // save layer size in superframe index
          superframe.sizes[superframe.count++] = frame_pkt_size;
          superframe.magnitude |= frame_pkt_size;
          break;
        }
        case VPX_CODEC_PSNR_PKT: {
          int i;
          svc_log(svc_ctx, SVC_LOG_DEBUG,
                  "SVC frame: %d, layer: %d, PSNR(Total/Y/U/V): "
                  "%2.3f  %2.3f  %2.3f  %2.3f \n",
                  si->encode_frame_count, si->layer,
                  cx_pkt->data.psnr.psnr[0], cx_pkt->data.psnr.psnr[1],
                  cx_pkt->data.psnr.psnr[2], cx_pkt->data.psnr.psnr[3]);
          svc_log(svc_ctx, SVC_LOG_DEBUG,
                  "SVC frame: %d, layer: %d, SSE(Total/Y/U/V): "
                  "%2.3f  %2.3f  %2.3f  %2.3f \n",
                  si->encode_frame_count, si->layer,
                  cx_pkt->data.psnr.sse[0], cx_pkt->data.psnr.sse[1],
                  cx_pkt->data.psnr.sse[2], cx_pkt->data.psnr.sse[3]);
          for (i = 0; i < COMPONENTS; i++) {
            si->psnr_sum[si->layer][i] += cx_pkt->data.psnr.psnr[i];
            si->sse_sum[si->layer][i] += cx_pkt->data.psnr.sse[i];
          }
          break;
        }
        case VPX_CODEC_STATS_PKT: {
          size_t new_size = si->rc_stats_buf_used +
              cx_pkt->data.twopass_stats.sz;

          if (new_size > si->rc_stats_buf_size) {
            char *p = (char*)realloc(si->rc_stats_buf, new_size);
            if (p == NULL) {
              svc_log(svc_ctx, SVC_LOG_ERROR, "Error allocating stats buf\n");
              break;
            }
            si->rc_stats_buf = p;
            si->rc_stats_buf_size = new_size;
          }

          memcpy(si->rc_stats_buf + si->rc_stats_buf_used,
                 cx_pkt->data.twopass_stats.buf, cx_pkt->data.twopass_stats.sz);
          si->rc_stats_buf_used += cx_pkt->data.twopass_stats.sz;
          break;
        }
        default: {
          break;
        }
      }
    }
  }
  // add superframe index to layer data list
  sf_create_index(&superframe);
  layer_data = ld_create(superframe.buffer, superframe.index_size);
  ld_list_add(&cx_layer_list, layer_data);

  // get accumulated size of layer data
  si->frame_size = ld_list_get_buffer_size(cx_layer_list);
  if (si->frame_size == 0) return VPX_CODEC_ERROR;

  // all layers encoded, create single buffer with concatenated layers
  if (si->frame_size > si->buffer_size) {
    free(si->buffer);
    si->buffer = malloc(si->frame_size);
    if (si->buffer == NULL) {
      ld_list_free(cx_layer_list);
      return VPX_CODEC_MEM_ERROR;
    }
    si->buffer_size = si->frame_size;
  }
  // copy layer data into packet
  ld_list_copy_to_buffer(cx_layer_list, (uint8_t *)si->buffer);

  ld_list_free(cx_layer_list);

  svc_log(svc_ctx, SVC_LOG_DEBUG, "SVC frame: %d, kf: %d, size: %d, pts: %d\n",
          si->encode_frame_count, si->is_keyframe, (int)si->frame_size,
          (int)pts);
  ++si->frame_within_gop;
  ++si->encode_frame_count;

  return VPX_CODEC_OK;
}

const char *vpx_svc_get_message(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return NULL;
  return si->message_buffer;
}

void *vpx_svc_get_buffer(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return NULL;
  return si->buffer;
}

size_t vpx_svc_get_frame_size(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return 0;
  return si->frame_size;
}

int vpx_svc_get_encode_frame_count(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return 0;
  return si->encode_frame_count;
}

int vpx_svc_is_keyframe(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return 0;
  return si->is_keyframe;
}

void vpx_svc_set_keyframe(SvcContext *svc_ctx) {
  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return;
  si->frame_within_gop = 0;
}

static double calc_psnr(double d) {
  if (d == 0) return 100;
  return -10.0 * log(d) / log(10.0);
}

// dump accumulated statistics and reset accumulated values
const char *vpx_svc_dump_statistics(SvcContext *svc_ctx) {
  int number_of_frames, number_of_keyframes, encode_frame_count;
  int i, j;
  uint32_t bytes_total = 0;
  double scale[COMPONENTS];
  double psnr[COMPONENTS];
  double mse[COMPONENTS];
  double y_scale;

  SvcInternal *const si = get_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return NULL;

  svc_log_reset(svc_ctx);

  encode_frame_count = si->encode_frame_count;
  if (si->encode_frame_count <= 0) return vpx_svc_get_message(svc_ctx);

  svc_log(svc_ctx, SVC_LOG_INFO, "\n");
  number_of_keyframes = encode_frame_count / si->kf_dist + 1;
  for (i = 0; i < si->layers; ++i) {
    number_of_frames = encode_frame_count;

    if (svc_ctx->encoding_mode == ALT_INTER_LAYER_PREDICTION_IP &&
        (i == 1 || i == 3)) {
      number_of_frames -= number_of_keyframes;
    }
    svc_log(svc_ctx, SVC_LOG_INFO,
            "Layer %d Average PSNR=[%2.3f, %2.3f, %2.3f, %2.3f], Bytes=[%u]\n",
            i, (double)si->psnr_sum[i][0] / number_of_frames,
            (double)si->psnr_sum[i][1] / number_of_frames,
            (double)si->psnr_sum[i][2] / number_of_frames,
            (double)si->psnr_sum[i][3] / number_of_frames, si->bytes_sum[i]);
    // the following psnr calculation is deduced from ffmpeg.c#print_report
    y_scale = si->width * si->height * 255.0 * 255.0 * number_of_frames;
    scale[1] = y_scale;
    scale[2] = scale[3] = y_scale / 4;  // U or V
    scale[0] = y_scale * 1.5;           // total

    for (j = 0; j < COMPONENTS; j++) {
      psnr[j] = calc_psnr(si->sse_sum[i][j] / scale[j]);
      mse[j] = si->sse_sum[i][j] * 255.0 * 255.0 / scale[j];
    }
    svc_log(svc_ctx, SVC_LOG_INFO,
            "Layer %d Overall PSNR=[%2.3f, %2.3f, %2.3f, %2.3f]\n", i, psnr[0],
            psnr[1], psnr[2], psnr[3]);
    svc_log(svc_ctx, SVC_LOG_INFO,
            "Layer %d Overall MSE=[%2.3f, %2.3f, %2.3f, %2.3f]\n", i, mse[0],
            mse[1], mse[2], mse[3]);

    bytes_total += si->bytes_sum[i];
    // clear sums for next time
    si->bytes_sum[i] = 0;
    for (j = 0; j < COMPONENTS; ++j) {
      si->psnr_sum[i][j] = 0;
      si->sse_sum[i][j] = 0;
    }
  }

  // only display statistics once
  si->encode_frame_count = 0;

  svc_log(svc_ctx, SVC_LOG_INFO, "Total Bytes=[%u]\n", bytes_total);
  return vpx_svc_get_message(svc_ctx);
}

void vpx_svc_release(SvcContext *svc_ctx) {
  SvcInternal *si;
  if (svc_ctx == NULL) return;
  // do not use get_svc_internal as it will unnecessarily allocate an
  // SvcInternal if it was not already allocated
  si = (SvcInternal *)svc_ctx->internal;
  if (si != NULL) {
    free(si->buffer);
    if (si->rc_stats_buf) {
      free(si->rc_stats_buf);
    }
    free(si);
    svc_ctx->internal = NULL;
  }
}

size_t vpx_svc_get_rc_stats_buffer_size(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return 0;
  return si->rc_stats_buf_used;
}

char *vpx_svc_get_rc_stats_buffer(const SvcContext *svc_ctx) {
  const SvcInternal *const si = get_const_svc_internal(svc_ctx);
  if (svc_ctx == NULL || si == NULL) return NULL;
  return si->rc_stats_buf;
}