# Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license

# Parameters
nc: 80 # number of classes
depth_multiple: 0.33 # model depth multiple
width_multiple: 0.50 # layer channel multiple
anchors:
  - [10, 13, 16, 30, 33, 23] # P3/8
  - [30, 61, 62, 45, 59, 119] # P4/16
  - [116, 90, 156, 198, 373, 326] # P5/32

# YOLOv5 v6.0 backbone
backbone:
  # [from, number, module, args]
  [
    [-1, 1, Conv, [64, 6, 2, 2]], # 0-P1/2
    [-1, 1, Conv, [128, 3, 2]], # 1-P2/4
    [-1, 3, C3, [128]],
    [-1, 1, Conv, [256, 3, 2]], # 3-P3/8
    [-1, 6, C3, [256]],
    [-1, 1, Conv, [512, 3, 2]], # 5-P4/16
    [-1, 9, C3, [512]],
    [-1, 1, Conv, [1024, 3, 2]], # 7-P5/32
    [-1, 3, C3, [1024]],
    [-1, 1, SPPF, [1024, 5]], # 9
  ]

# # YOLOv5 v6.0 head
# head: [
#     [-1, 1, Conv, [512, 1, 1]],
#     [-1, 1, nn.Upsample, [None, 2, "nearest"]],
#     [[-1, 6], 1, Concat, [1]], # cat backbone P4
#     [-1, 3, C3, [512, False]], # 13

#     [-1, 1, Conv, [256, 1, 1]],
#     [-1, 1, nn.Upsample, [None, 2, "nearest"]],
#     [[-1, 4], 1, Concat, [1]], # cat backbone P3
#     [-1, 3, C3, [256, False]], # 17 (P3/8-small)

#     [-1, 1, Conv, [256, 3, 2]],
#     [[-1, 14], 1, Concat, [1]], # cat head P4
#     [-1, 3, C3, [512, False]], # 20 (P4/16-medium)

#     [-1, 1, Conv, [512, 3, 2]],
#     [[-1, 10], 1, Concat, [1]], # cat head P5
#     [-1, 3, C3, [1024, False]], # 23 (P5/32-large)

#     [[17, 20, 23], 1, Detect, [nc, anchors]], # Detect(P3, P4, P5)
#   ]

# YOLOv5 v6.0 head (PAN + WeightedAdd)
head: [
  # ---------- Top-down FPN ----------
  [-1, 1, Conv, [512, 1, 1]],                     # 10: reduce P5
  [-1, 1, nn.Upsample, [None, 2, "nearest"]],     # 11
  [[-1, 6], 1, WeightedAdd, [2]],                 # 12: P5 + backbone P4
  [-1, 3, C3, [512, False]],                      # 13

  [-1, 1, Conv, [256, 1, 1]],                     # 14: reduce
  [-1, 1, nn.Upsample, [None, 2, "nearest"]],     # 15
  [[-1, 4], 1, WeightedAdd, [2]],                 # 16: P4 + backbone P3
  [-1, 3, C3, [256, False]],                      # 17 (P3/8)

  # ---------- Bottom-up PAN ----------
  [-1, 1, Conv, [256, 3, 2]],                     # 18: downsample
  [[-1, 13], 1, WeightedAdd, [2]],                # 19: P3 -> P4
  [-1, 3, C3, [512, False]],                      # 20 (P4/16)

  [-1, 1, Conv, [512, 3, 2]],                     # 21: downsample
  [[-1, 10], 1, WeightedAdd, [2]],                # 22: P4 -> P5
  [-1, 3, C3, [1024, False]],                     # 23 (P5/32)

  [[17, 20, 23], 1, Detect, [nc, anchors]],       # Detect(P3, P4, P5)
]