#Dynamic Input Introduction

When the model input tensor properties validShape or stride contains -1, it means that the model input is dynamic and you need to fill in the dynamic dimension according to the actual input.

The following rules should be followed when filling in stride:

• Make sure the filled value satisfies $stride[idx] >= stride[idx+1] * validShape.dimensionSize[idx+1]$, where idx represents the current dimension.

• For stride of Y and UV inputs, due to some hardware constraints, fixed alignment requirement needs to be ensured in the W direction, where S100/S100P requires 32-byte alignment, which means you need to align the input according to stride.

Here, using the S100 model as an example, the stride is required to be 32-byte aligned, and the model has three inputs:

• input_y : validShape = [1,-1,-1,1]，stride = [-1,-1,1,1]
• input_uv : validShape = [1,-1,-1,2]，stride = [-1,-1,2,1]
• input_roi : validShape = [1,4]，stride = [16,4]

input_y and input_uv are dynamic inputs, and are Y and UV inputs. Assume that the actually inputs: input_y's validShape = [1,220,220,1], input_uv's validShape = [1,110,110,2]. stride is calculated as follows to ensure that the dynamic dimension is aligned to 32, where ALIGN_32 represents 32-byte alignment:

• input_y :

  stride[3] = 1;

  stride[2] = 1;

  stride[1] = ALIGN_32(stride[2] * validShape.dimensionSize[2]) = ALIGN_32(1 * 220) = 224;

  stride[0] = ALIGN_32(stride[1] * validShape.dimensionSize[1]) = ALIGN_32(224 * 220) = 49280;

• input_uv :

  stride[3] = 1;

  stride[2] = 2;

  stride[1] = ALIGN_32(stride[2] * validShape.dimensionSize[2]) = ALIGN_32(2 * 110) = 224;

  stride[0] = ALIGN_32(stride[1] * validShape.dimensionSize[1]) = ALIGN_32(224 * 110) = 24640;

You need to set the following properties when preparing the input, and align the input data according to stride:

• input_y : validShape = [1,220,220,1]，stride = [49280,224,1,1]
• input_uv : validShape = [1,110,110,2]，stride = [24640,224,2,1]
• input_roi : validShape = [1,4]，stride = [16,4]