struct ncTensorDescriptor_t
| Info | Value |
|---|---|
| Header | mvnc.h |
| Version | 2.0 |
| See also | struct ncGraphHandle_t, struct ncFifoHandle_t, ncGraphOption_t, ncFifoOption_t, ncGraphGetOption(), ncFifoGetOption() |
Overview
The ncTensorDescriptor_t struct describes graph inputs and outputs.
| Member | Type | Description |
|---|---|---|
| n | unsigned int | The number of tensors in the batch. Only 1 currently supported. |
| c | unsigned int | For image tensors, this is the number of channels per pixel. For non-image tensors, this is always 1. |
| w | unsigned int | For image tensors, this is the width in pixels. For non-image tensors, this is always 1. |
| h | unsigned int | The height of the tensor. For non-image tensors, this is always 1. |
| totalSize | unsigned int | For image tensors, this is the height in pixels. For non-image tensors, this is always 1. |
| cStride | unsigned int | Stride (distance between elements in bytes) in the channel dimension. |
| wStride | unsigned int | Stride (distance between elements in bytes) in the horizontal dimension. |
| hStride | unsigned int | Stride (distance between elements in bytes) in the vertical dimension. |
| dataType | ncFifoDataType_t | The tensor’s data type (FP16 or FP32). |
Notes
- You can use ncGraphGetOption() to get arrays of input or output ncTensorDescriptor_t structs for a graph.
- If your application’s input tensor is not in a channel minor format (i.e. RGB/BGR), you can create a ncTensorDescriptor struct with appropriate values for the stride fields and pass it to ncFifoSetOption() for NC_RW_HOST_TENSOR_DESCRIPTOR. This currently cannot be used to perform scaling (n/c/h/w fields must match those in the NC_RO_GRAPH_TENSOR_DESCRIPTOR for this FIFO. See the examples below.
Examples
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// The n/c/w/h fields for the RW_HOST_TENSOR_DESCRIPTOR must match the dimensions of the RO_GRAPH_TENSOR_DESCRIPTOR, so start with that
struct ncTensorDescriptor_t inputTensorDesc;
unsigned int length = sizeof(struct ncTensorDescriptor_t);
ncGraphGetOption(graphHandle, NC_RO_GRAPH_INPUT_TENSOR_DESCRIPTORS, &inputTensorDesc, &length);
struct ncTensorDescriptor_t hostTensorDesc = inputTensorDesc;
// Set the tensor data type
hostTensorDesc.dataType = NC_FIFO_FP32;
// For channel-minor data with FP32 data type, there are 4 bytes between each element of the channel
// The horizontal stride (wStride), vertical stride (hStride), and totalSize can be calculated from there
hostTensorDesc.cStride = sizeof(float); //FP32
hostTensorDesc.wStride = hostTensorDesc.cStride * hostTensorDesc.c;
hostTensorDesc.hStride = hostTensorDesc.wStride * hostTensorDesc.w;
hostTensorDesc.totalSize = hostTensorDesc.hStride * hostTensorDesc.h;
// Set the option
length = sizeof(struct ncTensorDescriptor_t);
ncFifoSetOption(bufferIn, NC_RW_FIFO_HOST_TENSOR_DESCRIPTOR, &hostTensorDesc, length);
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