transform_unit_sample (nvbuf_utils pixel format conversion)

• Overview
• Building and Running
• Flow
• Key Structure and Classes

---

Overview

The NVIDIA buffering utility, nvbuf_utils provide a wrapper to simplify the use case of applications/plugins for buffering and transform, composite, or blending.

The transform unit sample demonstrates the use of nvbuf_utils for conversion from one pixel-format to another. Supported pixel formats, filters, composites and other properties are described in the nvbuf_utils.

Supported pixel formats are:

• NV12
• NV21
• NV12_709
• ARGB32
• XRGB32
• YUV420
• YVU420
• YUV420_709

---

Building and Running

Prerequisites

• You have followed steps 1-3 in Building and Running.
• If you are building from your host Linux PC (x86), you have followed step 4 in Building and Running.

To build

• Enter:

   $ cd /usr/src/jetson_multimedia_api/samples/unittest_samples/transform_unit_sample
   $ make
  

To run

• Enter:

   $ ./transform_sample <in-file> <in-pix-fmt> <in-width> <in-height> <out-file> <out-pixfmt>
  

To view supported options

Enter:

   $ ./transform_sample --help

Example

  $ ./transform_sample ../../data/Video/sample_outdoor_car_1080p_10fps.yuv
  yuv420 1920 1080 sample_outdoor_car_1080p_10fps_nv12.yuv nv12

---

Flow

The following steps show the flow through this sample.

1. Create input and output DMA mapped hardware buffers.
2. Define the transformation parameters.
3. Call the NvBufferTransform which transforms the input DMA buffer to the output DMA buffer, both exported as fd.
4. The application writes the transformed buffer into a file.

---

Key Structure and Classes

The sample uses the nvbuf_utils functions:

Element	Description
NvBufferMemMap	Gets mem mapped virtual Address of the plane.
NvBufferMemUnMap	Unmaps mapped virtual Address of the plane.
NvBufferGetParams	Gets the buffer parameters.
NvBufferCreateEx	Allocates a hardware buffer.
NvBufferMemSyncForCpu	Syncs hw memory cache for the CPU.
NvBufferMemSyncForDevice	Syncs hw memory cache for the device.
NvBufferTransform	Transforms one DMA buffer to another DMA buffer.
NvBufferDestroy	Destroys hw buffer.