03_video_cuda_enc (CUDA processing with encode)

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

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Overview

The Video CUDA Encoder sample demonstrates how to capture use libv4l2 API to encode H.264/H.265 video streams. Before beginning encoding, it uses the NVIDIA^® CUDA^® API to render a black rectangle on the input YUV image data; the same buffer is used and shared by the decode component.

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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/03_video_cuda_enc
   $ make
  

To run

• Enter:

   $ ./video_cuda_enc <in-file> <in-width> <in-height> <encoder-type> <out-file> [OPTIONS]
  

Example

   $ ./video_cuda_enc ../../data/Video/sample_outdoor_car_1080p_10fps.yuv 1920 1080 H264 test.h264

Note

The video_cuda_enc sample consumes a YUV file. If you do not already have a YUV file, you can use the video_dec_cuda sample to generate one. For example:

 $ cd /usr/src/jetson_multimedia_api/samples/02_video_dec_cuda/
 $ ./video_dec_cuda ../../data/Video/sample_outdoor_car_1080p_10fps.h264 H264 --disable-rendering \
   -o ../../data/Video/sample_outdoor_car_1080p_10fps.yuv -f 2

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Flow

The following diagram shows the flow through this sample.

The NvEGLImageFromFd NV-defined API returns an EGLImage pointer from the file descriptor buffer that is allocated by Tegra. CUDA then uses EGLImage buffer to render the rectangle. The buffer then performs the video encode operation and encodes it to either an H.264 or H.265 video stream.

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Key Structure and Classes

The struct context_t global structure manages all of the resources in the application.

NvVideoConverter	Description
class NvVideoEncoder	This class contains all video encode related elements and functions.
EGLImageHKR	Specifies the EGLImage used for CUDA processing.

The NvVideoConverter class packages all video converting related elements and functions. The sample uses the following key members:

NvVideoConverter	Description
output_plane	Specifies the output plane.
capture_plane	Specifies the capture plane.
createVideoEncoder	Static function to create video encode object.
setExtControls	Sets external control to V4l2 device.
setOutputPlaneFormat	Sets the output plane format.
[setCapturePlaneFormat](NvVideoConverter::setCapturePlaneFormat]	Sets the capture plane format.
isInError	Checks if under error state.

Class NvVideoEncoder contains two key elements: output_plane and capture_plane. These objects are derived from class type NvV4l2ElementPlane. The sample uses the following key members:

NvV4l2ElementPlane	Description
setupPlane	Sets up the plane of V4l2 element.
deinitPlane	Destroys the plane of V4l2 element.
setStreamStatus	Starts/stops the stream.
setDQThreadCallback	Sets the callback function of dqueue buffer thread.
startDQThread	Starts the thread of dqueue buffer.
stopDQThread	Stops the thread of dqueue buffer.
qBuffer	Queues the V4l2 buffer.
dqBuffer	Dqueues V4l2 buffer.
getNumBuffers	Gets the number of V4l2 buffers.
getNthBuffer	Gets the nth V4l2 buffer.

Two global functions are used to create and destroy EGLImage from the dmabuf file descriptor:

Global Function	Description
NvEGLImageFromFd	Creates an EGLImage from dmabuf fd.
NvDestroyEGLImage	Destroys the EGLImage.