encoder_unit_sample (video encode unit samples)

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

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Overview

The encode_sample application is a unit level implementation that demonstrates how to encode H.264 video streams.

The application reads YUV input buffers from a file, performs H.264 video encoding, and saves the encoded bitstream to an elementary .264 file.

The application runs on file source simulated input buffers, and so does not require a camera.

Supported video formats are:

• H.264

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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/unittest_samples/encoder_unit_sample
   $ make
  

To run

• Enter:

  $ ./encode_sample <in-file> <in-width> <in-height> <out-file>
  

Example

   $ ./encode_sample ../../data/Video/sample_outdoor_car_1080p_10fps.yuv 1920 1080 sample_outdoor_car_1080p_10fps.h264

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Flow

The following steps show the flow through this sample.

• The encoder instance is created.
• V4L2_EVENT_EOS is subscribed.
• Output Plane and Capture Plane are set up.
• External controls are set.
• The Output Plane receives input in YUV frame format and delivers it to the Encoder for encoding.
• The Capture Plane transfers encoded frames to the application in bitstream format.
• The encoded bitstream is written to a file.
• For the Output Plane the application supports MMAP memory type. For the Capture Plane it supports MMAP memory type.

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Key Structure and Classes

The sample uses the following key class:

Element	Description
Buffer	Class modeled on v4l2_buffer structure.

The key structures and functions used in the sample are:

Function	Description
encoder_process_blocking	Function loop to DQ and EnQ buffers on output plane till eos is signalled.
dq_buffer	Function to dequeue a buffer from the plane.
capture_plane_callback	Callback function when enc_cap_thread is created.
q_buffer	Function to queue a buffer on the plane.
req_buffers_on_capture_plane	Function to request for buffers on the encoder capture plane.
req_buffers_on_output_plane	Function to request for buffers on the encoder output plane.
set_capture_plane_format	Function to set the format on the encoder capture plane.
set_output_plane_format	Function to set the format on the encoder output plane.
set_ext_controls	Function to set the value of controls.
subscribe_event	Function to subscrive to a V4L2 event.