Accelerated Decode with ffmpeg¶

The NVIDIA ffmpeg package supports hardware-accelerated decode on NVIDIA^® Jetson™ device.

An application can use accelerated decode to read video files in the following elementary formats and container formats and dump them in YUV 420 format:

H.264
H.265
VP8
VP9
MPEG2
MPEG4

Note

The ffmpeg package does not support MPEG4 container files.

To install the ffmpeg binary package¶

Enter this command:
```
$ sudo apt install ffmpeg
```

To get source files for the ffmpeg package¶

Enter this command:
```
$ apt source ffmpeg
```

To include the ffmpeg library in Jetson Linux builds¶

Add the following lines to /etc/apt/sources.list:

$ echo "deb https://repo.download.nvidia.com/jetson/ffmpeg main main" | sudo tee -a /etc/apt/sources.list
$ echo "deb-src https://repo.download.nvidia.com/jetson/ffmpeg main main" | sudo tee -a /etc/apt/sources.list

Enter this command:
```
$ sudo apt update
```

Decode Functional Flow¶

This section describes the function flow of the ffmpeg decoding process:

Call nvv4l2dec_init_decoder() to create a new V4L2 Video Decoder object on the device node /dev/nvhost-nvdec.
Call subscribe_event() to subscribe to resolution change events.
Call set_output_plane_format() to set the format on the output plane.
Call capture_thread() to start a capture thread.
Call set_capture_plane_format() to set the format on the capture plane.
Call nvv4l2dec_decode() to read buffers from ffmpeg and start the decode process.
Call nvv4l2dec_decoder_get_frame() to get the hardware-accelerated decoded data and pass it to ffmpeg for dumping.
Call nvv4l2dec_decoder_close() to destroy the buffers and close the device.

The following table describes the key structure.

Element	Description
nvPacket	Contains information about input packets.
nvFrame	Contains information about decoded frames.
nvCodingType	Specifies a different codec type.
BufferPlane	Holds the buffer plane parameters.
Buffer	Holds the buffer information.
context_t	Defines the decoder context.

This table describes the key function:

Element	Description
nvv4l2dec_create_decoder	Creates a new V4L2 Video Decoder object on the device node `/dev/nvhost-nvdec`.
subscribe_event	Subscribes to resolution change events.
set_output_plane_format	Sets the format on the output plane.
req_buffers_on_output_plane	Requests buffers on the output plane to be filled from the input bit stream.
dq_buffer	Dequeues the V4L2 buffer.
q_buffer	Queues the V4L2 buffer.
capture_thread	Starts the capture thread.
dq_event	Dequeues an event reported by the V4L2 device.
req_buffers_on_capture_plane	Requests buffers on the capture plane.
set_capture_plane_format	Sets the capture plane format.