Boost Your App's Latency with AMF DM Library - AMD Media SDK Tutorial

Table of Contents

1. Introduction
2. What is AMF DM?
3. Physical Connection between Display Controller and Video Compression Engine
4. Display Encode Mode
5. Low Latency Applications: Wireless Display and Remote Desktop
6. AMF DM Library: C++ API for Developers
7. Configuring AMF DM Library
8. Capture and Compression of Desktop
9. Configuring Audio Stream
10. Multiplexing Options
11. Sample Application and Source Code
12. Creating Encoder Object
13. Configuring Physical Connection
14. Cloning the Virtual Display
15. Configuring the Video Encoder
16. Starting the Encoding Process
17. Getting Compressed Frames
18. Storing Compressed Frames
19. Ending the Encoding Session
20. Demo: AMF DM in Action
21. Recap of Learned Concepts
22. Conclusion
23. FAQ

Introduction

The AMF DM library, developed by AMD, offers a powerful solution for developers to leverage the functionality of AMF DM in their applications. This article will delve into the details of AMF DM, including its physical connection between the display controller and the video compression engine, its display encode mode, and its suitability for low latency applications such as wireless display and remote desktop.

What is AMF DM?

AMF DM (Advanced Media Framework Display Manager) is a library provided by AMD that allows developers to utilize the capabilities of AMD APUs and discrete GPUs. It enables a direct physical connection between the display controller and the video compression engine, making it an ideal solution for tasks such as H.264 encoding.

Physical Connection between Display Controller and Video Compression Engine

AMD APUs and discrete GPUs establish a direct physical connection between the display controller and the video compression engine. This unique connection allows for efficient video compression, with the video compression engine handling H.264 encoding directly. This capability is known as display encode mode.

Display Encode Mode

Display encode mode is a feature provided by AMD APUs and discrete GPUs that enables the video compression engine to perform real-time H.264 encoding. This mode is particularly advantageous for low latency applications, such as wireless display and remote desktop, where capturing and compressing video in a single step is essential.

Low Latency Applications: Wireless Display and Remote Desktop

The display encode mode offered by AMF DM is particularly suited for low latency applications. Tasks such as wireless display and remote desktop benefit from the ability to quickly capture and compress video without introducing significant delays. This makes AMF DM a reliable solution for real-time streaming and remote access scenarios.

AMF DM Library: C++ API for Developers

To facilitate the integration of AMF DM functionality into applications, AMD provides a C++ API known as the AMF DM Library. This library allows developers to access and utilize the features of AMF DM seamlessly. By using the AMF DM Library, developers can implement efficient video encoding and streaming capabilities into their applications.

Configuring AMF DM Library

The AMF DM Library offers various configuration options to fine-tune the encoding process. Developers can specify parameters such as usage type (wireless display, low latency, etc.), output format (transport stream, elementary stream), and encoder settings (bitrate, buffer sizes, etc.). These configuration options provide developers with flexibility in tailoring AMF DM to their specific requirements.

Capture and Compression of Desktop

One of the key features of AMF DM is its ability to capture and compress the desktop in real-time. By utilizing the AMF DM Library, developers can easily capture the desktop and compress it into an H.264 elementary stream. This capability is vital for applications that require real-time streaming or remote access.

Configuring Audio Stream

In addition to video capture and compression, AMF DM also allows developers to capture the audio stream. Developers have the option to either capture the audio stream separately or multiplex it with the video stream into a transport stream. This flexibility ensures that developers can create comprehensive multimedia solutions using AMF DM.

Multiplexing Options

AMF DM provides developers with the ability to multiplex the captured video and audio streams into a transport stream. This feature allows for the integration of video and audio data into a single stream, enabling synchronized playback and transmission. Developers can choose the multiplexing option that best suits their application's requirements.

Sample Application and Source Code

To provide developers with a clear understanding of how to use AMF DM, AMD offers a sample application in the Media SDK 1.0 release. The sample application demonstrates the configuration and usage of AMF DM through source code. Developers can reference this sample application to implement AMF DM functionality in their own projects.

Creating Encoder Object

The first step in using AMF DM is to create an encoder object using the AMF CreateEncoder function. This encoder object is responsible for handling the encoding process and provides the necessary interface for configuring and controlling the encoding session.

Configuring Physical Connection

After creating the encoder object, the next step is to configure the physical connection between the display controller and the video compression engine. This is achieved by invoking the AcquireRemoteDisplay method on the encoder object. This method sets up a virtual display, which is presented to the operating system as an actual display.

Cloning the Virtual Display

Once the virtual display is established, developers can configure it in various ways. One common option is to clone the display, which creates an exact replica of the physical display. This can be achieved by using the SetDisplayConfig method with the STC_TOPOLOGY_CLONE flag. Cloning the display ensures that both the virtual and physical displays show the same content.

Configuring the Video Encoder

Before starting the encoding process, developers need to configure the video encoder. This can be done by using the SetProperty method on the encoder object. The SetProperty method allows developers to set various parameters, such as bitrate, buffer sizes, and encoding options, based on their specific requirements.

Starting the Encoding Process

Once the encoder object and the virtual display are configured, the encoding process can be initiated by calling the Start method on the encoder object. The encoding process runs in a loop, capturing and compressing frames according to the specified configuration. The encoding session continues until a specified number of frames are processed or a stop command is issued.

Getting Compressed Frames

During the encoding process, developers can retrieve the compressed frames using the GetNextFrame method. This method retrieves the compressed frames from a queue, allowing developers to access and manipulate the frames as needed. The compressed frames can be stored in a file, transmitted over a network, or used for further processing, depending on the application's requirements.

Storing Compressed Frames

In the sample application, the compressed frames are stored in a file. This demonstrates one of the possible ways to handle the compressed frames generated by AMF DM. However, developers have the flexibility to choose the appropriate storage or transmission method based on their specific needs.

Ending the Encoding Session

Once the encoding process is complete, the encoding session can be stopped by calling the Stop method on the encoder object. Stopping the encoding session ensures that the final frames are processed and any ongoing encoding tasks are terminated gracefully.

Demo: AMF DM in Action

To showcase the capabilities of AMF DM, a demo application is provided. The demo application captures the desktop for a specified number of frames and displays the captured frames on a virtual display. The captured frames, stored as H.265 elementary streams, can be played back using FFplay or used for further processing.

Recap of Learned Concepts

In this article, we have explored the features and functionality of AMF DM. We have learned about the direct physical connection between the display controller and the video compression engine, the display encode mode, and the suitability of AMF DM for low latency applications. Additionally, we have discussed the AMF DM library, its configuration options, and the process of capturing and compressing the desktop. AMF DM offers developers a robust solution for efficient video encoding and streaming.

Conclusion

AMF DM provides developers with a powerful toolset for integrating video encoding and streaming capabilities into their applications. With its direct physical connection between the display controller and the video compression engine, AMF DM is well-suited for low latency applications such as wireless display and remote desktop. By leveraging the AMF DM Library and following the provided sample application, developers can easily implement AMF DM functionality and enhance their applications with real-time video encoding and streaming features.

FAQ

Q: Can AMF DM be used with both AMD APUs and discrete GPUs? A: Yes, AMF DM can be used with both AMD APUs and discrete GPUs. It leverages the direct physical connection between the display controller and the video compression engine present in both these hardware configurations.

Q: Is AMF DM suitable for applications requiring low latency? A: Yes, AMF DM's display encode mode is specifically designed for low latency applications. It allows for real-time video compression, making it an ideal choice for tasks such as wireless display and remote desktop.

Q: Can I configure the audio stream while using AMF DM? A: Yes, AMF DM provides options for configuring the audio stream. Developers can choose to capture the audio stream separately or multiplex it with the video stream into a transport stream.

Q: Is it possible to clone the virtual display created by AMF DM? A: Yes, AMF DM allows developers to clone the virtual display. By configuring the display using the appropriate API calls, developers can create an exact replica of the physical display.

Q: Can I store the compressed frames generated by AMF DM in a different format? A: Yes, AMF DM generates compressed frames in H.265 elementary stream format by default. However, developers have the flexibility to manipulate and store the frames in different formats based on their specific requirements.