Texas Instruments Codec Engine Server manual What is a Codec Server?, What is the Execution Flow?

Overview

2.1.1What is a Codec Server?

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A Codec Server is a binary that integrates codecs, framework components, and system code. When the Codec Server is on a DSP, it uses DSP/BIOS as the DSP kernel.

In the context of the DaVinci DM644x platforms (and other GPP+DSP platforms), a Codec Server is a DSP binary. It includes a DSP/BIOS task thread that responds to requests from a client to create codecs, provide performance information (MIPS and MEM usage).

A Codec Server performs similarly to a web server. Just as the term "web server" can refer to the actual hardware, the configured software, or the executing daemon, the term "Codec Server" can refer to the DSP, the configured image loaded on the DSP, or the executing task.

The GPP application uses the VISA APIs to invoke remote codecs on the DSP. From the perspective of the GPP application, codec execution is completely transparent, and behaves the same whether the codecs are local (on the GPP) or remote (on the DSP). When remote, Codec Engine automatically manages the necessary creation, communication, invocation, and eventual deletion of codecs from the DSP.

2.1.2What is the Execution Flow?

As an example of the execution flow, on a dual-CPU system, such as the DM644x device, the following steps summarize the execution flow when a GPP application uses a remote codec to perform audio encode on the DSP. After opening the engine, the application makes calls to the VISA APIs, which manage the three phases of remote codec execution as follows:

1)The application calls the VISA creation API (for example, AUDENC_create() ) to create an algorithm instance on the DSP:

■First, a generic instance object is created on the GPP to hold the necessary state, handles, function pointers, etc.

■A local "node" object is created to receive communication from the "remote" node.

■A "create" message is formed to signal the function dispatcher on the DSP to create the remote node instance.

■The creation message is sent to the dispatcher on the DSP.

■On the DSP, the dispatcher receives the "create" message. Some error checks are performed, and the DSP-side state objects are created and initialized.

Configuring a Codec Server 2-3