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Minor updates to MediaPipe graph documentation: use Graph/CalculatorGraphConfig instead of GraphConfig and mention that node can be a subgraph.

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MediaPipe Team 2023-02-09 17:17:40 -08:00 committed by Copybara-Service
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docs/framework_concepts/graphs.md
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@ -12,26 +12,25 @@ nav_order: 2
{:toc} {:toc}
--- ---
## GraphConfig ## Graph
A `GraphConfig` is a specification that describes the topology and functionality A `CalculatorGraphConfig` proto specifies the topology and functionality of a
of a MediaPipe graph. In the specification, a node in the graph represents an MediaPipe graph. Each `node` in the graph represents a particular calculator or
instance of a particular calculator. All the necessary configurations of the subgraph, and specifies necessary configurations, such as registered
node, such its type, inputs and outputs must be described in the specification. calculator/subgraph type, inputs, outputs and optional fields, such as
Description of the node can also include several optional fields, such as
node-specific options, input policy and executor, discussed in node-specific options, input policy and executor, discussed in
[Synchronization](synchronization.md). [Synchronization](synchronization.md).
`GraphConfig` has several other fields to configure the global graph-level `CalculatorGraphConfig` has several other fields to configure global graph-level
settings, eg, graph executor configs, number of threads, and maximum queue size settings, e.g. graph executor configs, number of threads, and maximum queue size
of input streams. Several graph-level settings are useful for tuning the of input streams. Several graph-level settings are useful for tuning the
performance of the graph on different platforms (eg, desktop v.s. mobile). For performance of the graph on different platforms (e.g., desktop v.s. mobile). For
instance, on mobile, attaching a heavy model-inference calculator to a separate instance, on mobile, attaching a heavy model-inference calculator to a separate
executor can improve the performance of a real-time application since this executor can improve the performance of a real-time application since this
enables thread locality. enables thread locality.
Below is a trivial `GraphConfig` example where we have series of passthrough Below is a trivial `CalculatorGraphConfig` example where we have series of
calculators : passthrough calculators :
```proto ```proto
# This graph named main_pass_throughcals_nosubgraph.pbtxt contains 4 # This graph named main_pass_throughcals_nosubgraph.pbtxt contains 4
@ -65,7 +64,7 @@ To modularize a `CalculatorGraphConfig` into sub-modules and assist with re-use
of perception solutions, a MediaPipe graph can be defined as a `Subgraph`. The of perception solutions, a MediaPipe graph can be defined as a `Subgraph`. The
public interface of a subgraph consists of a set of input and output streams public interface of a subgraph consists of a set of input and output streams
similar to a calculator's public interface. The subgraph can then be included in similar to a calculator's public interface. The subgraph can then be included in
an `CalculatorGraphConfig` as if it were a calculator. When a MediaPipe graph is a `CalculatorGraphConfig` as if it were a calculator. When a MediaPipe graph is
loaded from a `CalculatorGraphConfig`, each subgraph node is replaced by the loaded from a `CalculatorGraphConfig`, each subgraph node is replaced by the
corresponding graph of calculators. As a result, the semantics and performance corresponding graph of calculators. As a result, the semantics and performance
of the subgraph is identical to the corresponding graph of calculators. of the subgraph is identical to the corresponding graph of calculators.
@ -151,7 +150,7 @@ protobuf specified for a MediaPipe calculator. These "graph options" can be
specified where a graph is invoked, and used to populate calculator options and specified where a graph is invoked, and used to populate calculator options and
subgraph options within the graph. subgraph options within the graph.
In a CalculatorGraphConfig, graph options can be specified for a subgraph In a `CalculatorGraphConfig`, graph options can be specified for a subgraph
exactly like calculator options, as shown below: exactly like calculator options, as shown below:
``` ```
@ -178,7 +177,7 @@ node {
} }
``` ```
In a CalculatorGraphConfig, graph options can be accepted and used to populate In a `CalculatorGraphConfig`, graph options can be accepted and used to populate
calculator options, as shown below: calculator options, as shown below:
``` ```
@ -188,7 +187,7 @@ graph_options: {
node: { node: {
calculator: "ImageToTensorCalculator" calculator: "ImageToTensorCalculator"
input_stream: "IMAGE:multi_backend_image" input_stream: "IMAGE:image"
node_options: { node_options: {
[type.googleapis.com/mediapipe.ImageToTensorCalculatorOptions] { [type.googleapis.com/mediapipe.ImageToTensorCalculatorOptions] {
keep_aspect_ratio: true keep_aspect_ratio: true
@ -247,9 +246,9 @@ NOTE: The current approach is experimental and subject to change. We welcome
your feedback. your feedback.
Please use the `CalculatorGraphTest.Cycle` unit test in Please use the `CalculatorGraphTest.Cycle` unit test in
`mediapipe/framework/calculator_graph_test.cc` as sample code. Shown `mediapipe/framework/calculator_graph_test.cc` as sample code. Shown below is
below is the cyclic graph in the test. The `sum` output of the adder is the sum the cyclic graph in the test. The `sum` output of the adder is the sum of the
of the integers generated by the integer source calculator. integers generated by the integer source calculator.
![a cyclic graph that adds a stream of integers](https://mediapipe.dev/images/cyclic_integer_sum_graph.svg "A cyclic graph") ![a cyclic graph that adds a stream of integers](https://mediapipe.dev/images/cyclic_integer_sum_graph.svg "A cyclic graph")