[ViPPET] Implementation of common pipeline element selection

[p-zak]

Common Pipeline Element Selection

• Unified the logic for selecting pipeline elements (encoder, decoder, postprocessing, compositor) based on the chosen device (CPU, GPU.0, GPU.N, OTHER) using the new PipelineElementsSelector and PipelineElementSelectionInstructions classes from _common/common.py.
• Replaced hardcoded and duplicated element selection code in simplevs/pipeline.py and smartnvr/pipeline.py with a shared, maintainable approach.
• The selection now supports dynamic mapping for VAAPI suffixes and fallback to default elements.

New Features

• Compositor Device Selection:
  • Added support for selecting the compositor device in the UI (app.py), configuration (config.yaml), and pipeline logic.
  • The compositor_device parameter is now propagated and used for element selection.

Fixes and Improvements

• Fixed incorrect or inconsistent element selection for various device types, especially for GPU.N cases.
• Updated tests to reflect the new element selection logic and ensure correct pipeline construction for all device scenarios.
• Improved error handling and logging for missing pipeline elements.
• Minor fixes in parameter propagation and meta file writing.

Tests

• Updated and extended unit tests for both pipelines to cover new selection logic and device scenarios.
• Ensured tests check for correct element usage, parameter propagation, and output structure.

[Copilot]

Pull Request Overview

This PR implements a common pipeline element selection system to unify and improve how pipeline elements (encoder, decoder, postprocessing, compositor) are selected based on device types across the visual pipeline evaluation tool.

• Introduces shared PipelineElementsSelector and PipelineElementSelectionInstructions classes for consistent element selection logic
• Adds compositor device selection support throughout the UI, configuration, and pipeline implementation
• Replaces hardcoded element selection with dynamic mapping that supports VAAPI suffixes and fallback mechanisms

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pipelines/_common/common.py	New shared classes for pipeline element selection logic with device-specific mappings
pipelines/smartnvr/pipeline.py	Refactored to use common element selector, added compositor device support, improved error handling
pipelines/simplevs/pipeline.py	Refactored to use common element selector, streamlined decoder/postprocessing logic
tests/pipelines_tests/smartnvr_tests/pipeline_test.py	Updated test expectations to match new element selection behavior
tests/pipelines_tests/simplevs_tests/pipeline_test.py	Updated test expectations for new decoder elements and added GPU-specific tests
app.py	Added compositor device dropdown to UI with proper rendering logic
pipelines/smartnvr/config.yaml	Enabled compositor device parameter
pipelines/simplevs/config.yaml	Disabled compositor device parameter (not applicable)
utils.py	Added compositor_device parameter handling

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[lamalexck]

I believe videoconvert is CPU based.
On platform with GPU, we want to use vapostproc instead

[lamalexck]

Lets not use vaapiXXXX elements. They have been deprecated.

[tjanczak]

do not use vaapi elements - they are deprecated for >1 year and will be removed in upcoming GStreamer releaes