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110 lines
4.1 KiB
Markdown
110 lines
4.1 KiB
Markdown
---
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title: Scenarios
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short-description: The GstValidate Scenario format
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...
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# GstValidate Scenario File Format
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To be able to define a list of actions to execute on a [`GstPipeline`],
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a dedicated file format is used. The name of the scenario is the name of
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the file without its `.scenario` extension. The scenario file format is
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based on the [`GstStructure`] serialized format which is a basic, type
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aware, key value format. It takes the type of the action in the first
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comma separated field, and then some key value pairs in the form
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`parameter=value` separated by commas. The values type will be guessed
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if not casted as in `parameter=(string)value`. You can force the type
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guessing system to actually know what type you want by giving it the
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right hints. For example to make sure the value is a double, you should
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add a decimal (ie. `1` will be considered as a `int`, but `1.0` will be
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considered as a `double` and `"1.0"` will be considered as a `string`).
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For example to represent a seek action, you should add the following
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line in the `.scenario` file.
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seek, playback-time=10.0, start=0.0, flags=accurate+flush
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The files to be used as scenario should have a `.scenario` extension and
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should be placed either in
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`$USER_DATA_DIR/gstreamer-1.0/validate/scenarios` ,
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`$GST_DATADIR/gstreamer-1.0/validate/scenarios` or in a path defined in
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the \$GST\_VALIDATE\_SCENARIOS\_PATH environment variable.
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Each line in the `.scenario` file represent an action (you can also use
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`\ ` at the end of a line write a single action on multiple lines).
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Usually you should start you scenario with a `meta` structure
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in order for the user to have more information about the
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scenario. It can contain a `summary` field which is a string explaining
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what the scenario does and then several info fields about the scenario.
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You can find more info about it running:
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gst-validate-1.0 --inspect-action-type action_type_name
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So a basic scenario file that will seek three times and stop would look
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like:
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```
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meta, summary="Seeks at 1.0 to 2.0 then at \
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3.0 to 0.0 and then seeks at \
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1.0 to 2.0 for 1.0 second (between 2.0 and 3.0).", \
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seek=true, duration=5.0, min-media-duration=4.0
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seek, playback-time=1.0, rate=1.0, start=2.0, flags=accurate+flush
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seek, playback-time=3.0, rate=1.0, start=0.0, flags=accurate+flush
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seek, playback-time=1.0, rate=1.0, start=2.0, stop=3.0, flags=accurate+flush
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```
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Many action types have been implemented to help users define their own
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scenarios. For example there are:
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- `seek`: Seeks into the stream.
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- `play`: Set the pipeline state to `GST_STATE_PLAYING`.
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- `pause`: Set the pipeline state to `GST_STATE_PAUSED`.
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- `stop`: Stop the execution of the pipeline.
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> **NOTE**: This action actually posts a [`GST_MESSAGE_REQUEST_STATE`]
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> message requesting [`GST_STATE_NULL`] on the bus and the application
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> should quit.
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To get all the details about the registered action types, you can list
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them all with:
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```
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gst-validate-1.0 --inspect-action-type
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```
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and to include transcoding specific action types:
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```
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gst-validate-transcoding-1.0 --inspect-action-type
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```
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Many scenarios are distributed with `gst-validate`, you can list them
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all using:
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```
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gst-validate-1.0 --list-scenarios
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```
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You can find more information about the scenario implementation and
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action types in the [`GstValidateScenario` section].
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[`GstPipeline`]: GstPipeline
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[`GstStructure`]: GstStructure
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[`GST_MESSAGE_REQUEST_STATE`]: GST_MESSAGE_REQUEST_STATE
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[`GST_STATE_NULL`]: GST_STATE_NULL
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[`GstValidateScenario` section]: GstValidateScenario
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## Default variables
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Any action can use the default variables:
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- `$(position)`: The current position in the pipeline as reported by
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[gst_element_query_position()](gst_element_query_position)
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- `$(duration)`: The current duration of the pipeline as reported by
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[gst_element_query_duration()](gst_element_query_duration)
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- `$(TMPDIR)`: The default temporary directory as returned by `g_get_tmp_dir`.
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- `$(SCENARIO_PATH)`: The path of the running scenario.
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- `$(SCENARIO_DIR)`: The directory the running scenario is in.
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- `$(SCENARIO_NAME)`: The name the running scenario
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It is also possible to set variables in scenario with the `set-vars` action. |