Analyze Tracks Workflow Operation

ID: analyze-tracks


The analyze-tracks operation analyzes specified tracks in the mediapackage and sets workflow instance variables based on the tracks audio and video properties. These variables can then be used to control if workflow operations should be executed.

Note that this operation should be preceded by the inspect workflow operation handler.

For all tracks matching the flavor specified by the mandatory configuration key source-flavor, the following workflow instance variables may be set:

Name Example Description
flavor_media presenter_source_media=true Track with specific favor exists
flavor_audio presenter_source_audio=true Track contains at least one audio stream
flavor_video presenter_source_video=true Track contains at least one video stream
flavor_subtitle presenter_source_subtitle=true Track contains at least one subtitle stream
flavor_resolution_x presenter_source_resolution_x=1280 Horizontal resolution of the video stream
flavor_resolution_y presenter_source_resolution_y=720 Vertical resolution of the video stream
flavor_aspect presenter_source_aspect=4/3 Exact aspect ratio of the video stream
flavor_aspect_snap presenter_source_aspect_snap=4/3 Nearest specified aspect ratio of the video
flavor_framerate presenter_source_framerate=30.0 Framerate of the video stream

Parameter Table

Configuration Key Example Description
source-flavor* presentation/work The "flavor" of the track to use as a source input
aspect-ratio 4/3,16/9 Snap to these aspect ratios if specified
fail-no-tracks false Fail if flavor matches no tracks (Default: false)

* mandatory configuration key

Note that if there are multiple video streams with one flavor, only the information from the last video stream are taken.

Snap to Aspect Ratio

Snap-to-aspect can be used to deal with slightly off resolutions. Given an SAR of 1, for example, a video with the resolution of 640x481 pixels has almost an aspect ration of 4/3, but is 1 pixel too wide. For special encoding options or cover generation, it would still be reasonable to use the 4/3 settings. If 4/3 is listed in the aspect-ratio option, …_aspect_snap would be set to 4/3.

Operation Example

    description="Analyze tracks in media package and set control variables">
    <configuration key="source-flavor">*/source</configuration>
    <configuration key="aspect-ratio">4/3,16/9</configuration>

If a video track with a resolution of 1280x720 and an included audio stream is passed to this operation as presentiation/source, the resulting variables would be: