Development

This document describes how to develop and extend django-video-transcoding.

Developing

Running tests

$> src/manage.py test

Type checking

$> pip install mypy django-stubs
$> cd src && mypy \
    --config-file=../mypy.ini \
    -p video_transcoding \
    -p django_stubs_ext

Configuration

  • All configuration is stored in video_transcoding.defaults module.

  • Most important variables are configured from ENV

  • settings.VIDEO_TRANSCODING_CONFIG may be used for overriding defaults.

Extending

Celery application

  • if you are running transcoder in docker, make sure that celery master process has pid 1 (docker will send SIGTERM to it by default)

  • when using separate celery app, send SIGUSR1 from master to workers to trigger soft shutdown handling (see video_transcoding.celery.send_term_to_children)

  • celery master should set process group in order to send SIGUSR1 to workeres (see video_transcoding.celery.set_same_process_group)

Transcoding implementation

  • extend video_transcoding.tasks.TranscodeVideo to change task behavior

  • top-level transcoding strategy is selected in TranscodeVideo.init_strategy, see video_transcoding.strategy.ResumableStrategy as an example

  • see video_transcoding.transcoding.transcoder module for low-level transcoding steps examples

  • dealing with different intermediate files requires metadata extraction and specific logic for this process is implemented in video_transcoding.transcoding.extract.Extractor subclasses.

  • missing metadata is restored by different analyzers in video_transcoding.transcoding.analysis module.

Model inheritance

  • For preset-related models use <Model>Base abstract models defined in video_transcoding.models.

  • For overriding Video model set VIDEO_TRANSCODING_CONFIG["VIDEO_MODEL"] key to app_label.ModelName in settings.

  • Connect other django models to Video using video_transcoding.models.get_video_model().

  • When Video is overridden, video model admin is not registered automatically. As with migrations, this should be done manually.