When a user adds a new GIF to the Media library, or updates an existing GIF, GIF2HTML5 will start the image transformation process. This plugin does not handle the actual file transformation routine. The transformation is handled by a standalone web application. GIF2HTML5 sends the URL of the GIF to the web application, and the web application responds asynchronously with a POST handled via admin_post. When the GIF2HTML5 plugin receives the POST from the web application, it receives MP4, OGV, and WebM video URLs, and a poster image URL, and saves those as post meta fields of the GIF attachment. The GIF2HTML5 plugin filters post content, and replaces img elements with video elements when the video file replacements are available.
