Clip insertion metadata support

When clips are inserted into an episode, the metadata for the episode is preserved. We attempt to copy all existing ID3 tags (or M4A metadata tags) to the output file. Clip insertion always produces an MP3 to be served to listeners, so the metadata is always consequently in ID3v2.3 format.

Chapter support

If the episode has ID3 chapters, we will attempt to update the timecodes for the chapters to match the updated time positions within the episode. We do this by increasing the start and end times of each chapter if those timecodes fall after the timecode of a placement of a clip in the episode. They are moved forward by the sum of the preceding clips' durations.

Episode artwork

At this time we do not copy episode artwork into the ID3 metadata of the updated episode audio. Artwork for an episode is still linked from your feed. Support for artwork embedded in ID3 metadata is mixed.