The chalkboard timeline (the total duration or play time) is determined by the play time of the video file you choose, so you MUST add a video or audio file to the chalkboard before you can add any other items such as slides, chapters, or checkpoints. You can only add one media file to a chalkboard, but you could externally combine multiple media files into a single file if you want to use more than one media file in a chalkboard.

The media file you choose must meet the following requirements:

• DigitalChalk currently supports the following video formats:
  • .3GP, .AVI, .DIVX, .DV, .FLV, .MOV, .M4V, .MP4, .MPEG, .MPG, .WMV
• DigitalChalk currently supports the following audio formats:
  • .AU, .MP3,.WAV, and .WMA files.
• The maximum file size supported for upload is 1GB (or 500MB)
• The duration (play time) of the file cannot not exceed 60 minutes

If the file format you are trying to upload does not match one of the listed above, try going here instead.