Real-time control of playback rates in presentations

A method for playing a presentation, comprising:

• loading a first frame from a source into a player via a network, the first frame representing a first portion of the presentation after scaling by a first time-scaling factor, wherein the first audio frame has a first channel index value that identifies the first audio frame as being scaled by the first time scaling factor;
• playing the first portion of the presentation based on data from the first audio frame;
• receiving a request to change playing from the first time scaling factor to a second time scaling factor;
• requesting from the source a second audio frame that has a second channel index value that identifies the second frame as being scaled by the second time-scaling factor;
• and
• playing the second frame after the first to provide a real-time change in the time-scale of the presentation.

A method for playing an audio presentation on a receiver that is connected via a network to a source having a multi-channel data structure representing the audio presentation, the method comprising:

• determining available bandwidth on the network;
• selecting a first channel of the multi-channel data structure from a plurality of channels that represent the audio presentation after time-scaling by a desired time-scaling factor, wherein the first channel contains data that is compressed using a compression process that provides highest audio quality at the available bandwidth;
• receiving a first frame from the first channel;
• and
• playing the first frame.

A method for controlling display of web pages, comprising:

• assigning a series of web pages to respective index values of audio data that represent an audio portion of a presentation;
• playing audio generated from the audio data;
• and
• displaying each web page in response to the playing reaching in the audio data an index value assigned to the web page.

A method for authoring a presentation for playback on a computing system, comprising:

• assigning time index values to audio data for the presentation;
• assigning a range of the time index values to each image represented by graphics data for the presentation;
• and
• constructing a file containing the audio data and the graphics data, wherein the file has a format indicating display of each image occurs during playing of the audio data that has assigned time index values in the range assigned to the image.