Qtch

qtch (.qtch) is a filetype used by QuickTime to store audio or video files streamed from a server on the client's computer hard drive.

The first 16 bytes are:

This file type seems to have been introduced with QuickTime Player 7.x. The file is normally stored in any sub-directories of the following location:

Comparison with QuickTime Player 6.x

Previously QuickTime Player 6.x would store these audio and video(a/v) streams as files on the hard drive that had auto generated names such as '59B8794Ad01'. Unlike qtch files, these files had the correct a/v magic number and could be played by an appropriate player.

For example the first 16 bytes of an m4v file are:

Using the Firefox browser the location of these files would be:

File Format Comparison between QuickTime Player 6.x and QuickTime Player 7.x

Although the files have different headers their a/v payload can often be the same(see iTunes exception below). In this example the same a/v file was streamed from a server and stored on the hard drive using QuickTime Player 6.x and QuickTime Player 7.x respectively :