The MCI_PLAY Command Returns No Response for Five or More Seconds (308928)

CAUSE

In Windows XP, digital audio playback is enabled by installing a filter driver named Redbook.sys in the CD-ROM device driver stack. This driver emulates audio playback operations by reading the data from the audio CD digitally and sending it to kernel streaming. This works well, but MCI seems to send a PAUSE_AUDIO request between tracks, then sends a seek to reposition the head in the optical drive, and then sends a PLAY_AUDIO command to resume audio. Redbook.sys, when it finishes a previous PLAY_AUDIO command, sets its internal state to "not playing." Then, when the PAUSE_AUDIO request occurs, Redbook.sys does not handle this request because it is not playing audio at the time, and sends it down the remainder of the device stack.

When this command is sent down the device stack, some drives (not all) report ABORTED_COMMAND at the ATAPI layer because the drive is not playing audio. This error is automatically (and correctly) retried by the upper layers (Cdrom.sys, in this case) with a one-second pause to allow the drive's firmware to recover from this sort of error. Windows believes the ABORTED_COMMAND response to be a very serious error, which should not be reported by drives in normal operation, including getting commands that are invalid at a given point in time. This command is therefore sent six times, with a one-second pause between each, resulting in a five-second delay.

   Date         Time   Version      Size    File name
   ----------------------------------------------------
   01-Oct-2001  21:55  5.1.2600.14  55,936  Redbook.sys