Abstract: A portable media device (PMD) can produce an isochronous audio/video experience when the PMD provides a digital audio signal to the accessory while displaying analog video on an accessory-independent display. The accessory can communicate audio latency information to the PMD. The PMD can delay a video portion of a presentation, relative to providing the digital audio signal to the accessory, based on the audio latency information communicated by the accessory. As a result, the user may perceive an isochronous presentation of the audio and video portions of the presentation.

Abstract: Improved approaches to update computer program code residing within a computing device are disclosed. By maintaining a former version of the computer program code, the computing device remains operable even if the update to the computer program code fails. Hence, the invention permits reliable updates to computer program code, which is particularly useful for firmware (e.g., boot-up code) of computing devices. For control and security, each version of computer program code can include authentication information. Before the computer program code is used, the computer program code can be required to be authenticated using the authentication information.

Abstract: A portable media device (PMD) can produce an isochronous audio/video experience when the PMD provides a digital audio signal to the accessory while displaying analog video on an accessory-independent display. The accessory can communicate audio latency information to the PMD. The PMD can delay a video portion of a presentation, relative to providing the digital audio signal to the accessory, based on the audio latency information communicated by the accessory. As a result, the user may perceive an isochronous presentation of the audio and video portions of the presentation.

Abstract: Improved techniques for performing accelerated video presentation on a media device are disclosed. The improved techniques enable smooth, uniform accelerated video presentation by displaying key frames from a video file in a periodic fashion. The rate and direction of accelerated video presentation can be controlled. The improved techniques are well suited for use with portable media devices.

Abstract: Improved techniques to partially encrypt media files are disclosed. The encryption serves to cryptographically secure only a portion of the media data within a media file, while the remaining portion of the media data is not cryptographically secured. Although only partial encryption is used, the portion being encrypted serves to substantially disrupt usefulness of other parts of the media file which are not encrypted. In other words, the partial encryption renders the media file substantially unusable by unauthorized users. In one embodiment, the partial encryption is performed by a host device and thereafter the partially encrypted media file is delivered to a client device. The client device, if authorized, can subsequently decrypt the partially encrypted media file and utilize (e.g., play) the media file. However, since the media files are only partially encrypted, the decryption is likewise also only partial, which makes decryption faster and less resource intensive.

Abstract: Improved techniques for presenting sound effects at a portable media device are disclosed. The sound effects can be output as audio sounds to an internal speaker, an external speaker, or both. In addition, the audio sounds for the sound effects can be output together with other audio sounds pertaining to media assets (e.g., audio tracks being played). In one embodiment, the sound effects can serve to provide auditory feedback to a user of the portable media device. A user interface can facilitate a user's selection of sound effect usages, types or characteristics.

Abstract: An improved portable media device and methods for operating a media device are disclosed. According to one aspect, the portable media device has the capability to store media device status information in persistent memory before powering down. Thereafter, when the portable media device is again powered up, the stored media player status information can be retrieved and utilized. According to another aspect, the portable media device can form and/or traverse a media asset playlist in an efficient manner.

Abstract: Improved approaches to update computer program code residing within a computing device are disclosed. By maintaining a former version of the computer program code, the computing device remains operable even if the update to the computer program code fails. Hence, the invention permits reliable updates to computer program code, which is particularly useful for firmware (e.g., boot-up code) of computing devices. For control and security, each version of computer program code can include authentication information. Before the computer program code is used, the computer program code can be required to be authenticated using the authentication information.