Method and system for allowing a media player to transfer digital audio to an accessory

• US 7,826,318 B2
• Filed: 06/26/2007
• Issued: 11/02/2010
• Est. Priority Date: 04/27/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Fletcher, Daniel R., Filson, John B., Novotney, Donald J., Archibald, John, Tupman, David, Holden, Paul, Twycross, Barry
• Primary Examiner(s): Edun; Muhammad N
• Application Number:
  US11/768,897
• Publication Number:
  US 20080025172A1
• Time in Patent Office: 1,225 Days
• Field of Search: None
• US Class Current: 369/47.28
• CPC Class Codes: G06F 3/16 Sound input; Sound output speech processing G10L
• CPC Class Codes: H04L 12/40117 Interconnection of audio or video/imaging devices home automation networks H04L12/2803; bitstream network arrangements specially adapted for distribution of digital video signals H04N7/24

Abstract

Digital audio can be transferred between a portable media player and an accessory. In one embodiment, an interface protocol is used to determine the sample rate capabilities of an accessory, allowing digital audio data for a track to be transmitted to the accessory at a sample rate supported by the accessory. When the sample rate of an audio track is not supported by the accessory, the media player can convert the sample rate of the track to a rate supported by the accessory and transmit the track after conversion. The media player also can use the interface protocol to inform the accessory if the sampling rate should be changed, e.g., due to tracks having different sample rates. The accessory then can send a request to the media player to change the sample rate. The media player then can transmit the digital audio data using the new sample rate.

Claims

1. A method for transmitting digital audio data to an accessory by a media player, the method comprising:

identifying a stored sample rate for a first track of digital audio data to be played, wherein the first track is stored on the media player;

selecting a first playback sample rate for the first track, wherein the first playback sample rate is based on a list of sample rates supported by the accessory and the stored sample rate for the first track;

transmitting to the accessory, using an accessory protocol, information indicating the first playback sample rate; and

delivering the digital audio data of the first track to the accessory at the first playback sample rate.

2. The method of claim 1 further comprising:

obtaining from the accessory, using the accessory protocol, the list of sample rates for digital audio supported by the accessory.

3. The method of claim 1 wherein delivering the digital audio data includes delivering the digital audio data using a digital audio transfer protocol.

4. The method of claim 3 wherein the digital audio transfer protocol corresponds to a Universal Serial Bus (USB) audio protocol.

5. The method of claim 4 further comprising:

prior to delivering the digital data of the first track, receiving from the accessory, using the USB audio protocol, an instruction to set a sample rate of a digital audio output interface to the first playback sample rate.

6. The method of claim 1 wherein in the event that the stored sample rate for the first track and the first playback sample rate are different, delivering the digital audio data further includes:

converting, within the media player, the digital audio data from the stored sample rate for the first track to the first playback sample rate.

7. The method of claim 1 further comprising:

identifying a stored sample rate associated with a second track of digital audio data to be played, wherein the second track is stored on the media player; and

selecting a second playback sample rate for the second track, wherein the second playback sample rate is based on the list of sample rates supported by the accessory and the stored sample rate for the second track.

8. The method of claim 7 further comprising:

in the event that the second playback sample rate is different from the first playback sample rate, transmitting to the accessory, using the accessory protocol, information indicating the second playback sample rate; and

delivering the digital audio data of the second track to the accessory at the second playback sample rate.

9. The method of claim 7 wherein in the event that the stored sample rate for the second track and the second playback sample rate are different, delivering the digital audio data further includes:

converting, within the media player, the digital audio data from the stored sample rate for the second track to the second playback sample rate.

10. The method of claim 1 wherein obtaining the list of sample rates supported by the accessory includes:

transmitting to the accessory, using the accessory protocol, a command requesting the list of sample rates supported by the accessory; and

receiving from the accessory, using the accessory protocol, a responsive command that includes the list of sample rates supported by the accessory.

11. A method for obtaining digital audio from a media player by an accessory, the method comprising:

receiving from the media player, using an accessory protocol, an identification of a first playback sample rate associated with a first track of digital audio data to be played, the first track being a track stored on the media player, wherein the first playback sample rate is selected by the media player and is a sample rate supported by the accessory;

configuring a digital audio transfer protocol between the accessory and the media player to receive data at the first playback sample rate; and

receiving from the media player, using the digital audio transfer protocol, the digital audio data of the first track at the first playback sample rate.

12. The method of claim 11 further comprising:

providing to the media player, using the accessory protocol, a list of sample rates supported by the accessory.

13. The method of claim 11 wherein the digital audio protocol corresponds to a Universal Serial Bus (USB) audio protocol, the method further comprising:

configuring a USB connection between the media player and the accessory to operate in a USB audio mode.

14. The method of claim 13 wherein the USB audio mode is a combined USB human interface device (HID) and audio mode.

15. The method of claim 13 wherein configuring the USB connection to operate in the USB audio mode includes:

sending to the media player an accessory identifying signal identifying the accessory as being capable of receiving digital audio from the media player,

wherein in response to the accessory identifying signal, the media player presents the USB audio mode to the accessory as a default USB configuration.

16. The method of claim 15 wherein sending the accessory identifying signal includes applying an accessory identifying resistance across two pins of a connector coupling the media player and the accessory.

17. The method of claim 15 wherein sending the signal includes transmitting to the media player, using the accessory protocol, a device identifying command that includes data identifying the accessory as being capable of receiving digital audio from the media player.

18. The method of claim 13 wherein configuring the digital audio transfer protocol includes sending to the media player an instruction to set a sample rate of a digital audio output interface of the media player to the first playback sample rate.

19. The method of claim 11 wherein the first playback sample rate is different from a stored sample rate associated with the first track as stored in the media player.

20. The method of claim 11 further comprising:

receiving, from the media player using the accessory protocol, an identification of a second playback sample rate associated with a second track of digital audio data to be played, the second track being a track stored on the media player, wherein the second playback sample rate is selected by the media player and is one of the sample rates included in the list of sample rates supported by the accessory.

21. The method of claim 20 further comprising:

in the event that the second playback sample rate is different from the first playback sample rate, reconfiguring the digital audio transfer protocol to receive data at the second playback sample rate; and

receiving, from the media player using the digital audio transfer protocol, the digital audio data of the second track at the second playback sample rate.

22. The method of claim 11 further comprising:

receiving from the media player, using the accessory protocol, a command requesting a list of sample rates supported by the accessory,

wherein the act of providing the list of sample rates supported by the accessory is performed in response to the received command requesting the list of sample rates supported by the accessory.

23. A media player comprising:

an interface configured to communicate with an accessory, the interface being configured to support a digital audio transfer protocol for transferring digital audio to the accessory and further configured to support an accessory protocol for exchanging with the accessory commands and information related to the delivery of digital audio data;

a storage device configured to store media assets including a plurality of tracks of digital audio data, each track having a stored sample rate associated therewith; and

a processor coupled to the storage device and the interface,

wherein the processor is configured to;

select a first sample rate for a first stored track of digital audio data based on the stored sample rate associated with the first stored track and a list of sample rates supported by the accessory;

communicate to the accessory, using the accessory protocol, the selected sample rate; and

deliver to the accessory, using the digital audio transfer protocol, the digital audio data of the first stored track at the first selected sample rate.

24. The media player of claim 23 wherein the processor is further configured to obtain from the accessory, using the accessory protocol, a list of sample rates supported by the accessory.

25. The media player of claim 23 wherein the interface includes a Universal Serial Bus (USB) interface.

26. The media player of claim 25 wherein the digital audio transfer protocol corresponds to a USB audio protocol.

27. The media player of claim 23 wherein the processor is further configured such that, in the event that the first selected sample rate and the first stored sample rate are different, the processor converts the digital audio data of the first track from the first stored sample rate to the first selected sample rate.

28. The media player of claim 23 wherein the processor is further configured to select a second sample rate for a second stored track of digital audio data based on the stored sample rate associated with the second stored track and the list of sample rates supported by the accessory;

to communicate to the accessory, using the accessory protocol, the selected sample rate; and

to deliver to the accessory, using the digital data transfer protocol, the digital audio data of the second stored track at the second selected sample rate.

29. An accessory for use with a media player, the accessory comprising:

an interface configured to communicate with the media player, the interface being configured to support a digital audio transfer protocol for receiving digital audio from the media player and further configured to support an accessory protocol for exchanging with the media player commands and information related to the delivery of digital audio data; and

a controller coupled to the interface and to an audio output section,

wherein the controller is configured to;

receive from the media player, using the accessory protocol, information identifying a first playback sample rate associated with a first track of digital audio data to be played, the first track being a track stored on the media player, wherein the first playback sample rate is selected by the media player and is a sample rate supported by the accessory;

operate the interface, using the digital audio transfer protocol, to receive data at the first playback sample rate; and

deliver the digital audio data to the audio output section.

30. The accessory of claim 29 wherein the controller is further configured to provide to the media player, using the accessory protocol, a list of sample rates supported by the accessory.

31. The accessory of claim 29 wherein the digital audio transfer protocol corresponds to a Universal Serial Bus (USB) audio protocol.

32. The accessory of claim 29 wherein the controller is further configured to:

receive, from the media player using the accessory protocol, an identification of a second playback sample rate associated with a second track of digital audio data to be played, the second track being a track stored on the media player, wherein the second playback sample rate is selected by the media player and is one of the sample rates included in the list of sample rates supported by the accessory; and

in the event that the second playback sample rate is different from the first playback sample rate, reconfigure the digital audio transfer interface to receive data at the second playback sample rate.

33. The accessory of claim 29 wherein the interface includes:

a connector having a plurality of pins configured to mate with a corresponding plurality of pins of a connector of the media player, and

an accessory identifying resistance connected between two of the plurality of pins of the connector.

34. The accessory of claim 29 wherein the audio output section includes:

a digital to analog converter configured to convert a stream of digital audio data to an analog audio signal.

35. The accessory of claim 34 wherein the audio output section further includes:

a speaker coupled to receive the analog audio signal and configured to produce sounds in response to the analog audio signal.