Apple Inc.

Other

William George Stewart

Joe S Abuan

Douglas S Wyatt

Jeffrey Chandler Moore

Gerhard Lengeling

James E McCartney

Anthony Joseph Guetta

Shyh-Shiaw Kuo

Alan Cannistraro

Gregory R Chapman

Deepak R Iyer

Eric Joseph Johnson

Andrew E Rostaing

Roger N Pantos

Frank M Baumgarte

Berkat S Tung

Eric A Allamanche

Meriko Borogove

Jim Normile

Kelly B Jacklin

Roger A Powell

Hong Kaura

Doug Wyatt

Zhenheng Li

Kevin Christopher Rogers

Michael Stephen Hopkins

Kevin Christopher Rodger

Gerhard H Lengeling

Douglas Wyatt

James Mccartney

According to one embodiment, a media system communicates with an aggregate device that includes multiple media output devices. When providing media data for presentation, the system adjusts for device clock drift by resampling the media data provided to a media output device based at least in part on a device clock rate difference between a device clock of one of the media output devices and a device clock of another of the media output devices.

Using a plurality of buffers to provide audio for synchronized playback to multiple audio devices having separate device clocks

An operating system of a device receives, from an application executing on that device, data that identifies a category of hardware resources that the application needs to use in order to function. That category is mapped to a specified set of hardware resources of the device. The operating system also receives, from the application, data that identifies a mode. The mode corresponds to an intended use of a set of hardware resources and is mapped to a group of hardware resource settings that are consistent with the intended use. The operating system allocates, to the application, a particular set of hardware resources that are mapped to the category. The operating system configures one or more hardware resources in the particular set of hardware resources in conformity with a particular group of settings that are mapped to the mode.

Audio configuration based on selectable audio modes

Techniques are provided for determining, at an audio processing device, whether to produce high quality or low quality audio output based on one or more factors. The one or more factors may include the type of output device (e.g., headphones, built-in speakers, or USB audio devices) that is connected to the audio processing device and whether certain operations (e.g., mixing and/or scaling) are to be performed on the decoded audio content. Thus, the highest quality audio output is produced based on current conditions of the audio system, which includes the output device. If the current conditions of the audio system indicate that producing high quality audio output does not yield sufficient perceived benefits, then the audio processing device may produce lower quality audio output.

Automatic audio configuration based on an audio output device

Systems and methods for switching between encoded media streams are disclosed. A system may be configured to receive at least two media streams of differing qualities that are associated with an identical media asset. The system can seamlessly switch between a first media stream and a second media stream using an algorithm that can determine which frames of a second stream must be discarded to sync the second stream with the first media stream. The two media streams can then be cross faded to switch from the first media stream to the second media stream.

Systems and methods for seamlessly switching between media streams

An application and audio driver communicate audio data via a ring buffer using a system interface. An application reads or writes data from the buffer in a unit of data. Positions within the buffer correspond to a particular time. To write data to the buffer at a particular position in the buffer that corresponds to a particular time, an application is awaken a period of time ('client-side offset') before the driver reaches the position. The period of time is computed based on a variety factors. One factor is the amount of time the system interface assumes an application uses to write the unit of data to the buffer. For operations that entail the application inserting data into the buffer, the application may specify a weight value to apply to the factor to reduce it and the latency period.

IO latency reduction

Methods, systems, and apparatus are presented for decoding an audio signal that includes bandwidth extension data. An audio signal that includes core audio data and bandwidth extension data can be received in a decoder. The core audio data can be associated with a core portion of an audio signal, such as the frequency range below a cutoff frequency, and the bandwidth extension data can be associated with an extended portion of the audio signal, such as a frequency range above the cutoff frequency. The core audio data can be decoded to generate a decoded core audio signal in a time domain representation. Further, an extended portion of the audio signal can be reconstructed in accordance with extension data and decoded core audio signal. Additionally, the decoded core audio signal can be lowpass filtered and the extended portion can be highpass filtered before being combined to generate a decoded output signal.

Enhanced audio decoder

Storing audio data encoded in any of a plurality of different audio encoding formats is enabled by parametrically defining the underlying format in which the audio data is encoded, in audio format and packet table chunks. A flag can be used to manage storage of the size of the audio data portion of the file, such that premature termination of an audio recording session does not result in an unreadable corrupted file. This capability can be enabled by initially setting the flag to a value that does not correspond to a valid audio data size and that indicates that the last chunk in the file contains the audio data. State information for the audio data, to effectively denote a version of the file, and a dependency indicator for dependent metadata, may be maintained, where the dependency indicator indicates the state of the audio data on which the metadata is dependent.

Universal container for audio data

A hybrid audio encoding technique incorporates both ABR, or CBR, and VBR encoding modes. For each audio coding block, after a VBR quantization loop meets the NMR target, a second quantization loop might be called to adaptively control the final bitrate. That is, if the NMR-based quantization loop results in a bitrate that is not within a specified range, then a bitrate-based CBR or ABR quantization loop determines a final bitrate that is within the range and is adaptively determined based on the encoding difficulty of the audio data. Excessive bitrates from use of conventional VBR mode are eliminated, while still providing much more constant perceptual sound quality than use of conventional CBR mode can achieve.

Bitrate constrained variable bitrate audio encoding

Some embodiments of the invention provide a computer system for processing an audio track. This system includes at least on DSP for processing the audio track. It also includes an application for editing the audio track. To process audio data in a first interval of the audio track, the application first asks and obtains from the DSP an impulse response parameter related to the DSP's processing of audio data. From the received impulse response parameter, the application identifies a second audio track interval that is before the first interval. To process audio data in the first interval, the application then directs the DSP to process audio data within the first and second intervals.

Method and apparatus for efficiently accounting for the temporal nature of audio processing

An audio system communicates with an aggregate device that includes multiple audio devices. When providing audio data for playback, the system compensates for presentation latency differences between the various audio devices. In addition, the system adjusts for device clock drift by selecting a master device and resampling the audio data provided to the other devices based on the difference between the device clock of the master device and the device clocks of the other devices.

System having a plurality of buffers for providing audio for synchronized playback to multiple audio devices

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Cupertino, CA, United States of America

William George Stewart