Control apparatus to control operation of a data buffer to which data items are written according to a write pointer which advances in position in response to an input data item rate and from which data items are read according to a read pointer which advances in position in response to an output data item rate, comprises: a detector configured to detect an occupancy difference between a current buffer occupancy and a target buffer occupancy, in which the current buffer occupancy represents a difference between the read and write pointers; an output data item interpolator configured to interpolate a data item at an interpolated data buffer location displaced by a read offset displacement from a data buffer location pointed to by the read pointer; and output control circuitry configured, in response to a current occupancy difference exceeding a threshold occupancy difference, to change the read pointer from an initial read pointer to a target read pointer by a change amount so as to reduce the occupancy difference, the output control circuitry being configured to progressively vary the read offset displacement so as to define an interpolated data buffer location which progresses over the output of a transitional group of data items towards the location pointed to by the target read pointer; the output control circuitry being further configured, when the occupancy difference is less than the threshold occupancy difference and the interpolated data buffer location is aligned with the target read pointer, to inhibit operation of the output data item interpolator and to control output of an output data item from the data buffer location pointed to by the read pointer.

Example techniques involve pre-caching media content. An example implementation involves a first playback device detecting, via at least one proximity sensor, motion in proximity to the proximity sensor. In response, the first playback device sends, to a second playback device, one or more first messages indicating that the first playback device detected motion. Afterwards, the first playback device receives, via the network interface from the second playback device in response to the one or more first messages, one or more second messages that instruct the first playback device to pre-cache, from a network source, a portion of audio content indicated in a playback queue associated with a playback device group including the first playback device and the second playback device. The first playback device receives a command to play back the playback queue and plays back the audio content indicated in the playback queue jointly with the second playback device.

An audio processor circuit includes a storage circuit, a digital-to-analog converter circuit, and an amplifier circuit. The storage circuit is configured to store digital audio data from an electrical device. The digital-to-analog converter circuit is configured to convert the digital audio data from the storage circuit into an analog audio signal. The amplifier circuit is configured to provide an output audio signal to an audio playing circuit according to the analog audio signal. If a total data volume of the digital audio data stored in the storage circuit is not a multiple of a throughput or the total data volume of the digital audio data stored in the storage circuit is equal to or greater than an upper limit value, the amplifier circuit is turned off such that the amplifier circuit stops providing the output audio signal to the audio playing circuit.

The present disclosure relates to systems and methods for synchronizing audio and video. The systems and methods may perform operations including: obtaining a data stream including a sequence of video frames and a sequence of audio samples; inputting the sequence of video frames into a video channel, the sequence of video frames being processed and outputted from the video channel; inputting, for processing, the sequence of audio samples into an audio channel, the audio channel including a data buffer configured to buffer processed audio samples, a volume threshold of the data buffer being determined according to a time for processing one or more successive video frames; determining that a data volume of audio samples buffered in the data buffer exceeds the volume threshold; and in response to a determination that the data volume of buffered audio samples exceeds the volume threshold, outputting the buffered audio samples from the audio channel.

It is common that in an audio system, there are multiple data rates that need to be synchronized. For example, a sending device has its own crystal or clock, and a receiving device has another. Typical solutions introduce a lot of latency. According to various embodiments of the invention, a data management mechanism and technique are presented. The data management mechanism and technique pertains to managing media data such as those in an audio system, for example, managing the consumption of digital audio data in USB audio. The data management mechanism may include a dynamic buffer, which can be automatically controlled and adjusted to address issues (e.g., latency) in data consumption.

A control device of media playback system receives a user command to initiate playback of video content and associated audio content and transmits a BLUETOOTH message based on the command to a video playback device. The video playback device receives the BLUETOOTH message, obtains the media content via a local area network (LAN), and determines an indication of when to begin playback of the media content. The video playback device transmits the indication to an audio playback device via the LAN and outputs the video content in lip-synchrony with playback of the corresponding audio content by the audio playback device. While outputting the video content in lip-synchrony with playback of the corresponding audio content by the audio playback device, the video playback device transmits timing information via the LAN to the audio playback device to maintain lip-synchrony with playback of the corresponding audio content by the audio playback device.

According to certain embodiments, an electronic device comprises a communication circuit, a memory including a buffer configured to store audio data received from an external electronic device via the communication circuit, an audio output circuit, and a processor electrically connected to the communication circuit, the memory, and the audio output circuit.

Techniques for media content tamper protection and detection are described. In some embodiments, the protection method is performed at an encoder. The encoder obtains a first sequence of signatures within a group of pictures and a second sequence of signatures for audio frames corresponding to the group of pictures. The encoder then combines the first sequence of signatures and the second sequence of signatures to generate a combined signature, and the combined signature is then embedded in a transport stream for transmission to a client device. In some embodiments, the detection method is performed at a client device, where the client device, in response to detecting a first message in the transport stream, starts calculation of signatures for a group of pictures and corresponding audio frames. The client device then uses the calculated signatures to validate an expected signature for the group of pictures and the corresponding audio frames.

Aspects of the subject disclosure may include, for example, accessing adaptive streaming information for a multimedia content segment, determining available access bandwidths for a plurality of video tracks and a plurality of audio tracks identified by the adaptive streaming information, selecting one of a plurality of candidate track pairings identified by the adaptive streaming information based on the available access bandwidths, obtaining video content of the multimedia content segment via a video track of the selected track pairing, and obtaining audio content of the multimedia content segment via an audio track of the selected track pairing. Other embodiments are disclosed.

Novel techniques are described for lock-free sharing of a circular buffer. Embodiments can provide shared, lock-free, constant-bitrate access by multiple consumer systems to a live stream of audiovisual information being recorded to a circular buffer by a producer. For example, when a producer system writes a data stream to the circular buffer, the producer system records shared metadata. When a consumer system desires to begin reading from the shared buffer at a particular time, the shared metadata is used to compute a predicted write pointer location and corresponding dirty region around the write pointer at the desired read time. A read pointer of the consumer system can be set to avoid the dirty region, thereby permitting read access to a stable region of the circular buffer without relying on a buffer lock.