A multi-channel and multi-zone audio environment is provided. Various inventions are disclosed that allow playback devices on one or more networks to provide an effective multi-channel and a multi-zone audio environment using timing information. According to one example, timing information is used to coordinate playback devices connected over a low-latency network to provide audio along with a video display. In another example, timing information is used to coordinate playback devices connected over a mesh network to provide audio in one or more zones or zone groups.

Techniques for wireless transmission of data are provided, in which data representing a plurality of frames of a time-sequential signal are encoded. The encoded data are temporarily retained in a memory buffer before wireless transmission. A current number of frames of the encoded data awaiting transmission is determined, and a compression rate is selected for encoding the next frame of data of the time-sequential signal based on the determined number of stored frames in the memory buffer. The selected compression rate is used to encode the next frame of the time-sequential signal, which is added to the encoded data stored in the memory buffer and wirelessly transmitted from the memory buffer. The present disclosure is applicable to a smartphone and a portable player, for example.

To improve integrity of time synchronization, a node in a safety rated system verifies that its clock remains synchronized to another clock. Two adjacent, time-synchronized nodes transmit diagnostic messages to each other at an agreed upon interval and generate timestamps when the diagnostic message is received from the other node. The nodes then transmit their respective timestamp back to the sending node. Clock drift is detected by comparing a difference between the two timestamps at which the messages were received against a threshold. To avoid accidental detection of clock drift, a difference in transmission delays between the two nodes is stored in a FIFO buffer. Each node monitors the average of the data in the FIFO buffer. If the average deviates from the target value by too great a value, then the node determines the values of the clocks have skewed beyond an acceptable range and generates a fault condition.

In a network having at least one slave node including a slave clock, a method of adjusting the slave clock relative to a master clock of a master node includes, at the slave node, correcting a time of day of the slave clock using (a) a slave pulse signal having a known slave pulse rate, (b) a time-of-day counter of the slave node, and (c) a master pulse signal, based on values of the slave clock at nearest corresponding edges of the slave pulse signal and the master pulse signal, and correcting a frequency of the slave clock using the slave pulse signal, a clock signal of the slave node, and the master pulse signal, based on values of the slave clock at nearest corresponding edges of the master pulse signal. No other clock signal from outside the slave node is used for the corrections.

A method of operating a network device is provided that includes using a first deserializer to receive first data bits via a first data lane and to output a first data block, using a second deserializer to receive second data bits via a second data lane and to output a second data block, generating a first timestamp for the first data block, generating a second timestamp for the second data block, using a first data buffer to receive the first data block and the first timestamp, and using a second data buffer to receive the second data block and the second timestamp. The first and second data buffers can serve as deskew components along a clock domain boundary. The first and second timestamps can be obtained by timestamping an arrival of data at a same point in each of the first and second data lanes before the clock domain boundary.

A multi-channel and multi-zone audio environment is provided. Various inventions are disclosed that allow playback devices on one or more networks to provide an effective multi-channel and a multi-zone audio environment using timing information. According to one example, timing information is used to coordinate playback devices connected over a low-latency network to provide audio along with a video display. In another example, timing information is used to coordinate playback devices connected over a mesh network to provide audio in one or more zones or zone groups.

In a network having at least one slave node including a slave clock, a method of adjusting the slave clock relative to a master clock of a master node includes, at the slave node, correcting a time of day of the slave clock using (a) a slave pulse signal having a known slave pulse rate, (b) a time-of-day counter of the slave node, and (c) a master pulse signal, based on values of the slave clock at nearest corresponding edges of the slave pulse signal and the master pulse signal, and correcting a frequency of the slave clock using the slave pulse signal, a clock signal of the slave node, and the master pulse signal, based on values of the slave clock at nearest corresponding edges of the master pulse signal. No other clock signal from outside the slave node is used for the corrections.

A module including a first slice and a second slice. The first slice and the second slice receive data from a plurality of inputs. A first stage of the first slice selects a first subset of the inputs in synchronization with an edge of a first clock. In synchronization with a second clock, a second stage of the first slice selects an input from the first subset. A first stage of the second slice selects a second subset of the inputs in synchronization with an edge of the second clock. In synchronization with the first clock, a second stage of the second slice selects an input from the second subset.

A multi-channel and multi-zone audio environment is provided. Various inventions are disclosed that allow playback devices on one or more networks to provide an effective multi-channel and a multi-zone audio environment using timing information. According to one example, timing information is used to coordinate playback devices connected over a low-latency network to provide audio along with a video display. In another example, timing information is used to coordinate playback devices connected over a mesh network to provide audio in one or more zones or zone groups.