A jitter buffer control for controlling a provision of a decoded audio content on the basis of an input audio content is configured to select a frame-based time scaling or a sample-based time scaling in a signal-adaptive manner. An audio decoder uses such a jitter buffer control.

A receiving device uses an elastic buffer that is wider than the number of data elements transferred in each cycle. To compensate for frequency differences between the transmitter and the receiver, the transmitting device periodically sends a skip request with a default number of skip data elements. If the elastic buffer is filling, the receiving device ignores one or more of the skip data elements. If the elastic buffer is emptying, the receiving device adds one or more skip data elements to the skip request. To maintain the ordering of data despite the manipulation of the skip data elements, two rows of the wide elastic buffer are read at a time. This allows construction of a one-row result from any combination of the data elements of the two rows. The column pointers are adjusted appropriately, to ensure that they continue to point to the next data to be read.

A system for synchronizing a local audio processing clock rate of a digital signal processor (DSP) to an audio clock rate of a network to which the DSP is connected. The system includes an adjustable clock synthesizer that is configured to establish the local audio processing clock rate of the DSP. The DSP is configured to generate events that are associated with the local audio processing clock rate of the DSP. The DSP is further configured to monitor the generated events over time and based on the monitored events cause the adjustable clock synthesizer to adjust the local audio processing clock rate of the DSP to better match the network audio clock rate.

A system for synchronizing a local audio processing clock rate of a digital signal processor (DSP) to an audio clock rate of a network to which the DSP is connected. The system includes an adjustable clock synthesizer that is configured to establish the local audio processing clock rate of the DSP. The DSP is configured to generate events that are associated with the local audio processing clock rate of the DSP. The DSP is further configured to monitor the generated events over time and based on the monitored events cause the adjustable clock synthesizer to adjust the local audio processing clock rate of the DSP to better match the network audio clock rate.

Provided is a wireless audio synchronization method, a wireless audio playback device and a wireless audio transceiving system. The method includes sampling based on a first local clock signal of the wireless audio playback device a received wireless signal; determining a peak moment corresponding to a current wireless data packet; counting based on the first local clock signal a time difference between peak moments corresponding to the current and previous wireless data packets and adjusting a clock cycle of the first local clock signal based on a counting result so that the counting result approaches a predetermined count value; and playing after a predetermined number of clock cycles of the first local clock signal the data segment or its preset part according to a second local clock signal of the wireless audio playback device, where there is a fixed frequency multiple relationship between the first and second local clock signals.

A control plane, available to all of the line cards in a system, is used to exchange time stamps to align the Time of Day counters in the master line cards. The master line cards are locked to a system clock distributed over the backplane by a timing card. The timing card is locked to timing of a slave line card that is synchronized with the grand master. Each master line card synchronizes updating its Time of Day counter based on a time stamp exchange and a local clock locked to the system clock and without the use of a 1 pulse per second signal.

A transmitting system includes an outputting apparatus and a multiplexing apparatus. The outputting apparatus transmits MMTP packets to which an NTP short format timestamp is added. The multiplexing apparatus multiplexes the MMTP packets. The multiplexing apparatus includes an extractor, a controller, a determiner, a management information generator, a continuity determiner, and a transmission timing adjuster. The transmission timing adjuster writes, for adjustment of a transmission timing of an MMTP packet being close to an MMTP packet in which an NTP short format timestamp value is discontinuous, time information taking a leap second processing into consideration, to the NTP short format timestamp of the MMTP packet.

Systems and methods for controlling isochronous data streams are disclosed. Particular aspects of the present disclosure are designed to be used with almost any isochronous data stream, but are well-suited for use with the Universal Serial Bus (USB) protocol. Further, aspects of the present disclosure are flexible to accommodate existing configuration possibilities within the USB protocol as well as accommodate proposed future changes in the USB protocol. The flexibility of the systems and methods is provided by calculating: (1) drift between a USB host system time and the application and (2) drift between the USB host system and a USB device clock. Based on these two drift calculations, a time stamp may be synthesized to program a next delivery schedule. Using this time stamp, jitter correction can take place and uniformly-sized packets may be assembled to pass to an application processor.

A receiving device uses an elastic buffer that is wider than the number of data elements transferred in each cycle. To compensate for frequency differences between the transmitter and the receiver, the transmitting device periodically sends a skip request with a default number of skip data elements. If the elastic buffer is filling, the receiving device ignores one or more of the skip data elements. If the elastic buffer is emptying, the receiving device adds one or more skip data elements to the skip request. To maintain the ordering of data despite the manipulation of the skip data elements, two rows of the wide elastic buffer are read at a time. This allows construction of a one-row result from any combination of the data elements of the two rows. The column pointers are adjusted appropriately, to ensure that they continue to point to the next data to be read.

The audio outputs 29 of each of a plurality of telecommunications terminals in a packet switched system are synchronized by having each terminal transmit a stream of packets whose rate, and therefore duration is determined according to a clock generator 25, and is thus indicative of the rate at which the terminal is generating its audio output. The signals from each terminal are transmitted to a common server. For each terminal, the server uses a master dock to compare the duration of the packet stream with an expected duration, and calculates an offset value which is returned to the respective terminal. Each terminal stores the offset value it receives (20) and uses it to adjust the output of its clock generator 25 so that its operations can be synchronized to the server. This allows all the terminals' digital-to-analog conversion processes to be synchronized such that all their analog outputs are coordinated, allowing co-located acoustic outputs to be synchronous. A second embodiment maintains synchronization by maintaining the volume of the data buffer 23 serving the audio output 29 within predetermined limits.