Data transfer method and system for loudspeakers in a digital sound reproduction system

Abstract

The present publication describes a data transfer method and system in a digital sound reproduction system. The method comprises method steps for generating a digital audio stream for multiple channels in a host data source, e.g. a computer ( 1 ), the audio stream is formed by multiple consecutive samples, receiving the digital audio stream sent by the host data source ( 1 ) through a digital data transmission network by several digital receivers ( 2 ) each of which including a microcontroller with a clock, the receivers ( 2 ) further including means for generating an audio signal. In accordance with the invention the host data source ( 1 ) sends repeatedly a synchronization sample ( 60 ) to at least one receiver ( 2 ), the receiver ( 2 ) replies to the synchronization sample ( 60 ) by a return sample ( 61 ), the host ( 1 ) calculates a latency (T) for each receiver ( 2 ) based on the sending time (Th 1 ) of the synchronization sample ( 60 ) and the reception time (Th 2 ) of the return sample ( 61 ) and the processing time (Tt 1 −Tt 2 ) of the receiver ( 2 ), the host ( 1 ) sends to the receiver ( 2 ) information of the calculated latency (T) in combination with the time stamp the measurement time, based on this information the receiver ( 2 ) adjusts the function of its clock, and the above synchronization steps are repeated continuously.

1 - 15 . (canceled) 
     
     
         16 . A data transfer method in a digital sound reproduction system, comprising method steps for
 generating a digital audio stream for multiple channels in a host data source, e.g. a computer, the audio stream is formed by multiple consecutive samples,   receiving the digital audio stream sent by the host data source through a digital data transmission network by several digital receivers each of which including a microcontroller with a clock, the receivers further including means for generating an audio signal,   
       wherein
 the host data source sends repeatedly a synchronization sample to at least one receiver, 
 the receiver replies to the synchronization sample by a return sample, 
 the host calculates a latency (T) for each receiver based on the sending time (Th 1 ) of the synchronization sample and the reception time (Th 2 ) of the return sample and the processing time (Tt 2 −Tt 1 ) of the receiver, 
 the host sends to the receiver information of the calculated latency (T) in combination with the time stamp the measurement time, 
 based on this information the receiver adjusts the function of its clock, and 
 the above synchronization steps are repeated continuously. 
 
     
     
         17 . Method according to  claim 16 , wherein the digital audio stream is transmitted wirelessly to the receiver. 
     
     
         18 . Method according to  claim 16  or  17 , wherein the receiver compensates for the clock difference by setting the local clock rate in order to obtain synch of the microcontroller of the receiver. 
     
     
         19 . Method according to  claim 16  or  17 , wherein the host compares the calculated latency (T) with a reference latency and if the calculated latency (T) is larger than the reference latency, no adjustment information is sent to the receiver and the host starts a routine to redefine the reference latency. 
     
     
         20 . Method according to  claim 19 , wherein the clock difference is compensated for by adding or removing samples to/from the audio data stream and adjusting clock value accordingly. 
     
     
         21 . A data transfer system for a digital sound reproduction system, comprising
 a host data source, e.g., a computer for generating a digital audio stream for multiple channels, the audio stream is formed by multiple consecutive samples,   a transmission path for the host data source,   multiple digital receivers capable to communicate over the transmission path with the host data source, the receivers including
 means for receiving the digital audio stream sent by the host data source 
 a microcontroller with a clock, and 
 means for generating an audio signal, 
   
       wherein
 the host computer has means for sending repeatedly a synchronization sample to at least one receiver, 
 the receiver has means for replying to the synchronization sample by a return sample, 
 the host includes further means for 
 calculating a latency (T) for each receiver based on the sending time (Th 1 ) of the synchronization sample and the reception time (Th 2 ) of the return sample and the processing time (Tt 2 −Tt 1 ) of the receiver, 
 sending to the each receiver information of the calculated latency (T) in combination with the time stamp the measurement time, 
 whereby based on this information the receiver includes means for adjusting the function of its clock, and 
 the system includes means for repeating the above synchronization steps continuously. 
 
     
     
         22 . The system according to  claim 21 , wherein it includes means for transmitting the digital audio stream wirelessly to the receiver. 
     
     
         23 . The system according to  claim 21  or  22 , wherein the receiver includes means for compensating for the clock difference by setting the clock frequency of the microcontroller of the receiver. 
     
     
         24 . The system according to  claim 21  or  22 , wherein the host includes means for comparing the calculated latency (T) with a reference latency and if the calculated latency (T) is larger than the reference latency, no adjustment information is sent to the receiver and the host starts a routine to redefine the reference latency. 
     
     
         25 . The system according to any previous system  claim 21  or  22 , wherein the system includes means for compensating for the clock difference by adding or removing samples to/from the audio data stream. 
     
     
         26 . A synchronization method in a digital sound reproduction system, comprising method steps for
 generating a digital audio stream in a host data source, e.g. a computer,   receiving the digital audio stream sent by the host data source through a digital data transmission network by several digital receivers each of which including a microcontroller with a clock, the receivers further including means for generating an audio signal, whereby the receivers are grouped in a predetermined manner,   
       wherein
 the host data source sends repeatedly a synchronization sample to all receivers of a group, 
 the receivers reply to the synchronization samples by return samples, 
 the host calculates a latency times (T) for each sample and each receiver based on sending time (Th 1 ) of the synchronization sample and the reception time (Th 2 ) of the return sample and the processing time (Tt 2 −Tt 1 ) of the receiver, and 
 based on the calculated latency times (T) the host forms statistically a reference latency value, below which time most of the latency times are. 
 
     
     
         27 . Method according to  claim 26 , wherein the digital audio stream is transmitted wirelessly to the receiver. 
     
     
         28 . Method according to  claim 26  or  27 , wherein the reference latency is set such that at least 80% of the measured and calculated latency values are below the reference latency. 
     
     
         29 . Method according to  claim 26  or  27 , wherein the reference latency is set such that at least 50% of the measured and calculated latency values are below the reference latency. 
     
     
         30 . Method according to  claim 26  or  27 , wherein it includes the following steps:
 1. Sending ECHO REQ to receiver, 
 2. Getting timestamp TSsend for the packet containing ECHO REQ from timestamp driver, 
 3. Receiving ECHO RESP, whereby it will contain receiver ProcessingLatency, which is amount of microseconds receiver spent between receipt of the ECHO REQ and sending of ECHO RESP 
 4. Getting timestamp TSrecv for the ECHO RESP packet 
 5. Calculating Roundtrip latency is TSrecv—TSsend—ProcessingLatency