Method and device for buffering data for multiplexing
View Patent ↗The invention relates to a method and device for buffering data for multiplexing. The invention also relates to a method of multiplexing and to a multiplexer arrangement using the method and device for buffering data for multiplexing. In one embodiment the invention can be applied to the buffering of non-traffic data, such as firmware updates or other supplementary information, before multiplexing the non-traffic data with traffic data, such as television data of television channels, to form a satellite broadcast channel. In embodiments of the invention, non-traffic data for multiplexing is buffered and then read out again for multiplexing at a rate which is a function of buffer fullness. The non-traffic data may be multiplexed with at least one traffic data channel. A multiplexer can view the non-traffic data channel as another multiplexing input and can allocate the available bit rate between the traffic data channels and the non-traffic data accordingly.
1. A method for buffering of non-traffic data for a multiplexer arranged for multiplexing the non-traffic data with at least one traffic data channel, comprising the steps of:
storing received non-traffic data in a buffer;
determining a desired playout rate for non-traffic data in the buffer based on buffer fullness and based on a previous playout rate associated with previously transmitted non-traffic data;
requesting the desired playout rate for playout of the non-traffic data;
receiving, in response to the request for the desired playout rate, a non-traffic playout rate for playout of the non-traffic data; and
reading non-traffic data out of the buffer at the non-traffic playout rate for multiplexing with the at least one traffic data channel.
2. The method as claimed in claim 1 , in which the at least one traffic data channel is a television data traffic channel.
3. The method as claimed in claim 1 further comprising the step of determining the desired playout rate for non-traffic data in the buffer as a linear function of a buffer fullness measure.
4. The method as claimed in claim 1 further comprising the steps of:
identifying, based on a buffer fullness measure, an increase in fullness of the buffer; comparing the buffer fullness measure to a maximum playout rate threshold (T max ); and
increasing a maximum desired playout rate upon determining the buffer fullness measure is less than the maximum playout rate threshold (T max ).
5. The method as claimed in claim 1 further comprising the step of supplying a rate request corresponding to the desired playout rate to a multiplex controller controlling the multiplexing operation.
6. The method as claimed in claim 5 wherein the non-traffic playout rate is received from the multiplex controller controlling the multiplexing operation.
7. The method as claimed in claim 1 further comprising the step of informing a multiplexer controller of an overflow condition of the buffer.
8. A method of multiplexing non-traffic data with at least one traffic data channel comprising the steps of:
buffering non-traffic data as claimed in claim 5 ;
receiving a rate request for traffic data in one or more traffic data channel;
allocating an available bit rate to traffic data in each traffic data channel and allocating the non-traffic playout rate to the non-traffic data channel based on the received rate requests and the desired playout rate; and
multiplexing the non-traffic data read out from the buffer with the traffic data from one or more traffic data channels according to the bit rate allocation.
9. The method of multiplexing as claimed in claim 8 , where the step of allocating the available bit rate comprises the steps of:
allocating the desired playout rate for buffered non-traffic data; and
allocating the remaining bit rate to traffic data in traffic channels according to the received rate requests.
10. Device for buffering of non-traffic data, for a multiplexer arranged for multiplexing the non-traffic data with traffic data in one or more traffic channels, comprising:
a buffer for receiving and storing the non-traffic data, and coupled for supplying the stored non-traffic data for multiplexing with the at least one traffic data channel; and
a demand unit for:
determining a desired playout rate for non-traffic data in the buffer based on buffer fullness and based on a previous playout rate associated with previously transmitted non-traffic data;
requesting the desired playout rate for playout of the non-traffic data;
receiving, in response to the request for the desired playout rate, a non-traffic playout rate for playout of the non-traffic data; and
causing non-traffic data to be read out at the non-traffic playout rate for multiplexing with the at least one traffic data channel.
11. The device as claimed in claim 10 wherein the demand unit is coupled to the buffer to receive a buffer fullness measure from the buffer and the demand unit being operable to determine the desired playout rate as a linear function of the buffer fullness measure.
12. The device as claimed in claim 10 wherein the demand unit is coupled to the buffer to receive a buffer fullness measure from the buffer and the demand unit is further operable to:
identify, based on the buffer fullness measure, an increase in fullness of the buffer;
compare the buffer fullness measure to a maximum playout rate threshold(T max ); and
increase a maximum desired playout rate upon determining the buffer fullness measure is less than the maximum playout rate threshold (T max ).
13. The device as claimed in claim 10 wherein the demand unit is coupled to a multiplex controller controlling the multiplex operation of a multiplexer and is operable to send a rate request, corresponding to the desired playout rate to the multiplexer.
14. The device as claimed in claim 13 wherein the demand unit is coupled to the multiplex controller controlling the multiplex operation and is operable to receive the non-traffic playout rate from the multiplex controller.
15. A multiplexer arrangement for multiplexing non-traffic data with traffic data in one or more traffic channels comprising:
a device for buffering of non-traffic data, as claimed in claim 10 ; and
a multiplex controller operable to receive rate requests for traffic data in one or more traffic data channels; and coupled to the demand unit and operable to receive therefrom the desired playout rate for the non-traffic data;
the multiplex controller being operable to allocate an available bit rate to each traffic data channel and to the non-traffic data based on the received rate requests and the desired playout rate received from the demand unit; and
the multiplex controller being operable to multiplex the non-traffic data read out from the buffer at the non-traffic playout rate with the traffic data from one or more traffic data channels according to the bit rate allocation.
16. The multiplexer arrangement as claimed in claim 15 wherein the multiplex controller is coupled to the demand unit, and is operable to send the non-traffic playout rate allocated to the non-traffic data to the demand unit.