Method and apparatus for processing data in a processing unit being a thread in a multithreading environment

#This application claims the benefit, under 35 U.S.C. § 119 of European Patent Application 04013686.3, filed Jun. 10, 2004.

#This invention relates to a method for processing data in a processing unit. In particular, the invention relates to a method for processing data in a processing unit, wherein the processing unit generates data frames for an output unit by combining data from a plurality of input units, and wherein said processing unit, input units and output unit are threads in a multithreading environment.

#Audio-visual (AV) presentations that are coded according to the Motion Picture Expert Group (MPEG) standard ISO/IEC-14496-1, known as MPEG-4 Systems, may consist of several data streams, e.g. one or more streams for video, one or more streams for audio, and others. The audio streams may have individual, usually standardized sample rates, e.g. 8 kb/s, 16 kb/s, 22.05 kb/s, 32 kb/s, 44.1 kb/s or 48 kb/s for different types of audio streams. Further, these streams consist of packets or frames with attached time-stamps.

#Exemplary embodiments of the invention are described with reference to the accompanying drawings, which show in

#FIG. 1 a conventional single-input audio processing system;

#FIG. 2 an extended conventional audio processing system;

#In the following, the problem with prior art systems is described in more detail before preferred embodiments of the invention are described.

#FIG. 2 shows a processing unit 14 being the center of a system with several multimedia source streams, which are decoded by separate decoders 11,12,13 and buffered in separate buffers 11b,12b,13b. The decoders 11,12,13 belong to separate time domains or threads that are independent from the time domain of the processing unit 14. The processing unit 14 synchronizes the timestamps between the data from different sources. The output of the processing unit 14 is sent to a frame-oriented FIFO buffer 15. A signal 18 from the buffer 15 transmits the buffer filling level to the processing unit 14, thus requesting more data so as to prevent an underflow when the filling of the buffer 15 is below a defined level. The output of the buffer 15 is driven by an output module 16, which requires in regular intervals data at the buffer output 17. Thus, the output module determines the filling and also the frame-rate of the FIFO buffer 15. The frame size of the output buffer 15 depends on the requirements of the output module 16, but usually the buffer 15 is very large, e.g. fifteen frames. In a typical software realization of such a system, the output module 16 runs in its own thread that is independent from the other threads, particularly from the input buffer threads and the thread of the processing unit 14.

#The output buffer 15 is the communication element between the processing unit 14 thread and the output module 16 thread. When filling of the output buffer 15 is requested, the processing unit 14 writes data into the output buffer 15 until the buffer is full. Then the processing unit waits i.e. does nothing or performs other tasks, until the output module 16 has read a data block from the output buffer 15. Therefore the output module 16 determines the filling of the output buffer 15, which in turn determines activation of the processing unit 14.