USBB17AP77016-XXX-B11 NEC Electronics, USBB17AP77016-XXX-B11 Datasheet - Page 29

• Manufacturer Part Number: USBB17AP77016-XXX-B11
• Description: DSP middleware(WMA (Windows Media Audio)decoder)
• Manufacturer: NEC Electronics

2.5.3
memory) and an output buffer is required to store the PCM data of the decoding results (X memory). Any symbol
name can be assigned to these buffers, providing names used by the µ SAP77016-B11 or other applications are not
duplicated.
with the system configuration. Recommended output buffer sizes are shown in Table 2-5 Recommended Output
Buffer Size.
stream data sent from the host CPU (X or Y memory), and a serial output buffer to output PCM data to the DAC (X or
Y memory) are required in addition to the I/O buffers used by the µ SAP77016-B11.
Output Buffer Size.
of input data calculated from the equation below. For example, to store the input data required to obtain the output
results of the recommended output buffer size × 2 samples, the size of the input data receive buffer should be the
average input data amount calculated using the equation below, with the appropriate value from Table 2-5
Recommended Output Buffer Size as the number of output samples, × 2 words. The average input data amount
calculated in this way will reach a maximum value of 558 words when the bit rate is 192 kbps and the sampling
frequency is 44.1 kHz.
data in the buffer, even if a larger buffer is secured. To counter this problem, it is recommended to construct a system
in which a command requesting input data can be sent from the DSP side to the CPU.
public
public
public
public
I_O_BUFFER_X
INPUT_BUFFER:
HOST_IN_BUFF:
OUTPUT_BUFFER:
SERIAL_OUT_BUFF:
end
In order for the µ SAP77016-B11 to perform decoding, an input buffer is required to input the bit stream data (X
The input buffer must have a capacity of at least 64 words and the size of the output buffer should be set to accord
Note that when performing decoding in real time, buffers such as an input data receive buffer to receive the bit
The size of the serial output buffer must be equivalent to the buffer size shown in Table 2-5 Recommended
Set the size of the input data receive buffer to accord with the system configuration, based on the average amount
Note, however, that if data that includes video data is received in addition to audio data, there may be insufficient
Average input data amount =
I/O buffers
INPUT_BUFFER
HOST_IN_BUFF
OUTPUT_BUFFER
SERIAL_OUT_BUFF
XRAMSEG
DS
DS
DS
DS
Figure 2-5. Example of Securing I/O Buffers
64;
1536;
4096;
4096;
Number of output samples
Sampling frequency [kHz]
CHAPTER 2 LIBRARY SPECIFICATIONS
Bit rate [kbps]/16
User’s Manual U15683EJ1V0UM
[Words]
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