參數(shù)資料
型號： SAA2502
廠商： NXP Semiconductors N.V.
英文描述： ISO/MPEG Audio Source Decoder
中文描述： 的ISO / MPEG音頻信源解碼器
文件頁數(shù)： 19/64頁
文件大?。?/td> 318K
代理商： SAA2502
1997 Nov 17
19
Philips Semiconductors
Preliminary specification
ISO/MPEG Audio Source Decoder
SAA2502
7.4.5
S
CALE FACTOR
CRC
PROTECTION
MPEG specifies an optional 16 bit CRC that may be used
to verify whether an important part of each audio frame is
received correctly. The following data items is protected by
this CRC:
Bytes 3 and 4 of the first 4 bytes of each frame,
containing most of the frame header information
Allocation information
Scale factor select information (layer II only).
The scale factors are not protected by this scheme.
The DAB specification includes CRC protection for scale
factors. The 32 sub-bands are divided into the following
4 blocks:
Block 0 = sub-bands 0 to 3
Block 1 = sub-bands 4 to 7
Block 2 = sub-bands 8 to 15
Block 3 = sub-bands 16 to 31.
Each block is protected by an 8-bit CRC if that block of
sub-bands is (partly) inside the current sub-band limit.
The required scale factor CRCs are stored in the last bytes
of the previous audio frame:
The last two bytes of each frame are reserved for
ancillary data; DAB specification calls this Fixed
Program Associated Data (FPAD)
Minimum 2 and maximum 4 bytes before FPAD are
reserved for scale factor CRCs. The number of CRC
bytes present is be derived from the sub-band limit of the
following audio frame
Bytes before the CRCs are available for more ancillary
data; DAB specification calls this extended Program
Associated Data (XPAD), as far as not occupied by
MPEG coded input data.
The DAB type of scale factor CRC protection, extended to
all valid sample frequency plus bit rate combinations of
MPEG1 and MPEG2, and to layer I, is fully supported by
the SAA2502. (DAB is restricted to MPEG1 layer II, to
48 kHz sample frequency and does not support free
format bit rate). Requirements for scale factor CRC
handling is indicated by the SFCRC control flag.
7.4.6
H
ANDLING OF ERRORS IN THE CODED INPUT DATA
The SAA2502 is able to handle certain types of errors in
the input data. Three error categories will be handled:
Errors flagged by the coded input data error flag CDEF
CRC failures (if MPEG and/or scale factor error
protection is active)
MPEG audio frame syntax errors.
Error flags in the input data will effect the decoding process
if the corrupted data is inside the header, bit allocation or
scale factor select information part of a frame (then the
SAA2502 will ‘soft’ mute that frame) or inside the scale
factor field (then the most recent valid scale factor of the
same sub-band will be copied).
Error flags in other data fields will be ignored. If MPEG
and/or scale factor CRCs are active the CRC result has
priority over CDEF flags inside the protected fields. In
applications where the MPEG CRC is always present, the
protection bit (which is not CRC protected) in the MPEG
header may be overruled by setting control flag CRCACT.
Thus the SAA2502 is robust for data errors in the
protection bit.
相關(guān)PDF資料
PDF描述
SAA2502H ISO/MPEG Audio Source Decoder
SAA2503 MPEG2 audio decoder(MPEG2 音頻譯碼器)
SAA2503HT MPEG2 audio decoder
SAA2505H-M1 Digital multi-channel audio IC DUET
SAA2505 Digital multi-channel audio IC DUET
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SAA2502H 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:ISO/MPEG Audio Source Decoder
SAA2503 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:MPEG2 audio decoder
SAA2503HT 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:MPEG2 audio decoder
SAA2505 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital multi-channel audio IC DUET
SAA2505H 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital multi-channel audio IC DUET
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*