ITU-T G 726 APP II-1991 Description of the Digital Test Sequences for the Verification of the G 726 40 32 24 and 16 kbit s ADPCM Algorithm - Series G Transmission Systems and Media.pdf
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1、 STD-ITU-T RECMN G-72b APPEND II-ENGL 1771 D 48b2571 Ob37213 7T2 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.726 Appendix II Test Vectors (03/9 I ) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital transmission systems -
2、Terminal equipments - Coding of analogue signals by methods other than PCM Description of the digital test sequences for the verification of the G.726 40,32, 24 and 16 kbit/s ADPCM algorithm STD-ITU-T RECMN G-72b APPEND II-ENGL 1991 D LiAb2591 Ob3721q 839 = FOREWORD ITU (International Telecommunicat
3、ion Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a
4、 view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recom
5、mendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. INTELLECTUAL PROPERTY RIGHTS The ITU draws
6、attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members
7、or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU hadhad not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may
8、 not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1997 Ail rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without pe
9、rmission in writing from the ITU. STD.ITU-T RECMN G.72b APPEND II-ENGL 1991 m 4b257L Ob37215 775 DESCRIPTION OF THE DIGITAL TEST SEQUENCES FOR THE VERIFICATION OF THE G.726 40,32,24 AND 16 KBIT/S ADPCM ALGORITHM 1 Introduction This guide describes the test sequences (vectors) for the ADPCM algorithm
10、s of Recommendation G.726 at the four fixed bit rates (16 kbit/s, 24 kbits, 32 kbit/s, 40 kbit/s) for both A-law and p-law. It reproduces mainly the text of the CCITT collective letter No. 1 IKV, dated 21/03/1991, the only amendments corresponding to the grouping on two 3%“ disks of the files which
11、were previously on four 5%“ disks. The tests are arranged in two separate diskettes, one for the p-law and one for the A-law. For each law, the diskette contains the reset test vectors and the homing test vectors. The diskettes are of the 3 ?4 MS-DOS format. Within each diskette, the files are distr
12、ibuted in subdirectories that correspond to individual bit rates for the homing and reset case. A READ.ME file lists the contents of each diskette. 2 General description The verification testing procedure consists in applying an input sequence to an ADPCM implementation and veriQing that the output
13、sequence is the same sequence in the output file for the same test conditions (PCM coding law, type of input, initial state of the implementation). There are three types of input sequences. The first type consists of various sinusoidal PCM inputs that are representative of the signals expected in no
14、rmal operation. These are called “normal inputs“. A second group of input sequences is the set of “overload inputs“ that contain PCM signals of very large amplitudes. The third group is the set of ADPCM sequences that can exercise the algorithm in a manner that is not possible with any PCM input seq
15、uence. They test the arithmetic and algorithmic performance of the ADPCM decoder by driving it to states that are unreachable by PCM signals under normal conditions. For example, these states may result fi-om errors on the transmission line. These intermediate sequences will be denoted as “I-inputs“
16、. The values (or samples) contained in a test file are given in ASCII hexadecimal representation with two hexadecimal characters per 8-bit value. In files with 5-bit ADPCM values, the three most significant bits are set to O. Files containing 4-bit ADPCM values have the four most significant bits or
17、 each value set to O. Files that contain 3-bit ADPCM values have the five most significant bits of each word set to O. For files containing 2-bit ADPCM values, the six most significant bits are set to O. All PCM A-law inputs are in the format specified by Table 1a/G.711, i.e. the even bits are inver
18、ted. Each line in any file contains up to 32 values (or 64 characters) and ends with a line feed character. Two more hexadecimal characters representing the result of a checksum computation over the entire file are appended to each file. This checksum is the remainder of the division of 255 of the s
19、um of all sample values (two hexadecimal characters comprise a sample value) in the file. I 1 It has been noted that these diskettes do not always copy correctly using DISKCOPY due to the interaction of DISKCOPY with certain character sequences found in the test sequences. Either files should be cop
20、ied individually using COPY, or XCOPY should be used instead of DISKCOPY. Recommendation G.726 - Appendix II - Test vectors (03/91) 1 STD-ITU-T RECMN G*72b APPEND II-ENGL 1991 m qAb2591 Ob3721b bOL W S c 3 Test configurations Test sequences are derived for the two configurations shown in Figures 1 a
21、nd 2, respectively. The configuration of Figure 1 is the arrangement with the encoder transmitting to the decoder for error- free operation. The configuration of Figure 2 allows for input ADPCM words that would not normally emanate from an encoder and a PCM input word. The word formats of the variou
22、s sequences are detailed in Table 1. Encoder c Decoder , SD S b I ADPCM output sequence Decoder SD Figure 1 - Encoder and decoder configuration ADPCM input sequence PCM output sequence Name S I SD Table 1 -Word format of test sequences Description PCM input word ADPCM word PCM output word Word forma
23、t Identical to that of SP described in the sub-block COMPRESS of the synchronous coding adjuster (4.2.8/G. 72 6). As specified in the sub-block RECONST of the inverse adaptive quantizer (4.2.3/G.726). Identical to that of SP described in the sub-block COMPRESS (4.2.8G.726). 4 Test combinations The i
24、nitial state of the implementation may be either the reset state of the algorithm defined in Table 2 or a well-defined initial state that follows the application of an initialization (or homing) sequence. Accordingly, there are two types of test sequences, reset sequences and homing sequences. 2 Rec
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