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89:. Where circuit costs are high and loss of voice quality is acceptable, it sometimes makes sense to compress the voice signal even further. An ADPCM algorithm is used to map a series of 8-bit ÎĽ-law (or a-law) PCM samples into a series of 4-bit ADPCM samples. In this way, the capacity of the line is doubled. The technique is detailed in the
131:(QMF) to get two subbands of the signal. When the ADPCM bitstream of each subband is obtained, the results are multiplexed, and the next step is storage or transmission of the data. The decoder has to perform the reverse process, that is, demultiplex and decode each subband of the bitstream and recombine them.
84:
PCM (Europe and most of the rest of the world). These are logarithmic compression systems where a 13- or 14-bit linear PCM sample number is mapped into an 8-bit value. This system is described by international standard
141:
Referring to the coding process, in some applications as voice coding, the subband that includes the voice is coded with more bits than the others. It is a way to reduce the file size.
68:, a standard audio signal for a single phone call is encoded as 8000 analog samples per second, of 8 bits each, giving a 64 kbit/s digital signal known as
37:
Typically, the adaptation to signal statistics in ADPCM consists simply of an adaptive scale factor before quantizing the difference in the DPCM encoder.
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with two channels and ADPCM coding of each. Before the digitization process, it catches the analog signal and divides it in frequency bands with
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308:. ITU-T Recommendation G.722 (11/88), "7 kHz audio-coding within 64 kbit/s".
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Recommended
Practices for Enhancing Digital Audio Compatibility in Multimedia Systems
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265:(September 1973). "Adaptive quantization in differential PCM coding of speech".
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404:"FFmpeg/adpcmenc.c at ee4aa388b2231e988eccdab652c55df080d6ad45 · FFmpeg/FFmpeg"
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to develop the legacy audio codecs ADPCM DVI, IMA ADPCM, and DVI4.
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supports ADPCM encoding on 64 simultaneous audio channels.
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communications. In the early 1990s, ADPCM was also used by
296:– legacy IMA ADPCM specification, Retrieved on 2009-07-06.
760:
726:
154:
69:
256:
318:
Jerry D. Gibson; Toby Berger; Tom
Lookabaugh (1998).
346:"Differences Between PCM/ADPCM Wave Files Explained"
123:operating at 48, 56 and 64 kbit/s, based on
1644:
229:
107:
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379:"FFmpeg General Documentation - Audio Codecs"
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16:Technique used to encode voices in telephony
20:Adaptive differential pulse-code modulation
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13:
321:Digital Compression for Multimedia
281:10.1002/j.1538-7305.1973.tb02007.x
164:audio codecs supporting ADPCM are
102:Interactive Multimedia Association
28:differential pulse-code modulation
14:
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268:The Bell System Technical Journal
80:PCM (North America and Japan) or
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96:ADPCM techniques are used in
356:. 2011-09-24. Archived from
236:. McGraw-Hill Professional.
76:encoding on a DS0 is either
7:
233:Principles of Digital Audio
194:
144:
108:Split-band or subband ADPCM
10:
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1503:Compressed data structures
825:RLE + BWT + MTF + Huffman
493:Asymmetric numeral systems
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862:Discrete cosine transform
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792:LZ77 + Huffman + context
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129:quadrature mirror filters
119:standard wideband speech
1567:Smallest grammar problem
354:Microsoft Knowledge Base
230:Ken C. Pohlmann (2005).
40:ADPCM was developed for
1508:Compressed suffix array
1057:Nyquist–Shannon theorem
206:Audio data compression
1537:Kolmogorov complexity
1405:Video characteristics
782:LZ77 + Huffman + ANS
350:KB 89879 Revision 3.0
211:Pulse-code modulation
32:signal-to-noise ratio
1627:Compression software
1221:Compression artifact
1177:Psychoacoustic model
151:Windows Sound System
1617:Compression formats
1256:Texture compression
1251:Standard test image
1067:Silence compression
324:. Morgan Kaufmann.
201:Audio coding format
153:supported ADPCM in
1525:Information theory
1380:Display resolution
1206:Chroma subsampling
595:Byte pair encoding
540:Shannon–Fano–Elias
263:Flanagan, James L.
74:signal compression
26:) is a variant of
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1439:Deblocking filter
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331:978-1-55860-369-1
243:978-0-07-144156-8
50:James L. Flanagan
44:by P. Cummiskey,
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1653:Data compression
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275:(7): 1105–1118.
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802:LZSS + Huffman
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187:The DSP in the
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78:ÎĽ-law (mu-law)
72:. The default
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360:on 2013-12-31
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170:adpcm_ima_wav
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98:voice over IP
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42:speech coding
38:
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33:
29:
25:
21:
1663:Audio codecs
1583:Hutter Prize
1547:Quantization
1452:Compensation
1246:Quantization
1115:
969:Compensation
926:
535:Shannon–Fano
475:Entropy type
414:. Retrieved
412:. 2017-02-15
407:
398:
387:. Retrieved
373:
362:. Retrieved
358:the original
349:
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182:adpcm_yamaha
181:
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166:adpcm_ima_qt
165:
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133:
111:
95:
63:
60:In telephony
39:
36:
23:
19:
18:
1542:Prefix code
1395:Frame types
1216:Color space
1042:Convolution
772:LZ77 + ANS
683:Incremental
656:Other types
575:Levenshtein
1647:Categories
1599:Mark Adler
1557:Redundancy
1474:Daubechies
1457:Estimation
1390:Frame rate
1312:Daubechies
1272:Chain code
1231:Macroblock
1037:Companding
974:Estimation
894:Daubechies
600:Lempel–Ziv
560:Exp-Golomb
488:Arithmetic
416:2018-02-05
389:2013-12-30
364:2013-12-30
218:References
93:standard.
1576:Community
1400:Interlace
786:Zstandard
565:Fibonacci
555:Universal
513:Canonical
178:adpcm_swf
66:telephony
56:in 1973.
54:Bell Labs
1562:Symmetry
1530:Timeline
1513:FM-index
1358:Bit rate
1351:Concepts
1199:Concepts
1062:Sampling
1015:Bit rate
1008:Concepts
710:Sequitur
545:Tunstall
518:Modified
508:Adaptive
466:Lossless
195:See also
189:GameCube
174:adpcm_ms
157:files.
145:Software
1520:Entropy
1469:Wavelet
1448:Motion
1307:Wavelet
1287:Fractal
1282:Deflate
1265:Methods
1052:Latency
965:Motion
889:Wavelet
806:LHA/LZH
756:Deflate
705:Re-Pair
700:Grammar
530:Shannon
503:Huffman
459:methods
1631:codecs
1592:People
1495:Theory
1462:Vector
979:Vector
796:Brotli
746:Hybrid
645:Snappy
498:Golomb
409:GitHub
383:FFmpeg
328:
240:
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115:is an
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1385:Frame
1343:Video
1327:SPIHT
1236:Pixel
1191:Image
1145:ACELP
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1106:ÎĽ-law
1101:A-law
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904:SPIHT
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113:G.722
91:G.726
87:G.711
82:A-law
24:ADPCM
1434:DPCM
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1172:MDCT
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872:MDCT
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717:LDCT
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640:LZWL
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625:LZRW
615:LZJB
385:.org
326:ISBN
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180:and
160:The
149:The
48:and
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1429:DCT
1373:VBR
1368:CBR
1363:ABR
1322:EZW
1317:DWT
1302:RLE
1292:KLT
1277:DCT
1160:LSP
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1140:LPC
1133:FFT
1030:VBR
1025:CBR
1020:ABR
954:LSP
949:LAR
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899:DWT
884:FFT
879:DST
867:DCT
766:LZS
761:LZX
737:RLE
732:PPM
727:PAQ
722:MTF
690:DMC
668:CTW
663:BWT
635:LZW
620:LZO
610:LZ4
605:842
277:doi
155:WAV
70:DS0
64:In
52:at
1649::
1297:LP
1128:FT
1121:DM
673:CM
406:.
381:.
352:.
348:.
273:52
271:.
261:;
184:.
176:,
172:,
168:,
34:.
1633:)
1629:(
449:e
442:t
435:v
419:.
392:.
367:.
334:.
283:.
279::
246:.
22:(
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