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The two methods are mathematically identical: picking an interpolation function in the second scheme is equivalent to picking the impulse response of the filter in the first scheme. Linear interpolation is equivalent to a triangular impulse response; windowed sinc approximates a
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Moon missions were converted to the conventional TV rates for the viewers at home. Digital interpolation schemes were not practical at that time, so analog conversion was used. This was based on a TV rate camera viewing a monitor displaying the Apollo slow-scan images.
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Treat the samples as geometric points and create any needed new points by interpolation. Choosing an interpolation method is a trade-off between implementation complexity and conversion quality (according to application requirements). Commonly used are:
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the values of the new samples directly from the old samples. The latter approach is more satisfactory since it introduces less noise and distortion. Two possible implementation methods are as follows:
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each frame is shown twice. Since 50 is not exactly 2×24, the movie will run 50/48 = 4% faster, and the audio pitch will be 4% higher, an effect known as
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For example, the irrational ratio 2, corresponding to one equal-temperament semitone, might be approximated by 196/185 (roughly 0.99994 semitones).
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Conceptual approaches to sample-rate conversion include: converting to an analog continuous signal, then re-sampling at the new rate, or
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In satellite and medical image processing, sample rate conversion is necessary for image enhancement, scale change, and image rotation
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has a sampling rate of 44.1 kHz; to transfer it to a digital medium that uses 48 kHz, method 1 above can be used with
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and audio/visual systems, where different sampling rates may be used for engineering, economic, or historical reasons.
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systems use different sampling rates, and
American television, European television, and movies all use different
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Using Farrow filter on the basis of piecewise cubic polynomial interpolation for digital signal resampling
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are swapped. Per above, in both cases, the low-pass filter should be set to 22.05 kHz.
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If the ratio of the two sample rates is (or can be approximated by) a fixed rational number
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that would otherwise occur when transferring recorded material between such systems.
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363:= 147 (since 48000/44100 = 160/147). For the reverse conversion, the values of
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for further information on sample-rate conversion filter design/implementation.
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is sometimes used to refer to systems that incorporate sample-rate conversion.
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A field is half of an interlaced frame – just the odd or even lines.
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rather than twice, or digital interpolation (see above) can be used in a
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Digital resampling by using polynomial interpolation. Farrow filter
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Techniques and processing that may involve sample-rate conversion:
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582:"An efficient algorithm for sample rate conversion from CD to DAT"
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Multi-Rate
Processing and Sample Rate Conversion: A Tutorial
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alternate movie frames are shown 2 and 3 times, respectively
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248:-th sample from the filtered output, to obtain the result.
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to obtain a new discrete representation of the underlying
472:(2nd ed.). Upper Saddle River, N.J.: Prentice Hall.
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174:. Sample-rate conversion prevents changes in speed and
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Lyons, Richard (2010). "10. Sample Rate
Conversion".
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580:Rajamani, K.; Yhean-Sen Lai; Furrow, C. W. (2000).
60:. Unsourced material may be challenged and removed.
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279:In method 1, a slow pre-computation (such as the
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537:An alternative and more satisfactory approach...
553:(Second ed.). Da Capo Press. p. 101.
379:Sample rate conversion in multiple dimensions:
240:: generate an intermediate signal by inserting
27:Changing the sampling rate of a discrete signal
181:More specific types of resampling include:
319:Movies (shot at 24 frames per second) are
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120:Learn how and when to remove this message
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652:. Englewood Cliffs, NJ: Prentice-Hall.
646:Crochiere, R.E.; Rabiner, L.R. (1983).
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495:Understanding Digital Signal Processing
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404:Techniques used in related processes:
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337:twelfth frame can be repeated 3 times
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213:multi-rate digital signal processing
58:adding citations to reliable sources
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18:Multi-rate digital signal processing
684:The Quest For The Perfect Resampler
649:Multirate Digital Signal Processing
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674:Digital Audio Resampling Home Page
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468:Discrete-time signal processing
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137:sampling-frequency conversion
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521:Antoniou, Andreas (2006).
384:Multivariate interpolation
164:Compact Disc Digital Audio
710:Digital signal processing
523:Digital Signal Processing
256:(for film/video frames),
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69:"Sample-rate conversion"
321:converted to television
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133:Sample-rate conversion
54:improve this article
601:2000ISPL....7..288R
303:Film and television
622:Bill Wood (2005),
551:Genesis of a Music
462:Schafer, Ronald W.
458:Oppenheim, Alan V.
168:Digital Audio Tape
631:, NASA, p. 5
625:Apollo Television
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47:verification
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595:(10): 288.
399:Transcoding
225:calculating
211:. The term
199:downscaling
172:frame rates
659:0136051626
444:References
292:upsampling
288:decimation
219:Techniques
203:decimation
184:upsampling
141:resampling
110:April 2011
80:newspapers
351:Audio on
189:upscaling
704:Category
375:See also
298:Examples
262:windowed
597:Bibcode
359:= 160,
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409:Dither
313:Apollo
205:; and
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415:Notes
347:Audio
258:cubic
201:, or
176:pitch
101:JSTOR
87:books
654:ISBN
555:ISBN
527:ISBN
499:ISBN
474:ISBN
367:and
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