Sampling (signal processing): Difference between revisions

Revision as of 22:18, 26 January 2025

Revision as of 04:53, 31 January 2025

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| [[44,100 Hz]]

| [[Audio CD]], also most commonly used with [[MPEG-1]] audio ([[VCD]], [[SVCD]], [[MP3]]). Originally chosen by [[Sony]] because it could be recorded on modified video equipment running at either 25 frames per second (PAL) or 30 frame/s (using an NTSC ''monochrome'' video recorder) and cover the 20 kHz bandwidth thought necessary to match professional analog recording equipment of the time. A [[PCM adaptor]] would fit digital audio samples into the analog video channel of, for example, [[PAL]] video tapes using 3 samples per line, 588 lines per frame, 25 frames per second. Practical frequency response for 44,100 Hz sample rate is: 2 Hz - 20 kHz

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| 47,250 Hz

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| [[48,000 Hz]]

| The standard audio sampling rate used by professional digital video equipment such as tape recorders, video servers, vision mixers and so on. This rate was chosen because it could reconstruct frequencies up to 22&nbsp;kHz and work with 29.97&nbsp;frames per second NTSC video – as well as 25&nbsp;frame/s, 30&nbsp;frame/s and 24&nbsp;frame/s systems. With 29.97&nbsp;frame/s systems it is necessary to handle 1601.6 audio samples per frame delivering an integer number of audio samples only every fifth video frame.<ref name=AES5/> Also used for sound with consumer video formats like DV, [[digital TV]], [[DVD]], and films. The professional [[serial digital interface]] (SDI) and High-definition Serial Digital Interface (HD-SDI) used to connect broadcast television equipment together uses this audio sampling frequency. Most professional audio gear uses 48&nbsp;kHz sampling, including [[mixing console]]s, and [[digital recording]] devices. Practical frequency response for 48,000&nbsp;Hz sample rate is: 2 Hz - 22 kHz

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| 50,000&nbsp;Hz

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| 64,000&nbsp;Hz

| Uncommonly used, but supported by some hardware<ref>{{Cite web|url=http://www.rme-audio.de/en/products/hdsp_9632.php|title=RME: Hammerfall DSP 9632|website=www.rme-audio.de|access-date=2018-12-18|quote=Supported sample frequencies: Internally 32, 44.1, 48, 64, 88.2, 96, 176.4, 192&nbsp;kHz.}}</ref><ref>{{Cite web|url=https://www.pioneer-audiovisual.eu/uk/products/sx-s30dab|title=SX-S30DAB {{!}} Pioneer|website=www.pioneer-audiovisual.eu|access-date=2018-12-18|quote=Supported sampling rates: 44.1&nbsp;kHz, 48&nbsp;kHz, 64&nbsp;kHz, 88.2&nbsp;kHz, 96&nbsp;kHz, 176.4&nbsp;kHz, 192&nbsp;kHz}}</ref> and software.<ref>{{Cite web|url=https://steinberg.help/wavelab_pro/v9.5/en/wavelab/topics/master_section/master_section_customize_sample_rate_menu_dialog_r.html|title=Customize Sample Rate Menu|last1=Cristina Bachmann|first1=Heiko Bischoff|last2=Schütte|first2=Benjamin|website=Steinberg WaveLab Pro|language=en-US|access-date=2018-12-18|quote=Common Sample Rates: 64 000 Hz}}</ref><ref>{{Cite web|url=https://getsatisfaction.com/m-audio/topics/m-track-2x2m-cubase-pro-9-can-t-change-sample-rate|title=M Track 2x2M Cubase Pro 9 can ́t change Sample Rate|website=M-Audio|language=en-US|access-date=2018-12-18|quote=[Screenshot of Cubase]}}</ref>

| 64 kHz sample rate is regarded by professional DAC designers as an optimal sample rate: it is fast enough to include what we can hear, yet slow enough to do it pretty accurately. Faster rate means less accuracy. 64 kHz sample rate is also the closest one to the recommended 58 kHz<ref>{{Cite book|title=Coding High Quality Digital Audio|last=Stuart|first=J. Robert|date=1998|quote=both psychoacoustic analysis and experience tell us that the minimum rectangular channel necessary to ensure transparency uses linear PCM with 18.2-bit samples at 58&nbsp;kHz. ... there are strong arguments for maintaining integer relationships with existing sampling rates – which suggests that 88.2&nbsp;kHz or 96&nbsp;kHz should be adopted.|citeseerx = 10.1.1.501.6731}}</ref> by J. Robert Stuart and 60-70 kHz<ref>{{Cite web|url=https://www.gearslutz.com/board/showpost.php?p=1234224&postcount=74|title=To mix at 96k or not?|last=Lavry|first=Dan|website=Gearslutz|language=en|access-date=2018-11-10|quote=Nowdays [sic] there are a number of good designers and ear people that find 60-70KHz sample rate to be the optimal rate for the ear. It is fast enough to include what we can hear, yet slow enough to do it pretty accurately.}}</ref>by Dan Lavry from Lavry Engineering, Inc.

Advantages:

* double of 32 kHz standard sampling frequency

* 1/3 of 192 kHz sampling frequency

* the same crystal oscillator can be used which drives 32, 48, 96, 128, 192, 256, 384 kHz sample rates so no additional cost

The conclusion of this section, then, is that both psychoacoustic analysis and experience tell us that the minimum rectangular channel necessary to ensure transparency uses linear PCM with 18.2-bit samples at 58kHz.<ref>{{cite web |last1=Stuart |first1=J. Robert |title=Coding High Quality Digital Audio |url=http://decoy.iki.fi/dsound/ambisonic/motherlode/source/coding2.pdf |publisher=Meridian Audio Ltd, Stonehill, Stukeley Meadows, Huntingdon, PE18 6ED, United Kingdom |access-date=26 January 2025}}</ref>

Uncommonly used, but supported by some hardware<ref>{{Cite web|url=http://www.rme-audio.de/en/products/hdsp_9632.php|title=RME: Hammerfall DSP 9632|website=www.rme-audio.de|access-date=2018-12-18|quote=Supported sample frequencies: Internally 32, 44.1, 48, 64, 88.2, 96, 176.4, 192&nbsp;kHz.}}</ref><ref>{{Cite web|url=https://www.pioneer-audiovisual.eu/uk/products/sx-s30dab|title=SX-S30DAB {{!}} Pioneer|website=www.pioneer-audiovisual.eu|access-date=2018-12-18|quote=Supported sampling rates: 44.1&nbsp;kHz, 48&nbsp;kHz, 64&nbsp;kHz, 88.2&nbsp;kHz, 96&nbsp;kHz, 176.4&nbsp;kHz, 192&nbsp;kHz}}</ref> and software.<ref>{{Cite web|url=https://steinberg.help/wavelab_pro/v9.5/en/wavelab/topics/master_section/master_section_customize_sample_rate_menu_dialog_r.html|title=Customize Sample Rate Menu|last1=Cristina Bachmann|first1=Heiko Bischoff|last2=Schütte|first2=Benjamin|website=Steinberg WaveLab Pro|language=en-US|access-date=2018-12-18|quote=Common Sample Rates: 64 000 Hz}}</ref><ref>{{Cite web|url=https://getsatisfaction.com/m-audio/topics/m-track-2x2m-cubase-pro-9-can-t-change-sample-rate|title=M Track 2x2M Cubase Pro 9 can ́t change Sample Rate|website=M-Audio|language=en-US|access-date=2018-12-18|quote=[Screenshot of Cubase]}}</ref>

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| 88,200&nbsp;Hz

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| 96,000&nbsp;Hz

| [[DVD-Audio]], some [[LPCM]] DVD tracks, [[BD-ROM]] (Blu-ray Disc) audio tracks, [[HD DVD]] (High-Definition DVD) audio tracks. Some professional recording and production equipment is able to select 96&nbsp;kHz sampling. This sampling frequency is twice the 48&nbsp;kHz standard commonly used with audio on professional equipment. Practical frequency response for 96,000&nbsp;Hz sample rate is: 2 Hz - 44 kHz

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| 176,400&nbsp;Hz