Запись видео на аудиокассету

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Запись видео на аудиокассету

Post by Shaos »

Вот сегодня увидел: https://hackaday.com/2020/04/03/full-colour-full-motion-video-on-an-audio-cassette/


https://www.youtube.com/watch?v=D5zV1mC4E3w

Там человек пишет цветное видео 100x75 (причём с черезстрочной развёрткой) на 2 аудиоканала (один канал яркость, второй канал - цвет) с помощью питона и потом играет его джаваскриптом:
cassette-video-screenshot.jpg
И сразу вспомнились мои потуги середины 80х сделать запись видео на кассетный магнитофон с помощью диска нипкова :mrgreen:

P.S. У нас тут тема поднималась несколько раз, но я решил создать новый топик т.к. именно про запись ВИДЕО (несколько кадров в секунду) на АУДИО кассету (с обычной скоростью на немодифицированный мафон) в прямую нигде не говорилось (хотя думалось):

2004: светодиодный волчок
2014: 130 лет «электрическому телескопу» Нипкова
2016: НедоSSTV для инопланетян
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Re: Запись видео на аудиокассету

Post by Shaos »

А вот собственно о чём мне думалось сколько-то лет назад - во первых, видео должно влезать в один канал (хотя бы и чёрно-белое), чтобы аудиодорожка шла вторым каналом (ибо без звука неинтересно). Во-вторых, записывать точки яркости одну за другой бессмысленно, т.к. разрешение и частота кадров будут очень фиговые (см. выше). И в результате возникла у меня идея использовать разные частоты - спектр ведь может писаться целиком, передавая много информации в единицу времени. Можно строки видео гнать параллельно на разных частотах! Отталкиваясь от спектра прямоугольного сигнала (мы ведь будем работать с цифровыми генераторами):
fourier_series.jpg
можно попытаться выбрать частоты, которые бы гармониками друг на друга не накладывались:
spectrum_of_square_wave.jpg
хоть в реальности спектр и не настолько "красив" (все картинки взяты из https://practicalee.com/superposition/):
spectrum_of_square_wave2.jpg
Сделать снизу кадра - низкие частоты (скажем от 100 Гц - тогда при частоте кадров 12.5/сек у нас в одну строку теоретически влезет 8 периодов), сверху кадра - высокие (допустим до 16 кГц, чтобы оставаться в диапазоне нормальных аудиокассет) и также хотелось бы оставаться в рамках аппаратного кодирования и декодирования в аналоговой форме - без DSP
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Re: Запись видео на аудиокассету

Post by Shaos »

Можно частоты строк расположить так, чтобы можно было музыкальной шкалой покрыть и постараться скажем не залезать в 10% от гармоник 3,5,7,9...

P.S. На самом деле подобные эксперименты уже ставились некоторыми музыкантами-экспериментаторами:
Screenshot from 2020-04-03 17-30-59.png
Screenshot from 2020-04-03 17-31-25.png
(источник https://www.mentalfloss.com/article/61815/how-musicians-put-hidden-images-their-songs)

P.P.S. У них там правда линейная шкала частот, а я почему-то склоняюсь к логарифмической (музыкальной)...

P.P.P.S. Похоже "Demon face" всё-таки было в логарифмической шкале - см. http://www.bastwood.com/?page_id=10
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Re: Запись видео на аудиокассету

Post by Shaos »

Начиная со 110 Гц (нота Ля второй октавы) и до 16 кГц располагаются 88 нот и если фильтровать их аналоговыми фильтрами, то рядом стоящие ноты не различить - надо как минимум на треть октавы их развести (см. https://electronics.stackexchange.com/questions/373638/band-pass-filter-for-musical-note-separation):

Code: Select all

A2    110.00 00
A#2   116.54
B2    123.47
C3    130.81
C#3   138.59    01
D3    146.83
D#3   155.56
E3    164.81
F3    174.61       02
F#3   185.00
G3    196.00
G#3   207.65
A3    220.00          03
A#3   233.08
B3    246.94
C4    261.63
C#4   277.18             04
D4    293.66
D#4   311.13 --
E4    329.63 --
F4    349.23 --             05
F#4   369.99                
G4    392.00    --
G#4   415.30    --
A4    440.00    --             06
A#4   466.16                   
B4    493.88       --
C5    523.25 --    --
C#5   554.37 --    --             07
D5    587.33 --                   
D#5   622.25          --
E5    659.25    --    --
F5    698.46 -- --    --             08
F#5   739.99 -- --                   
G5    783.99 --          --
G#5   830.61 --    --    --
A5    880.00    -- --    --             09
A#5   932.33 -- -- --                   
B5    987.77 -- --          --
C6   1046.50 -- --    --    --
C#6  1108.73       -- --    --             10
D6   1174.66    -- -- --    
D#6  1244.51    -- --          --
E6   1318.51    -- --    --    --
F6   1396.91          -- --    --             11
F#6  1479.98       -- -- --    
G6   1567.98       -- --          --
G#6  1661.22       -- --    --    --
A6   1760.00             -- --    --             12
A#6  1864.66          -- -- --    
B6   1975.53          -- --          --
C7   2093.00          -- --    --    --
C#7  2217.46                -- --    --             13
D7   2349.32             -- -- --    
D#7  2489.02             -- --          --
E7   2637.02             -- --    --    --
F7   2793.83                   -- --    --             14
F#7  2959.96                -- -- --      
G7   3135.96                -- --          --
G#7  3322.44                -- --    --    --
A7   3520.00                      -- --    --             15
A#7  3729.31                   -- -- --    
B7   3951.07                   -- --          --
C8   4186.01                   -- --    --    --
C#8  4434.92                         -- --    --             16
D8   4698.63                      -- -- --    
D#8  4978.03                      -- --          --
E8   5274.04                      -- --    --    --
F8   5587.65                            -- --    --             17
F#8  5919.91                         -- -- --    
G8   6271.93                         -- --          --
G#8  6644.88                         -- --    --    --
A8   7040.00                               -- --    --             18
A#8  7458.62                            -- -- --    
B8   7902.13                            -- --          --
C9   8372.02                            -- --    --    --
C#9  8869.84                                  -- --    --             19
D9   9397.26                               -- -- --    
D#9  9956.06                               -- --          --
E9  10548.08                               -- --    --    --
F9  11175.30                                     -- --    --             20
F#9 11839.82                                  -- -- --    
G9  12543.86                                  -- --          --
G#9 13289.76                                  -- --    --    --
A9  14080.00                                        -- --    --             21
A#9 14917.24                                     -- -- --    
B9  15804.26                                     -- --          --
C10 16744.04                                     -- --    --    --
т.е. имея 3 частоты на октаву получаем 22 строки видео (правда восьмая строка попадает на пятую гармонику частоты первой строки, точнее строка N попадает на пятую гармонику строки N-8 - гармоники отложены по вертикали под каждым номером строки - 3я, 5я, 7я и 9я плюс-минус 10%)
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Re: Запись видео на аудиокассету

Post by Shaos »

Если разнести видеостроками на полоктавы, то тогда каждая строка N будет попадать в зону 3ей гармоники строки N-3 отступая всего на 6%, а гармоники 5,7 и 9 будут аккуратно обойдены:

Code: Select all

A2    110.00 00
A#2   116.54
B2    123.47
C3    130.81
C#3   138.59    
D3    146.83
D#3   155.56    01
E3    164.81
F3    174.61    
F#3   185.00
G3    196.00       
G#3   207.65
A3    220.00       02
A#3   233.08
B3    246.94       
C4    261.63
C#4   277.18          
D4    293.66
D#4   311.13 --       03
E4    329.63 --
F4    349.23 --       
F#4   369.99    
G4    392.00             
G#4   415.30       
A4    440.00    --       04
A#4   466.16    --    
B4    493.88    --       
C5    523.25 --          
C#5   554.37 --             
D5    587.33 --             
D#5   622.25       --       05
E5    659.25       --    
F5    698.46 --    --       
F#5   739.99 -- --          
G5    783.99 -- --             
G#5   830.61 -- --             
A5    880.00          --       06
A#5   932.33 --       --    
B5    987.77 -- --    --       
C6   1046.50 -- -- --          
C#6  1108.73    -- --             
D6   1174.66    -- --             
D#6  1244.51             --       07
E6   1318.51    --       --    
F6   1396.91    -- --    --       
F#6  1479.98    -- -- --          
G6   1567.98       -- --             
G#6  1661.22       -- --             
A6   1760.00                --       08
A#6  1864.66       --       --    
B6   1975.53       -- --    --       
C7   2093.00       -- -- --          
C#7  2217.46          -- --             
D7   2349.32          -- --             
D#7  2489.02                   --       09
E7   2637.02          --       --
F7   2793.83          -- --    --       
F#7  2959.96          -- -- -- 
G7   3135.96             -- --             
G#7  3322.44             -- --    
A7   3520.00                      --       10
A#7  3729.31             --       --
B7   3951.07             -- --    --       
C8   4186.01             -- -- -- 
C#8  4434.92                -- --             
D8   4698.63                -- --    
D#8  4978.03                         --       11
E8   5274.04                --       --
F8   5587.65                -- --    --       
F#8  5919.91                -- -- -- 
G8   6271.93                   -- --             
G#8  6644.88                   -- --    
A8   7040.00                            --       12
A#8  7458.62                   --       --
B8   7902.13                   -- --    --       
C9   8372.02                   -- -- --   
C#9  8869.84                      -- --             
D9   9397.26                      -- --    
D#9  9956.06                               --       13
E9  10548.08                      --       --
F9  11175.30                      -- --    --       
F#9 11839.82                      -- -- -- 
G9  12543.86                         -- --             
G#9 13289.76                         -- --    
A9  14080.00                                  --       14
A#9 14917.24                         --       --
B9  15804.26                         -- --    --       
C10 16744.04                         -- -- -- 
и у нас будет только 15 строк...
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Re: Запись видео на аудиокассету

Post by Shaos »

А если взять 4 ноты на октаву, мы получим 30 видеострок (слегка залезши за пределы 16 кГц), но зато каждая будет попадать в зону всех гармоник предыдущих нот (с отступом порядка 6%):

Code: Select all

A2    110.00 00
A#2   116.54
B2    123.47
C3    130.81    01
C#3   138.59    
D3    146.83
D#3   155.56       02
E3    164.81       
F3    174.61    
F#3   185.00          03
G3    196.00          
G#3   207.65       
A3    220.00             04
A#3   233.08             
B3    246.94          
C4    261.63                05
C#4   277.18                
D4    293.66                
D#4   311.13 --                06
E4    329.63 --                
F4    349.23 --                
F#4   369.99    --                07
G4    392.00    --                
G#4   415.30    --                
A4    440.00       --                08
A#4   466.16       --                
B4    493.88       --                
C5    523.25 --       --                09
C#5   554.37 --       --                
D5    587.33 --       --                
D#5   622.25    --       --                10
E5    659.25    --       --                
F5    698.46 -- --       --             
F#5   739.99 --    --       --                11
G5    783.99 --    --       --                
G#5   830.61 -- -- --       --             
A5    880.00    --    --       --                12
A#5   932.33 -- --    --       --                
B5    987.77 -- -- -- --       --             
C6   1046.50 --    --    --       --                13
C#6  1108.73    -- --    --       --                
D6   1174.66    -- -- -- --       --             
D#6  1244.51    --    --    --       --                14
E6   1318.51       -- --    --       --                
F6   1396.91       -- -- -- --       --             
F#6  1479.98       --    --    --       --                15
G6   1567.98          -- --    --       --                
G#6  1661.22          -- -- -- --       --             
A6   1760.00          --    --    --       --                16
A#6  1864.66             -- --    --       --                
B6   1975.53             -- -- -- --       --             
C7   2093.00             --    --    --       --                17
C#7  2217.46                -- --    --       --                
D7   2349.32                -- -- -- --       --             
D#7  2489.02                --    --    --       --                18
E7   2637.02                   -- --    --       --                
F7   2793.83                   -- -- -- --       --             
F#7  2959.96                   --    --    --       --                19
G7   3135.96                      -- --    --       --                
G#7  3322.44                      -- -- -- --       --             
A7   3520.00                      --    --    --       --                20
A#7  3729.31                         -- --    --       --                
B7   3951.07                         -- -- -- --       --             
C8   4186.01                         --    --    --       --                21
C#8  4434.92                            -- --    --       --                
D8   4698.63                            -- -- -- --       --             
D#8  4978.03                            --    --    --       --                22
E8   5274.04                               -- --    --       --    
F8   5587.65                               -- -- -- --       -- 
F#8  5919.91                               --    --    --       --                23
G8   6271.93                                  -- --    --       --
G#8  6644.88                                  -- -- -- --       --
A8   7040.00                                  --    --    --       --                24
A#8  7458.62                                     -- --    --       --
B8   7902.13                                     -- -- -- --       --
C9   8372.02                                     --    --    --       --                25
C#9  8869.84                                        -- --    --       --
D9   9397.26                                        -- -- -- --       --
D#9  9956.06                                        --    --    --       --                26
E9  10548.08                                           -- --    --       --
F9  11175.30                                           -- -- -- --       --
F#9 11839.82                                           --    --    --       --                27
G9  12543.86                                              -- --    --       --
G#9 13289.76                                              -- -- -- --       --
A9  14080.00                                              --    --    --       --                28
A#9 14917.24                                                 -- --    --       --
B9  15804.26                                                 -- -- -- --       --
C10 16744.04                                                 --    --    --       --                29
Возможно если готовить видео программно, то можно и каждую ноту генерить чистыми синусоидами без гармоник (все 88), а аппаратный декодер (скажем на операционниках) будет выделять сигналы в своих расширенных диапазонах спектра и показывать меньшее количество строк...

P.S. Под спойлером более детальные цифры, подсчитанные с помощью программы, представленной в сообщениях ниже:

 30

Code: Select all

TRY 2^0.250000 (MUSICAL)
0: 110.000000
1: 130.812783
2: 155.563492
3: 184.997211
4: 220.000000
5: 261.625565
6: 311.126984
 in 3rd with 0 (6%)
7: 369.994423
 in 3rd with 1 (6%)
8: 440.000000
 in 3rd with 2 (6%)
9: 523.251131
 in 5th with 0 (5%)
 in 3rd with 3 (6%)
10: 622.253967
 in 5th with 1 (5%)
 in 3rd with 4 (6%)
11: 739.988845
 in 7th with 0 (4%)
 in 5th with 2 (5%)
 in 3rd with 5 (6%)
12: 880.000000
 in 7th with 1 (4%)
 in 5th with 3 (5%)
 in 3rd with 6 (6%)
13: 1046.502261
 in 9th with 0 (5%)
 in 7th with 2 (4%)
 in 5th with 4 (5%)
 in 3rd with 7 (6%)
14: 1244.507935
 in 11th with 0 (2%)
 in 9th with 1 (5%)
 in 7th with 3 (4%)
 in 5th with 5 (5%)
 in 3rd with 8 (6%)
15: 1479.977691
 in 11th with 1 (2%)
 in 9th with 2 (5%)
 in 7th with 4 (4%)
 in 5th with 6 (5%)
 in 3rd with 9 (6%)
16: 1760.000000
 in 11th with 2 (2%)
 in 9th with 3 (5%)
 in 7th with 5 (4%)
 in 5th with 7 (5%)
 in 3rd with 10 (6%)
17: 2093.004522
 in 11th with 3 (2%)
 in 9th with 4 (5%)
 in 7th with 6 (4%)
 in 5th with 8 (5%)
 in 3rd with 11 (6%)
18: 2489.015870
 in 11th with 4 (2%)
 in 9th with 5 (5%)
 in 7th with 7 (4%)
 in 5th with 9 (5%)
 in 3rd with 12 (6%)
19: 2959.955382
 in 11th with 5 (2%)
 in 9th with 6 (5%)
 in 7th with 8 (4%)
 in 5th with 10 (5%)
 in 3rd with 13 (6%)
20: 3520.000000
 in 11th with 6 (2%)
 in 9th with 7 (5%)
 in 7th with 9 (4%)
 in 5th with 11 (5%)
 in 3rd with 14 (6%)
21: 4186.009045
 in 11th with 7 (2%)
 in 9th with 8 (5%)
 in 7th with 10 (4%)
 in 5th with 12 (5%)
 in 3rd with 15 (6%)
22: 4978.031740
 in 11th with 8 (2%)
 in 9th with 9 (5%)
 in 7th with 11 (4%)
 in 5th with 13 (5%)
 in 3rd with 16 (6%)
23: 5919.910763
 in 11th with 9 (2%)
 in 9th with 10 (5%)
 in 7th with 12 (4%)
 in 5th with 14 (5%)
 in 3rd with 17 (6%)
24: 7040.000000
 in 11th with 10 (2%)
 in 9th with 11 (5%)
 in 7th with 13 (4%)
 in 5th with 15 (5%)
 in 3rd with 18 (6%)
25: 8372.018090
 in 11th with 11 (2%)
 in 9th with 12 (5%)
 in 7th with 14 (4%)
 in 5th with 16 (5%)
 in 3rd with 19 (6%)
26: 9956.063479
 in 11th with 12 (2%)
 in 9th with 13 (5%)
 in 7th with 15 (4%)
 in 5th with 17 (5%)
 in 3rd with 20 (6%)
27: 11839.821527
 in 11th with 13 (2%)
 in 9th with 14 (5%)
 in 7th with 16 (4%)
 in 5th with 18 (5%)
 in 3rd with 21 (6%)
28: 14080.000000
 in 11th with 14 (2%)
 in 9th with 15 (5%)
 in 7th with 17 (4%)
 in 5th with 19 (5%)
 in 3rd with 22 (6%)
29: 16744.04 (ADDED)

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Re: Запись видео на аудиокассету

Post by Shaos »

Попробовал подвигать ноты чуток (после каждой пятой - дополнительный сдвиг), чтобы не попадало хотя бы на третью гармонику других нот (за пределами плюс-минус 10%), 3/5 попадают в 6% зону пятой гармоники и почти все попадают почти точно в седьмую и девятую гармоники других нот (что есть не очень хорошо):

Code: Select all

A2    110.00<00
A#2   116.54
B2    123.47
C3    130.81
C#3   138.59<<<<01
D3    146.83
D#3   155.56
E3    164.81
F3    174.61<<<<<<<02
F#3   185.00
G3    196.00
G#3   207.65
A3    220.00<<<<<<<<<<03
A#3   233.08
B3    246.94
C4    261.63
C#4   277.18<<<<<<<<<<<<<04
D4    293.66
D#4   311.13 33
E4    329.63 33
F4    349.23 33
F#4   369.99<<<<<<<<<<<<<<<<05
G4    392.00    33
G#4   415.30    33
A4    440.00    33
A#4   466.16<<<<<<<<<<<<<<<<<<<06
B4    493.88       33
C5    523.25 55    33
C#5   554.37 55    33
D5    587.33<55<<<<<<<<<<<<<<<<<<<07
D#5   622.25          33
E5    659.25    55    33
F5    698.46 77 55    33
F#5   739.99<77<55<<<<<<<<<<<<<<<<<<<08
G5    783.99 77          33
G#5   830.61 77    55    33
A5    880.00    77 55    33
A#5   932.33<99<77<55<<<<<<<<<<<<<<<<<<<09
B5    987.77 99 77
C6   1046.50 99 77    55    33
C#6  1108.73       77 55    33
D6   1174.66    99 77 55    33
D#6  1244.51<<<<99<77<<<<<<<<<<<<<<<<<<<<<<10
E6   1318.51    99 77    55    33
F6   1396.91          77 55    33
F#6  1479.98       99 77 55    33
G6   1567.98<<<<<<<99<77<<<<<<<<<<<<<<<<<<<<<<11
G#6  1661.22       99 77          33
A6   1760.00             77 55    33
A#6  1864.66          99 77 55    33
B6   1975.53<<<<<<<<<<99<77<55<<<<<<<<<<<<<<<<<<<12
C7   2093.00          99 77          33
C#7  2217.46                   55    33
D7   2349.32             99 77 55    33
D#7  2489.02<<<<<<<<<<<<<99<77<55<<<<<<<<<<<<<<<<<<<13
E7   2637.02             99 77          33
F7   2793.83                77    55    33
F#7  2959.96                   77 55    33
G7   3135.96<<<<<<<<<<<<<<<<99<77<55<<<<<<<<<<<<<<<<<<<14
G#7  3322.44                99 77
A7   3520.00                99 77    55    33
A#7  3729.31                      77 55    33
B7   3951.07                   99 77 55    33
C8   4186.01<<<<<<<<<<<<<<<<<<<99<77<<<<<<<<<<<<<<<<<<<<<<15
C#8  4434.92                   99 77    55    33
D8   4698.63                         77 55    33
D#8  4978.03                      99 77 55    33
E8   5274.04<<<<<<<<<<<<<<<<<<<<<<99<77<<<<<<<<<<<<<<<<<<<<<<16
F8   5587.65                      99 77          33
F#8  5919.91                            77 55    33
G8   6271.93                         99 77 55    33
G#8  6644.88<<<<<<<<<<<<<<<<<<<<<<<<<99<77<55<<<<<<<<<<<<<<<<<<<17
A8   7040.00                         99 77          33
A#8  7458.62                                  55    33
B8   7902.13                            99 77 55    33
C9   8372.02<<<<<<<<<<<<<<<<<<<<<<<<<<<<99<77<55<<<<<<<<<<<<<<<<<<<18
C#9  8869.84                            99 77          33
D9   9397.26                               77    55    33
D#9  9956.06                                  77 55    33
E9  10548.08<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<99<77<55<<<<<<<<<<<<<<<<<<<19
F9  11175.30                               99 77
F#9 11839.82                               99 77    55    33
G9  12543.86                                     77 55    33
G#9 13289.76                                  99 77 55    33
A9  14080.00<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<99<77<<<<<<<<<<<<<<<<<<<<<<20
A#9 14917.24                                  99 77    55    33
B9  15804.26                                        77 55    33
C10 16744.04                                     99 77 55    33
Неудобство такого подхода - все ноты задействованы, а это значит надо иметь 12 генераторов...
Я тут за главного - если что шлите мыло на me собака shaos точка net
User avatar
Shaos
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Posts: 24008
Joined: 08 Jan 2003 23:22
Location: Silicon Valley

Re: Запись видео на аудиокассету

Post by Shaos »

Вообще чтобы не попадать ни в какие нечётные гармоники, надо просто брать по одной ноте из октавы (т.е. частота каждой строки отличается от предыдущей ровно в 2 раза):

Code: Select all

0: 110.000000
1: 220.000000
2: 440.000000
3: 880.000000
4: 1760.000000
5: 3520.000000
6: 7040.000000
7: 14080.000000
но это будет только 8 строк - неинтересно

А вообще можно совсем от нот отказаться - я набросал небольшую программку (если кому интересно - под спойлером), которая ищет самый подходящий набор частот, чтобы каждая частота не попадала в 10% окрестности нечётных гаромник 3,5,7,9 и 11 других частот (по возможности)

 test1.c

Code: Select all

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

int main()
{
  int i,j,l,p,lmax=0;
  double o,d,f,s,d1;
  double m = 2;
  double a[256];
  double b = 0;
  for(s=0.03;s<1.001;s+=0.001)
  {
   printf("TRY 2^%lf\n",s);
   m = pow(2.0,s);
   f = 110.0;
   i = 0;
   l = 120;
   while(f<16000.0)
   {
     printf("%i: %lf\n",i,f);
     for(j=0;j<i;j++)
     {
         o = f/10;
         d = a[j]*3;
         if(f >= d-o && f <= d+o)
         {
             p = (int)(fabs(f-d)*100.0/f);
             printf(" in 3rd with %i (%i%%)\n",j,p);
             if(30+p < l) l = 30+p;
         }
         d = a[j]*5;
         if(f >= d-o && f <= d+o)
         {
             p = (int)(fabs(f-d)*100.0/f);
             printf(" in 5th with %i (%i%%)\n",j,p);
             if(50+p < l) l = 50+p;
         }
         d = a[j]*7;
         if(f >= d-o && f <= d+o)
         {
             p = (int)(fabs(f-d)*100.0/f);
             printf(" in 7th with %i (%i%%)\n",j,p);
             if(70+p < l) l = 70+p;
         }
         d = a[j]*9;
         if(f >= d-o && f <= d+o)
         {
             p = (int)(fabs(f-d)*100.0/f);
             printf(" in 9th with %i (%i%%)\n",j,p);
             if(90+p < l) l = 90+p;
         }
         d = a[j]*11;
         if(f >= d-o && f <= d+o)
         {
             p = (int)(fabs(f-d)*100.0/f);
             printf(" in 11th with %i (%i%%)\n",j,p);
             if(110+p < l) l = 110+p;
         }
     }
     a[i] = f;
     f *= m;
     i++;
   }
   if(l > lmax)
   {
     lmax = l;
     b = s;
     printf("BEST %lf (%i with %i lines)\n",b,l,j+1);
   }
 }
}

и вот что она нашла

если устраивает попадание в окрестности 9й гармоники и больше, то можно получить 17 строк:

Code: Select all

TRY 2^0.435000
0: 110.000000
1: 148.710192
2: 201.042919
3: 271.792100
4: 367.438685
5: 496.744338
6: 671.554052
7: 907.881198
 in 9th with 0 (9%)
8: 1227.374426
 in 11th with 0 (1%)
 in 9th with 1 (9%)
9: 1659.300783
 in 11th with 1 (1%)
 in 9th with 2 (9%)
10: 2243.226704
 in 11th with 2 (1%)
 in 9th with 3 (9%)
11: 3032.642482
 in 11th with 3 (1%)
 in 9th with 4 (9%)
12: 4099.862224
 in 11th with 4 (1%)
 in 9th with 5 (9%)
13: 5542.648155
 in 11th with 5 (1%)
 in 9th with 6 (9%)
14: 7493.166084
 in 11th with 6 (1%)
 in 9th with 7 (9%)
15: 10130.092403
 in 11th with 7 (1%)
 in 9th with 8 (9%)
16: 13694.981660
 in 11th with 8 (1%)
 in 9th with 9 (9%)
если 7я гармоника с отступом в 5% ок, то можно получить 20 строк:

Code: Select all

TRY 2^0.361000
0: 110.000000
1: 141.274739
2: 181.441381
3: 233.028034
4: 299.281588
5: 384.372074
6: 493.655131
7: 634.009089
8: 814.267897
 in 7th with 0 (5%)
9: 1045.777132
 in 9th with 0 (5%)
 in 7th with 1 (5%)
10: 1343.108104
 in 11th with 0 (9%)
 in 9th with 1 (5%)
 in 7th with 2 (5%)
11: 1724.974971
 in 11th with 1 (9%)
 in 9th with 2 (5%)
 in 7th with 3 (5%)
12: 2215.412625
 in 11th with 2 (9%)
 in 9th with 3 (5%)
 in 7th with 4 (5%)
13: 2845.289458
 in 11th with 3 (9%)
 in 9th with 4 (5%)
 in 7th with 5 (5%)
14: 3654.250232
 in 11th with 4 (9%)
 in 9th with 5 (5%)
 in 7th with 6 (5%)
15: 4693.211343
 in 11th with 5 (9%)
 in 9th with 6 (5%)
 in 7th with 7 (5%)
16: 6027.565523
 in 11th with 6 (9%)
 in 9th with 7 (5%)
 in 7th with 8 (5%)
17: 7741.297691
 in 11th with 7 (9%)
 in 9th with 8 (5%)
 in 7th with 9 (5%)
18: 9942.271007
 in 11th with 8 (9%)
 in 9th with 9 (5%)
 in 7th with 10 (5%)
19: 12769.015831
 in 11th with 9 (9%)
 in 9th with 10 (5%)
 in 7th with 11 (5%)
а если подобраться к 3ей гармонике на 6% (расстояние между двумя соседними нотами), то можно получить 39 строк, правда при этому будут прямые попадания в 7ю и 9ю гармоники - см. под спойлер

 39

Code: Select all

TRY 2^0.187000
0: 110.000000
1: 125.223343
2: 142.553506
3: 162.282060
4: 184.740928
5: 210.307970
6: 239.413337
7: 272.546714
8: 310.265551
 in 3rd with 0 (6%)
9: 353.204451
 in 3rd with 0 (6%)
 in 3rd with 1 (6%)
10: 402.085838
 in 3rd with 1 (6%)
 in 3rd with 2 (6%)
11: 457.732117
 in 3rd with 2 (6%)
 in 3rd with 3 (6%)
12: 521.079509
 in 5th with 0 (5%)
 in 3rd with 3 (6%)
 in 3rd with 4 (6%)
13: 593.193802
 in 5th with 0 (7%)
 in 5th with 1 (5%)
 in 3rd with 4 (6%)
 in 3rd with 5 (6%)
14: 675.288282
 in 5th with 1 (7%)
 in 5th with 2 (5%)
 in 3rd with 5 (6%)
 in 3rd with 6 (6%)
15: 768.744148
 in 7th with 0 (0%)
 in 5th with 2 (7%)
 in 5th with 3 (5%)
 in 3rd with 6 (6%)
 in 3rd with 7 (6%)
16: 875.133748
 in 7th with 1 (0%)
 in 5th with 3 (7%)
 in 5th with 4 (5%)
 in 3rd with 7 (6%)
 in 3rd with 8 (6%)
17: 996.247034
 in 9th with 0 (0%)
 in 7th with 2 (0%)
 in 5th with 4 (7%)
 in 5th with 5 (5%)
 in 3rd with 8 (6%)
 in 3rd with 9 (6%)
18: 1134.121675
 in 11th with 0 (6%)
 in 9th with 1 (0%)
 in 7th with 3 (0%)
 in 5th with 5 (7%)
 in 5th with 6 (5%)
 in 3rd with 9 (6%)
 in 3rd with 10 (6%)
19: 1291.077343
 in 11th with 0 (6%)
 in 11th with 1 (6%)
 in 9th with 2 (0%)
 in 7th with 4 (0%)
 in 5th with 6 (7%)
 in 5th with 7 (5%)
 in 3rd with 10 (6%)
 in 3rd with 11 (6%)
20: 1469.754738
 in 11th with 1 (6%)
 in 11th with 2 (6%)
 in 9th with 3 (0%)
 in 7th with 5 (0%)
 in 5th with 7 (7%)
 in 5th with 8 (5%)
 in 3rd with 11 (6%)
 in 3rd with 12 (6%)
21: 1673.160018
 in 11th with 2 (6%)
 in 11th with 3 (6%)
 in 9th with 4 (0%)
 in 7th with 6 (0%)
 in 5th with 8 (7%)
 in 5th with 9 (5%)
 in 3rd with 12 (6%)
 in 3rd with 13 (6%)
22: 1904.715374
 in 11th with 3 (6%)
 in 11th with 4 (6%)
 in 9th with 5 (0%)
 in 7th with 7 (0%)
 in 5th with 9 (7%)
 in 5th with 10 (5%)
 in 3rd with 13 (6%)
 in 3rd with 14 (6%)
23: 2168.316609
 in 11th with 4 (6%)
 in 11th with 5 (6%)
 in 9th with 6 (0%)
 in 7th with 8 (0%)
 in 5th with 10 (7%)
 in 5th with 11 (5%)
 in 3rd with 14 (6%)
 in 3rd with 15 (6%)
24: 2468.398681
 in 11th with 5 (6%)
 in 11th with 6 (6%)
 in 9th with 7 (0%)
 in 7th with 9 (0%)
 in 5th with 11 (7%)
 in 5th with 12 (5%)
 in 3rd with 15 (6%)
 in 3rd with 16 (6%)
25: 2810.010320
 in 11th with 6 (6%)
 in 11th with 7 (6%)
 in 9th with 8 (0%)
 in 7th with 10 (0%)
 in 5th with 12 (7%)
 in 5th with 13 (5%)
 in 3rd with 16 (6%)
 in 3rd with 17 (6%)
26: 3198.898970
 in 11th with 7 (6%)
 in 11th with 8 (6%)
 in 9th with 9 (0%)
 in 7th with 11 (0%)
 in 5th with 13 (7%)
 in 5th with 14 (5%)
 in 3rd with 17 (6%)
 in 3rd with 18 (6%)
27: 3641.607487
 in 11th with 8 (6%)
 in 11th with 9 (6%)
 in 9th with 10 (0%)
 in 7th with 12 (0%)
 in 5th with 14 (7%)
 in 5th with 15 (5%)
 in 3rd with 18 (6%)
 in 3rd with 19 (6%)
28: 4145.584219
 in 11th with 9 (6%)
 in 11th with 10 (6%)
 in 9th with 11 (0%)
 in 7th with 13 (0%)
 in 5th with 15 (7%)
 in 5th with 16 (5%)
 in 3rd with 19 (6%)
 in 3rd with 20 (6%)
29: 4719.308322
 in 11th with 10 (6%)
 in 11th with 11 (6%)
 in 9th with 12 (0%)
 in 7th with 14 (0%)
 in 5th with 16 (7%)
 in 5th with 17 (5%)
 in 3rd with 20 (6%)
 in 3rd with 21 (6%)
30: 5372.432416
 in 11th with 11 (6%)
 in 11th with 12 (6%)
 in 9th with 13 (0%)
 in 7th with 15 (0%)
 in 5th with 17 (7%)
 in 5th with 18 (5%)
 in 3rd with 21 (6%)
 in 3rd with 22 (6%)
31: 6115.944983
 in 11th with 12 (6%)
 in 11th with 13 (6%)
 in 9th with 14 (0%)
 in 7th with 16 (0%)
 in 5th with 18 (7%)
 in 5th with 19 (5%)
 in 3rd with 22 (6%)
 in 3rd with 23 (6%)
32: 6962.355251
 in 11th with 13 (6%)
 in 11th with 14 (6%)
 in 9th with 15 (0%)
 in 7th with 17 (0%)
 in 5th with 19 (7%)
 in 5th with 20 (5%)
 in 3rd with 23 (6%)
 in 3rd with 24 (6%)
33: 7925.903646
 in 11th with 14 (6%)
 in 11th with 15 (6%)
 in 9th with 16 (0%)
 in 7th with 18 (0%)
 in 5th with 20 (7%)
 in 5th with 21 (5%)
 in 3rd with 24 (6%)
 in 3rd with 25 (6%)
34: 9022.801386
 in 11th with 15 (6%)
 in 11th with 16 (6%)
 in 9th with 17 (0%)
 in 7th with 19 (0%)
 in 5th with 21 (7%)
 in 5th with 22 (5%)
 in 3rd with 25 (6%)
 in 3rd with 26 (6%)
35: 10271.503223
 in 11th with 16 (6%)
 in 11th with 17 (6%)
 in 9th with 18 (0%)
 in 7th with 20 (0%)
 in 5th with 22 (7%)
 in 5th with 23 (5%)
 in 3rd with 26 (6%)
 in 3rd with 27 (6%)
36: 11693.017939
 in 11th with 17 (6%)
 in 11th with 18 (6%)
 in 9th with 19 (0%)
 in 7th with 21 (0%)
 in 5th with 23 (7%)
 in 5th with 24 (5%)
 in 3rd with 27 (6%)
 in 3rd with 28 (6%)
37: 13311.261804
 in 11th with 18 (6%)
 in 11th with 19 (6%)
 in 9th with 20 (0%)
 in 7th with 22 (0%)
 in 5th with 24 (7%)
 in 5th with 25 (5%)
 in 3rd with 28 (6%)
 in 3rd with 29 (6%)
38: 15153.460957
 in 11th with 19 (6%)
 in 11th with 20 (6%)
 in 9th with 21 (0%)
 in 7th with 23 (0%)
 in 5th with 25 (7%)
 in 5th with 26 (5%)
 in 3rd with 29 (6%)
 in 3rd with 30 (6%)

P.S. Вот более точная реализация вышеприведённой последовательности на 40 строк (использовалась слегка модифицированная программа, которая начинает считать со 100 Гц и с чуть большей точностью):

 40

Code: Select all

TRY 2^0.186800
0: 100.000000
1: 113.823623
2: 129.558170
3: 147.467803
4: 167.853195
5: 191.056587
6: 217.467529
7: 247.529419
8: 281.746951
 in 3rd with 0 (6.4%)
9: 320.694586
 in 3rd with 0 (6.4%)
 in 3rd with 1 (6.4%)
10: 365.026195
 in 3rd with 1 (6.4%)
 in 3rd with 2 (6.4%)
11: 415.486039
 in 3rd with 2 (6.4%)
 in 3rd with 3 (6.4%)
12: 472.921260
 in 5th with 0 (5.7%)
 in 3rd with 3 (6.4%)
 in 3rd with 4 (6.4%)
13: 538.296110
 in 5th with 0 (7.1%)
 in 5th with 1 (5.7%)
 in 3rd with 4 (6.4%)
 in 3rd with 5 (6.4%)
14: 612.708132
 in 5th with 1 (7.1%)
 in 5th with 2 (5.7%)
 in 3rd with 5 (6.4%)
 in 3rd with 6 (6.4%)
15: 697.406592
 in 7th with 0 (0.3%)
 in 5th with 2 (7.1%)
 in 5th with 3 (5.7%)
 in 3rd with 6 (6.4%)
 in 3rd with 7 (6.4%)
16: 793.813446
 in 7th with 1 (0.3%)
 in 5th with 3 (7.1%)
 in 5th with 4 (5.7%)
 in 3rd with 7 (6.4%)
 in 3rd with 8 (6.4%)
17: 903.547220
 in 9th with 0 (0.3%)
 in 7th with 2 (0.3%)
 in 5th with 4 (7.1%)
 in 5th with 5 (5.7%)
 in 3rd with 8 (6.4%)
 in 3rd with 9 (6.4%)
18: 1028.450177
 in 11th with 0 (6.9%)
 in 9th with 1 (0.3%)
 in 7th with 3 (0.3%)
 in 5th with 5 (7.1%)
 in 5th with 6 (5.7%)
 in 3rd with 9 (6.4%)
 in 3rd with 10 (6.4%)
19: 1170.619248
 in 11th with 0 (6.0%)
 in 11th with 1 (6.9%)
 in 9th with 2 (0.3%)
 in 7th with 4 (0.3%)
 in 5th with 6 (7.1%)
 in 5th with 7 (5.7%)
 in 3rd with 10 (6.4%)
 in 3rd with 11 (6.4%)
20: 1332.441233
 in 11th with 1 (6.0%)
 in 11th with 2 (6.9%)
 in 9th with 3 (0.3%)
 in 7th with 5 (0.3%)
 in 5th with 7 (7.1%)
 in 5th with 8 (5.7%)
 in 3rd with 11 (6.4%)
 in 3rd with 12 (6.4%)
21: 1516.632880
 in 11th with 2 (6.0%)
 in 11th with 3 (6.9%)
 in 9th with 4 (0.3%)
 in 7th with 6 (0.3%)
 in 5th with 8 (7.1%)
 in 5th with 9 (5.7%)
 in 3rd with 12 (6.4%)
 in 3rd with 13 (6.4%)
22: 1726.286484
 in 11th with 3 (6.0%)
 in 11th with 4 (6.9%)
 in 9th with 5 (0.3%)
 in 7th with 7 (0.3%)
 in 5th with 9 (7.1%)
 in 5th with 10 (5.7%)
 in 3rd with 13 (6.4%)
 in 3rd with 14 (6.4%)
23: 1964.921811
 in 11th with 4 (6.0%)
 in 11th with 5 (6.9%)
 in 9th with 6 (0.3%)
 in 7th with 8 (0.3%)
 in 5th with 10 (7.1%)
 in 5th with 11 (5.7%)
 in 3rd with 14 (6.4%)
 in 3rd with 15 (6.4%)
24: 2236.545184
 in 11th with 5 (6.0%)
 in 11th with 6 (6.9%)
 in 9th with 7 (0.3%)
 in 7th with 9 (0.3%)
 in 5th with 11 (7.1%)
 in 5th with 12 (5.7%)
 in 3rd with 15 (6.4%)
 in 3rd with 16 (6.4%)
25: 2545.716748
 in 11th with 6 (6.0%)
 in 11th with 7 (6.9%)
 in 9th with 8 (0.3%)
 in 7th with 10 (0.3%)
 in 5th with 12 (7.1%)
 in 5th with 13 (5.7%)
 in 3rd with 16 (6.4%)
 in 3rd with 17 (6.4%)
26: 2897.627021
 in 11th with 7 (6.0%)
 in 11th with 8 (6.9%)
 in 9th with 9 (0.3%)
 in 7th with 11 (0.3%)
 in 5th with 13 (7.1%)
 in 5th with 14 (5.7%)
 in 3rd with 17 (6.4%)
 in 3rd with 18 (6.4%)
27: 3298.184043
 in 11th with 8 (6.0%)
 in 11th with 9 (6.9%)
 in 9th with 10 (0.3%)
 in 7th with 12 (0.3%)
 in 5th with 14 (7.1%)
 in 5th with 15 (5.7%)
 in 3rd with 18 (6.4%)
 in 3rd with 19 (6.4%)
28: 3754.112554
 in 11th with 9 (6.0%)
 in 11th with 10 (6.9%)
 in 9th with 11 (0.3%)
 in 7th with 13 (0.3%)
 in 5th with 15 (7.1%)
 in 5th with 16 (5.7%)
 in 3rd with 19 (6.4%)
 in 3rd with 20 (6.4%)
29: 4273.066902
 in 11th with 10 (6.0%)
 in 11th with 11 (6.9%)
 in 9th with 12 (0.3%)
 in 7th with 14 (0.3%)
 in 5th with 16 (7.1%)
 in 5th with 17 (5.7%)
 in 3rd with 20 (6.4%)
 in 3rd with 21 (6.4%)
30: 4863.759540
 in 11th with 11 (6.0%)
 in 11th with 12 (6.9%)
 in 9th with 13 (0.3%)
 in 7th with 15 (0.3%)
 in 5th with 17 (7.1%)
 in 5th with 18 (5.7%)
 in 3rd with 21 (6.4%)
 in 3rd with 22 (6.4%)
31: 5536.107299
 in 11th with 12 (6.0%)
 in 11th with 13 (6.9%)
 in 9th with 14 (0.3%)
 in 7th with 16 (0.3%)
 in 5th with 18 (7.1%)
 in 5th with 19 (5.7%)
 in 3rd with 22 (6.4%)
 in 3rd with 23 (6.4%)
32: 6301.397874
 in 11th with 13 (6.0%)
 in 11th with 14 (6.9%)
 in 9th with 15 (0.3%)
 in 7th with 17 (0.3%)
 in 5th with 19 (7.1%)
 in 5th with 20 (5.7%)
 in 3rd with 23 (6.4%)
 in 3rd with 24 (6.4%)
33: 7172.479329
 in 11th with 14 (6.0%)
 in 11th with 15 (6.9%)
 in 9th with 16 (0.3%)
 in 7th with 18 (0.3%)
 in 5th with 20 (7.1%)
 in 5th with 21 (5.7%)
 in 3rd with 24 (6.4%)
 in 3rd with 25 (6.4%)
34: 8163.975796
 in 11th with 15 (6.0%)
 in 11th with 16 (6.9%)
 in 9th with 17 (0.3%)
 in 7th with 19 (0.3%)
 in 5th with 21 (7.1%)
 in 5th with 22 (5.7%)
 in 3rd with 25 (6.4%)
 in 3rd with 26 (6.4%)
35: 9292.532991
 in 11th with 16 (6.0%)
 in 11th with 17 (6.9%)
 in 9th with 18 (0.3%)
 in 7th with 20 (0.3%)
 in 5th with 22 (7.1%)
 in 5th with 23 (5.7%)
 in 3rd with 26 (6.4%)
 in 3rd with 27 (6.4%)
36: 10577.097674
 in 11th with 17 (6.0%)
 in 11th with 18 (6.9%)
 in 9th with 19 (0.3%)
 in 7th with 21 (0.3%)
 in 5th with 23 (7.1%)
 in 5th with 24 (5.7%)
 in 3rd with 27 (6.4%)
 in 3rd with 28 (6.4%)
37: 12039.235728
 in 11th with 18 (6.0%)
 in 11th with 19 (6.9%)
 in 9th with 20 (0.3%)
 in 7th with 22 (0.3%)
 in 5th with 24 (7.1%)
 in 5th with 25 (5.7%)
 in 3rd with 28 (6.4%)
 in 3rd with 29 (6.4%)
38: 13703.494229
 in 11th with 19 (6.0%)
 in 11th with 20 (6.9%)
 in 9th with 21 (0.3%)
 in 7th with 23 (0.3%)
 in 5th with 25 (7.1%)
 in 5th with 26 (5.7%)
 in 3rd with 29 (6.4%)
 in 3rd with 30 (6.4%)
39: 15597.813541
 in 11th with 20 (6.0%)
 in 11th with 21 (6.9%)
 in 9th with 22 (0.3%)
 in 7th with 24 (0.3%)
 in 5th with 26 (7.1%)
 in 5th with 27 (5.7%)
 in 3rd with 30 (6.4%)
 in 3rd with 31 (6.4%)

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Re: Запись видео на аудиокассету

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Синхронизацию кадров можно делать путём посылки тишины и затем всех частот (белый шум?) в течении короткого промежутка времени - по идее так можно делать переменную частоту кадров - сколько таких пар тишина-шум было в течении секунды - такая и частота кадров...
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Re: Запись видео на аудиокассету

Post by Shaos »

Shaos wrote:если 7я гармоника с отступом в 5% ок, то можно получить 20 строк:

Code: Select all

TRY 2^0.361000
0: 110.000000
1: 141.274739
2: 181.441381
3: 233.028034
4: 299.281588
5: 384.372074
6: 493.655131
7: 634.009089
8: 814.267897
 in 7th with 0 (5%)
9: 1045.777132
 in 9th with 0 (5%)
 in 7th with 1 (5%)
10: 1343.108104
 in 11th with 0 (9%)
 in 9th with 1 (5%)
 in 7th with 2 (5%)
11: 1724.974971
 in 11th with 1 (9%)
 in 9th with 2 (5%)
 in 7th with 3 (5%)
12: 2215.412625
 in 11th with 2 (9%)
 in 9th with 3 (5%)
 in 7th with 4 (5%)
13: 2845.289458
 in 11th with 3 (9%)
 in 9th with 4 (5%)
 in 7th with 5 (5%)
14: 3654.250232
 in 11th with 4 (9%)
 in 9th with 5 (5%)
 in 7th with 6 (5%)
15: 4693.211343
 in 11th with 5 (9%)
 in 9th with 6 (5%)
 in 7th with 7 (5%)
16: 6027.565523
 in 11th with 6 (9%)
 in 9th with 7 (5%)
 in 7th with 8 (5%)
17: 7741.297691
 in 11th with 7 (9%)
 in 9th with 8 (5%)
 in 7th with 9 (5%)
18: 9942.271007
 in 11th with 8 (9%)
 in 9th with 9 (5%)
 in 7th with 10 (5%)
19: 12769.015831
 in 11th with 9 (9%)
 in 9th with 10 (5%)
 in 7th with 11 (5%)
Вот сгенерил звуковой файл в вышеописанном формате (назовём его Vsound20), смиксив прямоугольные сигналы (чтобы были гармоники) - сначала лесенкой каждая частота по отдельности, а потом все - Audacity нарисовал вот такую спектрограмму (логарифмическая шкала от 100 до 16000 Гц), на которой видно, что гармоники не только в большую сторону отражаются (т.е. вверх), но и в меньшую (т.е. вниз):
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Re: Запись видео на аудиокассету

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На линейной шкале эта лесенка выглядит так:
Vsound20-stairs-linear.jpg
Тут полоски одинаковой толщины (и гармоники лучше видно)

P.S. Видимо FFT в линейной шкале работает - тут как бы надо выбирать, либо мы генерим картинку, чтобы она в спектрогляделках хорошо выглядела, либо чтобы аппаратно декодилась хорошо в реальной железяке...
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Re: Запись видео на аудиокассету

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При сужении сигналов (чтобы утолкать несколько кадров в секунду) качество сильно ухудшилось - чтобы что-то увидеть пришлось ставить размер окна FFT 512 (а не 2048 как в прошом примере):
Vsound20-stairs2.jpg
Зато вроде получилось подобрать более-менее приемлемые временные характеристики - при частоте сэмплирования 44100 Гц я тут задаю ширину кадра в 4000 единиц (т.е. в 1 секунду влезет 11.025 кадров) из которых 500 единиц (11мс) это тишина, далее 500 единиц (другие 11мс) это все линии "гудят" (типа синхросигнал - на 110 Гц туда должно влезть 4.5 периода) и оставшиеся 3000 это собственно кадр - тут 20 ступенек у лесенки из которых в нижних частотах всё сливается, однако в высоких частотах чёткость можно увеличить думаю. Если хочется послушать (и посмотреть) это "видео" - MP3 приаттачен внизу...
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Re: Запись видео на аудиокассету

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MP3 кстати не сильно портит "картинку" :)
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Re: Запись видео на аудиокассету

Post by Shaos »

Взял картинку с полутонами:
shaos30x20.gif
Вот так вот она выглядит в спектре (при окне 1024 спектр несколько разъезжается, поэтому синхросигнал сильно шире 11мс):
Vsound20-sphere.png
А вот инвертированный вариант (8 кадров в секунду):
Vsound20-sphere.jpg
Тут видны наводки от гармоник, которых в реальности быть не должно, т.к. они будут отфильтрованы (надеюсь)
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Re: Запись видео на аудиокассету

Post by Lavr »

Я вот уже давно никак не могу найти - в какой-то советской книжке типа "Справочник радиолюбителя" в конце был описание
конструкции видеомагнитофона на бобинах и схемотехника его узлов.

Хотя в материале и писали, что это несерьёзно с протягой без БВГ, но всё было описано подробно...

Мне очень захотелось всё это перечитать, когда я увидел вот это: :roll:

Image

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