Data -> ADPCM -> Data

-=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- (c) WidthPadding Industries 1987 0\|571\|0 -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=-
Socoder -> Blitz -> Data -> ADPCM -> Data
Sat, 14 May 2022, 09:10
spinal	Data -> ADPCM -> Data OK, I've been trying to decode ADPCM audio using the many identical code examples online, but fail each and every time. So I thought I'd give it a go in blitz, using image data so I could SEE whats going on. Turns out, it either doesn't work OR I'm mis translating the code. Can anyone tell me which it is? Original example - https://www.avrfreaks.net/sites/default/files/Adpcm.c Blitz3D version ; Blitz3D Graphics 1024,900,0,2 Dim IndexTable(16) Dim StepSizeTable(89) For t = 0 To 15 Read IndexTable(t) Next ;/* Table of index changes / Data 255, 255, 255, 255, 2, 4, 6, 8 Data 255, 255, 255, 255, 2, 4, 6, 8 For t = 0 To 88 Read StepSizeTable(t) Next ;/ Quantizer Step size lookup table / Data 7, 8, 9, 10, 11, 12, 13, 14, 16, 17 Data 19, 21, 23, 25, 28, 31, 34, 37, 41, 45 Data 50, 55, 60, 66, 73, 80, 88, 97, 107, 118 Data 130, 143, 157, 173, 190, 209, 230, 253, 279, 307 Data 337, 371, 408, 449, 494, 544, 598, 658, 724, 796 Data 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066 Data 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358 Data 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899 Data 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 Global diff; / Difference between sample and predicted sample / Global QStep; / Quantizer step size / Global predsample; / Output of ADPCM predictor / Global diffq; / Dequantized predicted difference / Global index; / Index into step size table / Global prevsample Global previndex ; load an image myBitmap = LoadImage("eye.bmp") SetBuffer BackBuffer() DrawBlock myBitmap,0,0 Dim dataLine(1024) For y = 0 To ImageHeight(myBitmap) prevsample = 0 previndex = 0 For x = 0 To ImageWidth(myBitmap) GetColor(x,y) r = ColorRed() Shr 3 g = ColorGreen() Shr 2 b = ColorBlue() Shr 3 sixteenbit = (r Shl 15) + (g Shl 11) + b dataLine(x) = ADPCMEncoder(sixteenbit) ;Color 0,0,0 ;Plot x,y Next Flip For x = 0 To ImageWidth(myBitmap) sixteenbit = ADPCMDecoder(dataLine(x)) r = (sixteenbit Shr 15) Shl 3 g = ((sixteenbit Shr 11) Shl 2) And 255 b = (sixteenbit Shl 3) And 255 Color r,g,b Plot x,y Next If KeyHit(1) Then End Next Flip Color 255,255,255 Print "Press esc to end" While Not KeyHit(1) Wend End ;/**************************************************************************** ;* ADPCMEncoder - ADPCM encoder routine * ;****************************************************************************** ;* Input Variables: * ;* signed long sample - 16-bit signed speech sample * ;* Return Variable: * ;* char - 8-bit number containing the 4-bit ADPCM code * ;****************************************************************************/ Function ADPCMEncoder( sample ) ;Int code; / ADPCM output value / ;/ Restore previous values of predicted sample And quantizer Step ; size index ;/ predsample = prevsample index = previndex QStep = StepSizeTable(index) ;/ Compute the difference between the acutal sample (sample) And the ; the predicted sample (predsample) ;/ diff = sample - predsample If diff >= 0 Then code = 0 Else code = 8 diff = -diff End If ;/ Quantize the difference into the 4-bit ADPCM code using the ; the quantizer Step size ;/ ;/ Inverse quantize the ADPCM code into a predicted difference ; using the quantizer Step size ;/ diffq = QStep Shr 3 If diff >= QStep Then code = code Or 4 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 2 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 1 diffq = diffq + QStep End If ;/ Fixed predictor computes New predicted sample by adding the ; old predicted sample To predicted difference ;/ If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ;/ Check For overflow of the New predicted sample ;/ If predsample > 32767 Then predsample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ;/ Find New quantizer stepsize index by adding the old index ; To a table lookup using the ADPCM code ;/ index = index + IndexTable(code) ;/ Check For overflow of the New quantizer Step size index ;/ If index < 0 Then index = 0 If index > 88 Then index = 88 ;/ Save the predicted sample And quantizer Step size index For ; Next iteration ;/ prevsample = predsample; previndex = index; ;/ Return the New ADPCM code / Return ( code And 15 ) End Function ;/**************************************************************************** ;* ADPCMDecoder - ADPCM decoder routine * ;****************************************************************************** ;* Input Variables: * ;* char code - 8-bit number containing the 4-bit ADPCM code * ;* Return Variable: * ;* signed long - 16-bit signed speech sample * ;****************************************************************************/ Function ADPCMDecoder( code ) ;/ Restore previous values of predicted sample And quantizer Step ; size index ;/ predsample = prevsample index = previndex ;/ Find quantizer Step size from lookup table using index ;/ QStep = StepSizeTable(index) ;/ Inverse quantize the ADPCM code into a difference using the ; quantizer Step size ;/ diffq = QStep Shr 3 If code And 4 Then diffq = diffq + QStep If code And 2 Then diffq = diffq + (QStep Shr 1) If code And 1 Then diffq = diffq + (QStep Shr 2) ;/ Add the difference To the predicted sample ;/ If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ;/ Check For overflow of the New predicted sample ;/ If predsample > 32767 Then ample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ;/ Find New quantizer Step size by adding the old index And a ; table lookup using the ADPCM code ;/ index = index + IndexTable(code) ;/ Check For overflow of the New quantizer Step size index ;/ If index < 0 Then index = 0 If index > 88 Then index = 88 ;/ Save predicted sample And quantizer Step size index For Next ; iteration ;/ prevsample = predsample And 65535 previndex = index ;/ Return the New speech sample */ Return( predsample ) End Function --v The output I know ADPCM is lossy, so I don't expect the exact same image as a result, but surely it should look similar at least... Can it be a simple as some of the variable types being wrong? -=-=- Check out my excellent homepage!
Sat, 14 May 2022, 12:28
Jayenkai	Step One.. The bitshifting's wrong.. sixteenbit = (r Shl 11) + (g Shl 5) + b --v 11 and 5, not 15 and 11. (if you shift a number left 15, then chop it down to a 16 bit number, you ain't getting much out of it!!) (and don't forget to change the output to 11 and 5, too) Step Two.. Chop the value to 16 bits. (sixteenbit and $0000FFFF) .. Now delving into the rest of it! -=-=- ''Load, Next List!''
Sat, 14 May 2022, 13:16
Jayenkai	Sorry, brain said no!! I'll give it a go tomorrow. There's a mistype/delete thing near the end, though. If predsample > 32767 Then ample = 32767 --v should be predsample.. -=-=- ''Load, Next List!''
Sat, 14 May 2022, 14:27
spinal	I also thought of something that might make a difference, adpcm expects signed 16but audio samples, whereas my pixel data is unsigned, so it maybe needs to be -32767 before and +32767 after the conversion... -=-=- Check out my excellent homepage!
Sun, 15 May 2022, 01:17
spinal	Slightly better... ; Blitz3D Graphics 1024,900,0,2 Dim IndexTable(16) Dim StepSizeTable(89) For t = 0 To 15 Read IndexTable(t) Next ;/* Table of index changes / Data 255, 255, 255, 255, 2, 4, 6, 8 Data 255, 255, 255, 255, 2, 4, 6, 8 For t = 0 To 88 Read StepSizeTable(t) Next ;/ Quantizer Step size lookup table / Data 7, 8, 9, 10, 11, 12, 13, 14, 16, 17 Data 19, 21, 23, 25, 28, 31, 34, 37, 41, 45 Data 50, 55, 60, 66, 73, 80, 88, 97, 107, 118 Data 130, 143, 157, 173, 190, 209, 230, 253, 279, 307 Data 337, 371, 408, 449, 494, 544, 598, 658, 724, 796 Data 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066 Data 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358 Data 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899 Data 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 Global diff; / Difference between sample and predicted sample / Global QStep; / Quantizer step size / Global predsample; / Output of ADPCM predictor / Global diffq; / Dequantized predicted difference / Global index; / Index into step size table / Global prevsample Global previndex ; load an image myBitmap = LoadImage("eye.bmp") SetBuffer BackBuffer() DrawBlock myBitmap,0,0 Dim dataLine(1024) For y = 0 To ImageHeight(myBitmap) prevsample = 0 previndex = 0 For x = 0 To ImageWidth(myBitmap) GetColor(x,y) r = ColorRed() Shr 3 g = ColorGreen() Shr 2 b = ColorBlue() Shr 3 sixteenbit = (r Shl 11) + (g Shl 5) + b dataLine(x) = ADPCMEncoder(sixteenbit-32767) ;Color 0,0,0 ;Plot x,y Next Flip For x = 0 To ImageWidth(myBitmap) sixteenbit = (ADPCMDecoder(dataLine(x))+32727) r = ((sixteenbit Shr 11) Shl 3) And 255 g = ((sixteenbit Shr 5) Shl 2) And 255 b = (sixteenbit Shr 3) And 255 Color r,g,b Plot x,y + ImageHeight(myBitmap) Next If KeyHit(1) Then End Next Flip Color 255,255,255 Print "Press esc to end" While Not KeyHit(1) Wend End ;/**************************************************************************** ;* ADPCMEncoder - ADPCM encoder routine * ;****************************************************************************** ;* Input Variables: * ;* signed long sample - 16-bit signed speech sample * ;* Return Variable: * ;* char - 8-bit number containing the 4-bit ADPCM code * ;****************************************************************************/ Function ADPCMEncoder( sample ) ;Int code; / ADPCM output value / ;/ Restore previous values of predicted sample And quantizer Step ; size index ;/ predsample = prevsample index = previndex QStep = StepSizeTable(index) ;/ Compute the difference between the acutal sample (sample) And the ; the predicted sample (predsample) ;/ diff = sample - predsample If diff >= 0 Then code = 0 Else code = 8 diff = -diff End If ;/ Quantize the difference into the 4-bit ADPCM code using the ; the quantizer Step size ;/ ;/ Inverse quantize the ADPCM code into a predicted difference ; using the quantizer Step size ;/ diffq = QStep Shr 3 If diff >= QStep Then code = code Or 4 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 2 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 1 diffq = diffq + QStep End If ;/ Fixed predictor computes New predicted sample by adding the ; old predicted sample To predicted difference ;/ If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ;/ Check For overflow of the New predicted sample ;/ If predsample > 32767 Then predsample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ;/ Find New quantizer stepsize index by adding the old index ; To a table lookup using the ADPCM code ;/ index = index + indexTable(code) ;/ Check For overflow of the New quantizer Step size index ;/ If index < 0 Then index = 0 If index > 88 Then index = 88 ;/ Save the predicted sample And quantizer Step size index For ; Next iteration ;/ prevsample = predsample; previndex = index; ;/ Return the New ADPCM code / Return ( code And 15 ) End Function ;/**************************************************************************** ;* ADPCMDecoder - ADPCM decoder routine * ;****************************************************************************** ;* Input Variables: * ;* char code - 8-bit number containing the 4-bit ADPCM code * ;* Return Variable: * ;* signed long - 16-bit signed speech sample * ;****************************************************************************/ Function ADPCMDecoder( code ) ;/ Restore previous values of predicted sample And quantizer Step ; size index ;/ predsample = prevsample index = previndex ;/ Find quantizer Step size from lookup table using index ;/ QStep = StepSizeTable(index) ;/ Inverse quantize the ADPCM code into a difference using the ; quantizer Step size ;/ diffq = QStep Shr 3 If code And 4 Then diffq = diffq + QStep If code And 2 Then diffq = diffq + (QStep Shr 1) If code And 1 Then diffq = diffq + (QStep Shr 2) ;/ Add the difference To the predicted sample ;/ If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ;/ Check For overflow of the New predicted sample ;/ If predsample > 32767 Then predsample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ;/ Find New quantizer Step size by adding the old index And a ; table lookup using the ADPCM code ;/ index = index + indexTable(code) ;/ Check For overflow of the New quantizer Step size index ;/ If index < 0 Then index = 0 If index > 88 Then index = 88 ;/ Save predicted sample And quantizer Step size index For Next ; iteration ;/ prevsample = predsample And 65535 previndex = index ;/ Return the New speech sample */ Return( predsample ) End Function --v -=-=- Check out my excellent homepage!
Sun, 15 May 2022, 06:36
Jayenkai	Alternative source linkage Right from the very get go.. Your IndexTable should be -1's not 255's. -=-=- ''Load, Next List!''
Sun, 15 May 2022, 07:28
Jayenkai	Tip : You need to reset the prevsample and previndex at the start of the second for x loop, so that both start from zero, not just the first loop. -=-=- ''Load, Next List!''
Sun, 15 May 2022, 14:04
spinal	hmmm..... Can't tell if better or worse ; Blitz3D Graphics 1024,900,0,2 Dim IndexTable(16) Dim StepSizeTable(89) For t = 0 To 15 Read IndexTable(t) Next ;/* Table of index changes / Data -1, -1, -1, -1, 2, 4, 6, 8 Data -1, -1, -1, -1, 2, 4, 6, 8 For t = 0 To 88 Read StepSizeTable(t) Next ;/ Quantizer Step size lookup table / Data 7, 8, 9, 10, 11, 12, 13, 14, 16, 17 Data 19, 21, 23, 25, 28, 31, 34, 37, 41, 45 Data 50, 55, 60, 66, 73, 80, 88, 97, 107, 118 Data 130, 143, 157, 173, 190, 209, 230, 253, 279, 307 Data 337, 371, 408, 449, 494, 544, 598, 658, 724, 796 Data 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066 Data 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358 Data 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899 Data 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 Global diff; / Difference between sample and predicted sample / Global QStep; / Quantizer step size / Global predsample; / Output of ADPCM predictor / Global diffq; / Dequantized predicted difference / Global index; / Index into step size table / Global prevsample Global previndex ; load an image myBitmap = LoadImage("eye.bmp") SetBuffer BackBuffer() DrawBlock myBitmap,0,0 Dim dataLine(1024) For y = 0 To ImageHeight(myBitmap) prevsample = 0 previndex = 0 For x = 0 To ImageWidth(myBitmap) GetColor(x,y) r = ColorRed() Shr 3 g = ColorGreen() Shr 2 b = ColorBlue() Shr 3 sixteenbit = (r Shl 11) + (g Shl 5) + b dataLine(x) = ADPCMEncoder(sixteenbit-32767) ;Color 0,0,0 ;Plot x,y Next Flip prevsample = 0 previndex = 0 For x = 0 To ImageWidth(myBitmap) sixteenbit = ADPCMDecoder(dataLine(x))+32767 r = ((sixteenbit Shr 11) Shl 3) And 255 g = ((sixteenbit Shr 5) Shl 2) And 255 b = ( sixteenbit Shl 3) And 255 Color r,g,b Plot x,y + ImageHeight(myBitmap) Next If KeyHit(1) Then End Next Flip Color 255,255,255 Print "Press esc to end" While Not KeyHit(1) Wend End ;/**************************************************************************** ;* ADPCMEncoder - ADPCM encoder routine * ;****************************************************************************** ;* Input Variables: * ;* signed long sample - 16-bit signed speech sample * ;* Return Variable: * ;* char - 8-bit number containing the 4-bit ADPCM code * ;****************************************************************************/ Function ADPCMEncoder( sample ) ;Int code; / ADPCM output value / ;/ Restore previous values of predicted sample And quantizer Step ; size index ;/ predsample = prevsample index = previndex QStep = StepSizeTable(index) ;/ Compute the difference between the acutal sample (sample) And the ; the predicted sample (predsample) ;/ diff = sample - predsample If diff >= 0 Then code = 0 Else code = 8 diff = -diff End If ;/ Quantize the difference into the 4-bit ADPCM code using the ; the quantizer Step size ;/ ;/ Inverse quantize the ADPCM code into a predicted difference ; using the quantizer Step size ;/ diffq = QStep Shr 3 If diff >= QStep Then code = code Or 4 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 2 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 1 diffq = diffq + QStep End If ;/ Fixed predictor computes New predicted sample by adding the ; old predicted sample To predicted difference ;/ If code < 0 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ;/ Check For overflow of the New predicted sample ;/ If predsample > 32767 Then predsample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ;/ Find New quantizer stepsize index by adding the old index ; To a table lookup using the ADPCM code ;/ index = index + indexTable(code) ;/ Check For overflow of the New quantizer Step size index ;/ If index < 0 Then index = 0 If index > 88 Then index = 88 ;/ Save the predicted sample And quantizer Step size index For ; Next iteration ;/ prevsample = predsample; previndex = index; ;/ Return the New ADPCM code / Return ( code And 15 ) End Function ;/**************************************************************************** ;* ADPCMDecoder - ADPCM decoder routine * ;****************************************************************************** ;* Input Variables: * ;* char code - 8-bit number containing the 4-bit ADPCM code * ;* Return Variable: * ;* signed long - 16-bit signed speech sample * ;****************************************************************************/ Function ADPCMDecoder( code ) ;/ Restore previous values of predicted sample And quantizer Step ; size index ;/ predsample = prevsample index = previndex ;/ Find quantizer Step size from lookup table using index ;/ QStep = StepSizeTable(index) ;/ Inverse quantize the ADPCM code into a difference using the ; quantizer Step size ;/ diffq = QStep Shr 3 If code And 4 Then diffq = diffq + QStep If code And 2 Then diffq = diffq + (QStep Shr 1) If code And 1 Then diffq = diffq + (QStep Shr 2) ;/ Add the difference To the predicted sample ;/ If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ;/ Check For overflow of the New predicted sample ;/ If predsample > 32767 Then predsample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ;/ Find New quantizer Step size by adding the old index And a ; table lookup using the ADPCM code ;/ index = index + indexTable(code) ;/ Check For overflow of the New quantizer Step size index ;/ If index < 0 Then index = 0 If index > 88 Then index = 88 ;/ Save predicted sample And quantizer Step size index For Next ; iteration ;/ prevsample = predsample And 65535 previndex = index ;/ Return the New speech sample */ Return( predsample ) End Function --v -=-=- Check out my excellent homepage!
Sun, 15 May 2022, 15:45
Jayenkai	I can't manage this one!!! Been tweaking and poking and prodding it all day, and still getting nothing. Sorry -=-=- ''Load, Next List!''
Mon, 16 May 2022, 07:19
spinal	I have an idea to check how well I should expect it to work, I plan to load the raw image data into cooledit, save it as adpcm, reopen it, save it raw, redraw in blitz. Then I should at least know if this test is even possible. -=-=- Check out my excellent homepage!
Mon, 16 May 2022, 10:52
spinal	OK, did that test. Loaded the image in blitz, did the screen pixel to 16bit conversion, saved to output file. Loaded output file in cooledit, saved as ADPCM, closed cooledit. Loaded ADPCM file into cooledit again, saved as RAW PCM data. Loaded PCM data into blitz, converted the data from 16bit to RGB and plotted on the screen. Result, to the human eye it's exactly the same. So in theory, saving an image as ADPCM works 100%. But for some reason this code does not. -=-=- Check out my excellent homepage!
Mon, 16 May 2022, 14:19
spinal	Grrrrr, Closer, yet further... ; Blitz3D ; https://gist.github.com/jaames/ee3c1e4116e752b61cc8d075a198b9c0 Graphics 1024,900,0,2 Dim StepSizeTable(89) Dim IndexTable(16) For t = 0 To 15 Read IndexTable(t) Next ;/* Table of index changes / Data 255, 255, 255, 255, 2, 4, 6, 8 Data 255, 255, 255, 255, 2, 4, 6, 8 For t = 0 To 88 Read StepSizeTable(t) Next ;/ Quantizer Step size lookup table / Data 7, 8, 9, 10, 11, 12, 13, 14, 16, 17 Data 19, 21, 23, 25, 28, 31, 34, 37, 41, 45 Data 50, 55, 60, 66, 73, 80, 88, 97, 107, 118 Data 130, 143, 157, 173, 190, 209, 230, 253, 279, 307 Data 337, 371, 408, 449, 494, 544, 598, 658, 724, 796 Data 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066 Data 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358 Data 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899 Data 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 Global diff; signed long / Difference between sample and predicted sample / Global QStep; long / Quantizer step size / Global predsample; signed long / Output of ADPCM predictor / Global diffq; signed long / Dequantized predicted difference / Global index; Int / Index into step size table / Global prevsample; signed long Global previndex; Int Global predictor Global stepIndex ; load an image myBitmap = LoadImage("eye.bmp") SetBuffer BackBuffer() DrawBlock myBitmap,0,0 Dim dataLine(1024) For y = 0 To ImageHeight(myBitmap) prevsample = 0 previndex = 0 For x = 0 To ImageWidth(myBitmap) GetColor(x,y) r = ColorRed() Shr 3 g = ColorGreen() Shr 2 b = ColorBlue() Shr 3 sixteenbit = (r Shl 11) + (g Shl 5) + b dataLine(x) = ADPCMEncoder(sixteenbit) ;Color 0,0,0 ;Plot x,y Next Flip prevsample = 0 previndex = 0 For x = 0 To ImageWidth(myBitmap) sixteenbit = adpcmDecode(dataLine(x)) r = ( sixteenbit Shr 11) Shl 3 g = ((sixteenbit Shr 5) Shl 2) And 255 b = ( sixteenbit Shl 3) And 255 Color r,g,b Plot x,y + ImageHeight(myBitmap) Next If KeyHit(1) Then End Next Flip Color 255,255,255 Print "Press esc to end" While Not KeyHit(1) Wend End Function ADPCMEncoder(sample) sample = sample - 32768 ; sample should be signed 16bit (-32768 to 32767) code = 0 ; Int ; / Restore previous values of predicted sample And quantizer Step ; size index ; / predsample = prevsample index = previndex QStep = StepSizeTable(index) ; / Compute the difference between the acutal sample (sample) And the ; the predicted sample (predsample) ; / diff = sample - predsample; If diff >= 0 Then code = 0 Else code = 8 diff = -diff End If ; / Quantize the difference into the 4-bit ADPCM code using the ; the quantizer Step size ; / ; / Inverse quantize the ADPCM code into a predicted difference ; using the quantizer Step size ; / diffq = QStep Shr 3 If diff >= QStep Then code = code Or 4 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 2 diff = diff - QStep diffq = diffq + QStep End If QStep = QStep Shr 1 If diff >= QStep Then code = code Or 1 diffq = diffq + QStep End If ; / Fixed predictor computes New predicted sample by adding the ; old predicted sample To predicted difference ; / If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ; / Check For overflow of the New predicted sample ; / If predsample > 32767 Then predsample = 32767 Else If predsample < -32768 Then predsample = -32768 End If ; / Find New quantizer stepsize index by adding the old index ; To a table lookup using the ADPCM code ; / index = index + IndexTable(code) ; / Check For overflow of the New quantizer Step size index ; / If index < 0 Then index = 0 If index > 88 Then index = 88 ; / Save the predicted sample And quantizer Step size index For ; Next iteration ; / prevsample = predsample previndex = index ; / Return the New ADPCM code / Return code And 15 End Function Function adpcmDecode(code) ; / Restore previous values of predicted sample And quantizer Step ; size index ; / predsample = prevsample index = previndex ; / Find quantizer Step size from lookup table using index ; / QStep = StepSizeTable(index) ; / Inverse quantize the ADPCM code into a difference using the ; quantizer Step size ; / diffq = QStep Shr 3 If code And 1 Then diffq = diffq + QStep Shr 2 If code And 2 Then diffq = diffq + QStep Shr 1 If code And 4 Then diffq = diffq + QStep ; / Add the difference To the predicted sample ; / If code And 8 Then predsample = predsample - diffq Else predsample = predsample + diffq End If ; / Check For overflow of the New predicted sample ; / If predsample > 32767 Then predsample = 32767 If predsample < -32768 Then predsample = -32768 ; / Find New quantizer Step size by adding the old index And a ; table lookup using the ADPCM code ; / index = index + IndexTable(code) ; / Check For overflow of the New quantizer Step size index ; / If index < 0 Then index = 0 If index > 88 Then index = 88 ; / Save predicted sample And quantizer Step size index For Next ; iteration ; / prevsample = predsample previndex = index ; / Return the New speech sample */ Return predsample + 32768 End Function --v -=-=- Check out my excellent homepage!
Mon, 16 May 2022, 16:12
shroom_monk	I've never come across ADPCM before now, but here's some assorted thoughts after looking at this... It looks like ADPCM is a lossy compression format, so we shouldn't expect the final image to be identical to the initial image, as some data will be lost. Since it seems to be intended for audio rather than images, I don't think there's any guarantee that the data lost in compression will 'look' sensible in image form. But I don't know enough about this algorithm to know what that would look like. (e.g. if it mangles the high bits of your colour, then the colour will change massively) So it could be that your current result is already 'correct'! Although it certainly does look sufficiently weird that there is probably more to fix. Testing it on audio is going to be the only way to be sure though, I think. In the avrfreaks example your code is based on, the 'sample' input to 'ADPCMEncoder' is used purely to compare to the previous value to calculate 'diff'. Consequently I don't think your 'sample = sample - 32768' line does anything meaningful, since it doesn't change the result of the 'diff' calculation? Though if you are going to do that, you should probably initialise 'prevsample' with '-32768' to account for the shift there. Since I'm less familiar with the hidden corners of Blitz3D: does 'code And 8' behave equivalent to '(code And 8) != 0' as the equivalent C code does? If it does you're fine, but if not then that code won't be behaving as expected. Ditto for the other places using this pattern. Does bitshifting have higher order of precedence than maths operators in Blitz3D? If not, your 'If code And 1 Then diffq = diffq + QStep Shr 2' and similar line below it probably need some brackets around the bitshifting. I'd be tempted to add them regardless for clarity's sake. I think Jay is correct that your index sizes translated from '0xff' should be -1, not 255. Given the magnitude of the other indices, and especially given the fact that these values are added to an 'index' variable that is clamped at 88, I don't see how adding 255 can ever make any sense. It's worth noting that the avrfreaks code dates from 1996, and while I don't know what size an int was in those days and Google is being entirely unhelpful, I could believe that this code was relying on it being 8 bits rather than anything more. The GitHub Gist example linked from your code also uses -1. Other than the above, I can't see any other issues with your port, so hopefully it's some combination of the above. Hope that helps! -=-=- A mushroom a day keeps the doctor away... Keep It Simple, Shroom!
Tue, 17 May 2022, 00:47
spinal	OK, the best I have is the following image.... But I think you're correct, about an image perhaps not being a good test. I reconverted the image to and from ADPCM using cooledit, and got similar results, I don't know what went wrong with my first test, perhps I accidentally reloaded the original image again (!?). But here is what cooledit did to the picture... -=-=- Check out my excellent homepage!
Fri, 27 May 2022, 01:36
spinal	OK, next question... Graphics 320,240,0,2 Dim StepSizeTable(89) Dim IndexTable(16) For t = 0 To 15 Read IndexTable(t) Next ;/* Table of index changes / Data -1, -1, -1, -1, 2, 4, 6, 8 Data -1, -1, -1, -1, 2, 4, 6, 8 For t = 0 To 88 Read StepSizeTable(t) Next ;/ Quantizer Step size lookup table / Data 7, 8, 9, 10, 11, 12, 13, 14, 16, 17 Data 19, 21, 23, 25, 28, 31, 34, 37, 41, 45 Data 50, 55, 60, 66, 73, 80, 88, 97, 107, 118 Data 130, 143, 157, 173, 190, 209, 230, 253, 279, 307 Data 337, 371, 408, 449, 494, 544, 598, 658, 724, 796 Data 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066 Data 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358 Data 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899 Data 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 Global diff; signed long / Difference between sample and predicted sample / Global QStep; long / Quantizer step size / Global predsample; signed long / Output of ADPCM predictor / Global diffq; signed long / Dequantized predicted difference / Global index; Int / Index into step size table / Global prevsample; signed long Global previndex; Int Global predictor Global stepIndex myTuneSave = WriteFile("pcm.pcm") myTune = ReadFile("AquaticAmbiance_ima.wav") musicSize = FileSize("AquaticAmbiance_ima.wav") SeekFile(myTune, 32) ; skip to blockAlign blockAlign = ReadShort(myTune) SeekFile(myTune, 60) ; skip the header Print blockAlign textFile = WriteFile("textfile.txt") SeekFile(myTune, 60) ; skip the header ; get first values prevsample = ReadShort(myTune) previndex = ReadByte(myTune) Print previndex dummy = ReadByte(myTune) byteCount = 0 counter=0 While Not Eof(myTune) ; for some reason, simply putting text on the screen, slows the code to a snail pace ; with this commented out, it converts a whole song in a few seconds. ;percent = Int((counter 100) / musicSize) ;counter = counter + 1 ;If percent Mod 10 = 0 Then ;Color 0,0,0 ;Rect 0,0, 200,20,1 ;Color 255,255,255 ;Text 0,0, percent ;Flip(1) ;End If byteCount = byteCount + 1 If(byteCount = blockAlign-3) Then byteCount = 0 prevsample = ReadShort(myTune) previndex = ReadByte(myTune) prevsample = 0 ;previndex = 0 ;dummy = ReadByte(myTune) ;dummy = ReadByte(myTune) ;dummy = ReadByte(myTune) dummy = ReadByte(myTune) ; a$ = Right$(Hex$(FilePos(myTune)),4) + " : " ; a$ = a$ + Right$(Hex$(prevsample),2) + " " + Mid$(Hex$(prevsample),5,2) + " " ; a$ = a$ + Right$(Hex$(previndex),2) + " " + Right$(Hex$(dummy),2) ; WriteLine(textFile, a$) Else myByte = ReadByte(myTune) sixteenBit = adpcmDecode((myByte Shr 4) And 15) WriteShort(myTuneSave, sixteenBit) sixteenBit = adpcmDecode(myByte And 15) WriteShort(myTuneSave, sixteenBit) End If Wend CloseFile textFile CloseFile(myTune) CloseFile(myTuneSave) End Function adpcmDecode(code) predsample = prevsample index = previndex QStep = StepSizeTable(index) diffq = QStep Shr 3 If ((code And 4) <> 0) > 0 Then diffq = diffq + QStep If ((code And 2) <> 0) > 0 Then diffq = diffq + (QStep Shr 1) If ((code And 1) <> 0) > 0 Then diffq = diffq + (QStep Shr 2) If (code And 8) <> 0 Then predsample = predsample - diffq Else predsample = predsample + diffq End If If predsample > 32767 Then predsample = 32767 If predsample < -32768 Then predsample = -32768 index = index + IndexTable(code) If index < 0 Then index = 0 If index > 88 Then index = 88 prevsample = predsample previndex = index Return predsample End Function --v Currently, it seems, when reading the 'prevsample' from the file, it is read as a positive number. But it is realy a 2's compliment signed value. so this is always interpreted wrongly. Does blitz know anything about signes 16bit numbers? Here is an example of some of the readings... current sample, current index, prevsample, previndex 111, 26, 36, 26 -454, 22, 65038, 22 That 65038 is supposed to be interpreted as -498 \|edit\| This doesn't seem to be working... If (prevsample And 32768) = 1 Then ; invert all bits, add one, And make negative prevsample = -(~(prevsample + 1)) End If --v \|edit\| That's because it's wrong... If (prevsample And 32768) <> 0 Then ; invert all bits, add one, And make negative prevsample = -(~(prevsample + 1)And 32767) End If --v -=-=- Check out my excellent homepage!
Fri, 27 May 2022, 03:45
spinal	Aha! ; Blitz3D ; https://gist.github.com/jaames/ee3c1e4116e752b61cc8d075a198b9c0 ;Graphics 320,240,0,2 Dim StepSizeTable(89) Dim IndexTable(16) For t = 0 To 15 Read IndexTable(t) Next ;/* Table of index changes / Data -1, -1, -1, -1, 2, 4, 6, 8 Data -1, -1, -1, -1, 2, 4, 6, 8 For t = 0 To 88 Read StepSizeTable(t) Next ;/ Quantizer Step size lookup table / Data 7, 8, 9, 10, 11, 12, 13, 14, 16, 17 Data 19, 21, 23, 25, 28, 31, 34, 37, 41, 45 Data 50, 55, 60, 66, 73, 80, 88, 97, 107, 118 Data 130, 143, 157, 173, 190, 209, 230, 253, 279, 307 Data 337, 371, 408, 449, 494, 544, 598, 658, 724, 796 Data 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066 Data 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358 Data 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899 Data 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 Global diff; signed long / Difference between sample and predicted sample / Global QStep; long / Quantizer step size / Global predsample; signed long / Output of ADPCM predictor / Global diffq; signed long / Dequantized predicted difference / Global index; Int / Index into step size table / Global prevsample; signed long Global previndex; Int Global predictor Global stepIndex myTuneSave = WriteFile("pcm.pcm") myTune = ReadFile("AquaticAmbiance_ima.wav") musicSize = FileSize("AquaticAmbiance_ima.wav") SeekFile(myTune, 32) ; skip to blockAlign blockAlign = ReadShort(myTune) SeekFile(myTune, 60) ; skip the header ; read first data prevsample = ReadShort(myTune) ; blitz doesnt know 16bit twos complement ; so need to convert to a negative number if needed If (prevsample And 32768) <> 0 Then ; invert all bits, add one, And make negative prevsample = -(~(prevsample + 1)And 32767) End If previndex = ReadByte(myTune) dummy = ReadByte(myTune) byteCount = 0 counter=0 nibbleCount = 0 SetBuffer BackBuffer() While Not Eof(myTune) ;percent = Int((counter 100) / musicSize) ;counter = counter + 1 ;If counter And 1023 = 0 Then ; Cls ; Print counter +"/"+ musicsize ; ;Text 0,0, percent ;End If If nibbleCount = 0 Then myByte = ReadByte(myTune) byteCount = byteCount + 1 sixteenBit = adpcmDecode(myByte And 15) ;sixteenBit = adpcmDecode((myByte Shr 4) And 15) WriteShort(myTuneSave, sixteenBit) Else ;sixteenBit = adpcmDecode(myByte And 15) sixteenBit = adpcmDecode((myByte Shr 4) And 15) WriteShort(myTuneSave, sixteenBit) End If nibbleCount = 1-nibbleCount If(byteCount = blockAlign-4) Then byteCount = 0 prevsample = ReadShort(myTune) ; blitz doesnt know 16bit twos complement ; so need to convert to a negative number if needed If (prevsample And 32768) <> 0 Then ; invert all bits, add one, And make negative prevsample = -(~(prevsample + 1)And 32767) End If previndex = ReadByte(myTune) dummy = ReadByte(myTune) End If ;Flip(1) Wend CloseFile(myTune) CloseFile(myTuneSave) End Function adpcmDecode(code) predsample = prevsample index = previndex QStep = StepSizeTable(index) diffq = QStep Shr 3 If ((code And 4) <> 0) > 0 Then diffq = diffq + QStep If ((code And 2) <> 0) > 0 Then diffq = diffq + (QStep Shr 1) If ((code And 1) <> 0) > 0 Then diffq = diffq + (QStep Shr 2) If (code And 8) <> 0 Then predsample = predsample - diffq Else predsample = predsample + diffq End If If predsample > 32767 Then predsample = 32767 If predsample < -32768 Then predsample = -32768 index = index + IndexTable(code) If index < 0 Then index = 0 If index > 88 Then index = 88 prevsample = predsample previndex = index Return predsample End Function --v The above code almost restores a file saved as IMA ADPCM as well as cooledit does. There is the occasional loud bit, I assume that either commercial software has some sort of filtering going on when loading, or I'm still missing something. But for my needs, this is probably close enough. -=-=- Check out my excellent homepage!
Mon, 30 May 2022, 04:51
spinal	Something is still wrong, I get a very regular 'burst' of volume, so it still isn't decoding correctly. How though, I have no idea. This is supposed to be one of, if not the simplest audio compressions there is. -=-=- Check out my excellent homepage!