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ciderpress/app/CassetteDialog.cpp

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/*
* CiderPress
* Copyright (C) 2007 by faddenSoft, LLC. All Rights Reserved.
* See the file LICENSE for distribution terms.
*/
/*
* Apple II cassette I/O functions.
*/
#include "StdAfx.h"
#include "CassetteDialog.h"
#include "CassImpTargetDialog.h"
#include "GenericArchive.h"
#include "Main.h"
#include "../diskimg/DiskImg.h" // need kStorageSeedling
#include <math.h>
/*
* Tape layout:
* 10.6 seconds of 770Hz (8192 cycles * 1300 usec/cycle)
* 1/2 cycle at 400 usec/cycle, followed by 1/2 cycle at 500 usec/cycle
* Data, using 500 usec/cycle for '0' and 1000 usec/cycle for '1'
* There is no "end" marker, except perhaps for the absence of data
*
* The last byte of data is an XOR checksum (seeded with 0xff).
*
* BASIC uses two sections, each with the full 10-second lead-in and a
* checksum byte). Integer BASIC writes a two-byte section with the length
* of the program, while Applesoft BASIC writes a three-byte section with
* the length followed by a one-byte "run" flag (seen: 0x55 and 0xd5).
*
* Applesoft arrays, loaded with "RECALL", have a three-byte header, and
* may be confused with BASIC programs. Shape tables, loaded with "SHLOAD",
* have a two-byte header and may be confused with Integer programs.
*
* The monitor ROM routine uses a detection threshold of 700 usec to tell
* the difference between 0s and 1s. When reading, it *outputs* a tone for
* 3.5 seconds before listening. It doesn't try to detect the 770Hz tone,
* just waits for something under (40*12=)440 usec.
*
* The Apple II hardware changes the high bit read from $c060 every time it
* detects a zero-crossing on the cassette input. I assume the polarity
* of the input signal is reflected by the polarity of the high bit, but
* I'm not sure, and in the end it doesn't really matter.
*
* Typical instructions for loading data from tape look like this:
* - Type "LOAD" or "xxxx.xxxxR", but don't hit <return>.
* - Play tape until you here the tone.
* - Immediately hit stop.
* - Plug the cable from the Apple II into the tape player.
* - Hit "play" on the recorder, then immediately hit <return>.
* - When the Apple II beeps, it's done. Stop the tape.
*
* How quickly do we need to sample? The highest frequency we expect to
* find is 2KHz, so anything over 4KHz should be sufficient. However, we
* need to be able to resolve the time between zero transitions to some
* reasonable resolution. We need to tell the difference between a 650usec
* half-cycle and a 200usec half-cycle for the start, and 250/500usec for
* the data section. Our measurements can comfortably be off by 200 usec
* with no ill effects on the lead-in, assuming a perfect signal. (Sampling
* every 200 usec would be 5Hz.) The data itself needs to be +/- 125usec
* for half-cycles, though we can get a little sloppier if we average the
* error out by combining half-cycles.
*
* The signal is less than perfect, sometimes far less, so we need better
* sampling to avoid magnifying distortions in the signal. If we sample
* at 22.05KHz, we could see a 650usec gap as 590, 635, or 680, depending
* on when we sample and where we think the peaks lie. We're off by 15usec
* before we even start. We can reasonably expect to be off +/- twice the
* "usecPerSample" value. At 8KHz, that's +/- 250usec, which isn't
* acceptable. At 11KHz we're at +/- 191usec, which is scraping along.
*
* We can get mitigate some problems by doing an interpolation of the
* two points nearest the zero-crossing, which should give us a more
* accurate fix on the zero point than simply choosing the closest point.
* This does potentially increase our risk of errors due to noise spikes at
* points near the zero. Since we're reading from cassette, any noise spikes
* are likely to be pretty wide, so averaging the data or interpolating
* across multiple points isn't likely to help us.
*
* Some tapes seem to have a low-frequency distortion that amounts to a DC
* bias when examining a single sample. Timing the gaps between zero
* crossings is therefore not sufficient unless we also correct for the
* local DC bias. In some cases the recorder or media was unable to
* respond quickly enough, and as a result 0s have less amplitude
* than 1s. This throws off some simple correction schemes.
*
* The easiest approach is to figure out where one cycle starts and stops, and
* use the timing of the full cycle. This gets a little ugly because the
* original output was a square wave, so there's a bit of ringing in the
* peaks, especially the 1s. Of course, we have to look at half-cycles
* initially, because we need to identify the first "short 0" part. Once
* we have that, we can use full cycles, which distributes any error over
* a larger set of samples.
*
* In some cases the positive half-cycle is longer than the negative
* half-cycle (e.g. reliably 33 samples vs. 29 samples at 48KHz, when
* 31.2 is expected for 650us). Slight variations can lead to even
* greater distortion, even though the timing for the full signal is
* within tolerances. This means we need to accumulate the timing for
* a full cycle before making an evaluation, though we still need to
* examine the half-cycle timing during the lead-in to catch the "short 0".
*
* Because of these distortions, 8-bit 8KHz audio is probably not a good
* idea. 16-bit 22.05KHz sampling is a better choice for tapes that have
* been sitting around for 25-30 years.
*/
/*
; Monitor ROM dump, with memory locations rearranged for easier reading.
; Increment 16-bit value at 0x3c (A1) and compare it to 16-bit value at
; 0x3e (A2). Returns with carry set if A1 >= A2.
; Requires 26 cycles in common case, 30 cycles in rare case.
FCBA: A5 3C 709 NXTA1 LDA A1L ;INCR 2-BYTE A1.
FCBC: C5 3E 710 CMP A2L
FCBE: A5 3D 711 LDA A1H ; AND COMPARE TO A2
FCC0: E5 3F 712 SBC A2H
FCC2: E6 3C 713 INC A1L ; (CARRY SET IF >=)
FCC4: D0 02 714 BNE RTS4B
FCC6: E6 3D 715 INC A1H
FCC8: 60 716 RTS4B RTS
; Write data from location in A1L up to location in A2L.
FECD: A9 40 975 WRITE LDA #$40
FECF: 20 C9 FC 976 JSR HEADR ;WRITE 10-SEC HEADER
; Write loop. Continue until A1 reaches A2.
FED2: A0 27 977 LDY #$27
FED4: A2 00 978 WR1 LDX #$00
FED6: 41 3C 979 EOR (A1L,X)
FED8: 48 980 PHA
FED9: A1 3C 981 LDA (A1L,X)
FEDB: 20 ED FE 982 JSR WRBYTE
FEDE: 20 BA FC 983 JSR NXTA1
FEE1: A0 1D 984 LDY #$1D
FEE3: 68 985 PLA
FEE4: 90 EE 986 BCC WR1
; Write checksum byte, then beep the speaker.
FEE6: A0 22 987 LDY #$22
FEE8: 20 ED FE 988 JSR WRBYTE
FEEB: F0 4D 989 BEQ BELL
; Write one byte (8 bits, or 16 half-cycles).
; On exit, Z-flag is set.
FEED: A2 10 990 WRBYTE LDX #$10
FEEF: 0A 991 WRBYT2 ASL
FEF0: 20 D6 FC 992 JSR WRBIT
FEF3: D0 FA 993 BNE WRBYT2
FEF5: 60 994 RTS
; Write tape header. Called by WRITE with A=$40, READ with A=$16.
; On exit, A holds $FF.
; First time through, X is undefined, so we may get slightly less than
; A*256 half-cycles (i.e. A*255 + X). If the carry is clear on entry,
; the first ADC will subtract two (yielding A*254+X), and the first X
; cycles will be "long 0s" instead of "long 1s". Doesn't really matter.
FCC9: A0 4B 717 HEADR LDY #$4B ;WRITE A*256 'LONG 1'
FCCB: 20 DB FC 718 JSR ZERDLY ; HALF CYCLES
FCCE: D0 F9 719 BNE HEADR ; (650 USEC EACH)
FCD0: 69 FE 720 ADC #$FE
FCD2: B0 F5 721 BCS HEADR ;THEN A 'SHORT 0'
; Fall through to write bit. Note carry is clear, so we'll use the zero
; delay. We've initialized Y to $21 instead of $32 to get a short '0'
; (165usec) for the first half and a normal '0' for the second half;
FCD4: A0 21 722 LDY #$21 ; (400 USEC)
; Write one bit. Called from WRITE with Y=$27.
FCD6: 20 DB FC 723 WRBIT JSR ZERDLY ;WRITE TWO HALF CYCLES
FCD9: C8 724 INY ; OF 250 USEC ('0')
FCDA: C8 725 INY ; OR 500 USEC ('0')
; Delay for '0'. X typically holds a bit count or half-cycle count.
; Y holds delay period in 5-usec increments:
; (carry clear) $21=165us $27=195us $2C=220 $4B=375us
; (carry set) $21=165+250=415us $27=195+250=445us $4B=375+250=625us
; Remember that TOTAL delay, with all other instructions, must equal target
; On exit, Y=$2C, Z-flag is set if X decremented to zero. The 2C in Y
; is for WRBYTE, which is in a tight loop and doesn't need much padding.
FCDB: 88 726 ZERDLY DEY
FCDC: D0 FD 727 BNE ZERDLY
FCDE: 90 05 728 BCC WRTAPE ;Y IS COUNT FOR
; Additional delay for '1' (always 250us).
FCE0: A0 32 729 LDY #$32 ; TIMING LOOP
FCE2: 88 730 ONEDLY DEY
FCE3: D0 FD 731 BNE ONEDLY
; Write a transition to the tape.
FCE5: AC 20 C0 732 WRTAPE LDY TAPEOUT
FCE8: A0 2C 733 LDY #$2C
FCEA: CA 734 DEX
FCEB: 60 735 RTS
; Read data from location in A1L up to location in A2L.
FEFD: 20 FA FC 999 READ JSR RD2BIT ;FIND TAPEIN EDGE
FF00: A9 16 1000 LDA #$16
FF02: 20 C9 FC 1001 JSR HEADR ;DELAY 3.5 SECONDS
FF05: 85 2E 1002 STA CHKSUM ;INIT CHKSUM=$FF
FF07: 20 FA FC 1003 JSR RD2BIT ;FIND TAPEIN EDGE
; Loop, waiting for edge. 11 cycles/iteration, plus 432+14 = 457usec.
FF0A: A0 24 1004 RD2 LDY #$24 ;LOOK FOR SYNC BIT
FF0C: 20 FD FC 1005 JSR RDBIT ; (SHORT 0)
FF0F: B0 F9 1006 BCS RD2 ; LOOP UNTIL FOUND
; Timing of next transition, a normal '0' half-cycle, doesn't matter.
FF11: 20 FD FC 1007 JSR RDBIT ;SKIP SECOND SYNC H-CYCLE
; Main byte read loop. Continue until A1 reaches A2.
FF14: A0 3B 1008 LDY #$3B ;INDEX FOR 0/1 TEST
FF16: 20 EC FC 1009 RD3 JSR RDBYTE ;READ A BYTE
FF19: 81 3C 1010 STA (A1L,X) ;STORE AT (A1)
FF1B: 45 2E 1011 EOR CHKSUM
FF1D: 85 2E 1012 STA CHKSUM ;UPDATE RUNNING CHKSUM
FF1F: 20 BA FC 1013 JSR NXTA1 ;INC A1, COMPARE TO A2
FF22: A0 35 1014 LDY #$35 ;COMPENSATE 0/1 INDEX
FF24: 90 F0 1015 BCC RD3 ;LOOP UNTIL DONE
; Read checksum byte and check it.
FF26: 20 EC FC 1016 JSR RDBYTE ;READ CHKSUM BYTE
FF29: C5 2E 1017 CMP CHKSUM
FF2B: F0 0D 1018 BEQ BELL ;GOOD, SOUND BELL AND RETURN
; Print "ERR", beep speaker.
FF2D: A9 C5 1019 PRERR LDA #$C5
FF2F: 20 ED FD 1020 JSR COUT ;PRINT "ERR", THEN BELL
FF32: A9 D2 1021 LDA #$D2
FF34: 20 ED FD 1022 JSR COUT
FF37: 20 ED FD 1023 JSR COUT
FF3A: A9 87 1024 BELL LDA #$87 ;OUTPUT BELL AND RETURN
FF3C: 4C ED FD 1025 JMP COUT
; Read a byte from the tape. Y is $3B on first call, $35 on subsequent
; calls. The bits are shifted left, meaning that the high bit is read
; first.
FCEC: A2 08 736 RDBYTE LDX #$08 ;8 BITS TO READ
FCEE: 48 737 RDBYT2 PHA ;READ TWO TRANSITIONS
FCEF: 20 FA FC 738 JSR RD2BIT ; (FIND EDGE)
FCF2: 68 739 PLA
FCF3: 2A 740 ROL ;NEXT BIT
FCF4: A0 3A 741 LDY #$3A ;COUNT FOR SAMPLES
FCF6: CA 742 DEX
FCF7: D0 F5 743 BNE RDBYT2
FCF9: 60 744 RTS
; Read two bits from the tape.
FCFA: 20 FD FC 745 RD2BIT JSR RDBIT
; Read one bit from the tape. On entry, Y is the expected transition time:
; $3A=696usec $35=636usec $24=432usec
; Returns with the carry set if the transition time exceeds the Y value.
FCFD: 88 746 RDBIT DEY ;DECR Y UNTIL
FCFE: AD 60 C0 747 LDA TAPEIN ; TAPE TRANSITION
FD01: 45 2F 748 EOR LASTIN
FD03: 10 F8 749 BPL RDBIT
; the above loop takes 12 usec per iteration, what follows takes 14.
FD05: 45 2F 750 EOR LASTIN
FD07: 85 2F 751 STA LASTIN
FD09: C0 80 752 CPY #$80 ;SET CARRY ON Y
FD0B: 60 753 RTS
*/
/*
* ==========================================================================
* CassetteDialog
* ==========================================================================
*/
BEGIN_MESSAGE_MAP(CassetteDialog, CDialog)
ON_NOTIFY(LVN_ITEMCHANGED, IDC_CASSETTE_LIST, OnListChange)
ON_NOTIFY(NM_DBLCLK, IDC_CASSETTE_LIST, OnListDblClick)
//ON_MESSAGE(WMU_DIALOG_READY, OnDialogReady)
ON_COMMAND(IDC_IMPORT_CHUNK, OnImport)
ON_COMMAND(IDHELP, OnHelp)
ON_CBN_SELCHANGE(IDC_CASSETTE_ALG, OnAlgorithmChange)
END_MESSAGE_MAP()
BOOL CassetteDialog::OnInitDialog(void)
{
CRect rect;
const Preferences* pPreferences = GET_PREFERENCES();
CDialog::OnInitDialog(); // does DDX init
CWnd* pWnd;
pWnd = GetDlgItem(IDC_IMPORT_CHUNK);
pWnd->EnableWindow(FALSE);
pWnd = GetDlgItem(IDC_CASSETTE_INPUT);
pWnd->SetWindowText(fFileName);
/* prep the combo box */
CComboBox* pCombo = (CComboBox*) GetDlgItem(IDC_CASSETTE_ALG);
ASSERT(pCombo != NULL);
int defaultAlg = pPreferences->GetPrefLong(kPrCassetteAlgorithm);
if (defaultAlg > CassetteData::kAlgorithmMIN &&
defaultAlg < CassetteData::kAlgorithmMAX)
{
pCombo->SetCurSel(defaultAlg);
} else {
LOGI("GLITCH: invalid defaultAlg in prefs (%d)", defaultAlg);
pCombo->SetCurSel(CassetteData::kAlgorithmZero);
}
fAlgorithm = (CassetteData::Algorithm) defaultAlg;
/*
* Prep the listview control.
*
* Columns:
* [icon] Index | Format | Length | Checksum OK
*/
CListCtrl* pListView = (CListCtrl*) GetDlgItem(IDC_CASSETTE_LIST);
ASSERT(pListView != NULL);
ListView_SetExtendedListViewStyleEx(pListView->m_hWnd,
LVS_EX_FULLROWSELECT, LVS_EX_FULLROWSELECT);
int width0, width1, width2, width3, width4;
pListView->GetClientRect(&rect);
width0 = pListView->GetStringWidth(L"XXIndexX");
width1 = pListView->GetStringWidth(L"XXFormatXmmmmmmmmmmmmmm");
width2 = pListView->GetStringWidth(L"XXLengthXm");
width3 = pListView->GetStringWidth(L"XXChecksumXm");
width4 = pListView->GetStringWidth(L"XXStart sampleX");
//width5 = pListView->GetStringWidth("XXEnd sampleX");
pListView->InsertColumn(0, L"Index", LVCFMT_LEFT, width0);
pListView->InsertColumn(1, L"Format", LVCFMT_LEFT, width1);
pListView->InsertColumn(2, L"Length", LVCFMT_LEFT, width2);
pListView->InsertColumn(3, L"Checksum", LVCFMT_LEFT, width3);
pListView->InsertColumn(4, L"Start sample", LVCFMT_LEFT, width4);
pListView->InsertColumn(5, L"End sample", LVCFMT_LEFT,
rect.Width() - (width0+width1+width2+width3+width4)
/*- ::GetSystemMetrics(SM_CXVSCROLL)*/ );
/* add images for list; this MUST be loaded before header images */
// LoadListImages();
// pListView->SetImageList(&fListImageList, LVSIL_SMALL);
// LoadList();
CenterWindow();
//int cc = PostMessage(WMU_DIALOG_READY, 0, 0);
//ASSERT(cc != 0);
if (!AnalyzeWAV())
OnCancel();
return TRUE;
}
#if 0
/*
* Dialog construction has completed. Start the WAV analysis.
*/
LONG
CassetteDialog::OnDialogReady(UINT, LONG)
{
//AnalyzeWAV();
return 0;
}
#endif
void CassetteDialog::OnListChange(NMHDR*, LRESULT* pResult)
{
LOGI("List change");
CListCtrl* pListView = (CListCtrl*) GetDlgItem(IDC_CASSETTE_LIST);
CButton* pButton = (CButton*) GetDlgItem(IDC_IMPORT_CHUNK);
pButton->EnableWindow(pListView->GetSelectedCount() != 0);
*pResult = 0;
}
void CassetteDialog::OnListDblClick(NMHDR* pNotifyStruct, LRESULT* pResult)
{
LOGI("Double click!");
CListCtrl* pListView = (CListCtrl*) GetDlgItem(IDC_CASSETTE_LIST);
if (pListView->GetSelectedCount() == 1)
OnImport();
*pResult = 0;
}
void CassetteDialog::OnAlgorithmChange(void)
{
CComboBox* pCombo = (CComboBox*) GetDlgItem(IDC_CASSETTE_ALG);
ASSERT(pCombo != NULL);
LOGI("+++ SELECTION IS NOW %d", pCombo->GetCurSel());
fAlgorithm = (CassetteData::Algorithm) pCombo->GetCurSel();
AnalyzeWAV();
}
void CassetteDialog::OnImport(void)
{
/*
* Figure out which item they have selected.
*/
CListCtrl* pListView = (CListCtrl*) GetDlgItem(IDC_CASSETTE_LIST);
ASSERT(pListView != NULL);
assert(pListView->GetSelectedCount() == 1);
POSITION posn;
posn = pListView->GetFirstSelectedItemPosition();
if (posn == NULL) {
ASSERT(false);
return;
}
int idx = pListView->GetNextSelectedItem(posn);
/*
* Set up the import dialog.
*/
CassImpTargetDialog impDialog(this);
impDialog.fFileName = "From.Tape";
impDialog.fFileLength = fDataArray[idx].GetDataLen();
impDialog.SetFileType(fDataArray[idx].GetFileType());
if (impDialog.DoModal() != IDOK)
return;
/*
* Write the file to the currently-open archive.
*/
GenericArchive::LocalFileDetails details;
details.SetEntryKind(GenericArchive::LocalFileDetails::kFileKindDataFork);
details.SetLocalPathName(L"Cassette WAV");
details.SetStrippedLocalPathName(impDialog.fFileName);
details.SetAccess(0xe3); // unlocked, backup bit set
details.SetFileType(impDialog.GetFileType());
if (details.GetFileType() == kFileTypeBIN) {
details.SetExtraType(impDialog.fStartAddr);
} else if (details.GetFileType() == kFileTypeBAS) {
details.SetExtraType(0x0801);
} else {
details.SetExtraType(0x0000);
}
details.SetStorageType(DiskFS::kStorageSeedling);
time_t now = time(NULL);
NuDateTime ndt;
GenericArchive::UNIXTimeToDateTime(&now, &ndt);
details.SetCreateWhen(ndt);
details.SetArchiveWhen(ndt);
details.SetModWhen(ndt);
CString errMsg;
fDirty = true;
if (!MainWindow::SaveToArchive(&details, fDataArray[idx].GetDataBuf(),
fDataArray[idx].GetDataLen(), NULL, -1, &errMsg, this))
{
goto bail;
}
bail:
if (!errMsg.IsEmpty()) {
CString msg;
msg.Format(L"Unable to import file: %ls.", (LPCWSTR) errMsg);
ShowFailureMsg(this, msg, IDS_FAILED);
return;
}
}
bool CassetteDialog::AnalyzeWAV(void)
{
SoundFile soundFile;
CWaitCursor waitc;
CListCtrl* pListCtrl = (CListCtrl*) GetDlgItem(IDC_CASSETTE_LIST);
CString errMsg;
long sampleOffset;
int idx;
if (soundFile.Create(fFileName, &errMsg) != 0) {
ShowFailureMsg(this, errMsg, IDS_FAILED);
return false;
}
const WAVEFORMATEX* pFormat = soundFile.GetWaveFormat();
if (pFormat->nChannels < 1 || pFormat->nChannels > 2 ||
(pFormat->wBitsPerSample != 8 && pFormat->wBitsPerSample != 16))
{
errMsg.Format(L"Unexpected PCM format (%d channels, %d bits/sample)",
pFormat->nChannels, pFormat->wBitsPerSample);
ShowFailureMsg(this, errMsg, IDS_FAILED);
return false;
}
if (soundFile.GetDataLen() % soundFile.GetBPS() != 0) {
errMsg.Format(L"Unexpected sound data length (%ld, samples are %d bytes)",
soundFile.GetDataLen(), soundFile.GetBPS());
ShowFailureMsg(this, errMsg, IDS_FAILED);
return false;
}
pListCtrl->DeleteAllItems();
sampleOffset = 0;
for (idx = 0; idx < kMaxRecordings; idx++) {
long fileType;
bool result;
result = fDataArray[idx].Scan(&soundFile, fAlgorithm, &sampleOffset);
if (!result)
break;
AddEntry(idx, pListCtrl, &fileType);
fDataArray[idx].SetFileType(fileType);
}
if (idx == 0) {
LOGI("No Apple II files found");
/* that's okay, just show the empty list */
}
return true;
}
void CassetteDialog::AddEntry(int idx, CListCtrl* pListCtrl, long* pFileType)
{
CString tmpStr;
const CassetteData* pData = &fDataArray[idx];
const unsigned char* pDataBuf = pData->GetDataBuf();
ASSERT(pDataBuf != NULL);
tmpStr.Format(L"%d", idx);
pListCtrl->InsertItem(idx, tmpStr);
*pFileType = kFileTypeBIN;
if (pData->GetDataLen() == 2) {
tmpStr.Format(L"Integer header ($%04X)",
pDataBuf[0] | pDataBuf[1] << 8);
} else if (pData->GetDataLen() == 3) {
tmpStr.Format(L"Applesoft header ($%04X $%02x)",
pDataBuf[0] | pDataBuf[1] << 8, pDataBuf[2]);
} else if (pData->GetDataLen() > 3 && idx > 0 &&
fDataArray[idx-1].GetDataLen() == 2)
{
tmpStr = L"Integer BASIC";
*pFileType = kFileTypeINT;
} else if (pData->GetDataLen() > 3 && idx > 0 &&
fDataArray[idx-1].GetDataLen() == 3)
{
tmpStr = L"Applesoft BASIC";
*pFileType = kFileTypeBAS;
} else {
tmpStr = L"Binary";
}
pListCtrl->SetItemText(idx, 1, tmpStr);
tmpStr.Format(L"%d", pData->GetDataLen());
pListCtrl->SetItemText(idx, 2, tmpStr);
if (pData->GetDataChkGood())
tmpStr.Format(L"Good (0x%02x)", pData->GetDataChecksum());
else
tmpStr.Format(L"BAD (0x%02x)", pData->GetDataChecksum());
pListCtrl->SetItemText(idx, 3, tmpStr);
tmpStr.Format(L"%ld", pData->GetDataOffset());
pListCtrl->SetItemText(idx, 4, tmpStr);
tmpStr.Format(L"%ld", pData->GetDataEndOffset());
pListCtrl->SetItemText(idx, 5, tmpStr);
}
/*
* ==========================================================================
* CassetteData
* ==========================================================================
*/
bool CassetteDialog::CassetteData::Scan(SoundFile* pSoundFile, Algorithm alg,
long* pStartOffset)
{
const int kSampleChunkSize = 65536; // should be multiple of 4
const WAVEFORMATEX* pFormat;
ScanState scanState;
long initialLen, dataLen, chunkLen, byteOffset;
long sampleStartIndex;
unsigned char* buf = NULL;
float* sampleBuf = NULL;
int bytesPerSample;
bool result = false;
unsigned char checkSum;
int outByteIndex, bitAcc;
bytesPerSample = pSoundFile->GetBPS();
assert(bytesPerSample >= 1 && bytesPerSample <= 4);
assert(kSampleChunkSize % bytesPerSample == 0);
byteOffset = *pStartOffset;
initialLen = dataLen = pSoundFile->GetDataLen() - byteOffset;
sampleStartIndex = byteOffset/bytesPerSample;
LOGI("CassetteData::Scan(off=%ld / %ld) len=%ld alg=%d",
byteOffset, sampleStartIndex, dataLen, alg);
pFormat = pSoundFile->GetWaveFormat();
buf = new unsigned char[kSampleChunkSize];
sampleBuf = new float[kSampleChunkSize/bytesPerSample];
if (fOutputBuf == NULL) // alloc on first use
fOutputBuf = new unsigned char[kMaxFileLen];
if (buf == NULL || sampleBuf == NULL || fOutputBuf == NULL) {
LOGI("Buffer alloc failed");
goto bail;
}
memset(&scanState, 0, sizeof(scanState));
scanState.algorithm = alg;
scanState.phase = kPhaseScanFor770Start;
scanState.mode = kModeInitial0;
scanState.positive = false;
scanState.usecPerSample = 1000000.0f / (float) pFormat->nSamplesPerSec;
checkSum = 0xff;
outByteIndex = 0;
bitAcc = 1;
/*
* Loop until done or out of data.
*/
while (dataLen > 0) {
int cc;
chunkLen = dataLen;
if (chunkLen > kSampleChunkSize)
chunkLen = kSampleChunkSize;
cc = pSoundFile->ReadData(buf, byteOffset, chunkLen);
if (cc < 0) {
LOGI("ReadData(%d) failed", chunkLen);
goto bail;
}
ConvertSamplesToReal(pFormat, buf, chunkLen, sampleBuf);
for (int i = 0; i < chunkLen / bytesPerSample; i++) {
int bitVal;
if (ProcessSample(sampleBuf[i], sampleStartIndex + i,
&scanState, &bitVal))
{
if (outByteIndex >= kMaxFileLen) {
LOGI("Cassette data overflow");
scanState.phase = kPhaseEndReached;
} else {
/* output a bit, shifting until bit 8 lights up */
assert(bitVal == 0 || bitVal == 1);
bitAcc = (bitAcc << 1) | bitVal;
if (bitAcc > 0xff) {
fOutputBuf[outByteIndex++] = (unsigned char) bitAcc;
checkSum ^= (unsigned char) bitAcc;
bitAcc = 1;
}
}
}
if (scanState.phase == kPhaseEndReached) {
dataLen -= i * bytesPerSample;
break;
}
}
if (scanState.phase == kPhaseEndReached)
break;
dataLen -= chunkLen;
byteOffset += chunkLen;
sampleStartIndex += chunkLen / bytesPerSample;
}
switch (scanState.phase) {
case kPhaseScanFor770Start:
case kPhaseScanning770:
// expected case for trailing part of file
LOGI("Scan ended while searching for 770");
goto bail;
case kPhaseScanForShort0:
case kPhaseShort0B:
LOGI("Scan ended while searching for short 0/0B");
//DebugBreak(); // unusual
goto bail;
case kPhaseReadData:
LOGI("Scan ended while reading data");
//DebugBreak(); // truncated WAV file?
goto bail;
case kPhaseEndReached:
LOGI("Scan found end");
// winner!
break;
default:
LOGI("Unknown phase %d", scanState.phase);
assert(false);
goto bail;
}
LOGI("*** Output %d bytes (bitAcc=0x%02x, checkSum=0x%02x)",
outByteIndex, bitAcc, checkSum);
if (outByteIndex == 0) {
fOutputLen = 0;
fChecksum = 0x00;
fChecksumGood = false;
} else {
fOutputLen = outByteIndex-1;
fChecksum = fOutputBuf[outByteIndex-1];
fChecksumGood = (checkSum == 0x00);
}
fStartSample = scanState.dataStart;
fEndSample = scanState.dataEnd;
/* we're done with this file; advance the start offset */
*pStartOffset = *pStartOffset + (initialLen - dataLen);
result = true;
bail:
delete[] buf;
delete[] sampleBuf;
return result;
}
void CassetteDialog::CassetteData::ConvertSamplesToReal(const WAVEFORMATEX* pFormat,
const unsigned char* buf, long chunkLen, float* sampleBuf)
{
int bps = ((pFormat->wBitsPerSample+7)/8) * pFormat->nChannels;
int bitsPerSample = pFormat->wBitsPerSample;
int offset = 0;
assert(chunkLen % bps == 0);
if (bitsPerSample == 8) {
while (chunkLen > 0) {
*sampleBuf++ = (*buf - 128) / 128.0f;
//LOGI("Sample8(%5d)=%d float=%.3f", offset, *buf, *(sampleBuf-1));
//offset++;
buf += bps;
chunkLen -= bps;
}
} else if (bitsPerSample == 16) {
while (chunkLen > 0) {
short sample = *buf | *(buf+1) << 8;
*sampleBuf++ = sample / 32768.0f;
//LOGI("Sample16(%5d)=%d float=%.3f", offset, sample, *(sampleBuf-1));
//offset++;
buf += bps;
chunkLen -= bps;
}
} else {
assert(false);
}
//LOGI("Conv %d", bitsPerSample);
}
/* width of 1/2 cycle in 770Hz lead-in */
const float kLeadInHalfWidth = 650.0f; // usec
/* max error when detecting 770Hz lead-in, in usec */
const float kLeadInMaxError = 108.0f; // usec (542 - 758)
/* width of 1/2 cycle of "short 0" */
const float kShortZeroHalfWidth = 200.0f; // usec
/* max error when detection short 0 */
const float kShortZeroMaxError = 150.0f; // usec (50 - 350)
/* width of 1/2 cycle of '0' */
const float kZeroHalfWidth = 250.0f; // usec
/* max error when detecting '0' */
const float kZeroMaxError = 94.0f; // usec
/* width of 1/2 cycle of '1' */
const float kOneHalfWidth = 500.0f; // usec
/* max error when detecting '1' */
const float kOneMaxError = 94.0f; // usec
/* after this many 770Hz half-cycles, start looking for short 0 */
const long kLeadInHalfCycThreshold = 1540; // 1 full second
/* amplitude must change by this much before we switch out of "peak" mode */
const float kPeakThreshold = 0.2f; // 10%
/* amplitude must change by at least this much to stay in "transition" mode */
const float kTransMinDelta = 0.02f; // 1%
/* kTransMinDelta happens over this range */
const float kTransDeltaBase = 45.35f; // usec (1 sample at 22.05KHz)
bool CassetteDialog::CassetteData::ProcessSample(float sample, long sampleIndex,
ScanState* pScanState, int* pBitVal)
{
if (pScanState->algorithm == kAlgorithmZero)
return ProcessSampleZero(sample, sampleIndex, pScanState, pBitVal);
else if (pScanState->algorithm == kAlgorithmRoundPeak ||
pScanState->algorithm == kAlgorithmSharpPeak ||
pScanState->algorithm == kAlgorithmShallowPeak)
return ProcessSamplePeak(sample, sampleIndex, pScanState, pBitVal);
else {
assert(false);
return false;
}
}
bool CassetteDialog::CassetteData::ProcessSampleZero(float sample, long sampleIndex,
ScanState* pScanState, int* pBitVal)
{
long timeDelta;
bool crossedZero = false;
bool emitBit = false;
/*
* Analyze the mode, changing to a new one when appropriate.
*/
switch (pScanState->mode) {
case kModeInitial0:
assert(pScanState->phase == kPhaseScanFor770Start);
pScanState->mode = kModeRunning;
break;
case kModeRunning:
if (pScanState->prevSample < 0.0f && sample >= 0.0f ||
pScanState->prevSample >= 0.0f && sample < 0.0f)
{
crossedZero = true;
}
break;
default:
assert(false);
break;
}
/*
* Deal with a zero crossing.
*
* We currently just grab the first point after we cross. We should
* be grabbing the closest point or interpolating across.
*/
if (crossedZero) {
float halfCycleUsec;
int bias;
if (fabs(pScanState->prevSample) < fabs(sample))
bias = -1; // previous sample was closer to zero point
else
bias = 0; // current sample is closer
/* delta time for zero-to-zero (half cycle) */
timeDelta = (sampleIndex+bias) - pScanState->lastZeroIndex;
halfCycleUsec = timeDelta * pScanState->usecPerSample;
//LOGI("Zero %6ld: half=%.1fusec full=%.1fusec",
// sampleIndex, halfCycleUsec,
// halfCycleUsec + pScanState->halfCycleWidth);
emitBit = UpdatePhase(pScanState, sampleIndex+bias, halfCycleUsec,
pBitVal);
pScanState->lastZeroIndex = sampleIndex + bias;
}
/* record this sample for the next go-round */
pScanState->prevSample = sample;
return emitBit;
}
bool CassetteDialog::CassetteData::ProcessSamplePeak(float sample, long sampleIndex,
ScanState* pScanState, int* pBitVal)
{
/* values range from [-1.0,1.0), so range is 2.0 total */
long timeDelta;
float ampDelta;
float transitionLimit;
bool hitPeak = false;
bool emitBit = false;
/*
* Analyze the mode, changing to a new one when appropriate.
*/
switch (pScanState->mode) {
case kModeInitial0:
assert(pScanState->phase == kPhaseScanFor770Start);
pScanState->mode = kModeInitial1;
break;
case kModeInitial1:
assert(pScanState->phase == kPhaseScanFor770Start);
if (sample >= pScanState->prevSample)
pScanState->positive = true;
else
pScanState->positive = false;
pScanState->mode = kModeInTransition;
/* set these up with something reasonable */
pScanState->lastPeakStartIndex = sampleIndex;
pScanState->lastPeakStartValue = sample;
break;
case kModeInTransition:
/*
* Stay here until two adjacent samples are very close in amplitude
* (or we change direction). We need to adjust our amplitude
* threshold based on sampling frequency, or at higher sample
* rates we're going to think everything is a transition.
*
* The approach here is overly simplistic, and is prone to failure
* when the sampling rate is high, especially with 8-bit samples
* or sound cards that don't really have 16-bit resolution. The
* proper way to do this is to keep a short history, and evaluate
* the delta amplitude over longer periods. [At this point I'd
* rather just tell people to record at 22.05KHz.]
*
* Set the "hitPeak" flag and handle the consequences below.
*/
if (pScanState->algorithm == kAlgorithmRoundPeak)
transitionLimit = kTransMinDelta *
(pScanState->usecPerSample / kTransDeltaBase);
else
transitionLimit = 0.0f;
if (pScanState->positive) {
if (sample < pScanState->prevSample + transitionLimit) {
pScanState->mode = kModeAtPeak;
hitPeak = true;
}
} else {
if (sample > pScanState->prevSample - transitionLimit) {
pScanState->mode = kModeAtPeak;
hitPeak = true;
}
}
break;
case kModeAtPeak:
/*
* Stay here until we're a certain distance above or below the
* previous peak. This also keeps us in a holding pattern for
* large flat areas.
*/
transitionLimit = kPeakThreshold;
if (pScanState->algorithm == kAlgorithmShallowPeak)
transitionLimit /= 4.0f;
ampDelta = pScanState->lastPeakStartValue - sample;
if (ampDelta < 0)
ampDelta = -ampDelta;
if (ampDelta > transitionLimit) {
if (sample >= pScanState->lastPeakStartValue)
pScanState->positive = true; // going up
else
pScanState->positive = false; // going down
/* mark the end of the peak; could be same as start of peak */
pScanState->mode = kModeInTransition;
}
break;
default:
assert(false);
break;
}
/*
* If we hit "peak" criteria, we regard the *previous* sample as the
* peak. This is very important for lower sampling rates (e.g. 8KHz).
*/
if (hitPeak) {
/* compute half-cycle amplitude and time */
float halfCycleUsec; //, fullCycleUsec;
/* delta time for peak-to-peak (half cycle) */
timeDelta = (sampleIndex-1) - pScanState->lastPeakStartIndex;
/* amplitude peak-to-peak */
ampDelta = pScanState->lastPeakStartValue - pScanState->prevSample;
if (ampDelta < 0)
ampDelta = -ampDelta;
halfCycleUsec = timeDelta * pScanState->usecPerSample;
//if (sampleIndex > 584327 && sampleIndex < 590000) {
// LOGI("Peak %6ld: amp=%.3f height=%.3f peakWidth=%.1fusec",
// sampleIndex-1, pScanState->prevSample, ampDelta,
// halfCycleUsec);
// ::Sleep(10);
//}
if (sampleIndex == 32739)
LOGI("whee");
emitBit = UpdatePhase(pScanState, sampleIndex-1, halfCycleUsec, pBitVal);
/* set the "peak start" values */
pScanState->lastPeakStartIndex = sampleIndex-1;
pScanState->lastPeakStartValue = pScanState->prevSample;
}
/* record this sample for the next go-round */
pScanState->prevSample = sample;
return emitBit;
}
bool CassetteDialog::CassetteData::UpdatePhase(ScanState* pScanState,
long sampleIndex, float halfCycleUsec, int* pBitVal)
{
float fullCycleUsec;
bool emitBit = false;
if (pScanState->halfCycleWidth != 0.0f)
fullCycleUsec = halfCycleUsec + pScanState->halfCycleWidth;
else
fullCycleUsec = 0.0f; // only have first half
switch (pScanState->phase) {
case kPhaseScanFor770Start:
/* watch for a cycle of the appropriate length */
if (fullCycleUsec != 0.0f &&
fullCycleUsec > kLeadInHalfWidth*2.0f - kLeadInMaxError*2.0f &&
fullCycleUsec < kLeadInHalfWidth*2.0f + kLeadInMaxError*2.0f)
{
//LOGI(" scanning 770 at %ld", sampleIndex);
pScanState->phase = kPhaseScanning770;
pScanState->num770 = 1;
}
break;
case kPhaseScanning770:
/* count up the 770Hz cycles */
if (fullCycleUsec != 0.0f &&
fullCycleUsec > kLeadInHalfWidth*2.0f - kLeadInMaxError*2.0f &&
fullCycleUsec < kLeadInHalfWidth*2.0f + kLeadInMaxError*2.0f)
{
pScanState->num770++;
if (pScanState->num770 > kLeadInHalfCycThreshold/2) {
/* looks like a solid tone, advance to next phase */
pScanState->phase = kPhaseScanForShort0;
LOGI(" looking for short 0");
}
} else if (fullCycleUsec != 0.0f) {
/* pattern lost, reset */
if (pScanState->num770 > 5) {
LOGI(" lost 770 at %ld width=%.1f (count=%ld)",
sampleIndex, fullCycleUsec, pScanState->num770);
}
pScanState->phase = kPhaseScanFor770Start;
}
/* else we only have a half cycle, so do nothing */
break;
case kPhaseScanForShort0:
/* found what looks like a 770Hz field, find the short 0 */
if (halfCycleUsec > kShortZeroHalfWidth - kShortZeroMaxError &&
halfCycleUsec < kShortZeroHalfWidth + kShortZeroMaxError)
{
LOGI(" found short zero (half=%.1f) at %ld after %ld 770s",
halfCycleUsec, sampleIndex, pScanState->num770);
pScanState->phase = kPhaseShort0B;
/* make sure we treat current sample as first half */
pScanState->halfCycleWidth = 0.0f;
} else
if (fullCycleUsec != 0.0f &&
fullCycleUsec > kLeadInHalfWidth*2.0f - kLeadInMaxError*2.0f &&
fullCycleUsec < kLeadInHalfWidth*2.0f + kLeadInMaxError*2.0f)
{
/* found another 770Hz cycle */
pScanState->num770++;
} else if (fullCycleUsec != 0.0f) {
/* full cycle of the wrong size, we've lost it */
LOGI(" Lost 770 at %ld width=%.1f (count=%ld)",
sampleIndex, fullCycleUsec, pScanState->num770);
pScanState->phase = kPhaseScanFor770Start;
}
break;
case kPhaseShort0B:
/* pick up the second half of the start cycle */
assert(fullCycleUsec != 0.0f);
if (fullCycleUsec > (kShortZeroHalfWidth + kZeroHalfWidth) - kZeroMaxError*2.0f &&
fullCycleUsec < (kShortZeroHalfWidth + kZeroHalfWidth) + kZeroMaxError*2.0f)
{
/* as expected */
LOGI(" Found 0B %.1f (total %.1f), advancing to 'read data' phase",
halfCycleUsec, fullCycleUsec);
pScanState->dataStart = sampleIndex;
pScanState->phase = kPhaseReadData;
} else {
/* must be a false-positive at end of tone */
LOGI(" Didn't find post-short-0 value (half=%.1f + %.1f)",
pScanState->halfCycleWidth, halfCycleUsec);
pScanState->phase = kPhaseScanFor770Start;
}
break;
case kPhaseReadData:
/* check width of full cycle; don't double error allowance */
if (fullCycleUsec != 0.0f) {
if (fullCycleUsec > kZeroHalfWidth*2 - kZeroMaxError*2 &&
fullCycleUsec < kZeroHalfWidth*2 + kZeroMaxError*2)
{
*pBitVal = 0;
emitBit = true;
} else
if (fullCycleUsec > kOneHalfWidth*2 - kOneMaxError*2 &&
fullCycleUsec < kOneHalfWidth*2 + kOneMaxError*2)
{
*pBitVal = 1;
emitBit = true;
} else {
/* bad cycle, assume end reached */
LOGI(" Bad full cycle time %.1f in data at %ld, bailing",
fullCycleUsec, sampleIndex);
pScanState->dataEnd = sampleIndex;
pScanState->phase = kPhaseEndReached;
}
}
break;
default:
assert(false);
break;
}
/* save the half-cycle stats */
if (pScanState->halfCycleWidth == 0.0f)
pScanState->halfCycleWidth = halfCycleUsec;
else
pScanState->halfCycleWidth = 0.0f;
return emitBit;
}
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