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Use a helper function for validated BCD decoding.
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This means that all the VBI codes that use BCD now check whether all the
digits are valid.
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@atsampson
atsampson authored and Simon Inns committed Jan 2, 2020
1 parent 72cafd7 commit 8a245f2
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Showing 3 changed files with 83 additions and 107 deletions.
8 changes: 0 additions & 8 deletions tools/library/tbc/testvbidecoder/testvbidecoder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -99,10 +99,8 @@ void testDecode()
assertSame(decoder.decode(0, 0x80EEEE, 0), expected);
assertSame(decoder.decode(0, 0, 0x80EEEE), expected);

#if 0
// EE1015 - lead-out code in line 16
assertSame(decoder.decode(0x80EEEE, 0x80EEEE, 0), expected);
#endif
}

cerr << "IEC 60857-1986 - 10.1.3 Picture numbers\n";
Expand Down Expand Up @@ -169,10 +167,8 @@ void testDecode()
{
Vbi expected;

#if 0
// Ignore invalid second digit
assertSame(decoder.decode(0, 0x84ADDD, 0), expected);
#endif
}

cerr << "IEC 60857-1986 - 10.1.6 Programme time code\n";
Expand All @@ -190,12 +186,10 @@ void testDecode()
{
Vbi expected;

#if 0
// Ignore invalid digits
assertSame(decoder.decode(0, 0xFADD23, 0), expected);
assertSame(decoder.decode(0, 0xF1DDA3, 0), expected);
assertSame(decoder.decode(0, 0xF1DD2A, 0), expected);
#endif
}

cerr << "IEC 60857-1986 - 10.1.7 Constant linear velocity code\n";
Expand Down Expand Up @@ -309,13 +303,11 @@ void testDecode()
{
Vbi expected;

#if 0
// Ignore invalid digits
assertSame(decoder.decode(0x84E223, 0, 0), expected);
assertSame(decoder.decode(0x8EEA23, 0, 0), expected);
assertSame(decoder.decode(0x8EE2A3, 0, 0), expected);
assertSame(decoder.decode(0x8EE22A, 0, 0), expected);
#endif
}
}

Expand Down
181 changes: 82 additions & 99 deletions tools/library/tbc/vbidecoder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -138,49 +138,24 @@ VbiDecoder::Vbi VbiDecoder::decode(qint32 vbi16, qint32 vbi17, qint32 vbi18)

// IEC 60857-1986 - 10.1.3 Picture numbers ------------------------------------------------------------------------

// Check for picture number on lines 17 and 18
quint32 bcdPictureNumber = 0;

// Check line 17
if ((vbi17 & 0xF00000) == 0xF00000 ) {
bcdPictureNumber = vbi17 & 0x07FFFF;
if (((bcdPictureNumber & 0xF0000) >> 16) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x0F000) >> 12) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x00F00) >> 8) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x000F0) >> 4) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x0000F) >> 0) > 9) bcdPictureNumber = 0;

if (bcdPictureNumber == 0) qDebug() << "VbiDecoder::decode(): VBI picture number on line 17 corrupt";
}
// Check for CAV picture number on lines 17 and 18.
// The first digit is masked to be in the range 0-7, as the top bit was
// used to duplicate stop code signalling on early discs -- so the picture
// number is 0-79999.

// Check line 18
if (((vbi18 & 0xF00000) == 0xF00000 ) && bcdPictureNumber == 0) {
bcdPictureNumber = vbi18 & 0x07FFFF;
if (((bcdPictureNumber & 0xF0000) >> 16) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x0F000) >> 12) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x00F00) >> 8) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x000F0) >> 4) > 9) bcdPictureNumber = 0;
if (((bcdPictureNumber & 0x0000F) >> 0) > 9) bcdPictureNumber = 0;
if ((vbi17 & 0xF00000) == 0xF00000) {
if (decodeBCD(vbi17 & 0x07FFFF, vbi.picNo)) {
vbi.type = VbiDecoder::VbiDiscTypes::cav;

if (bcdPictureNumber == 0) qDebug() << "VbiDecoder::decode(): VBI picture number on line 18 corrupt";
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Picture number is" << vbi.picNo;
}
}

if (bcdPictureNumber != 0) {
// This code indicates a CAV disc
vbi.type = VbiDecoder::VbiDiscTypes::cav;
if ((vbi18 & 0xF00000) == 0xF00000) {
if (decodeBCD(vbi18 & 0x07FFFF, vbi.picNo)) {
vbi.type = VbiDecoder::VbiDiscTypes::cav;

// Peform BCD to integer conversion:
vbi.picNo =
(10000 * ((bcdPictureNumber & 0xF0000) / (16*16*16*16))) +
( 1000 * ((bcdPictureNumber & 0x0F000) / (16*16*16))) +
( 100 * ((bcdPictureNumber & 0x00F00) / (16*16))) +
( 10 * ((bcdPictureNumber & 0x000F0) / 16)) +
( ((bcdPictureNumber & 0x0000F)));

// IEC 60856 amendment 2 states maximum picture number is 79,999
if (vbi.picNo <= 0 && vbi.picNo >= 80000) {
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI picture number is" << vbi.picNo << "(out of range - set to invalid!)";
vbi.picNo = -1;
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Picture number is" << vbi.picNo;
}
}

Expand All @@ -198,50 +173,45 @@ VbiDecoder::Vbi VbiDecoder::decode(qint32 vbi16, qint32 vbi17, qint32 vbi18)

// IEC 60857-1986 - 10.1.5 Chapter numbers ------------------------------------------------------------------------

// Check for chapter number on lines 17 and 18
// Note: The allowed chapter number range is 0 to 79
quint32 bcdChapterNumber = 80;
// Check for chapter number on lines 17 and 18.
// The first digit is masked to be in the range 0-7, as the top bit is used
// to mark the first 400 tracks of the chapter -- so the chapter number is
// 0-79.

if ( (vbi17 & 0xF00FFF) == 0x800DDD ) {
bcdChapterNumber = (vbi17 & 0x07F000) >> 12;
} else if ( (vbi18 & 0xF00FFF) == 0x800DDD ) {
bcdChapterNumber = (vbi18 & 0x07F000) >> 12;
if ((vbi17 & 0xF00FFF) == 0x800DDD) {
if (decodeBCD((vbi17 & 0x07F000) >> 12, vbi.chNo)) {
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Chapter number is" << vbi.chNo;
}
}

if (bcdChapterNumber < 80) {
// Peform BCD to integer conversion:
vbi.chNo =
( 10 * ((bcdChapterNumber & 0x000F0) / 16)) +
( ((bcdChapterNumber & 0x0000F)));

if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Chapter number is" << vbi.chNo;
} else {
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Chapter number not found";
if ((vbi18 & 0xF00FFF) == 0x800DDD) {
if (decodeBCD((vbi18 & 0x07F000) >> 12, vbi.chNo)) {
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Chapter number is" << vbi.chNo;
}
}

// IEC 60857-1986 - 10.1.6 Programme time code --------------------------------------------------------------------

bool clvProgrammeTimeCodeAvailable = false;
// Check for programme time code on lines 17 and 18
if ( (vbi17 & 0xF0FF00) == 0xF0DD00 ) {
vbi.clvHr = (vbi17 & 0x0F0000) >> 16;
vbi.clvMin = (vbi17 & 0x0000FF);
clvProgrammeTimeCodeAvailable = true;
} else if ( (vbi18 & 0xF0FF00) == 0xF0DD00 ) {
vbi.clvHr = (vbi18 & 0x0F0000) >> 16;
vbi.clvMin = (vbi18 & 0x0000FF);
clvProgrammeTimeCodeAvailable = true;
// Check for CLV programme time code on lines 17 and 18.
// Both hour and minute must be valid for us to trust the code.

if ((vbi17 & 0xF0FF00) == 0xF0DD00) {
qint32 hour;
if (decodeBCD((vbi17 & 0x0F0000) >> 16, hour) &&
decodeBCD(vbi17 & 0x0000FF, vbi.clvMin)) {
vbi.clvHr = hour;
}
}

if (clvProgrammeTimeCodeAvailable) {
// Perform BCD conversion
vbi.clvHr =
( 10 * ((vbi.clvHr & 0x000F0) / 16)) +
( ((vbi.clvHr & 0x0000F)));
vbi.clvMin =
( 10 * ((vbi.clvMin & 0x000F0) / 16)) +
( ((vbi.clvMin & 0x0000F)));
if ((vbi18 & 0xF0FF00) == 0xF0DD00) {
qint32 hour;
if (decodeBCD((vbi18 & 0x0F0000) >> 16, hour) &&
decodeBCD(vbi18 & 0x0000FF, vbi.clvMin)) {
vbi.clvHr = hour;
}
}

if (vbi.clvHr != -1) {
// Set the type to CLV for the field as well
vbi.type = VbiDecoder::VbiDiscTypes::clv;

Expand Down Expand Up @@ -588,41 +558,31 @@ VbiDecoder::Vbi VbiDecoder::decode(qint32 vbi16, qint32 vbi17, qint32 vbi18)

// IEC 60857-1986 - 10.1.10 CLV picture number --------------------------------------------------------------------

// Check for CLV picture number on line 16
qint32 clvPictureNumber = 0;
// Check for CLV picture number on line 16.
// Both second and picture number must be valid for us to trust the code.

if ((vbi16 & 0xF0F000) == 0x80E000) {
clvPictureNumber = vbi16;
}
qint32 sec;

if (clvPictureNumber != 0) {
// Get the x1, x3, x4 and x5 parameters
qint32 x1 = (clvPictureNumber & 0x0F0000) >> 16;
qint32 x3 = (clvPictureNumber & 0x000F00) >> 8;
// The first digit of the second is A-F, rather than 0-5.
quint32 x1 = (vbi16 & 0x0F0000) >> 16;

qint32 x4 = (clvPictureNumber & 0x0000F0) >> 4;
qint32 x5 = (clvPictureNumber & 0x00000F);
if (x1 >= 0xA &&
decodeBCD((vbi16 & 0x000F00) >> 8, sec) &&
decodeBCD(vbi16 & 0x0000FF, vbi.clvPicNo)) {

vbi.clvSec = ((x1 - 10) * 10) + x3;
vbi.clvPicNo = (x4 * 10) + x5;
vbi.clvSec = (10 * (x1 - 0xA)) + sec;

// Set the type to CLV for the field as well
vbi.type = VbiDecoder::VbiDiscTypes::clv;

if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI CLV picture number is" <<
vbi.clvSec << "seconds," <<
vbi.clvPicNo << "picture number";
}
// Set the type to CLV for the field as well
vbi.type = VbiDecoder::VbiDiscTypes::clv;

// Output the disc type here, as the CLV time-code determination can change it
if (vbi.type == VbiDecoder::VbiDiscTypes::cav) {
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Disc type is CAV";
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI picture number is" << vbi.picNo;
} else {
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI Disc type is CLV";
if (verboseDebug) qDebug() << "VbiDecoder::decode(): VBI CLV picture number is" <<
vbi.clvSec << "seconds," <<
vbi.clvPicNo << "picture number";

// Invalidate the CAV picture number
vbi.picNo = -1;
// Invalidate the CAV picture number
vbi.picNo = -1;
}
}

return vbi;
Expand Down Expand Up @@ -665,3 +625,26 @@ bool VbiDecoder::parity(quint32 x4, quint32 x5)
if (x51p && x52p && x53p) return true;
return false;
}

// Decode a BCD number from bcd into output.
// Returns true on success; if any digits aren't in the range 0-9, returns
// false and does not modify output.
bool VbiDecoder::decodeBCD(quint32 bcd, qint32 &output)
{
qint32 value = 0;

quint32 place = 1;
while (bcd != 0) {
quint32 digit = bcd & 0xF;
if (digit > 9) {
return false;
}

value += digit * place;
place *= 10;
bcd >>= 4;
}

output = value;
return true;
}
1 change: 1 addition & 0 deletions tools/library/tbc/vbidecoder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,7 @@ class VbiDecoder
private:
bool verboseDebug;
bool parity(quint32 x4, quint32 x5);
bool decodeBCD(quint32 bcd, qint32 &output);
};

#endif // VBIDECODER_H

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