I'm developing an embedded application where a device generates QR codes on an LCD screen.
the code generation part seems to work just fine, but I seem to have some trouble with decoding it.
I generate the QR code via the function
QRcode *qr = QRcode_encodeString8bit("http://some/url/", 0, QR_ECLEVEL_Q);
then convert it to a format that can be read by the image library to be displayed on the screen. However, while the "QR Droid" app on Android can read it and send me to the URL just fine, another one called "Qr Barcode Scanner" doesn't seem to recognize the code, even though it seems to detect the alignment points. Same goes for iOS - some apps read it fine and some apps just act like it's not a code.
What could be the possible cause of this problem? I tried different error correction levels and that's not it.
Thanks in advance for your replies..
Edit: Apparently the code was flipped horizontally. I changed how I convert it to a 16-bit image, and it worked. I'm putting down a code snippet for future reference, in case someone else stumbles upon the same issue.
QRcode *qr = QRcode_encodeString8bit(string, 0, QR_ECLEVEL_H);
int i, j;
for (i = 0; i < qr->width; i++) {
for (j = qr->width - 1; j >= 0; j--) { //flipped this
if (qr->data[(j * qr->width) + i] & 0x1)
*(qr_img++) = COLOR_16BIT_BLACK;
else
*(qr_img++) = COLOR_16BIT_WHITE;
}
}
In my case the code that works( compare with a qr code generator which outputs the same resoult) looks like this
QRcode *qr;
qr = QRcode_encodeString("ABC012345", 0, QR_ECLEVEL_H, QR_MODE_8, 1);
int i_qr, j_qr;
for (i_qr = 0; i_qr < qr->width; i_qr++) {
for (j_qr = 0; j_qr < qr->width; j_qr++) {
if (qr->data[(i_qr * qr->width) + j_qr] & 0x1)
printf("*");
else
printf(" ");
}
printf("\n");
}
#smparkes I'm not sure the QR code is flipped. zxing reads it OK, and it does not allow mirrored codes (not without TRY_HARDER).
Yes, mirror images of valid QR codes are never valid; rotations are. I suppose I would be surprised if the library just generates invalid QR codes all the time. QR Droid is just based on zxing too, so would be surprised if it goes out of its way to also read these invalid codes.
But then again the other bits of evidence suggest mirroring is the issue.
Related
Well, I certainly should go to python since I did several functions of this type, keyboard event and mouse event, but decide to try to learn the windows api.
My goal is to know when button 1 of the mouse is pressed.
I created this file in a very beginner way, it returns in mouseData only 0.
The curious thing is that whenever I run it, it flashes my monitor at short intervals in blinks, but between 1 second with it off. Very strange that, execution is not viable.
Could someone help me understand and try to execute to see if it is only here.
Code:
int main()
{
DWORD mouseData = 0;
MOUSEINPUT tagMouse;
tagMouse.dx = 0;
tagMouse.dy = 0;
tagMouse.mouseData = mouseData;
tagMouse.dwFlags = MOUSEEVENTF_XDOWN;
tagMouse.dwExtraInfo = 0;
INPUT tagInput;
tagInput.type = INPUT_MOUSE;
tagInput.mi = tagMouse;
while (true) {
if (GetAsyncKeyState(VK_DELETE)) break;
SendInput(1, &tagInput, sizeof(INPUT));
printf("KEYWORD: %d\n", mouseData);
Sleep(500);
}
system("pause");
return 0;
}
I can reproduce your reported 'symptoms' - and the effect is really brutal!
Now, while I cannot offer a full explanation, I can offer a fix! You have an uninitialized field in your tagMouse structure (the time member, which is a time-stamp used by the system). Setting this to zero (which tells the system to generate its own time-stamp) fixes the problem. So, just add this line to your other initializer statements:
//...
tagMouse.dwExtraInfo = 0;
tagMouse.time = 0; // Adding this line fixes it!
//...
Note: I, too, would appreciate a fuller explanation; however, an uninitialized field, to me, smells like undefined behaviour! I have tried a variety of other values (i.e. not zero) for the time field but haven't yet found one that works.
The discussion here on devblogs may help. This quote seems relevant:
And who knows what sort of havoc that will create if a program checks
the timestamps and notices that they are either from the future or
have traveled back in time.
I've been writing a program in C# that reads a .mov file. I'm able to parse through the entire thing, ignoring chunks I don't understand, and grabbing relevant info from chunks that I do.
What I'm trying to do is get the FPS from the file, but getting it hasn't been straightforward. I assume because the format can store many movies at different rates.
If someone could point me in the right direction, like which chunks (atoms) should I be looking at? I thought it was stts, but not all .mov files contain that chunk!
I was mistaken. The stts atom is always there, and that is where you get the information to calculate the FPS. The following code hasn't be thoroughly tested, but it did work with all the .mov files I have.
void ReadSTTS(BinaryReader reader)
{
int versionAndFlags = reader.ReadInt32(true);
int nEntries = reader.ReadInt32(true);
int sampleCount = 0;
int sampleDuration = 0;
for (int i = 0; i < nEntries; i++)
{
sampleCount += reader.ReadInt32(true);
sampleDuration += reader.ReadInt32(true);
}
FPS = (float)Math.Round((float)mediaTimeScale / ((float)mediaDuration / (float)sampleCount), 2);
}
mediaTimeScale and mediaDuration both come from the mvhd atom. ReadInt32(true) is an extension that changes the endianness, since I'm reading the .mov on a windows machine.
Good afternoon, I'm facing a problem on my c code and I don't know what is causing it.
Every time I try to print characters like these: "┌──┐" my program simply prints some strange characters, like on this screenshot:
I'm using Qt Creator on Windows, with Qt version 5.5.0 MSVC 64 bits. The compiler is the Microsoft Visual C++ Compiler 12.0 (amd64).
I tried changing the locale but with no success. The only way I found to print these characters was to define them as int variables with the ASCII code and printing them, but it led to some really extensive and ugly coding, like this:
int cSupEsq = 218; //'┌'
int cSupDir = 191; //'┐'
int cInfEsq = 192; //'└'
int cInfDir = 217; //'┘'
int mVert = 179; //'│'
int mHor = 196; //'─'
int espaco = 255; //' '
int letraO = 111; //'o'
//Inicia limpando a tela da aplicação
clrscr();
//Linha 1
printf("%c", cSupEsq);
for (i = 1; i < 79; i++) { printf("%c", mHor); }
printf("%c", cSupDir);
Is there any way I can make the program treat these characters correctly? What could be causing this problem?
Your solution to use the OEM code points is the right way to go, codepage 850/437 is the default code page for the console and therefore should work. You could also use SetConsoleOutputCP to ensure the correct code page is used for the console.
Having said that, what is happening when you do not use your workaround is that the source file is being saved using a different codepage ie. not codepage 850/437. The in memory representation of the source code is Unicode (probably UTF-8), when you save the file the in memory representation of the characters are mapped to the target code page for the file.
What you can do is to save the file using the 850/437 codepage as the target, I don't know how you do this in Qt Creator (If you can at all), in Visual Studio for example you can select the down arrow on the Save button and select "Save with encoding", you can then proceed to select the target codepage, in your case code page 850. This will ensure that the in memory code points are mapped correctly to the file to be compiled.
I hope that helps explain the issue.
It shouldn't be necessary to print the characters one at a time. Instead, you can use an escape sequence:
printf("\xDA\xBF\xC0\xD9\xB3\xC4\xFF");
I work in Code Composer Studio Version: 6.0.1.00040
with the card LCDK C6748, but I think this is a more general question, relating to CCS generally.
I'm trying to implement LMS for cancelling acoustic echoes,
this is the skeleton of my .c file:
void waitForInterrupt()
{
while (flag==0) {}
flag=0; // reach this line only when flag == 1
}
interrupt void interrupt4(void)
{
// Inputs
inputRight_micSignal = (float)input_right_sample();
// Outputs
outputLeft_referenceSignal= whiteNoiseSample;
codec_data.channel[RIGHT]= (uint16_t)outputRight_cleanedSound;
codec_data.channel[LEFT]= (uint16_t)outputLeft_referenceSignal;
output_sample(codec_data.uint);
flag = 1;
}
void main()
{
// variables decelerations
int i;
float filter_output;
// initialising filter coefficients
for (i=0 ; i<ADAPTIVE_FILT_SIZE ; i++) // initialise weights and delay line
{
w[i] = 0.0;
x[i] = 0.0;
}
// initialising the interrupt routine
L138_initialise_intr(FS_8000_HZ,ADC_GAIN_0DB,DAC_ATTEN_0DB,LCDK_MIC_INPUT);
while(1) // adaptive filtering routine
{
waitForInterrupt();
whiteNoiseSample = getPrnFiltered();
for (i = ADAPTIVE_FILT_SIZE-1; i > 0; i--) // update delay line - TDL:merge later with w loop (still make sure no magic NaN's appear)
{
x[i] = x[i-1];
}
x[0] = outputLeft_referenceSignal; // input to adaptive filter
filter_output = 0; //reseting filter output
// compute adaptive filter output
for (i = 0; i < ADAPTIVE_FILT_SIZE; i++)
filter_output += (w[i]*x[i]);
outputRight_cleanedSound = inputRight_micSignal - filter_output; // compute error
for (i = ADAPTIVE_FILT_SIZE-1; i >= 0; i--) // update weights and delay line
{
w[i] = w[i] + beta*outputRight_cleanedSound*x[i]; // w[i]+=beta*"error"*"reference"
}
from some reason when I put the arrays x[] and w[] in the "watch table"
and I suspend the running of the program (in order to examine w[] coefficients after awhile, I see that it is full of NaN's - while x[] contains "regular"
values.
when I put breakpoint inside the line where w[] is calculated:
w[i] = w[i] + beta*outputRight_cleanedSound*x[i]; // w[i]+=beta*"error"*"reference"
I see the flow goes there.
What could be the reason for the NaN's?
Is there a way to watch w[] in the "wach table"?
These three steps work for me:
1) First you need to make sure the variables are globally available (e.g. that they are not allocated on the stack).
2) You need to halt the processor before trying to read the variables. (In Debug view: Tools -> Debugger Options -> Auto Run and Launch Options).
3) Enable "halt the target before any debugger access" on the watch window and click the "auto-update" icon in the "Variables"-window.
I've uploaded a screenshot with red boxes around the stuff you need to touch.
See if that helps you :) Otherwise check out TI's Engineer2Engineer forum (E2E). In my experience the TI guys are quick to answer and I've gotten very competent help from them.
Tell me how it works for you :) ?
FWIW I'm using Code Composer Studio v.5.5.0.00077.
Hello I am studying for a test for an intro to C programming class and yesterday I was trying to write this program to print out the even prime numbers between 2 and whatever number the user enters and I spent about 2 hours trying to write it properly and eventually I did it. I have 2 pictures I uploaded below. One of which displays the correct code and the correct output. The other shows one of my first attempts at the problem which didn't work correctly, I went back and made it as similar to the working code as I could without directly copying and pasting everything.
unfortunately new users aren't allowed to post pictures hopefully these links below will work.
This fails, it doesn't print all numbers in range with natural square root:
for (i = 2; i <= x; i++)
{
//non relevant line
a = sqrt(i);
aa = a * a;
if (aa == i);
printf("%d ",i);
}
source: http://i.imgur.com/WGG6n.jpg
While this succeeds, and prints even numbers with natural sqaure root
for (i = 2; i <= x; i++)
{
a = sqrt(i);
aa = a * a;
if (aa == i && ((i/2) *2) == i)
printf("%d ", i);
}
source: http://i.imgur.com/Kpvpq.jpg
Hopefully you can see and read the screen shots I have here. I know that the 'incorrect code' picture does not have the (i/2)*2 == i part but I figured that it would still print just the odd and even numbers, it also has the code to calculate "sqrd" but that shouldn't affect the output. Please correct me if I'm wrong on that last part though.
And Yes I am using Dev-C++ which I've read is kinda crappy of a program but I initally did this on code::blocks and it did the same thing...
Please I would very much appreciate any advice or suggestions as to what I did wrong 2 hours prior to actually getting the darn code to work for me.
Thank you,
Adam
your code in 'that' includes:
if (aa == i);
// ^
printf(...);
[note the ; at the end of the if condition]
Thus, if aa == i - an empty statement happens, and the print always occures, because it is out of the scope of the if statement.
To avoid this issue in the future, you might want to use explicit scoping1 [using {, } after control flow statements] - at least during your first steps of programming the language.
1: spartan programmers will probably hate this statement
Such errors are common. I use "step Over", "Step Into", "Break Points" and "watch window" to debug my program. Using these options, you can execute your program line by line and keep track of the variables used in each line. This way, u'll know which line is not getting executed in the desired way.