https://wiki.freitagsrunde.org/index.php?action=history&feed=atom&title=C-Kurs%2FDTMF-Encoder%2FMusterl%C3%B6sung 2026-05-08T19:57:20Z Versionsgeschichte dieser Seite in FreitagsrundenWiki MediaWiki 1.31.16 https://wiki.freitagsrunde.org/index.php?title=C-Kurs/DTMF-Encoder/Musterl%C3%B6sung&diff=20395&oldid=prev 2013-03-05T17:37:14Z

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PaulG https://wiki.freitagsrunde.org/index.php?title=C-Kurs/DTMF-Encoder/Musterl%C3%B6sung&diff=14975&oldid=prev 2010-09-20T10:22:23Z

<p>Die Seite wurde neu angelegt: „&lt;pre&gt; #include &lt;stdlib.h&gt; #include &lt;stdio.h&gt; #include &lt;math.h&gt; unsigned char* generateSine(int ms, int freq, float amplitude, int *numSamples) { /* calculate...“</p> <p><b>Neue Seite</b></p><div>&lt;pre&gt;<br /> #include &lt;stdlib.h&gt;<br /> #include &lt;stdio.h&gt;<br /> #include &lt;math.h&gt;<br /> <br /> unsigned char* generateSine(int ms, int freq, float amplitude, int *numSamples) {<br /> /* calculate number of samples and factor for the sine function */<br /> *numSamples = ms * 8; // 8000 Hz sampling rate means 8 samples per millisecond<br /> double numPeriodic = 8000.0 / freq;<br /> double sinFac = 2 * M_PI / numPeriodic;<br /> <br /> unsigned char *sine = malloc(*numSamples * sizeof(unsigned char));<br /> <br /> /* generate samples */<br /> int i;<br /> for (i = 0; i &lt; *numSamples; i++) {<br /> double sineVal = sin(i * sinFac); // between -1 and 1<br /> unsigned char sample = (unsigned char) ((amplitude * sineVal + 1) * 0x7f);<br /> sine[i] = sample;<br /> }<br /> <br /> return sine;<br /> }<br /> <br /> unsigned char* mixPcm(unsigned char *a, unsigned char *b, int numSamples) {<br /> unsigned char *result = malloc(numSamples * sizeof(unsigned char));<br /> int i;<br /> for (i = 0; i &lt; numSamples; i++) {<br /> int aVal = a[i] - 127;<br /> int bVal = b[i] - 127;<br /> int rVal = aVal + bVal;<br /> result[i] = (unsigned char)(rVal + 127);<br /> }<br /> return result;<br /> }<br /> <br /> unsigned char* generateDtmfTone(int number, int ms, int *numSamples) {<br /> unsigned char *a;<br /> unsigned char *b;<br /> unsigned char *result;<br /> switch (number) {<br /> case 0:<br /> a = generateSine(ms, 941, 0.45, numSamples);<br /> b = generateSine(ms, 1336, 0.45, numSamples);<br /> break;<br /> case 1:<br /> a = generateSine(ms, 697, 0.45, numSamples);<br /> b = generateSine(ms, 1209, 0.45, numSamples);<br /> break;<br /> case 2:<br /> a = generateSine(ms, 697, 0.45, numSamples);<br /> b = generateSine(ms, 1336, 0.45, numSamples);<br /> break;<br /> case 3:<br /> a = generateSine(ms, 697, 0.45, numSamples);<br /> b = generateSine(ms, 1477, 0.45, numSamples);<br /> break;<br /> case 4:<br /> a = generateSine(ms, 770, 0.45, numSamples);<br /> b = generateSine(ms, 1209, 0.45, numSamples);<br /> break;<br /> case 5:<br /> a = generateSine(ms, 770, 0.45, numSamples);<br /> b = generateSine(ms, 1336, 0.45, numSamples);<br /> break;<br /> case 6:<br /> a = generateSine(ms, 770, 0.45, numSamples);<br /> b = generateSine(ms, 1477, 0.45, numSamples);<br /> break;<br /> case 7:<br /> a = generateSine(ms, 852, 0.45, numSamples);<br /> b = generateSine(ms, 1209, 0.45, numSamples);<br /> break;<br /> case 8:<br /> a = generateSine(ms, 852, 0.45, numSamples);<br /> b = generateSine(ms, 1336, 0.45, numSamples);<br /> break;<br /> case 9:<br /> a = generateSine(ms, 852, 0.45, numSamples);<br /> b = generateSine(ms, 1477, 0.45, numSamples);<br /> break;<br /> }<br /> result = mixPcm(a, b, *numSamples);<br /> free(a);<br /> free(b);<br /> return result;<br /> }<br /> <br /> unsigned char *generateSilence(int ms, int *numSamples) {<br /> *numSamples = ms * 8; // 8000 Hz sampling rate means 8 samples per millisecond<br /> unsigned char *result = malloc(*numSamples * sizeof(unsigned char));<br /> int i;<br /> for (i = 0; i &lt; *numSamples; i++) {<br /> result[i] = 127;<br /> }<br /> return result;<br /> }<br /> <br /> int main(int argc, char **argv) {<br /> if (argc != 2) {<br /> fprintf(stderr, &quot;no number given\n&quot;);<br /> return 0;<br /> }<br /> <br /> int number;<br /> if (1 != sscanf(argv[1], &quot;%u&quot;, &amp;number)) {<br /> fprintf(stderr, &quot;given argument is not a number\n&quot;);<br /> return 0;<br /> }<br /> <br /> FILE *f = fopen(argv[1], &quot;w&quot;);<br /> <br /> char *curNum = argv[1];<br /> while (*curNum != '\0') {<br /> int digit = *curNum++ - '0';<br /> <br /> int numSamples;<br /> unsigned char *tone = generateDtmfTone(digit, 800, &amp;numSamples);<br /> fwrite(tone, sizeof(unsigned char), numSamples, f);<br /> free(tone);<br /> tone = generateSilence(300, &amp;numSamples);<br /> fwrite(tone, sizeof(unsigned char), numSamples, f);<br /> free(tone);<br /> }<br /> <br /> fclose(f);<br /> }<br /> &lt;/pre&gt;</div>

Alexander Kührmann