Phpanaly.wav file and draw a png pattern waveform

Php analyzes and draws the waveform of audio files, which is rarely seen on the Internet. It is really easy to use Php fseek, fopen, fopen, pack/unpack functions, and powerful gd graphics library according to wav file specifications. Many may be unfamiliar with the pack/unpack functions and use Php to analyze and draw audio file waveforms, which are rarely seen on the Internet. It is really easy to use Php fseek, fopen, fopen, pack/unpack functions, and powerful gd graphics library according to wav file specifications. Many may be unfamiliar with pack/unpack functions. this is because Php uses perl, which provides a method for accessing complex binary data structures using the scripting language. My simplified program can only process RIFF audio files in PCM format (which is also the most common wav format), without restrictions, but the bit rate (BitsPerSample) should be 16.

Here are wave file format and MicroSoft wave soundfile format for reference. Here is an actual example (for more information, see downloading and downloading)

1 2

3 function wav_graph ($ file, $ f = 0, $ w = 0)

4 {

5 global $ DATA_DIR;

6

7 if (! Is_file ($ file) return 0;

8 $ fp = fopen ($ DATA_DIR. $ file, 'r ');

9 $ raw = fread ($ fp, 36 );

10 $ str = '';

11 $ header = unpack ('a4riff/VSize/A4Wav/A4Head/VHeadSize/vPCM/vChannels/VSampleRate/VByteRate/vBlockAlign/vSampleBits ', $ raw );

12 foreach ($ header as $ k => $ v)

13 $ str. = $ k. ':'. $ v .'';

14 fseek ($ fp, 36 $ header ['headsize']-16 );

15 $ raw = fread ($ fp, 8 );

16 $ data = unpack ('a4data/VDataSize ', $ raw );

17 foreach ($ data as $ k => $ v)

18 $ str. = $ k. ':'. $ v .'';

19

20 $ B = $ header ['samples'];

21 $ c = $ header ['channels'];

22 $ l = $ B * $ c/8; // sample frame length in bytes

23 $ s = $ data ['datasize ']/$ l; // total number of samples

24 $ r = $ header ['samplerate'];

25 if ($ f) $ h = pow (2, $ B)/$ f;

26 else {$ h = 200; $ f = pow (2, $ B-1)/$ h ;}

27 if ($ w = 0) $ w = round ($ r/1000); // default to show 1 k sample frames per minute

28

29 header ('content-type: image/png ');

30 $ im = imagecreate ($ s/$ w, $ h * $ c * 2 );

31 imagecolorallocate ($ im, 0xff, 0xff, 0xff); // white bg

32 $ color = imagecolorallocate ($ im, 0, 0,255); // black

33 // imagestring ($ im, 5, 5, 5, $ str, $ color );

34

35 $ x = 0; $ y = array (); $ yn = array ();

36 for ($ I = 0; $ I <$ c; $ I) $ y [$ I] = $ h * $ I $ h;

37 $ n = $ l * $ w;

38 while (1)

39 {

40 if ($ s = 0) break;

41 if ($ s <$ n) $ n = $ s;

42 $ samples = fread ($ fp, 1000 * $ n );

43 if ($ samples === FALSE) break;

44 $ packed = unpack ('s * ', $ samples );

45 foreach ($ packed as $ k => $ v)

46 {

47 $ cnt = ($ K-1) % ($ w * $ l );

48 if ($ cnt> $ c-1) continue;

49 $ yn [$ cnt] = $ h * $ cnt $ h-$ v/$ f;

50 imageline ($ im, $ x, $ y [$ cnt], $ x 1, $ yn [$ cnt], $ color );

51 $ y [$ cnt] = $ yn [$ cnt];

52 $ x;

53}

54 $ s-= $ n;

55}

56

57 imagepng ($ im );

58 imagedestroy ($ im );

59}

60

61 // wav_graph('audio2.wav ');

62?>