Phpanaly.wav file and draw a waveform in png format

Phpanaly.wave.png format waveforms are drawn and read from phpanaly.wav, and the waveforms in png format are drawn. the waveforms of audio files are analyzed and drawn using Php, which is rarely seen on the Internet. In fact, as long as you use Php fseek, fopen, fopen, pack/unpack functions, and powerful gd graphics libraries according to the wav file specifications, these are all very easy. "> <LINKhr

Using Php to analyze and draw the waveform of audio files is rarely seen on the Internet. In fact, it is 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. this is actually because Php uses perl and they provide methods to access complex binary data structures using scripting. 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)

　　

The following is a reference clip:

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?>