1687174미디(midi) 파일구조16871682010-01-22T14:12:33Zhttp://ec8.springnote.com/pages/16871742008-08-29T14:34:52Z<p>출처 : <a href="http://faydoc.tripod.com/formats/mid.htm">http://faydoc.tripod.com/formats/mid.htm</a></p>
<p>번역 : <a href="/pages/1093484" title="췌영" class="wiki">췌영</a></p>
<p> </p>
<h1>(.mid) 표준 미디 파일 구조</h1>
<p>표준 미디 파일은 어이 없는 놈이다. 전체적으로 볼때 어쩔 수 없는 것 처럼 보인다. 물론이다. 당신이 이것을 그렇게 보는것이 문제가 있는 것은 아니다. 음악작품을 다시 재생될 수 있는 형태로 묘사한다는 것은 결코 작은 일이 아니다. 그래서 복잡하긴 하지만, 미디파일의 포멧은 상당히 직관적으로 만들어져 있다. 난 이곳에 내가 미디파일의 전문가가 아님을 기록한다. 난 최근에 Gravis UltraSound board를 내 컴에 장착했고, 몇가지 미디 파일을 들어보고 생각했다. "내 미디 파일을 만들어 보고 싶어!"라고..열받는 몇시간이 지난 후, 난 이게 간단한 일이 아님을 알게됐다. 하지만 이 멍청한 파일포멧이 날 멈추게 할 수는 없었다. (더군다나, 난 와이프한테 컴퓨터는 절대 사용하기 어렵지 않다고 말했고, 난 거짓말쟁이를 싫어한다). 그러니까 이 문서에서 잘못된 정보를 찾거나 하면 나한테 알려주면 고치겠다. 이문서는 모든 미디 커맨드와 여러가지 가능성을 가진 미디 파일들을 커버하진 못한다. 이건 기본적인 미디파일을 만드려는 사람에게 유효한 문서이다.</p>
<h1>Overview</h1>
<p>미디(.MID) 파일은 기본적으로 2가지를 포함하고 있다. 그것은 Header chunk들과 Track chunk들이다. 섹션2 에서는 이 header chunks 에 대해서 이야기할거고 섹션3에서는 트랙청크에 대해서 이야기 할거다. 미디파일은 (파일포멧과 그 밖의 몇가지를 표현하는) 헤더청크가 '하나' 있다 (역: 뭐야 그럼 왜 복수표현을 쓴거야?) 하나의 트랙은 일종의 멀티 테입 덱 같은 거라소 생각하면 된다. (덱이 뭐임???). 각 트랙마다 목소리나 스태프 각 악기 원하는 뭐든 할당하면 된다.</p>
<p> </p>
<h1>Header Chunk</h1>
<p>Header chunk는 파이 앞부분에 나타난다. 그리고 파일을 3가지 방식으로 표현한다. 헤더청크는 언제나 다음과 같은 형태이다.</p>
<p>4D 54 68 64 00 00 00 06 ff ff nn nn dd dd<br /></p>
<p>맨 앞에 4바이트는 아스키 코드로 하면 "MThd"이다. 그리고 다음 4바이트는 헤더의 크기이다. (역.위에서는 0x06) 이것은 언제나 00 00 00 06 이다. 왜냐면 실제 헤더 사이즈는 언제나 6바이트이기 때문이다.</p>
<p> </p>
<p>ff ff 는 파일포멧이다. 여기에는 3가지 포멧이 들어갈 수 있다.</p>
<p><br /></p>
<table>
<tbody>
<tr>
<td>0</td>
<td>-</td>
<td>single-track</td>
</tr>
<tr>
<td>1</td>
<td>-</td>
<td>multiple tracks, synchronous</td>
</tr>
<tr>
<td>2</td>
<td>-</td>
<td>multiple tracks, asynchronous</td>
</tr>
</tbody>
</table>
<p>싱글 트랙은 말 그대로 하나의 트랙이다.</p>
<p> multiple tracks, synchronous 은 수직적으로 트랙들이 동기화 됨을 의미한다. 말하자면, 동시에 시작한다는 말이다, 그래서 음악의 각각 다른 파트를 묘사한다. multiple tracks, asynchronous 은 동시에 시작할 필요가 없고 비동기로 작동할 수 있다는 의미이다.</p>
<table>
<tbody>
<tr>
<td>nn nn</td>
<td>미디파일에 있는 트랙의 수이다.</td>
</tr>
<tr>
<td>dd dd</td>
<td>4분의 1노트에 얼마의 시간이 경과하는지 이다. (좀 있다 더 자세 설명하겠다)</td>
</tr>
</tbody>
</table>
<h1>Track Chunks</h1>
<p>헤더뒤의 나머지 부분들은 Track Chunks 들을 구성한다. 각 트랙들은 하나의 해더를 가지며, 우리가 좋아할만한 많은 미디 커맨드들을 가진다. 트랙에 달린 해더는 파일에 하나씩 있는 헤더랑 무척 비슷하다.</p>
<p><br />
4D 54 72 6B xx xx xx xx</p>
<p><br /></p>
<p>맨 앞에 4바이트는 아스키 코드로 "MTrk"이다 그뒤의 4바이트는 트랙의 (위 해더 길이를 포함하지 않는) 길이를 바이트단위로 알려준다.</p>
<p> </p>
<p><br />
Following the header are midi events. These events are identical to the actual data sent and received by MIDI ports on a synth with one addition. A midi event is preceded by a delta-time. A delta time is the number of ticks after which the midi event is to be executed. The number of ticks per quarter note was defined previously in the file header chunk. This delta-time is a variable-length encoded value. This format, while confusing, allows large numbers to use as many bytes as they need, without requiring small numbers to waste bytes by filling with zeros. The number is converted into 7-bit bytes, and the most-significant bit of each byte is 1 except for the last byte of the number, which has a msb of 0. This allows the number to be read one byte at a time, and when you see a msb of 0, you know that it was the last (least significant) byte of the number. According to the MIDI spec, the entire delta-time should be at most 4 bytes long.<br />
Following the delta-time is a midi event. Each midi event (except a running midi event) has a command byte which will always have a msb of 1 (the value will be >= 128). A list of most of these commands is in appendix A. Each command has different parameters and lengths, but the data that follows the command will have a msb of 0 (less than 128). The exception to this is a meta- event, which may contain data with a msb of 1. However, meta-events require a length parameter which alleviates confusion.<br />
One subtlety which can cause confusion is running mode. This is where the actual midi command is omitted, and the last midi command issued is assumed. This means that the midi event will consist of a delta-time and the parameters that would go to the command if it were included.</p>
<h1>Conclusion</h1>
<p>If this explanation has only served to confuse the issue more, the appendices contain examples which may help clarify the issue. Also, 2 utilities and a graphic file should have been included with this document:<br />
DEC.EXE - This utility converts a binary file (like .MID) to a tab-delimited text file containing the decimal equivalents of each byte.<br />
REC.EXE - This utility converts a tab-delimited text file of decimal values into a binary file in which each byte corresponds to one of the decimal values.<br />
MIDINOTE.PS - This is the postscript form of a page showing note numbers with a keyboard and with the standard grand staff. <a href="http://faydoc.tripod.com/formats/mid.htm#AppA"><span style="COLOR: #800080;">Appendix A</span></a></p>
<h1>MIDI Event Commands</h1>
<p>Each command byte has 2 parts. The left nybble (4 bits) contains the actual command, and the right nybble contains the midi channel number on which the command will be executed. There are 16 midi channels, and 8 midi commands (the command nybble must have a msb of 1). In the following table, x indicates the midi channel number. Note that all data bytes will be <128 (msb set to 0).</p>
<table>
<tbody>
<tr>
<td>Hex</td>
<td>Binary</td>
<td>Data</td>
<td>Description</td>
</tr>
<tr>
<td>8x</td>
<td>1000xxxx</td>
<td>nn vv</td>
<td>Note off (key is released)
<table>
<tbody>
<tr>
<td>nn</td>
<td>note number</td>
</tr>
<tr>
<td>vv</td>
<td>velocity</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>9x</td>
<td>1001xxxx</td>
<td>nn vv</td>
<td>Note on (key is pressed)
<table>
<tbody>
<tr>
<td>nn</td>
<td>note number</td>
</tr>
<tr>
<td>vv</td>
<td>velocity</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>Ax</td>
<td>1010xxxx</td>
<td>nn vv</td>
<td>Key after-touch
<table>
<tbody>
<tr>
<td>nn</td>
<td>note number</td>
</tr>
<tr>
<td>vv</td>
<td>velocity</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>Bx</td>
<td>1011xxxx</td>
<td>cc vv</td>
<td>Control Change
<table>
<tbody>
<tr>
<td>cc</td>
<td>controller number</td>
</tr>
<tr>
<td>vv</td>
<td>new value</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>Cx</td>
<td>1100xxxx</td>
<td>pp</td>
<td>Program (patch) change
<table>
<tbody>
<tr>
<td>pp</td>
<td>new program number</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>Dx</td>
<td>1101xxxx</td>
<td>cc</td>
<td>Channel after-touch
<table width="100%">
<tbody>
<tr>
<td>cc</td>
<td>channel number</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>Ex</td>
<td>1110xxxx</td>
<td>bb tt</td>
<td>Pitch wheel change (2000H is normal or no change)
<table>
<tbody>
<tr>
<td>bb</td>
<td>bottom (least sig) 7 bits of value</td>
</tr>
<tr>
<td>tt</td>
<td>top (most sig) 7 bits of value</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
<p>The following table lists meta-events which have no midi channel number. They are of the format:<br />
FF xx nn dd<br />
<br />
All meta-events start with FF followed by the command (xx), the length, or number of bytes that will contain data (nn), and the actual data (dd).</p>
<table>
<tbody>
<tr>
<td>Hex</td>
<td>Binary</td>
<td>Data</td>
<td>Description</td>
</tr>
<tr>
<td>00</td>
<td>00000000</td>
<td>nn ssss</td>
<td>Sets the track's sequence number.
<table>
<tbody>
<tr>
<td>nn</td>
<td>02 (length of 2-byte sequence number)</td>
</tr>
<tr>
<td>ssss</td>
<td>sequence number</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>01</td>
<td>00000001</td>
<td>nn tt ..</td>
<td>Text event- any text you want.
<table>
<tbody>
<tr>
<td>nn</td>
<td>length in bytes of text</td>
</tr>
<tr>
<td>tt</td>
<td>text characters</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>02</td>
<td>00000010</td>
<td>nn tt ..</td>
<td>Same as text event, but used for copyright info.
<table>
<tbody>
<tr>
<td>nn tt</td>
<td>same as text event</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>03</td>
<td>00000011</td>
<td>nn tt ..</td>
<td>Sequence or Track name
<table>
<tbody>
<tr>
<td>nn tt</td>
<td>same as text event</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>04</td>
<td>00000100</td>
<td>nn tt ..</td>
<td>Track instrument name
<table>
<tbody>
<tr>
<td>nn tt</td>
<td>same as text event</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>05</td>
<td>00000101</td>
<td>nn tt ..</td>
<td>Lyric
<table>
<tbody>
<tr>
<td>nn tt</td>
<td>same as text event</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>06</td>
<td>00000110</td>
<td>nn tt ..</td>
<td>Marker
<table>
<tbody>
<tr>
<td>nn tt</td>
<td>same as text event</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>07</td>
<td>00000111</td>
<td>nn tt ..</td>
<td>Cue point
<table>
<tbody>
<tr>
<td>nn tt</td>
<td>same as text event</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>2F</td>
<td>00101111</td>
<td>00</td>
<td>This event must come at the end of each track</td>
</tr>
<tr>
<td>51</td>
<td>01010001</td>
<td>03 tttttt</td>
<td>Set tempo
<table>
<tbody>
<tr>
<td>tttttt</td>
<td>microseconds/quarter note</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>58</td>
<td>01011000</td>
<td>04 nn dd ccbb</td>
<td>Time Signature
<table>
<tbody>
<tr>
<td>nn</td>
<td>numerator of time sig.</td>
</tr>
<tr>
<td>dd</td>
<td>denominator of time sig.
<table>
<tbody>
<tr>
<td>2</td>
<td>quarter</td>
</tr>
<tr>
<td>3</td>
<td>eighth</td>
</tr>
</tbody>
</table>
etc</td>
</tr>
<tr>
<td>cc</td>
<td>number of ticks in metronome click</td>
</tr>
<tr>
<td>bb</td>
<td>number of 32nd notes to the quarter note</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>59</td>
<td>01011001</td>
<td>02 sf mi</td>
<td>Key signature
<table>
<tbody>
<tr>
<td>sf</td>
<td>sharps/flats
<table>
<tbody>
<tr>
<td>-7</td>
<td>7 flats</td>
</tr>
<tr>
<td>0</td>
<td>key of C</td>
</tr>
<tr>
<td>7</td>
<td>7 sharps</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>mi</td>
<td>major/minor
<table>
<tbody>
<tr>
<td>0</td>
<td>major</td>
</tr>
<tr>
<td>1</td>
<td>minor</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td>7F</td>
<td>01111111</td>
<td>xx dd ..</td>
<td>Sequencer specific information
<table>
<tbody>
<tr>
<td>xx</td>
<td>number of bytes to be sent</td>
</tr>
<tr>
<td>dd</td>
<td>data</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
<p><br />
The following table lists system messages which control the entire system. These have no midi channel number. (these will generally only apply to controlling a midi keyboard, etc.)</p>
<table>
<tbody>
<tr>
<td>Hex</td>
<td>Binary</td>
<td>Data</td>
<td>Description</td>
</tr>
<tr>
<td>F8</td>
<td>11111000</td>
<td> </td>
<td>Timing clock used when synchronization is required.</td>
</tr>
<tr>
<td>FA</td>
<td>11111010</td>
<td> </td>
<td>Start current sequence</td>
</tr>
<tr>
<td>FB</td>
<td>11111011</td>
<td> </td>
<td>Continue a stopped sequence where left off</td>
</tr>
<tr>
<td>FC</td>
<td>11111100</td>
<td> </td>
<td>Stop a sequence</td>
</tr>
</tbody>
</table>
<p>The following table lists the numbers corresponding to notes for use in note on and note off commands.<br /></p>
<table width="100%">
<tbody>
<tr>
<td rowspan="2">Octave #</td>
<td colspan="12">Note Numbers</td>
</tr>
<tr>
<td>C</td>
<td>C#</td>
<td>D</td>
<td>D#</td>
<td>E</td>
<td>F</td>
<td>F#</td>
<td>G</td>
<td>G#</td>
<td>A</td>
<td>A</td>
<td>B</td>
</tr>
<tr>
<td>0</td>
<td>0</td>
<td>1</td>
<td>2</td>
<td>3</td>
<td>4</td>
<td>5</td>
<td>6</td>
<td>7</td>
<td>8</td>
<td>9</td>
<td>10</td>
<td>11</td>
</tr>
<tr>
<td>1</td>
<td>12</td>
<td>13</td>
<td>14</td>
<td>15</td>
<td>16</td>
<td>17</td>
<td>18</td>
<td>19</td>
<td>20</td>
<td>21</td>
<td>22</td>
<td>23</td>
</tr>
<tr>
<td>2</td>
<td>24</td>
<td>25</td>
<td>26</td>
<td>27</td>
<td>28</td>
<td>29</td>
<td>30</td>
<td>31</td>
<td>32</td>
<td>33</td>
<td>34</td>
<td>35</td>
</tr>
<tr>
<td>3</td>
<td>36</td>
<td>37</td>
<td>38</td>
<td>39</td>
<td>40</td>
<td>41</td>
<td>42</td>
<td>43</td>
<td>44</td>
<td>45</td>
<td>46</td>
<td>47</td>
</tr>
<tr>
<td>4</td>
<td>48</td>
<td>49</td>
<td>50</td>
<td>51</td>
<td>52</td>
<td>53</td>
<td>54</td>
<td>55</td>
<td>56</td>
<td>57</td>
<td>58</td>
<td>59</td>
</tr>
<tr>
<td>5</td>
<td>60</td>
<td>61</td>
<td>62</td>
<td>63</td>
<td>64</td>
<td>65</td>
<td>66</td>
<td>67</td>
<td>68</td>
<td>69</td>
<td>70</td>
<td>71</td>
</tr>
<tr>
<td>6</td>
<td>72</td>
<td>73</td>
<td>74</td>
<td>75</td>
<td>76</td>
<td>77</td>
<td>78</td>
<td>79</td>
<td>80</td>
<td>81</td>
<td>82</td>
<td>83</td>
</tr>
<tr>
<td>7</td>
<td>84</td>
<td>85</td>
<td>86</td>
<td>87</td>
<td>88</td>
<td>89</td>
<td>90</td>
<td>91</td>
<td>92</td>
<td>93</td>
<td>94</td>
<td>95</td>
</tr>
<tr>
<td>8</td>
<td>96</td>
<td>97</td>
<td>98</td>
<td>99</td>
<td>100</td>
<td>101</td>
<td>102</td>
<td>103</td>
<td>104</td>
<td>105</td>
<td>106</td>
<td>107</td>
</tr>
<tr>
<td>9</td>
<td>108</td>
<td>109</td>
<td>110</td>
<td>111</td>
<td>112</td>
<td>113</td>
<td>114</td>
<td>115</td>
<td>116</td>
<td>117</td>
<td>118</td>
<td>119</td>
</tr>
<tr>
<td>10</td>
<td>120</td>
<td>121</td>
<td>222</td>
<td>123</td>
<td>124</td>
<td>125</td>
<td>126</td>
<td>127</td>
<td colspan="4"> </td>
</tr>
</tbody>
</table>
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