問64
頻出度★☆☆
シンセサイザなどの電子楽器と PC を接続して演奏情報をやり取りするための規格はどれか。
平成24年度 春期 ITパスポート試験 問64
テクノロジ系情報メディア › マルチメディア技術
This question's explanation and your answers so far.
解説
問 64
Incorrectア
AVI (Audio Video Interleave) is a video file format that interleaves video data and audio data and stores them in a single file, and it has long been used on Windows. What it handles is already-recorded video and audio, not the performance instruction data sent from an electronic musical instrument. In addition, AVI is a file format for storage, not a standard for connecting an instrument to a PC, so it is wrong.
Incorrectイ
BMP (bitmap) is a still-image file format that records an image directly as a collection of pixels, and it is used as the standard image format on Windows. It is meant for saving still images and has nothing at all to do with sound or musical performance. It is also not used for connecting to an instrument, so it is wrong.
- ウ
正解 The correct answer is “ウ”, MIDI (Musical Instrument Digital Interface). MIDI is a standard defined for exchanging performance information between electronic musical instruments such as synthesizers and electronic pianos and a PC or other electronic instruments. It specifies both the hardware side, such as the connectors, and the software side, such as how the data is arranged. The performance information referred to here is not the sound itself (waveform data that records vibrations of the air), but data that expresses performance instructions: which pitch key was pressed and when (note on), when it was released (note off), how strongly it was pressed (velocity), which tone color to use (program change), what the tempo is, and so on. Think of it as digitizing the instructions written on a musical score and sending them as they are; the sound generator on the receiving side then produces sound exactly as instructed. Because only the instructions are sent, the amount of data is far smaller than waveform data, and afterwards the tone color, the tempo, or the pitch of a particular note can be edited individually. What the question asks for is a standard for “connecting” an electronic musical instrument and a PC and exchanging “performance information”, and among the choices only MIDI meets this condition.
Incorrectエ
MP3 (MPEG-1 Audio Layer-3) is an audio compression method and its file format. Through lossy compression that removes components which are hard for the human ear to hear, it makes the waveform data of audio smaller so that it can be stored and distributed. It is often contrasted with MIDI, but what MP3 handles is waveform data that records “the sound that was actually produced”, not performance information about “which note to sound and how”. Furthermore, MP3 is not a standard for connecting an instrument to a PC, so it is wrong.
ここがポイント
- MIDI is a standard for exchanging performance information (pitch, strength, length, tone color, tempo, and so on) between electronic musical instruments and a PC or a sound module. Because it handles performance instruction data rather than the sound waveform itself, the amount of data is small and the tone color or tempo can be edited individually afterwards. The key point is to remember it by contrast: MP3 and WAV, which also deal with sound, are recording formats for waveform data and therefore play a different role.
- Learn the representative multimedia file formats by organizing them by category: still images are BMP, JPEG, GIF, and PNG; video is AVI and MPEG; audio (waveform) is MP3 and WAV; and performance information is MIDI. If you have this classification in mind, you can narrow down the correct answer by using what the question deals with (a still image, video, audio, or performance information) as a clue.
用語