問78
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マルチメディアのファイル形式である MP3 はどれか。
平成21年度 春期 ITパスポート試験 問78
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 78
Incorrectア
Compression for G4 facsimile communication data means coding for black-and-white binary images, such as the MMR (Modified Modified READ) method, and it has nothing to do with MP3. MP3 is for audio and is not used for transmitting facsimile images.
- イ
正解 The correct answer is イ. MP3 stands for MPEG-1 Audio Layer-3, and it is the compression method that handles the audio (sound) part of the MPEG-1 video compression standard. It uses the characteristics of human hearing to discard frequency components that are hard to perceive and sounds that are masked by others, greatly reducing the amount of data. It is lossy compression (compression that cannot restore the original data exactly), and it can shrink audio of music-CD quality to about one tenth of its size. For this reason it has long been widely used in portable music players and music distribution services. Therefore the option that describes MP3 is イ, “a file compression format for audio data”.
Incorrectウ
The representative compression formats for color still-image data are JPEG (lossy) and PNG or GIF (lossless), not MP3. MP3 is not a format that handles still images.
Incorrectエ
The compression formats for digital video data are MPEG-1, MPEG-2, and MPEG-4 (such as H.264). MP3 only handles the audio part inside that MPEG-1 standard and does not handle the video itself. Note that its name resembles MPEG, which makes the two easy to confuse.
ここがポイント
- MP3 = MPEG-1 Audio Layer-3. Within the MPEG family of standards it is the lossy compression method in charge of “audio”, so its role differs from MPEG itself, which is for video.
- Memorize multimedia file formats grouped by data type: audio = MP3, AAC, WAV; still images = JPEG, GIF, PNG; video = MPEG, AVI, MP4; black-and-white binary facsimile = MH/MR/MMR.
用語