2009年4月26日 星期日

聲音格式、取樣率及取樣量




What's Color depth or Bit Depth? for mid-term exam

Color depth or bit depth, is a computer graphics term describing the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. This concept is also known as bits per pixel (bpp), particularly when specified along with the number of bits used. Higher color depth gives a broader range of distinct colors.
Color depth is only one aspect of color representation (formally, the gamut: which colors can be expressed), expressing how finely levels of color can be expressed (formally, gamut depth); the other aspect is how broad a range of colors can be expressed. The RGB color model, as used below, cannot express many colors, notably saturated colors such as yellow. Thus, the issue of color representation is not simply "sufficient color depth" but also "broad enough gamut".

from http://en.wikipedia.org/wiki/Color_depth

「位元」 是二進制位的簡稱,是最小的單位來處理電腦的數據資料。一個單位元能處理兩個數值的其中之一(0或1),我們必須把位元繼續結合成為更大的單位,稱為「位元組」,以成為更有意義的數據分析,一個位元組能容納八個位元。 位元深度也稱為像素深度或色彩深度,是用來度量影像中每個像素有多少色彩資訊可用來顯示或列印。較大的位元深度 (每像素較多資訊位元) 表示數位影像中具有較多的可用顏色,而色彩表現也較正確。例如: 黑白:影像中的每一點,又稱為像素(pixel),只佔1 bit(0或1)。 灰階:影像中包含深淺不同的灰色,每個像素佔8 bits,每點有 2^8=256 種變化。 16色:影像中最多用到 16 種顏色,每個像素佔4 bits,每點有 2^4=16 種變化。 256色:影像中最多用到 256 種顏色,每個像素佔8 bits,每點有 2^8=256 種變化。 全彩:影像中最多用到 1677 萬種顏色,每個像素佔24 bits,每點有 2^24 = 1677 萬種變化。
from http://www.idsvision.com.tw/phpbb2/viewtopic.php?t=447

What's Audacity? for mid-term exam

Audacity
1, 是一個跨平台的聲音編輯軟體,用於錄音和編輯音訊,是自由開放源代碼的軟體。
2, 可在Mac OS X、Microsoft Windows、GNU/Linux和其它作業系統上運作。
資料來源 from http://zh.wikipedia.org/wiki/Audacity
3, 這是一個音波編輯的工具軟體,支援 WAV(*.wav)、AIFF(*.aif)、AU(*.au)、IRCAM(*.snd)、MP3(*.mp3)和 Ogg Vorbis(與MP3同級)等音效檔案。
4, The definitions below are partly taken from whatis.techtarget.com
(1)Channels
(2)Sample Rate 取樣率
a、Sample:做為名詞之用時,表示一段錄進來的聲音(Audio);
做為動詞使用時,則表示錄一段取樣聲音的錄音動作。
b、Sample Rate 取樣率
在音波數位化的過程中,我們把每秒鐘聲音的取樣次數多少,叫取樣率(sampling rate )。
from http://river.glis.ntnu.edu.tw/page/multimedia/08.pdf
數位聲音訊號,是將聲波分割並將每一個分割點數字化後的訊號。對於每一秒鐘的聲波分
割的次數,就是所謂的取樣頻率。
取樣頻率越大,表示對聲波的分割越細,這樣的數位聲訊就更逼近於原始的聲音。
取樣頻率是以
Hz(赫茲)為單位,1 Hz代表每秒取樣一次;而 1 kHz(仟赫茲)代表每秒取樣
1000次。
CD音質的取樣頻率是44.1 kHz,也就是每秒取樣44100次。而DVD的標準規格則是96 kHz
的取樣頻率。 from
http://www.rolandtaiwan.com.tw/glossary/s.htm
(3)Bit Depth ( digital audio) 取樣量 ,每秒鐘取樣所得的儲存資訊多少,叫取樣量(sampling size)。 from http://river.glis.ntnu.edu.tw/page/multimedia/08.pdf
In digital audio, bit depth describes the number of bits of information recorded for each sample. Bit depth directly corresponds to the resolution of each sample in a set of digital audio data. Common examples of bit depth include CD audio, which is recorded at 16 bits, and DVD-Audio, which can support up to 24-bit audio. from http://en.wikipedia.org/wiki/Audio_bit_depth
(4)Compression / CODECs
(5)Common Audio Formats

應用多媒體教學自由軟體

This is 教育部校園自由軟體應用諮詢中心
http://ossacc.moe.edu.tw/modules/tinyd1/index.php?id=90

What's Graphics? for mid-term exam

一、向量圖:
1.由點、線、面所構成,它是由數學的運算構成的,運用數學公式的方式來記算並記錄
2.檔案小,放大不失真。
3.存檔格式 .AI, .CDR, .FH, .XAR, .WMF, .EPS, .PDF
二、點陣圖:
1.由像素點所構成。
2.檔案大,放大會失真,真實呈現圖像。
3.存檔格式 .CPT .PSD .BMP .TIFF .JPG .GIF

What's Multimedia & Hypermedia? for mid-term exam

一、What's Multimedia?
(一)整合多媒體和應用軟體在資訊系統內。
(二)包括文字、圖形、聲音、動畫、影像。

二、What's Hypermedia?
(一)數位媒介-結合電腦和通訊
(二)交談式
(三)非線性
(四)使用多種媒體,能被整合及改編在一個多樣性的組合體。

What's RSS? for mid-term exam

一、 Really Simple Syndication 企業聯合組織化
二、真正簡易整合 (系統); 簡易供稿系統; 簡易訊息聚合
三、是一種可以把網頁最新頭條、內容或更新說明傳給眾多使用者的技術, 許多使用者對很喜歡某些網站或社群、部落格的內容, 但卻因這些內容來源更新不定期, 或使用者無暇天天造訪, 而電子報太多又造成困擾, 則RSS就成為更好的選擇。

What's Blogfolio? for mid-term exam

一、 Blog + Portfolio = Blogfolio

What Blog in education ? for mid-term exam

一、容易建立、編輯、更新。
二、容易分享想法及資源
三、非常有效率地和使用者互動。
四、寫作者更新文章不需要太豐富的程式設計技巧、知識、編排和FTP(檔案上傳)
五、Blog是不斷地由寫作者和閱讀者的想法和談話相互交織所組成,有相互激勵作用。
六、提供擁有讀者群給學生的寫作環境且教師和同學可給與回饋。

What's Blog? for mid-term exam

一、意義
(一) 一個網站。
(二) 結合text, images, 可連結其它blogs和web pages及其相關議題的媒體。
(三) Blog可擁有一個或一群寫作者,文章被按時間順序貼上。
(四) Blog有選擇性可公開或隱密。
二、一般blog的外貌
(一)標題
(二)時間
(三)連結
(四)分類
(五)搜尋
(六)RSS feeds
(七)評論
三、blog的特徵
(一)由一個人維護
(二)依日常講話方式寫作
(三)更新日期依一天為基準
(四)提供連結網路平台(環境)

2009年4月17日 星期五

Blog 應用在教學上

Why Use Blogs in the Classroom?
There are many reasons to use blogs in the classroom. The best reasons are that blogs are easy to edit, easy to share ideas and resources, and most of all they provide an audience for your student's writing where the audience is willing to share back their thoughts about the student ideas. Blogging provides a real audience, not just the instructor or classmates. An audience for a blog may include their parents, their peers, students and adults from other states or from around the world. Taken from Blogging for ELT
Fernette and Brock Eide's research (Brain of a Blogger) shows that bogs can:
Promote critical and analytical thinking
Be a powerful promoter of creative, intuitive, and associational thinking
Promote analogical thinking
Be a powerful medium for increasing access and exposure to quality information
Combine the best of solitary reflection and social interaction.

2009年4月16日 星期四

Potentials of Mobile Learning

Potentials of Mobile Learning
M-learning is the use of wireless devices like mobile phone, pda, palms, etc. in the learning process. It has its own distinction from the E-learning and I think it does origin from the D-learning, so it should have the strong backup since it has developed from dozens of decades ago. M-learning surely has great potential with the fast development of the modern technology for it is greatly related with the technology development. In the past, people can use send normal SMS to the others, then they send MMS, files with audio, video, and so on. So we can just easily predict that in the near future M-learning will be one of the greatest sections of learning. And with the fast development of electronic devices, learners can just probably give the voice order to conduct the class in a super fast speed and this can also provide with them larger screen for reading. Or learner can also be given the wireless glasses for class with a small handset to control and they can see all the class content images through their glasses. This may be like movie scenario to some people but you are not sure what is going to happen tomorrow, especially in such a period with electronic devices upgrading everyday.
Schools can use m-learning devices freely. Instead of busy writing down and downloading the assignments given by the teachers, students can directly get all the materials they need in their mobile devices sent by the teacher and their feedback can go to the teachers immediately. And the use of m-learning devices in schools can greatly cut down the need for new teachers while the effect of the class is still the same or even better. And most of the students would become more interested in the use of new devices.
But I guess each step in history has its own advantages and disadvantages, and the adoption of m-learning in schools is no exception. As many writers and instructor have mentioned, the technology itself is neither good nor bad. It is just how people make use of it. And there will be different principles and regulations for different level of students. For the small children, the strict regulation is inevitable since they have less self-control and self-discipline and they may abuse the devices without monitoring. For the adult students, they are encouraged to make full use of all the available resources and devices to greatly enhance the learning process. The mobile devices in school use in the future will be like the using of all the updated computers in each computer course at present and that may not be far away.

http://guoqiangcui.wordpress.com/2008/02/19/potentials-on-mobile-learning/

What is a Blog?

Blog 參考網址
A Weblog or blog is a frequently updated website that often resembles an online journal. It can be a frequently posted list of interesting web sites/resources or personal diary of events and thoughts, or a combination of the two. Unlike most Web sites, a blog is produced with an active writer in mind, one who creates in an online writing space designed to communicate an identity, a personality and most importantly, a point of view. Blogs might also include photos, audio and/or video.

Another quote from Support Blogging website: "In a broader and more educational system, blogs are about communicating. You observe your experience, reflect on it, and then write about it. Other people read your reflections, respond from their perspectives by commenting or writing their own blog article. You read their perspectives, often learn something through their eyes, and write some more.

一般Blog的面貌
1、 Headlines 標題
2、Time Stamps 記錄時間
3、Permanent links 固定的鏈結
4、Categories 分類
5、Searches 搜尋
6、RSS feeds 簡易供稿系統
7、Comments 評論

Blog的特徵
1、通常由一個人維護
2、以聊天的方式寫作
3、以每天為一個單位更新
4、提供超鏈結環境

2009年4月6日 星期一

Audacity 音效編輯軟體應用教學

參考網路教學 http://163.17.156.130/moodle/mod/book/view.php?id=2012

Audacity 音效編輯軟體

這是一個音波編輯的工具軟體,支援 WAV(*.wav)、AIFF(*.aif)、AU(*.au)、IRCAM(*.snd)、MP3(*.mp3)和 Ogg Vorbis(與MP3同級)等音效檔案。

Record live audio.
(1)Convert tapes and records into digital recordings or CDs.
(2)Edit Ogg Vorbis, MP3, and WAV sound files.
(3)Cut, copy, splice, and mix sounds together.
(4)Change the speed or pitch of a recording.
(5)Can import WAV, AIF, AU, MP3, and Ogg Vorbis audio formats.
(6)Can export audio in WAV, MP3, and Ogg Vorbis formats.

Downloading and Installing Audacity
Go to Audacity site at http://audacity.sourceforge.net/download/
Select your operating system to download the latest version of the free Audacity sound editor.

The definitions below are partly taken from whatis.techtarget.com
(1)Channels
(2)Sample Rate
(3)Bit Depth
(4)Compression / CODECs
(5)Common Audio Formats

Channels :
A stereo audio signal has two discreet channels of audio whereas a mono signal has only one. A stereo signal can be mixed down to a mono signal. An uncompressed stereo digital audio file will be twice the size of a mono file.
Sample Rate
Sample rate is the number of samples of a sound that are taken per second to represent the event digitally. The more samples taken per second, the more accurate the digital representation of the sound can be. For example, the current sample rate for CD-quality audio is 44,100 samples per second.

The more samples per second that are taken, the more accurate the digital representation is of the analog waveform. Each sample is really only a number that contains the amplitude value of a waveform measured over time. This brings us to bit-depth.
Bit Depth
Bit depth defines how many bits are used to describe each of the samples taken from the sample rate (above). It describes the potential accuracy of a digital audio file. Higher bit depth audio will sound better than smaller bit-depth audio. 8 and 16-bit audio are currently the most common sample sizes. 8-bit audio takes up less hard drive space but is inherently noisier than 16 or 24 bit-depth audio. CD quality is 16-bit.
Bit depth is frequently encountered in specifications for hardware and in the specifications for what kind of digital audio a piece of software can capture and process.

Compression and CODECs
Audio files should always be captured and edited at the highest bit-depth and sample rate available - usually 16-bit 44.1 kHz stereo audio on most consumer level hardware. However, once edited, it can compressed using a CODEC (compression / decompression algorithm) to decrease the size of the file. This is how an uncompressed digital audio file is converted into to a streaming audio file for the Web, as well.
Common Audio Formats
(1)WAV - A digital audio standard developed by Microsoft and IBM. One minute of uncompressed audio at CD quality (16-bit, 44.1 kHz stereo) requires about 10 MB of storage.
(2)AIFF - or "Audio Interchange File Format" - An audio file format developed by Apple computer. MP3 - MPEG-1 Audio Layer-3 - A common compressed audio format often used for sharing music across the web (both illegally and legally).
(3)AAC - Advanced Audio Coding - Used both for commercial DVDs and Apple's iTunes Music Store for purchased songs.
(4)WMA - Microsoft's Windows Media file format. Version 9 of Windows Media is the competitor to AAC for online music sales.