Unformatted text preview: Audio in Flash CS5 Mary ET Boyle, Ph.D. Department of Cognitive Science, UCSD Flash and the audio formats:
mp3, wav, QuickTime, AIFF, AAC
• moving pictures expert group level‐2 layer‐3
• Cross platform standard
• Web and portable audio files wav
Waveform Audio File Fomat
• Microsoft and IBM audio file format standard
• Sample rates from 8 kilohertz (home phone quality) up to 48 kilohertz (DAT tapes).
• Can have bit depths from 8 to 32.
• Beware: can be really large files! QuickTime
• Apple’s solution to video and audio presentation
• .qt or .mov extension
• To create a QuickTime audio file, you need to make the movie self contained in QuickTime Pro AIFF
• Audio Interchange File Format
• Macintosh standard
• Same sample rates and bit depths as WAV format AAC
• Advanced Audio Coding
Newest standard Regarded to be better than MP3 formats
Widely used by: iTunes, PlayStation, Wii & iPhone • waveform • The higher the amplitude = the higher the pitch
• Audio is measured from peak to peak For any sound to be digitized, the wave needs to be sampled.
A sample is nothing more than a snapshot of a waveform between peaks at any given time. This snapshot is a digital number representing where, on the waveform, this snapshot was taken. How often the waveform is sampled is called the sample rate. Bit depth is the resolution of the sample.
A bit depth of 8 bits means that there are 256 potential samples between each peak. The greater the number of potential samples of a wave, the more accurate the sound. Downside: The more samples, the larger the file size! One wave cycle in 1 second is known as a hertz.
Audible sound uses thousands of these waves, and they are crammed into a 1‐
second time span and measured in that span. One thousand waveform cycles in 1 second is called a kilohertz (KHz) Audio CDs are sampled at 44.1 thousand waves per second (44.1 KHz). The two most common sound formats used in Flash are WAV and AIFF
Both based on the Interchange File Format (1985) Like video, audio contains a huge amount of data and must be compressed. Purpose of a codec.
enCODer/DECoder What makes MP3 files so small and good?
Perceptual encoding is the secret! Removes frequencies that are inaudible to the human ear. Perceptual encoders enable the user to decide on the bandwidth and sample rate. File > Import > Import to library Adding audio to flash.
Import to the Libary. When you open the Library and select the file, you will see the file’s waveform in the preview area.
To test the sound file, you can click on the Play button, which is the triangle located above the waveform in the preview area. Setting sound • In Library
properties • Dialog Box • Set to:
• MP3 The Sound Properties dialog box is opened when you double‐click an audio file in the Library. To preview and stop an audio file: click the Test
button – and then click Stop button to stop the playback.
If the audio file has been edited after being placed into Flash, you can click the Update
button to replace the imported copy with the edited version. Compression choices:
1. ADPCM: best suited for very short clips and looped sound.
2. MP3 Use for Flash Player v4 or newer. Not suited for looping sounds – b/c end of file is often padded.
3. Raw: No compression is applied. Best if Flash is for a DVD or CD.
4. 4. Speech – ideal for voice over narrations. Select MP3 for compression
Select: 48 kpbs
Select: Best in the Quality drop down menu.
Also select: Covert stereo to mono. File > Publish Settings > Flash event sound:
• Must load the sound completely event • As soon as the play head encounters the frame with this audio • Not locked to timeline continues Ideal for pops, clicks, and other very short sounds or in situations where the audio will be played more than once or looped. streaming sound:
• Can begin playing before fully loaded. streaming • Must be reloaded every time you want to play it. • Locked in step with timeline synced Ideal for longer background soundtracks that play only once.
Locked in step with the timeline, only realistic option for cartoon lip‐syncing. ...
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- Spring '08
- Hertz, File format, audio file, Waveform Audio File