Chapter 17 Using Video and Audio
Video is the Java Media Player application used for viewing
or saving video data in several formats. The Java Media Player is automatically
launched once you select the Audio/Video menu option
from the Applications menu. This is the default unless
you select the Audio option to customize your environment.
Audio is a CDE Motif application for playing, recording, or saving audio
data in AU (Sun), WAV (PC), or AIFF (Macintosh) format.
Video
Overview
Use the Java Media Player for viewing multimedia files. The Java Media
Framework (JMF) is an application programming interface (API) for incorporating
media data types into Java applications and applets. It is specifically designed
to take advantage of Java platform features.
Java Media Player Main Window
All video functions start with the main window.
You can open a video file by choosing Open file from the File menu.
Once you open a file, the main window alters to display the file and a control
panel at the bottom of the screen.
The control panel consists of the following icons and their respective
functions:
Click this button to begin playing a file.
Click this button to pause a file.
This button indicates how far a file has played.
Click this button to alternatively turn on or turn off the sound.
Click this button to increase or decrease the volume.
Click this button to view information on a file.
Supported Media Formats
The Java Media Player supports the following formats:
Aiff (.aiff)
AVI (.avi)
Audio:
Video
-
Cinepak
-
Indeo (iv31 and iv32)
-
JPEG (411, 422, 111)
GSM (.gsm)
MIDI (.midi)
MPEG-1 (.mpg)
This format is not available on Solaris x86.
MPEG audio (.mp2)
This format is not available on Solaris x86.
Quicktime (.mov)
Audio:
Video:
-
Cinepak
-
H.261
-
H.263
-
Indeo (iv31 and iv32)
-
JPEG (411, 422, 111)
-
Raw
-
RLE
-
SMC
RMF (.rmf)
Headspaces Rich Media Format audio files.
RTP
Audio:
Video:
-
JPEG (411, 422, 111)
-
H.261
-
H.263
Sun Audio (.au)
Vivo (.viv)
Video: H.263
Wave (.wav)
Using the Java Media Player
The following tasks can be performed on multimedia files using JMF.
To Open a New Java Media Player
To Exit the Java Media Player
-
From the File menu, select Exit.
The Java Media Player server shuts down 15 seconds after the last player
exits.
To Open a File
To Close a File
-
From the File menu, select Close player.
This will close the file but will not exit the Java Media Player.
To Open a URL
To Play a File
-
From the File menu, select Open file.
-
Enter the path or folder name in the text field.
-
From the Files window, double click the file that you want to open.
To Stop or Pause a File
To Rewind a File
To Forward a File
The file will begin playing from the point you placed the slider.
To Adjust the Volume
You can either adjust or mute the volume for a file. To adjust the volume
of a file:
To select mute for a file:
To Set the Play Rate for a File
-
Place the cursor over the triangle on the lower left of the screen.
-
Right-click the mouse button.
-
From the pull-down menu select one of the options.
-
1/10 speed - 1/10th the original rate
-
Half speed - 1/2 the original rate
-
Normal speed - the original rate
-
Double speed - twice the original rate
-
Triple speed - three times the original rate
-
Quadruple speed - four times the original rate
To Alter the Screen Size
-
Place the cursor over the screen.
-
Right-click the mouse button.
-
From the pull-down menu select a zoom option:
-
Half Size - Shrinks the screen to half its original size
-
Normal - Alters the screen to accommodate the picture
-
Double Size - Expands the screen to twice its original size
-
Quadruple Size - Adjusts the screen to 4 times its original
size
To Display Information on a Video File
Starting and Quitting Audio
There are several ways to start Audio:
To Start Audio From the Front Panel
-
Click the Voice Note control on the Applications subpanel to start the
application.
Audio runs in note mode, and automatically starts recording.
-
Click the Stop button to stop recording.
To Start Audio From the Command Line
You can start Audio and open files directly from the command line.
Type sdtaudio to start Audio.
Or:
Type sdtaudio filename
to start Audio and open a specific file.
To Start Audio From the Workspace Programs Menu
-
Place the mouse pointer anywhere on the background of the desktop (the
workspace) and click mouse button 3.
The Workspace menu appears.
-
Choose Programs, and then choose Audio from the Programs submenu.
The Audio main window is displayed.
To Exit Audio
Choose Exit from the File menu or Close from the Window menu, or hold
down the Alt key and press the F4 key with the mouse cursor over the Audio
main window to exit Audio.
Audio Main Window
All Audio functions start with the main window. Open an audio file by
choosing Open from the File menu; record by choosing New from the File menu
and clicking the Record Audio button; set startup, recording, or playing options
by choosing the appropriate item from the Options menu.
Voice Notes
In the same way
as Text Note allows you to rapidly create small text files and display them
on the desktop, Voice Note allows you to record an audio message and save
it on the desktop for playing later. For example, you might want to record
the pronunciation of a foreign name, or a useful quotation which you don't
want to type.
The Voice Note control is located on the Applications subpanel of the
Front Panel. When you click the Voice Note control it runs the Audio application,
which immediately starts recording from your host's microphone. To stop recording,
you click the Stop button or exit the Audio application.
The sound file that is created is displayed on your desktop when you
exit the Audio application. You can remove it by choosing Remove From Workspace
from the right-mouse button popup menu. You can remove it from your file system
by deleting it from your home directory.
Caution –
If you click the Voice Note control and neglect to stop Audio,
it can record and save a huge file that may eventually use up all your disk
space.
Displaying the Waveform Window
An audio file can be displayed with or without a waveform displayed.
The waveform is a graphic depiction of the sound levels of an audio file.
To Display the Waveform Window
-
To show the waveform window, click the Show Wave Window button.
-
To hide the waveform window, click the button again.
The button is a toggle, changing from Show Wave Window to Hide Wave
Window and back again to Show Wave Window as it is clicked.
If stereo viewing is enabled, the window depicts levels and volume individually
for left and right channels.
To Start Audio With the Waveform Displayed
-
Choose Startup from the Options menu.
The Options dialog box is displayed, with Startup selected as the Category.
If the Options dialog box is already displayed, choose Startup from the Category
menu.
-
Click Waveform View Enabled or Stereo View Enabled.
-
Click OK.
The Options dialog box closes. The next time you start Audio the monaural
or stereo waveform will be displayed. The Stereo View Enabled button is inactive
if the current audio file is in monaural format.
Opening and Playing Audio Files
You can open an audio file from the Audio File menu or by dragging and
dropping it from File Manager onto Audio. Once you have opened an audio file
or recorded something, you can play it from the beginning or from any point
in the file. You can specify whether an audio file will be played automatically
when it is opened.
To Open an Audio File
-
Choose Open from the File menu or hold down the Control key and press
``o'' with the mouse cursor over the Audio main window.
The Audio-Open File dialog box is displayed.
-
Navigate to the folder where the audio file is located.
Navigate by selecting a folder in the Folders list or by entering a
folder name in the Enter path or folder name text field.
-
Optional. Type an audio-file suffix (au, wav, aiff)
after the asterisk (*) in the Filter field.
Only files with the specified suffix will be listed in the Files field.
-
Press Return or click Update to update the change in the folder location
or filter field.
-
Select a file from the Files list.
-
Double-click the file in the Files list or select it and click OK.
The selected file is opened. If Automatically play audio file on Open
is selected in the Options-Play dialog box, the audio file starts playing.
Audio automatically detects the type of device accessed. If Audio is
started with a play-only device, only playback options and output sources
are available. If audio is started with a record-only device, such as a microphone,
only record options and input sources are available.
To Open an Audio File With Drag and Drop
-
Open File Manager and navigate to the folder where the audio file is
located.
-
Drag the audio file icon from File Manager and drop it on the Audio
main window.
The Selected file is opened. If Automatically play audio file on Open
is selected in the Options-Play dialog box, the audio file starts playing.
To Specify Play Options
-
Choose Play from the Options menu.
The Options dialog box is displayed, with Play selected as the Category.
If the Options dialog box is already displayed, choose Play from the Category
menu.
-
Determine whether files should automatically play when they are opened.
-
Click Automatically play audio file on Open to automatically
play files when they are opened.
-
Deselect Automatically play audio file on Open if you do not
want files to automatically start playing when opened.
-
Move the Set Default Play Volume and Balance Audio Output sliders to
desired positions.
Position the mouse pointer over the slider and press mouse button 1
as you move the mouse to change slider positions.
-
Click OK to apply the specified values and close the Options dialog
box.
To Play an Audio File
Once you have recorded something or opened an audio file,
you can play it, as follows. You can play AU, WAV, or AIFF files.
-
Click the Play Audio button.
When you click Play Audio, play begins at the play pointer position.
The file is played from the beginning if it has just been opened or if you
have just created the recording. If you click the Stop Playing button during
play and then click Play Audio, play begins at the previous stop point.
Note that the Play Audio button is a toggle: before play, it is Play
Audio; during play, it is Stop Playing.
-
Optional. Move the play pointer to a new start
play position.
To move the play pointer to the beginning of the file, click the Go
to Start button.
To move the play pointer to the end of the file, click the Go to End
button.
To move the play pointer to a position within the file:
-
If the waveform is not displayed, drag the slider with mouse
button 1.
-
If the waveform is displayed, click anywhere in the waveform
window.
-
Optional. Adjust the output volume by clicking
on the Increase Volume or Decrease Volume buttons.
To mute the output, click the Turn Sound Off button.
-
To stop playing the file, click the Stop Playing button.
Note –
The Play buttons are inactive when no file has been loaded or
recorded.
Recording With Audio
You can record and save audio files in three formats.
To Specify Record Options
You can specify audio format, sample rate, encoding method, channels,
record volume, and input balance in the Options dialog box. You can also specify
whether you will specify the values when you start recording, or if the set
values will be used automatically when recording or if you will specify the
values when you start recording.
-
Choose Record from the Options menu.
The Options dialog box is displayed, with Record selected as the Category.
If the Options dialog box is already displayed, choose Record from the Category
menu.
-
Choose AU, WAV, or AIFF from the Audio Format menu.
AU, which is the default, is Sun audio format. WAV is Microsoft PC format.
AIFF is Macintosh audio format.
-
Choose samples per second from the Sample Rate menu.
8.000kHz is the default. Other rates fall in a range between 5.510kHz
and 48.000kHz.
-
Choose an encoding method from the Encoding menu.
Encoding method options include u-law, A-law, and linear PCM.
-
Choose Mono or Stereo from the Channels menu.
Choose Mono, the default, for single-track recording, or Stereo for
multiple channels.
-
Determine whether to use the selected recording options as the default
for new files.
-
To use the selected recording options as the default, click
Use selected recording options as default for new files.
-
To specify recording options when you click Record Audio,
click Ask me when I start recording.
-
Set default record volume and balance the audio input.
Position the mouse pointer over the slider and press mouse button 1
as you move the mouse to set the Default Record Volume and Balance Audio Input
sliders to desired positions.
-
Click OK to apply the specified values and close the Options dialog
box.
To Create a Recording
You can record Audio files from a microphone, line-in, or CD source.
-
Specify recording options.
-
Choose New from the File menu or hold down the Control key and press
``n'' with the mouse cursor over the Audio main window.
If a previous recording has not been saved, you are asked if you want
to save it.
-
Prepare to record.
Be sure that the selected input device is connected to your computer
and ready for transmission, and that the microphone or other input device
is on.
-
Click Record Audio button and start recording.
Speak, sing, or play into the microphone or start transmission of audio
from a line-in or CD source. Recording starts as soon as you click Record
Audio unless you have specified Ask me when I start recording in the Options-Record
dialog box.
-
When recording is complete, click the Stop Recording button.
-
Click Play Audio button to play what you have just recorded.
Note –
The Record Audio button, which becomes the Stop Recording button
during recording, is inactive if a file is open; the button's function is
not displayed in the current function area when it is inactive. Similarly,
the Play and Go to buttons are inactive when no audio file has been opened
or recorded.
To Save an Audio File or a Recording
You can save an existing audio file or a new recording in AU, AIFF,
or WAV format.
-
Choose Save As from the File menu or hold down the Control key and press
``a'' with the mouse cursor over the Audio main window.
The Audio - Save As dialog box will be displayed.
-
Specify the folder in which you want to save the file.
Change to a different folder, if you wish. Press Return or click Update
to update the folder location.
-
Choose a format (AU, WAV, or AIFF) from the Audio Format menu.
AU, which is the default, is Sun audio format. WAV is Microsoft PC format.
AIFF is Macintosh audio format.
-
Type a name in the Enter file name field.
Audio files are usually named with .au, .wav, or .aiff suffixes for easy identification.
To overwrite an existing file, select the file in the Files list.
-
Click OK to save the audio file or recording.
To Specify Input and Output Device Options
You can specify output (play) and input (record) devices for playing
and recording. Audio automatically detects the type of device accessed. If
Audio is started with a play-only device, only playback options and output
sources are available. If Audio is started with a record-only device, such
as a microphone, only record options and input sources are available.
-
Choose Devices from the Options menu.
The Options dialog box is displayed, with Devices selected as the Category.
If the Options dialog box is already displayed, choose Devices from the Category
menu.
-
Select Speaker, Headphone, or Line Out as Output Sources.
Note that you can select more than one output source. Only devices that
are installed on your computer are active.
-
Select Microphone, Line In, CD, or Codec Loopback as the Input Source.
Only devices that are installed on your computer are active.
-
Click OK to apply the specified values and close the Options dialog
box.
To Display Information About an Audio File
To view file information, choose Get Info from the File menu.
The File Information dialog box is displayed.
Audio provides the following information about the current file:
-
File name
-
File size in kilobytes
-
File length in seconds
-
Number of channels
-
Sample rate (in kilohertz)
-
Encoding (how many bits, what standard, etc.)
Audio Control
Audio Control enables you to control the volume and balance levels for
playback and recording. Please refer to the following illustration for an
example of the Audio Control window.
Menus
There are three menu items available:
-
File — controls whether or not you want Mixer Mode enabled
(the default is enabled). Mixer mode enables you to listen to two audio sessions
at once. For example, while listening to a Sun Microsystems broadcast you
will also be able to hear the tone alerting you that you have new mail. Refer
to the following illustration for an example of the Mixer mode enabled.
File is also where you will find the Exit command when you are ready
to quit Audio Control.
-
View — controls your audio input and output. Toggling
the Applications Control shows/hides (toggles) all Master and all Application
processes.
-
Help — provides you with assistance in all areas of
Audio Control. Refer to the following illustration for an example showing
the Help pull-down menu.
Using the Tabs
There are two tabs, Playback and Record. Audio Control detects the type
of device being used and displays the appropriate tab. The Playback window
appears if used with a play-only device, such as speakers. The Record tab
appears when used with a record-only device, such as a microphone.
If your device supports both play and record, you can switch between
adjusting Playback (Output) and Record (Input) by selecting the corresponding
tab (toggles). If you have the Playback tab selected when you check the Application
Controls box, the Application control box also displays. Refer to the following
illustration for an example of this.
Master Output
The following controls are provided on the Master Output window:
-
Output Source — contains a list of available output
sources. You check and uncheck sources to turn them on and off. Your choices
are Built-in Speaker, Headphone, and Line Out. This list can grow to accommodate
additional output devices. Volume and balance levels apply to all sources
simultaneously, not to individual sources to turn them on and off.
-
Volume slider —for setting the master volume for all
sources. The absolute level is displayed in a text label next to the control
(the value is 50 in the figure above.) The displayed value changes as the
slider is moved up and down.
-
Balance slider — for setting the balance for all sources.
-
Mute — for simultaneously muting all output sources.
Controlling Master Recordings
You can control master recording parameters on the Master Recording
window. Access it by selecting the Record tab at the top of the window.
Please refer to the following illustration for an example of this.
The controls provided are:
-
Master Input — contains a list of the available input
sources. You can choose only one input source at a time. The default choices
are Microphone, CD ROM, and Line In. This list can grow to accommodate additional
input device.
-
Gain (db) slider — for setting the master
gain (recording volume). The level is displayed next to the control (the value
is 50 in the previous figure.) The displayed value changes as the slider
is moved up and down.
-
Monitor slider — for adjusting the volume of the incoming
audio that is sent to the output device(s). It allows you to monitor the
audio as it is being recorded.
-
Balance slider — for setting the recording balance for
the selected source.
Controlling the Master and Application Output
The Playback tab lets you control individual process audio output parameters.
You can access it by selecting the Application Controls option from the
View menu when the Playback tab is active. The new controls provided are
exactly the same as those provided for the Master Output, with the exception
that they are provided for one process at a time, rather than for an entire
output device. Processes that are currently using audio are displayed in the
list box at the top of the panel. By selecting a process, you can individually
control the volume, balance, and muting of that process. If you have multiple
audio channels, you can customize the individual volume and balance of each
channel.
Recording Using the Master and Application Input
You can control individual process' audio input parameters using the
Master and Application Input screen. You access it by selecting the Application
Controls option from the View menu when the Record tab is active. Refer to
the following illustration for an example of this.
The controls provided behave exactly the same as those provided for
the Master Output, with the exception that they are provided for one process
at a time, rather than for an entire output device. Processes that are currently
using audio are displayed in the list box at the top of the panel. By selecting
a process, you can individually control the gain, and balance of that process.
The Monitor volume is controllable only at the master level, so there is
no Monitor Volume Slider on the Application Input panel.
Using the Status Dialog
This dialog allows you to view playback and recording status at the
master level for each process. You can access it by selecting Status from
the View menu. Audio Control detects the type of device in use. If the device
supports playback, the Playback Status appears, if the device supports recording,
the Record Status appears. Please refer to the following illustration.
The controls provided are:
-
Process List Box — this is a list of the items available
for status monitoring. You can choose to view Master status or to see status
for each of the running processes that are using dev/audio. You can choose
only one process (or Master) to monitor at a time. As you select items in
the list, the Playback and Record panes in the lower portion of the dialog
update to reflect the status for the selected item being monitored.
-
Continuous Update Checkbox — status is displayed at
the time the dialog was invoked, unless you check Continuous Update. If Continuous
Update is checked, the status for the selected process is continuously monitored
and updated.
-
Update Now Button — if Continuous Update is not turned
on, you can update the display by clicking Update Now. If Continuous Update
is turned on, the Update Now button is disabled (grayed out.)
The status of each of the following parameters being monitored and is
represented by either an LED icon in the on or off state, or a text string
with the details of the status item being displayed.
Playback and Record
-
Open — The device is open by a process. The device may
be opened read only, write only, or read and write. Which is why there is
an open for play and one for record. These will be used only when mixing
is disabled.
-
Paused — The applications has commanded the device to
pause playing or recording. Just like Open, you can have one direction paused
while the other is active. Also, this will be used only when mixing is disabled.
-
Active — Sound is being played or recorded. In mixer
mode this means at least one stream is playing or recording. It is possible
that other streams will be paused. When the mixer is off then there can be
only a single play and record stream, so this means that single stream is
active.
-
Underflow — When playing there wasn't enough audio available
so the device underflowed and there is silence. With the mixer this means
that the stream didn't have enough sound to mix into the audio stream that
is being played, so that one stream will have silence.
-
Open-Waiting — When the mixer is turned of this means
a process is trying to open the audio device and can't because another process
already has the device open. When the mixer is enabled it means a process
is either trying to open the audio device a second time for the same direction,
or the mixer is out of resources and is waiting for another process to close
the audio device and free up a resource for use.
-
EOF Count — When playing it is possible to mark the
audio stream so that you know when a segment has been played. This is done
by doing a zero sized write and accepting signal. Each time this marker is
encountered while playing the EOF Count will be incremented by one and a signal
will be sent to the application.
-
Samples — The number of sample frames that has been
played or recorded. A sample frame is all samples to play one sample time.
For example, playing a mono audio stream means that one sample frame has one
sample, but playing a stereo stream means that one sample frame has two samples.
One for the left channel and one for the right channel.
-
Encoding — This combines two audio format properties,
precision and encoding. Precision is the number of bits each sample uses.
We support 16 bits and 8 bits. The encoding method determines any processing
of the audio sample. This is usually done to compress the size of the audio
stream so not as much data needs to be sent over the network or stored on
disk. We support "linear" which is linear pulse code modulation, AKA linear
PCM. We also support u-Law (u is for the Greek letter mu, which can't be reproduces
in simple text like this, but it can in postscript), and A-Law. When combined
together with precision we support 16-bit Linear PCM, 8-bit Linear PCM, 8-bit
u-Law, and 8-bit A-Law. Also, linear PCM may be signed or unsigned, we support
only signed.
-
Sample Rate — The number of times a second the audio
stream is sampled and thus converted from an analog signal to a digital number
for recording. Or converted from a digital number to an analog signal when
playing. The higher the number the greater the accuracy of the digital signal.
But a higher number also means more disk space is needed for storage or network
bandwidth is needed to transfer the data.
-
Channels — The number of samples in a sample frame.
Currently we support 1 (mono) or 2 (stereo).
-
Close Button — Dismisses the Status dialog.
Dieses Buch im PDF-Format herunterladen (2840 KB)