BTV
Version
6.0b3
User Manual
Written by Ben Bird
Contents
Introduction
BTV is an application for the Macintosh that allows you to view and capture live video and audio. It is compatible with a variety of video input devices including DV camcorders, USB and FireWire webcams, and PCI video input cards.
Viewing Video
Viewing modes
Live video can be displayed either in a window that can be resized and dragged around the screen, or full screen on an entire monitor. You can adjust the size and mode of the video display using the Video size menu:
There are five preset video sizes. Initially the capabilities of your video hardware will determine which sizes are set up. These video sizes apply to both window mode and full screen mode. You can enter your own values for these preset sizes by selecting Video sizes... from this menu.
When you switch to full screen mode, the Go to full screen mode item changes to Go to window mode, allowing you to switch back to window mode. When in full screen mode you can select the Fill the screen with video option - BTV will attempt to fill the screen with as much video as possible (depending on your screen resolution and capabilities of your video hardware).
Viewing 16:9 widescreen video
Video normally has an aspect ratio of 4:3, however widescreen video has a wider aspect ratio of 16:9. Since most video inputs are designed to work with 4:3 video, when viewing widescreen video there will be black borders at the top and bottom of the video image. BTV can crop the top and bottom of the video to remove these borders. You can turn this option on and off by selectingVideo sizes from the Video size menu (see the screenshot below).
If you are viewing widescreen video from a DV source on a widescreen monitor (such as the Apple Cinema Display) you can display the video fullscreen by doing the following: turn on cropping for widescreen video in the Video Sizes window (below), switch to full screen mode, and then select Fill the screen with video from the Video size menu. This setup only needs to be done once.
Multiple monitor support
If you have more than one monitor attached to your computer you can view full screen video on any monitor. You can choose which monitor displays full screen video using the Full screen monitor item in the Video size menu.
QuickTime Movies
The QuickTime Movie file format
Invented by Apple Computer, the QuickTime Movie file format is industry standard for storage, transfer and playback of various media on Macintosh Computers, and it is also widely used on Microsoft Windows PCs. It is a very flexible file format that has ability to store many different types of time based media such as video, sound, text, video effects, MIDI data, time code, and animations. BTV creates QuickTime movie files containing video and sound.
Virtually all video-related Macintosh software works with QuickTime files, so you can capture video with BTV and then open it with another video application. Also, BTV can open any QuickTime movie made by any other application.
A movies does not necessarily contain all of its data in a single file; it may contain references to several other movie files, or references to data elsewhere in the movie. This is useful because it allows data to be included in movies without increasing the movie's file size, since the data isn't actually in the movie itself but rather pointed to by a reference. BTV creates references when you use copy-and-paste operations to edit movies.
If you have a movie that contains references to other files then all the files must be present for the movie to be played back properly. When you open such a movie BTV attempts to find all the files; if any of the files cannot be found you will be asked to find them manually. To make a movie self contained with no references to other files, select Save as... from the File menu and turn on the Flatten option.
Transferring files to a Microsoft Windows PC
In order for a Windows PC to play back QuickTime movies, it must have QuickTime installed - this can be obtained from Apple. In addition, in order for the PC to be able to recognise a particular file, the file must have the correct file extension (.jpg .mov .dv etc.). File extensions can be added for you automatically if this option is set in the Preferences).
Fast Start movies
This is a method of saving a QuickTime movie in such a way that it can be played at the same time as it is being downloaded from a network (such as the Internet). You can create Fast Start movies by using the Export Movie... command from the File menu.
Streaming
Streaming is the process of playing a movie while it is being received over a network from a remote location (for example, over the Internet). This is different from Fast Start movies; the streamed video is transferred over the network in real time and is not saved to the computer's hard disk. Streamed video is broadcast by a Streaming Server.
To create movies that can be streamed by a Streaming Server, first choose suitable video and sound compression codecs (for more information about this topic see this section of the manual). Then export the movie as a Hinted Movie. This adds an extra "hint track" to the movie that enables the Streaming Server to stream the movie over the network. To export the movie in order to add a hint track, choose Export movie... from the File menu.
Compression Settings
There are a variety of compression settings that can be used for the capture of video, sound and still images. These can be configured by selecting Compression Settings from the Settings menu:
Video: Codec
This menu allows you to choose from the standard QuickTime video compression codecs. The codec chosen here is used whenever frames are being added to movies: normal movie capture, adding individual frames to movies, motion detection capture and time lapse capture. See below for detailed information about each compression codec available. If you choose the No recompression item from this menu, then the video data from the video input device is captured directly to the movie file with no recompression. This results in the highest quality capture with the best performance, however the resulting captured files will typically be very large (how large depends on the video format supplied by your video input device: DV devices supply already-compressed video and this will resut in reasonaly-sized captured files, however other devices supply completely uncompressed video and this will result in very large captured files).
Compression is a method of reducing the storage space needed for an image (or a frame of video in this case) while maintaining quality as much as possible. There is always a tradeoff between storage space and image quality. Compression methods are referred to as "codecs" because they specify both a compression and a decompression scheme.
Compression can significantly reduce the size of captured files. A measure of the amount of compression provided by the codec is the compression ratio. For example, if a compressed image uses half its original storage space then the compression ratio is 2:1.
Compression codecs are either lossless or lossy. A lossless compression codec is one that does not lose any data when it compresses an image – the original image can be perfectly reconstructed from the compressed data. Conversely, a lossy compression codec is one that loses data when it compresses an image – the original image can never be reconstructed perfectly from the compressed data.
Lossless compression codecs are suited for computer-generated images where there are large areas of constant colour. Lossy compression codecs need to be used to obtain good compression ratios for a photograph-type image, such as one in a stream of live video. Most compression codecs are lossy.
Note that each time an image is compressed by a lossy compression codec it loses some quality, so it is desirable to keep the number of times it is compressed as low as possible. If you are capturing video (or images) that are likely to be recompressed by a lossy compression codec in the future is it a good idea to choose a lossless (or at least high quality lossy) compression codec for the initial compression. This produces high file sizes initially but ensures that the quality of the final output is as high as possible.
For a list of available video codecs click here.
Video: Codec quality
Most codecs have a quality setting. The higher this setting the better quality the resulting image, but the more storage space is used. For compressing video to be sent over the Internet it is generally best to use a medium quality setting so that the resulting movie is reasonably small.
Video: Color depth
Some compression codecs support several different colour depths. Generally, the lower the colour depth the smaller the resulting file size but the lower the quality. Colour depths are named by the number of colours that are used in the image, for example 16 grays, 256 colors, thousands, millions etc.
If you choose Auto, BTV will pick the best color depth available that is supported by both the video input device and the compression codec.
Video: Frame rate
You can enter a desired frame rate here for captured video. This frame rate applies to normal video capture as well as motion detection capture.
If you leave this box empty, video is captured at the maximum possible rate. The maximum rate you will be able to obtain depends on your video input hardware, the speed of your computer and hard disk, and the type of compression codec in use. Reducing the frame rate proportionally affects the file size of the captured video, so for transmission of video over the internet it is advisable to limit the frame rate so that the file size of the resulting movie is reasonably small.
Video: Key frame rate
Entering a key frame rate allows you to use temporal compression. Depending on the content, video can have a high level of temporal redundancy, that is, very often one frame is quite similar to the next frame. Temporal compression exploits this redundancy to reduce the file size of the resulting movie. The success of temporal compression depends very much on the content of the video; if adjacent frames are very similar then file sizes can be significantly reduced but if adjacent frames in the video are generally quite different then the video is not suitable for temporal compression.
Temporal compression works by using "key frames" at regular intervals, followed by several "delta frames". The key frames contain the complete video image, the delta frames only contain the portions of the image that have changed since the last key frame.
For codecs that support temporal compression (for example MPEG-4), you can enter a key frame rate here. Note that the key frame rate that you enter here is the minimum key frame rate that is used; if the compressor codec decides that more key frames should be used it will do so (for example, if there is a segment of the video with a low temporal redundancy many key frames will be used but a different segment of the video with high temporal redundancy only the specified rate of key frames will be used).
Video: limit data rate
Some codecs allow you to enter a value here to limit the data rate (also referred to as the "bit rate"). This is useful when creating a movie that will be transferred of streamed over the Internet, so that you can make sure that the file size of the resulting movie fits a particular requirement. When you enter a value in this field the codec will automatically adjust its quality setting during compression to try to obtain the desired data rate.
Video: Options button
Some video codecs have extra configuration options; click this button to display and configure these options.
Video: Advanced
Click this button to display advanced video compression options. Currently there is one advanced option: Quality setting for decompressing incoming video. If the video input device is supplying compressed data, a software decompressor component is used to decompress this data so that it can be processed and/or displayed to the screen. This software decompressor may have several quality settings to adjust the quality/speed tradeoff when decompressing the video. For example, the Apple DV decompressor (which is used by BTV for decompressing video from DV devices) has a low quality mode (quality less than 50) that only uses a quarter of the DV data which is therefore faster.
Sound: Codec
This is similar to image compression in that sound compression reduces the data rate of digital audio at the expense of quality, but since sound is continuous (not discrete, like frames of video) it cannot be temporally compressed and all sound compression schemes are lossy.
The best sound compression schemes work on a principal known as "Perceptual Encoding". The idea is that the codec removes the data in the sound that humans cannot hear, therefore significantly reducing the amount of data while maintaining sound quality. Perceptual Encoding schemes can achieve very high compression ratios (10:1 or higher) without much loss of quality. The audio codecs available in BTV that use perceptual encoding are called "QDesign Music" and "Qualcomm PureVoice".
If you choose 'No recompression' from this menu, then the sound is captured directly from the sound input device with no additional software recompression. This generally results in the highest quality capture with the best performance.
For a list of available sound codecs click here.
Sound: Sample rate
Sound is continuous variations in air pressure that is converted to an analogue electrical signal by a microphone, and finally sampled and stored by the computer. When a sound wave is recorded on a computer it undergoes sampling. That is, at regular intervals the value of the sound wave is measured and stored, so that the computer builds up a digital representation of the sound wave.
The higher the sample frequency the more of the audio spectrum is accurately recorded. Using low sample rates cause noise to be introduced into the signal and reduces the range of audio frequencies that can be represented by the samples, so it is desirable to use a high sampling rate for best quality. 44kHz is the sample rate used in audio CDs and it can accurately reproduce the entire audio frequency range of human hearing.
The sampling rates that are supported in the hardware of the sound input device appear in the menu in bold text - other sample rates will have to be converted to in software.
Sound: Format
The other factor that determines the quality of sampling is the sample size. Each sample is stored on the computer as a number of bits. The higher the number of bits used to store a sample the more accurate the sampling is. Using a low number of bits introduces what is called "quantisation noise" into the sound. Audio CDs use 16 bit sample sizes.
Recording in stereo uses two sound channels and therefore uses more storage space, so if you are using a mono sound source it is best to switch this setting to mono.
As for the sample rate, the formats that are supported directly by the sound input device are listed in the format menus in bold text.
Sound: Options button
Some sound codecs have extra configuration options. Click this button to display and configure the codec's extra options.
Still image: Format
This menu allows you to choose the format that BTV uses when capturing still images. For a list of available still image formats click here.
Still image: Options button
Click this button to configure settings for the still image format. The settings window is specific to the format that you have selected, but generally it will contatain color depth settings.
Settings for sending files over the internet
Although the speed of internet connections are getting faster all the time, the majority of people around the world use modems for connecting to the internet. Sending large files (such as movies and images) over a slow modem connection can take a SInt32 time, so it is necessary to make the file sizes of your movies and images small before you send them over the internet. The following settings are suggested:
Use the JPEG format for still images. This produces small files and since JPEG is such a popular file format (on both Mac and PC) there should be no problem with viewing the file at the other end.
Video settings: if you have QuickTime 6 Pro use MPEG-4, otherwise use Sorenson. At medium to low quality these codecs produce small file sizes while still retaining good quality. Limit the frame rate of the video capture by typing in a value for the frame rate in the Compression Settings window. This can make a big difference to the file sizes so use the lowest frame rate that is acceptable. Also, use the smallest video size that is acceptable. Halving the video dimensions results in four times fewer pixels in the image, so this makes a big difference to the file size of the movie.
Sound settings: if the sound is speech then use Qualcomm PureVoice; if the sound is music then use QDesign Music. Both allow you to adjust the bit rate (quality setting), so choose a medium to low bit rate. Try using 16 bit, 22KHz sampling - this gives reasonably high quality and small file sizes with the above sound compression codecs.
The above compression settings generally require a lot of processing time, so if you are applying the compression on-the-fly as the movie is captured then you may get low frame rates unless you are using a very fast computer. In this case you can capture video in an intermediate format that is quick to compress, and then use the Export command (under the File menu) to compress the movie to your final compression settings. As an intermediate video format you should generally choose 'No recompression' for both sound and video from the Compression Settings window.
Remember when sending files to a Windows PC to include the three letter file extension that tells the PC what type of file it is. For JPEG files the extension is .jpg and for movie files the extension is .mov. BTV can add these file extensions for you if this option is turned on in the preferences).
Capturing movies and images
All options for capture are available from the Capture menu:
Selecting the Show Capture Controls floating window item in in the above menu opens a window that contains frame capture and movie capture controls:
When you choose Capture frame from the Capture menu or from the floating window, an image is captured from the video input and saved straight to the hard drive with an automatic name and destination. The destination can be set in the capture destination settings and the naming settings can be set in the preferences.
Alternatively, selecting Save as... from the Capture menu will display a window allowing you to choose a destination for the file, as well as the file format and other options.
When you start capturing a movie it is saved to the destination that you have specified and an automatic name is created for it. During video capture the Capture Controls window shows the elapsed time:
AppleScript
AppleScript is a way of controlling an application either from a written script or from another application. Once you get the hang of it it is easy and quick to write your own scripts that can control BTV. To write scripts you use the AppleScript Editor application (it is installed as a part of the operating system and should be in your /Applications/Utilities/ folder).
Once you open AppleScript Editor you should see a window like the one below. The 'tell' and 'end tell' commands are needed to define which application you are controlling, in this case BTV. Everything you want to tell BTV goes between these commands.
To see all available commands choose Open Dictionary... from the File menu in AppleScript Editor and select BTV. AppleScript Editor will show you all commands with a brief description of each one.
The two commands that you can use to launch BTV are activate and launch.
If
you tell BTV to activate it loads up and come to the front. In fact, any
time you tell BTV to activate it comes to the front.
If you tell BTV to launch it loads up in the background with no open windows
and awaits further instructions. The launch command is useful if you want
to define the viewing mode (full screen or window mode) before BTV switches
to the mode that was last used.
quit
Tells BTV to quit.
print
Tells BTV to print an object ("print window 0" prints the video window).
full
screen mode / window mode
Sets the video display to full screen mode or window mode
pause
/ resume
Pauses or resumes the video display
hide
mouse / show mouse
Hides or shows the mouse cursor. Only available in full screen mode.
mute
on / mute off
Turns the sound mute on or off
set
volume
Sets the computer speaker volume to a value between 0 and 7, for example:
set volume to 5
blank
other monitors / show other monitors
Turns on or off monitor blanking
set
width / set height
Sets the current video dimensions. For example:
set
width to 640
set height to 480
In window mode this resizes the window to the specified size; in full screen mode this adjusts the video display and centres it on the screen.
capture
frame
Captures a frame of video to the hard drive. Uses the current setting for
frame capture that are set in the preferences.
You can optionally specify a path and/or file name for the destination file,
and specify whether you want any previous file to be overwritten with the
new image file:
capture
frame
capture frame as "Hard disk:image1"
capture frame with overwrite
copy
Copies a frame from the video input to the clipboard. This only works if BTV is the front application so you need to use the activate command before
using the copy command.
start
recording
Starts recording a movie. As with frame capture you can optionally specify
the file name and/or path:
start
recording
start recording as "My Movie"
stop
recording
Stops a movie record operation.
set
video input device
Sets the current video input device to the name specified. To see the names
of all video input devices available on your system go to Video Settings... under the Settings menu and look at the source options. The name is not case
sensitive. For example:
set video input device "DV Video"
These commands are used to get and set the properties of an object. To view all properties for the objects go to AppleScript Editor, choose Open Dictionary... from the File menu and select BTV. Below are some examples of commands that involve common properties that are likely to be most useful:
Moving
Windows
Each window have a position and bounds property; the position property is
a point that defines the top left corner of the window, the bounds is a rectangle
that defines the complete bounds of the window. For example:
set position of window 0 to {400,100}
This sets the position of the video input window to the coordinates {400,100}. Note that the top left of the main monitor is {0,0}
Preferences
The preferences window is available by selecting 'Preferences...' from the Settings menu. There are three sections: General, Frame capture, and Movie capture.
Use
sound
This option controls whether sound input is used. If this option is off sound
will not be played while viewing video and will not be recorded while capturing
movies.
Remember
sound volume
If this option is on, the sound volume you set while watching video will be
remembered the next time you launch BTV.
Hide
cursor when switching to full screen mode
If this option is on then the mouse cursor is hidden when switching to full
screen mode.
Make
video window float above other applications
When this option is on the video window will float above the windows of all
other applications, allowing you to view the video even when BTV is not
the front application.
Image
capture method
There are three different ways to capture an image. These are labelled in
this menu as:
• QuickTime: Uses the standard QuickTime frame grabbing routine to capture an image. This should work reliably but is inefficient and therefore likely to be slow (it is especially slow when using USB video input devices).
• BTV: Uses BTV's own routines to capture the frame which is often significantly faster than the QuickTime method.
• Directly from screen: This is very fast but if there are other windows in front of the video or the video is partially off screen then this will appear in the captured image. There is no loss of quality when capturing from the screen but the maximum colour depth of the captured image is determined by the color depth of the screen. You can use this method to capture frames even during a movie capture; since the image comes from the screen it doesn't affect the video input at all.
Name
This option selects the type of automatic name used for saving image files.
If 'Data stamped' is chosen then the filename contains the date
in the format "day|month hour|minute|second", if 'Numeric'
is chosen then the files are incrementally numbered "001", "002"
up to "9999".
Creator
The creator is a four-character code that defines the application that owns
the file, so that if you double-click on the file it automatically opens in
that application. You can define the creator for image files by selecting
one listed in the pop-up menu, typing in the code, or clicking the 'Make
like...' button and selecting a similar file or the desired application.
Always
capture frames at..
You can make all captured frames a set size by entering the size here. This
applies to normal frame captures as well as frames captured during time lapse.
If you don't specify a size here then captures will be at the current size
of the video input window.
Deinterlace
captured and exported frames
Analogue video (PAL, NTSC and SECAM) is interlaced, that is, each frame of
video is made up of two fields on alternate horizontal lines. DV video can
also be interlaced. Since there is a time delay between the two fields, if
there is motion in the frame this will show up as jagged lines in the area
of the motion. If this option is turned on BTV will automatically deinterlace
any frames captured from the video input, exported from a movie, or copied
to the clipboard. This is done by eliminating the odd field and creating a
new odd field by interpolating pixels in the even field.
Open
image file after creation
If this option is on then the image file is be opened after it is created.
Play
click sound after capture
If this option is on a click sound is played when a frame is captured.
Limit
capture time
You can enter a time here to limit the total capture time for normal movie
captures (not timelapse, motion detection or DV stream capture since these
have separate capture time settings). When the time has elapsed the capture
is automatically stopped.
Name
This option selects the type of automatic name used for saving image files.
If 'Data stamped' is chosen then the filename contains the date
in the format "day|month hour|minute|second", if 'Numeric'
is chosen then the files are incrementally numbered "001", "002"
up to "9999".
Creator
The creator is a four-character code that defines the application that owns
the file, so that if you double-click on the file it automatically opens in
that application. You can define the creator for image files by selecting
one listed in the pop-up menu, typing in the code, or clicking the 'Make
like...' button and selecting a similar file or the desired application.
Always
capture movies at..
You can make all captured movies a set size by entering the size here. If
you don't specify a size here then captures will be at the current size of
the video input window.
Capture
video / Capture sound
These options control whether sound and/or video are captured. One of them
must be turned on.
Play
video during capture / Play sound during capture
These options allow you to control whether sound and video are played during
capture. Generally, turning these options off increases capture performance
resulting in higher frame rates (smoother, less 'jerky' video).
Preview
quality during capture
The lower the preview quality the faster the video preview, and therefore
the better the capture performance. If you select low or medium quality, not
all frames will be displayed to the screen, and the image quality may be reduced.
If you select high quality, all frames are displayed to the screen at the
highest image quality.
Display
settings before
When this options is on all capture settings are displayed and can be adjusted
before every movie capture.
Open
movie after
If this option is on then the movie file is be opened after it is captured.
Capture destinations
The capture destinations window is available by selecting Capture destinations... from the Settings menu. This window allows you to choose destinations for capture movie and image files:
Compression codecs
Following is a list of the video codecs available from the Compression Settings window under the Settings menu:
None
No compression at all, so results in very large inefficient files. It is preferable
to use a lossless compression codec instead, such as the Animation codec at
maximum quality. Supports all colour depths. Does not support spatial compression.
Animation
Best suited for computer-generated animations with broad areas of constant
colour. It is lossy at quality settings below maximum, but at the maximum
quality setting it is lossless and therefore generally used as an intermediate
work format. Supports all colour depths. Supports temporal compression.
Component
video
Not exactly a codec, but an image format that uses 4:2:2 YUV color space rather
than RGB. Good as an intermediate storage format for YUV video (such as from
a USB or FireWire webcam). Does not support temporal compression.
Video
Very fast compressing and decompressing with reasonable compression ratios.
Suitable for capturing video to the hard disk with high frame rates but unsuitable
for compressing video for transmission over the Internet. Supports 16 bit
colour. Supports temporal compression.
MPEG-4
(Requires QuickTime 6 Pro)
Produces the best quality video at the lowest data rates compared to any other
standard QuickTime codec. Can be used for high quality captures or low data
rate streaming, depending on the quality settings used. It is reasonably fast
to compress and decompress. Supports temporal compression and data rate limiting.
DV-NTSC
and DV-PAL
Used with digital camcorders. DV-NTSC is used by devices manufactured in the
US and Japan, and DV-PAL is used by devices manufactured in Europe. Some DV
camcorders offer a "Progressive Scan" feature that records each
frame as a single non-interlaced image instead of two separate interlaced
fields. This is vastly superior for viewing video on a computer monitor so
it should always be used when filming DV footage that will be viewed on a
computer. DV compression is similar to JPEG compression but is more efficient.
Supports 24 bit colour only. Moderate decompression speed and compression
ratios. Does not support temporal compression.
Sorenson
Produces highly compressed video ideal for transfer or streaming over the
Internet. Achieves higher image quality at lower data rates than other similar
compression codecs. Very efficient at data rates ranging from 2 to 200 KBps.
Very slow to compress and required quite a fast computer for smooth playback,
especially if the video size is large or the data rate is high. When using
Sorenson you should make sure that the horizontal and vertical video dimensions
are a multiple of 4. Supports 24 bit colour only. Supports temporal compression
and data rate limiting.
Motion
JPEG A and Motion JPEG B
Commonly used by hardware Motion JPEG compression cards. (There is very little
difference between the A and B variants). Compresses the two fields of interlaced
images separately, as opposed to Photo JPEG which is for non-interlaced images.
Often used as storage formats for large files that need to be archived with
good quality; it is lossy but at maximum quality the image degradation is
minimal. Quick to compress and decompress, with reasonable compression ratios.
Supports 24 bit colour, and greyscale. Does not support temporal compression.
Photo
JPEG
Generally used for high quality still non-interlaced images but it is too
slow to decompress to be used for video playback. Useful for intermediate
high quality storage of video with good compression ratios. Works well for
slide-show type movies that require a low frame rate and high quality compression.
Supports 24 bit colour, and greyscale. Does not support temporal compression.
Cinepak
Designed in 1990 for the Macintosh computers of the day, this codec is therefore
very quick to decompress on modern computers (it is quite slow to compress
however). It is a good choice if the video has to be played back on older
computers, but otherwise other codecs (such as Sorenson) offer higher quality
at lower bit rates. Suitable for Internet transfer or streaming. Uses a compression
ratio of at least 10:1, supports 8 and 24 bit colour, and greyscale. Supports
temporal compression and data rate limiting.
H.261
Designed originally for video conferencing, so it is optimised for low data
rates and for video that contains a small amount of motion (high temporal
redundancy). Quick to compress and decompress, with very high compression
ratios. Suitable for Internet transfer or streaming. Supports 24 bit colour
only. Supports temporal compression and data rate limiting.
H.263
Similar to H.261 but optimised for video sizes of 352x288, 176x144, or 128x96.
It is better than H.261 at higher bitrates.
Indeo
Video 4/5
Primarily designed for Windows, so can be used to transfer video between Mac
and PC without requiring QuickTime to be installed on the PC. High image quality
and high compression ratios, but quite slow to compress and decompress and
image quality of Sorenson is generally better. Supports 32 bit colour only.
Supports temporal compression and data rate limiting.
Graphics
Similar to the Animation codec, but only for 8 bit images. It is usually better
than the Animation codec for 8 bit images but it is slower to decompress.
Supports temporal compression.
BMP
Used for still images; inappropriate for video playback. Does minimal compression,
supports most colour depths. Does not support temporal compression.
Planar
RGB
This is a lossless RGB format. Supports 8, 24, and 32 bit colour depths. Does
not support temporal compression.
Following is a list of the audio codecs available from the Compression Settings window under the Settings menu:
None
No audio compression. The sound is recorded with the sample rate and bit
depth specified without loss of quality, producing high data rates.
QDesign
Music
Excellent for music. Very high compression ratio and high quality. Good choice
for internet transfer and streaming.
Qualcomm
PureVoice
Excellent for voice. Very high compression ratio and high quality. Good choice
for internet transfer and streaming.
ALaw
2:1
An Internet standard for compressed audio everywhere except in the US and
Japan. Low compression ratio and low quality. Generally not recommended.
uLaw
2:1
An Internet standard for compressed audio in the US and Japan. Low compression
ratio and low quality. Generally not recommended.
MACE
3:1 and MACE 6:1
Older Macintosh compressors. Low quality. Generally not recommended.
IMA
4:1
Good quality reproduction of music and other audio content. Supports 16 bit
samples only. Relatively low compression ratio.
32
bit Floating Point and 64 bit Floating Point
Increases the sample size to 32 or 64 bits. This allows for more accuracy
when converting to other sample sizes and applying effects, therefore producing
less quantisation noise.
24
bit Integer and 32 bit Integer
Increases the sample size to 24 or 32 bits. Only specialist professional audio
hardware uses 24 or 32 bit audio.
Following is a list of the still image formats available from the Compression Settings window under the Settings menu:
PICT
What used to be the standard Macintosh image file format (now not very widely
used). Lossless compression, so produces quite large files. Supports all
colour depths.
JPEG
Very widely used lossy image compression format that produces high quality
images at low file sizes (there is a quality setting to adjust the amount
of compression). You should always use this format for photographic type images
that will be transferred over the Internet or put on web sites. Supports 24
bit colour, and greyscale.
TIFF
Traditionally used for images produced by scanners, this is a widely used
file format. Can choose either lossless compression, or no compression at
all. Produces quite large files, supports most colour depths.
BMP
Microsoft Windows Bitmap file format. It is lossless and supports most colour
depths.
PNG
Designed as a replacement for the popular GIF file format (which is a very
useful format but is protected by a patent so that any manufacturer of software
that produces GIF files has to pay a licence fee to the inventors of the format).
PNG works well for computer generated images with a limited number of colours,
but also can be used for photographic type images. It is lossless and supports
all colour depths.
PSD
(Photoshop)
This is the native file format for the very popular industry standard image
editing application, Adobe Photoshop. Convenient to use if the images are
to be imported straight into Photoshop after capture. Lossless compression,
supports 8, 24 and 32 bit colour.
The JPEG, TIFF, PNG, BMP and PSD file formats are all commonly used on Windows PCs and so should be readable on any PC with graphics software, even if it does not have QuickTime installed on it. BMP and JPEG files should definitely be readable as these are standard formats on the PC.