Capturing .AVI files with WinTV
The WinTV PCI boards can capture motion video clips and save them to your harddisk in .AVI (Audio/Video Interleaved) format. This file contains digitized video and, optionally, audio. The WinTV USB has the same capability, however, some of the details explained below may differ from that of the PCI version.
WinTV gives high quality captured video by storing uncompressed digitized video in an AVI file. This compares with compression methods such as JPEG and MPEG, where some loss of video quality is accepted in order to reduce the amount of data stored. Uncompressed video capture creates high quality digital video movies, but requires optimized system performance to avoid lost video frames (called dropped frames.)
The WinTV PCI boards(including the D, HD, PVR, GO, impact VCB)and WinTV USB(including USB Live) models can capture .AVI files to your hard drive. (PCI models on Win 95/98/ME, NT4.0, and 2000, USB models on 98/ME/2000). The older ISA model WinTV boards(Cinema Pro, Prism, Celebrity, High-Q) will also be able to capture .AVI files to the harddisk, however, only on Win 9x systems.
Approximate File Sizes of captures
In all cases, the WinTV can capture .AVI files in real time video(30fps), at 320 X 240 resolution or smaller. A variety of video formats can be used, but the .AVI that will be captured will almost always be uncompressed, or with only slight compression.
No compression will result in very large file size, but better image quality. File sizes will approximately be about 25-40 Megabytes per minute, depending on the video format, the audio format, and actually how much action is taking place within the video.
To reduce the amount of hard disk space used by your digital videos, you can edit the video using one of the popular 32-bit digital video editors (such as Adobeís Premiere or U-Leadís MediaStudio). After editing, you can compress the video using a software playback format such as Indeo or Cinepak (both of these are supported by Windows95/98/ME). Typical compession achieved by these formats is 30:1.
How Long can I capture for?
Due to a limitation in Video for Windows(Microsoft), .AVI captures will cut off at 2 Gigabytes during captures.(You may be able to capture longer, however, capturing longer than 2 Gig will result only in a corrupted file). This should apply to all FAT16 and FAT32 partitioned drives. NTFS partitions should allow for 4 Gigabyte captures.
There are some 3rd party capture utilities that can be used to capture video, which claim to capture multiple .AVI files in sequence, and then sync these files into one large .AVI file, without dropping frames in between.
By Default, .AVI files will be saved as "Capture.avi" to the root C:\ directory on the harddrive, unless you specified to save the file elsewhere.
All audio capture is physically done by the Soundcard in the system, not the WinTV. If the settings are correct in the Wintv software(capture audio is selected), look under control panel-multimedia-audio. Here you will have a separate RECORDING and PLAYBACK section. Be sure that for each section, that the LINE IN for the mixer is present, it is not muted, and that the volume level is up. If this is the case, all should be working. If audio capture still fails, try connecting an external source (an external CD or stereo) into the LINE IN on the soundcard, and use Windows Soundrecorder to capture and playback a WAV file into the LINE IN. This will show if the soundcard is capturing and playing back audio into its LINE IN section. If it also fails, this indicates a soundcard/Linein problem.
Capturing in the WinTV 2000 Application
Clicking the RC button on the bottom right corner of the WinTV 2000 application will open the remote control interface. Within the remote control, you will find the "VCR" functions. These buttons are what controls .AVI capture. FILE, FMT, REC, PLAY, and MAIL functions are all part of the .AVI capture tools.
FILE: Clicking the File button will allow you to specify some pre-designated things to the .AVI file you are about to capture. Here you can specify what directory, drive, or folder that you want the file to be saved to (Look in:), what you want the file to be named(file name:), the frame rate, and if you wish to capture audio or not(checkmark in "capture audio" indicates that the soundcard is enabled for audio capture).
video buffers, dos buffers, and disable write cache are not used.
Set audio format will allow you to choose the audio compression and type that the sound will be captured in. This basically attaches to the soundcard driver in the system, and gives you the choices for the audio format and attributes that are available.
Record Mixer will open the soundcard's volume control mixer for recording(same as going to control panel/multimedia). Ensure that the soundcard has a Line In balance that is enabled by select, or that is not muted, and has an adequate volume level.
Video Compression will allow you to change the video compression of the file during capture. This differs from system to system, depending on what the actual video compression codecs are that have been installed on the PC. Video compression codecs can come from different sources, such as different hardware installations, software packages, or manually installing certain codecs on the system. Certain codecs will improve video quality, but result in even larger file sizes, where other codecs will result in much smaller files during capture, but lesser quality video.
A general overview of some of the more common codecs that you might find and their results can be found below.
FMT: The FMT button accesses the Video Format and size that you wish to use. The WinTV PCI and USB hardware can capture up to 320 X 240 only(352 X 240). Although, the larger image sizes are listed, they are not supported by the hardware.
The WinTV PCI offers a "BTYUV" format, which is recommended for optimum capture performance under Win 9x OS'. Using the BTYUV format, however, will prohibit the .AVI file from being played on another system that does not have the WinTV hardware installed. So, if the file is intended to be played on other systems, emailed, or put on the internet, it would be recommended to use one of the standard RGB formats(such as 15 bit RGB, or 24 bit RGB).
PLAY: The PLAY button will allow you to instantly playback an .AVI file that has been recorded with the WinTV. By clicking this button, it automatically will initialize Windows Media Player, or whatever the default .AVI player is on the system.
If you receive an error when clicking PLAY that "the default .AVI player on the system is not found", this would indicate that your .AVI player is not setup correctly for default playback. You may then, instead, manually open Windows Media Player(start/programs/accessories/entertainment/mediaplayer) and go to File/Open to manually playback the file that you just created.
MAIL: The last option in the WinTV VCR section is MAIL. Clicking this button after capturing an .AVI file will automatically insert the .AVI file into an E-mail for you so you may send it to a friend or family member. Be careful of the file size during capture before doing this, as very large files may not be sendable. NOTE: The MAIL feature works only with Microsoft Outlook or Outlook Express.
The following chart gives an example of some of the video compression codecs that may be used on a particular system in combination with some of the video formats that are available, and what you will see as a result. Some combinations may result in poor quality captures(many frames dropped, poor image quality, etc.), but a much smaller file size. Others may result in a huge file, and excellent quality(0 frames dropped). This chart is just to be used as an approximation, and may differ with the type of system being used, the content of the video that is being captured, and the sound format that is being captured as well.
The results were made using the WinTV PCI board on a P2 333Mhz system.
|Video Format||Frame size||Frame Rate||Length||Frames Dropped||Resulting File Size|
|Cinepak by Radius||15 Bit RGB||320 x 240||15.000||12 Seconds||85%||630K|
|Indeo Video R3.2||15 Bit RGB||320 x 240||15.000||12 Seconds||47%||850K|
|Microsoft Video 1||15 Bit RGB||320 x 240||15.000||12 Seconds||23%||9M|
|Indeo 5.10||15 Bit RGB||320 x 240||15.000||12 Seconds||76%||600K|
|Brooktree Prosummer video(32)||15 Bit RGB||320 x 240||15.000||12 Seconds||0%||7.32M|
|Brooktree YUV 411 raw||15 Bit RGB||320 x 240||15.000||12 Seconds||0%||20.5M|
|Indeo Video raw R1.2||15 Bit RGB||320 x 240||15.000||12 Seconds||0%||14.5M|
|Indeo Video 4.5||15 Bit RGB||320 x 240||15.000||12 Seconds||82%||500K|
|Full frames Uncompressed||15 Bit RGB||320 x 240||15.000||12 Seconds||0%||26M|
PCLEPIXL 32 bit Compressor
|YUY2||320 x 240||15.000||12 Seconds||1%||13M|
|PCLEPIXL 32 bit Compressor||24 Bit RGB||320 x 240||15.000||12 Seconds||1%||13M|
|Microsoft MPEG-4 Video codec||15 Bit RGB||320 x 240||15.000||12 Seconds||0%||1M|
|VDOnet/VDO Wave||15 Bit RGB||320 x 240||15.000||12 Seconds||0%||250K(poor quality)|
|No recompression||BTYUV||320 x 240||15.000||12 Seconds||0%||30M|
|Full frames Uncompressed||BTYUV||320 x 240||15.000||12 Seconds||0%||20M|
|Brooktree ProSummer video||BTYUV||320 x 240||15.000||12 Seconds||0%||7.3M|
|Indeo 5.10||BTYUV||320 x 240||15.000||12 Seconds||0%||4.41M|
BTYUV is only selectable with the WinTV PCI boards on Win 9X systems, (NT and 2000 do not have this option, so 15 Bit RGB would be recommended for capture).
15 Bit RGB would also be recommended when capturing with the WinTV USB.
It is recommended to close any other programs that might be running when capturing video to disk, to optimize performance of your capture. It is good to also close down any other programs that may be running in the backround and that are in your startup(such as anti-virus, VGA tools, etc.)
It is a good rule to frequently defragment your hard drive for better capture performance.
Do not use DoubleSpace or any other disk compression scheme! This severely slows down your hard disk.
Turn off screen savers, and do not connect to a local area network.
Most professionals capture video and audio separately. This allows them to lay down the audio track on top of the video tracks while editing. Capturing video separately will increase the performance of your video captures.
There are several hard disks on the market which are designed for higher performance video captures. These drives use 1:1 interleaving and track caching to eliminate gaps caused by a hard disk drive seeking to the next track. They are available with both IDE and SCSI interfaces.
Some 3rd Party software packages will allow you to take an existing .AVI file and compress it into an MPEG file. This is generally done for file storage, over anything else, as software MPEG compression will reduce the picture quality, but at the same time, drastically reduce the file size.
The WinTV PVR model can capture MPEG1 and MPEG2 video directly to the hard disk using a hardware MPEG Chip. This results in smooth, high quality MPEG captures.
Yes, you may use 3rd party .AVI capture programs that are compliant with the Video for Windows standard to capture .AVI clips with the WinTV hardware.
The Win/TV-Capture program is an easy to use program that previews live video, captures AVI files to disk, and then plays back the AVI file to your VGA screen. Win/TV-Capture can capture and playback video clips, but does not provide video editing capabilities. Programs such as Adobeís Premiere and U-Lead Media Studio can be used to edit your digital videos.
With Win/TV-Capture you can set the number of frames per second that are captured and the size of the video image. You need to do some experimentation to determine how much video your PC can store to the disk (in terms of image size and frames per second) because capturing video clips is very CPU and hard disk intensive.
Here is the Win/TV-Capture window:
Setting the video image size and image format
The maximum suggested video image capture size is 320x240. When playing back the video on slower PCís, a smaller image size might be needed. To set the image size, click on Options/VideoFormat.
The Win/TV-Capture program can use several different types of color formats when capturing video clips. For highest capture performance, choose the BTYUV format. This gives excellent capture image quality and frame rate, but will give slow performance on playback of 320x240 image size videos.
This format is great if you plan to edit your video clips in Adobe Premiere or MediaStudio, and plan to compress the digital videos using Cinepak or Indeo. If you do not plan to edit your videos and want good playback performance, choose a smaller image size (160x120) or try 15 bit RGB instead of BTYUV. Remember, capture and playback performance is determined by your system configuration, including CPU and hard disk speed.
|Video Digitizing Formats and Maximum Frame Rates||Color format||Capture
|32 bit RGB||160x120||15||...|
|24 bit RGB||160x120||15||...|
|15 bit RGB||320x240||15||...|
|YUY2||320x240||24||UYVY by byte swapping|
|BTYUV||320x240||30||3 words pack 8 pixels|
|YUV12||320x240||24||Verticle subsampled 4:2:2|
|YUV9||320x240||30||Verticle subsampled 4:1:1|
Setting the number of frames per second capturedTo set the number of frames per second captured, click on Capture/CaptureSetup. The maximum frame rate is 30 or 25, depending upon the TV standard using in your country. For example, in Nroth America, 30 frames per second is the standard, while in Europe 25 frames per second is used.
The number of video buffers will depend upon how much RAM you have in your system. The maximum number of buffers is 1000.
In the Capture Setup menu, you can also choose to capture audio with the video.
| After setting the video format, the number of frames
per second and possibly creating a new file name (by clicking on File/SetCaptureFile),
you can start capturing video by clicking on the CaptureVideo icon.
To preview live video, click on Options/PreviewVideo. This shows how your saved video clips will look after been captured. The colors will be limited to the number of colors used by your VGA display driver. For example, if your VGA display driver is in a 256 color mode, you will only see 256 colors in the Preview window, even though a 16-million color AVI file will be captured.
Note: You should not capture AVI files in Preview mode.
To capture audio along with video, the WinCast or Win/TVpci must be connected to a sound board capable of saving sound clips. The LineInput must also be selected as a source for the Sound Recorder. Do the following:
Capturing audio along with video puts a greater strain on your PC then capturing video alone. If your PC drops many frames while capturing audio and video together, then capture the audio separately with the audio capture utility from Windows. The audio can be merged with video later on during the video edit stage.
Captured image sizes can be either 160x120 or 320x240 pixels.
For the best trade off between image size and captured frames per second, use a 320 x 240 image. With a 486/66MHz processor (or better) and a reasonably fast hard disk drive, you should be able to capture 30 frames per second using the BTYUV format.This format uses a 2.5 :1 compression ratio compared to raw 24-bit per pixel video.
The consumption of hard disk space is dependant upon the size of the video image while capturing, the image format plus the number of frames/second. Using the BTYUV image format, the following chart shows hard disk space consumed:
|image size||frames/second||bytes per second||1 minute video|
|160x120||15 frames/sec||425 Kbytes/sec||26 Mbytes|
|320x240||15 frames/sec||850 Kbytes/sec||52 Mbytes|
|320x240||30 frames/sec||1.7 Mbytes/sec||104 Mbytes|
Video consumes quite a bit of hard disk space! At 320x240, you will only be able to store about 10 minutes of video on a 1 Gigabyte hard disk!
To reduce the amount of hard disk space used by your digital videos, you can edit the video using one of the popular 32-bit digital video editors (such as Adobeís Premiere or U-Leadís MediaStudio). After editing, you can compress the video using a software playback format such as Indeo or Cinepak (both of these are supported by Windows95/98). Typical compession achieved by these formats is 30:1.
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