Updated 02/01/2013Home » Guides » AVI Video Capture Guide

AVI Video Capture Guide

This guide allows you to capture video from any source into AVI format, saving disk space and reducing noise, using only freeware programs.

This guide allows you to get started with digital video capture fast and easily, using any low-end system, with a very acceptable quality. Please read the complete features list below for details.

This guide can be used to capture audio & video directly from any of these sources:

  • External video input using capture card.
  • Live TV channels from video capture card with TV tuner.
  • Any other video source recognized by the program used in the guide.
Notice this guide allows later edition/removal of segments such as commercials, etc. Those are simple tasks that do not involve any re-compression process.

These are the key features from this guide:
  • Capture long sequences with minimal disk usage.
  • Capture with image filters such as noise reduction, logo removal, etc.
  • Capture at resolutions up to 384x288 pixels.
  • Does not require video post-processing (re-compressing).
  • Excellent for medium and low-end systems.
Step 1: DScaler setup

DScaler is a free software that unfortunately comes bundled with certain bugs/errors than must be avoided in order to work with it. Do not go on your own configuring DScaler, because certain bugs can cause a major system crash.

After opening DScaler for the first time, you will be prompted to select certain settings regarding your system's performance and DScaler usage. After that, the following dialog will ask about your video capture card and tuner.

At the moment of updating this guide, DScaler already supported these chips:
  • BT848, BT878, BT879, and BT8x8 in general
  • SAA7130, and SAA713x in general
  • CX2388x in general

If you are unsure how to configure these settings, ask your capture's card manufacturer or vendor. If your manufacturer does not reveal the tuner's chip name, try selecting a tuner based on the following judgment:
  • Select a tuner with the format accordingly to your region's format.
  • If the card can tune radio, select one that includes FM. Our card here can tune FM natively.
After that you will be prompted to configure the sound mixer. If you are unsure which is your audio source, use the most common which is Line In. If you don't get sound later, return to this dialog from the Settings menu and try another source. Also, ensure this source is not muted in the Windows volume mixer. If you still don't have sound, you have probably selected an incorrect card model or tuner chip in the above dialog, which can be accessed from the Bt Card menu.

// Make sure to select your card's audio input from the Bt Card > Audio Input menu. Also, open the Windows Record Control and ensure to select the same source, otherwise you will get no sound in your captured videos.

If your capture card includes a TV tuner, configure it from the Channels > Setup menu. Select your location at the top list, and your TV format from the Format drop down list. Then click on the Scan button to begin the channel scanning process. Notice not always you'll have the same channel numbers as in your regular TV, because some channels might be skipped.

Also, you can use the WDM drivers from the Required Software list on this page, instead of DScalers own drivers. Notice these drivers will replace your current ones, and your original TV tuning software may stop working. Additionally, some things will change in DScaler's GUI when not using its internal video driver.

Warning: when changing the DScaler source from the Sources menu, make sure to stop video from the Actions menu before to avoid a possible system crash. The card's video source can be selected from the Bt Card > Video Input menu, this dos not require video stopping.

For advanced tech support regarding DScaler, ask at the DivXLand.org forum or DScaler's one.

Step 2: Image quality and filters

This step can be ommited if you are satisfied with the current image quality from your source.

DScaler features some interesting filters to improve the image quality. These can be activated from the Filters menu, and each one can be configured from Filters > Filter settings menu.

Since in this guide we are making a capture from a TV tuner with certain quality loss, we have enabled all 3 Noise reduction filters, and increased the values for some of them. You can also add any filter you think necessary and configure it, until you are satisfied with the image quality.

To change settings like brightness, contrast, hue, and color, use the menu Settings > Video Settings, or either Settings > Overlay adjustments. This last one requires video overlay on.

Step 3: Capture settings

To set the horizontal resolution for the video, go to BtCard > PixelWidth and select 384.

Go to Actions > Recording > Options and the following window will appear.

Select your Wave-in device, which is normally autodetected. Under Destination set the folder for the output video files. You can also set a file size limit to split the captured vide in several files. At Recording Height select the 1/2-height option for better performance. Click Compression Options and the following dialog will appear:

The audio codec cannot be changed here, but we will later convert it to MP3. At Video, click Configure and the codec selection dialog will show up.

Here, select the DivX or XviD codec from the list and click Configure. In general terms, configure the codec with these settings:
  • DivX only: Use a Portable profile (lower resolution = faster encoding)
  • DivX only: Use a Fast or Standard encoding performance
  • Make sure to select a Single-pass encoding mode
  • Disable Psychovisual Enhancements and Source Pre-processing settings (if available)
  • XviD only: select the Real-Time quality preset
  • Use the H.263 quantization type (if available)
The video bit rate value is essential for overall quality and file size limitation. The proper bitrate can be calculated using DivXLand Bitrate Calculator. Make sure to select the WAV (PCM) audio format.

Since DScaler can only capture with uncompressed WAV audio, we will convert the audio to MPEG Layer-3 format later with VirtualDub, where you'll also be able to edit the video if needed.

Step 4: Start video capture!

You should restart DScaler after configuring it for the first time, because certain settings are not updated until it's restarted. After reloading DScaler, access again the video codec configuration to ensure its settigns are correct and adjust them if necessary.

Go to Actions > Recording > Record or press Shift+R to start recording. To stop the capture, Actions > Recording > Stop or press Shift+S. Keep an eye on the frame dropping value at the right bottom in the status bar.

This value must be as low as possible, better if it's stable in zero. During the capture in this AMD Athlon XP 2000+ machine with 384 MB of RAM, frame dropping value was fixed in 0 and only ocassionally raised to 2 or 3 frames. Some advices to help your capture process:
  • Close other programs running on the background, including antivirus.
  • Defragment the hard disk(s) used by Windows and the capture file before recording.
  • Try to use an empty hard disk when possible. (an empty partition is not the same)
If you have high frame dropping values, probably something is not configured properly, so please ensure the following:
  • You have configured the DivX codec to make it encode as fast as possible
  • You are capturing at half-height resolution
  • You have just restarted Windows
  • You have closed all programs running in the background
  • You have tried enabling (and disabling) the overlay option (Settings > Overlay Adjustments)
Additionally, to capture files larger than 2 GB, you will require a Windows NT based system such as XP or 2000 with an NTFS file system. FAT32 partitions limit AVI file sizes to 2 GB each.

Step 5: Audio compression and (optional) video edition

To compress the captured video file, we'll have to convert the uncompressed PCM audio stream into MP3 format using VirtualDub as explained in the Video Edition Guide provided by DivXLand.org.

Once there, you'll also be able to cut video segments and do other simple video edition tasks, but ensure you don't recompress the video to avoid loss of quality, since the video is already compressed with the selected codec (DivX or XviD).


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