Chapter 5: RealMedia Recording Tips

RealEncoder comes with a variety of switches that allow you to create the highest-quality streaming media.

Because there is no single best process for delivering all types of streaming audio and video, RealEncoder provides several ways in which you can customize and streamline your recording.

This chapter discusses how to:

• increase RealEncoder performance

• use RealEncoder more effectively

• produce high-quality audio

• produce high-quality video

• record using the command line

Increasing RealEncoder Performance

A number of factors can influence how much of your system's resources are used during a recording session. Use these tips to get the best performance possible.

Multiple Streams

Generally, the more streams you create in a SureStream clip, the more processing power you need. Recording for more than two or three target audiences, using multiple audio codecs, or creating a backward-compatible stream can all effect performance.

Use the Statistics dialog to monitor performance, and then adjust target audience settings to get the performance you want. See "Monitoring Performance" and "Optimizing Target Audiences" for more information.

Disabling Viewers

By disabling the input source window, the output source window, and the audio level meter during live recording, you can lower the amount of resources needed to record. Consequently, you can increase the frame rate of your recorded file and decrease the time it takes to record your clip.

To disable viewers during recording:

1. Choose the View menu from the main RealEncoder window.

   Viewers that are currently active are designated with a checkmark:

   • Input Source

   • Encoded Output

   • Audio Meter

2. Select a viewer to disable it.

Using RealEncoder Effectively

RealEncoder has features that allow you to more easily use RealEncoder and increase efficiency while recording your media clips.

Live Capture-to-File

If you have a real-time capture station, you can use it to capture and compress directly into RealMedia format. The output of an audio or video device can be recorded by RealEncoder to a RealMedia file instead of a live broadcast.

This process eliminates the need to create and store intermediate audio or video files, which are very large and can take considerable disk space. It is also the fastest way to capture content like breaking news clips when time-to-post is important.

Drag-and-Drop Recording

RealEncoder supports drag-and-drop recording. This feature allows you to quickly convert an input audio or video file into RealMedia.

To use drag-and-drop with RealEncoder:

1. Click an input file icon and drag it onto an open RealEncoder window.

   This opens a new session with path and file name information entered appropriately.

2. Enter any descriptive information (title, author, and copyright) and customize recording settings before clicking Start.

Producing High-Quality Audio

This section describes how to successfully create quality sound for RealMedia clips. It gives you overall audio tips, shows you how to use the audio meter, and how to adjust the volume during recording.

General Audio Tips

Follow these tips in order to get the best quality from your different audio sources.

• Use high-quality source files or a recording input device.

• If you are not doing a live broadcast, capture or "digitize" the sound to a supported file format such as a .wav or .mov whenever possible.

  This allows you to use a sound editor to adjust the amplitude of your signal to maximize the available dynamic range. If you do not adjust the signal, the resulting RealMedia file may sound flat.

• If your original audio file signal exceeds the acceptable amplitude range, the file may be "clipped." Clipping can give rise to clicks or pops on playback. If your source file contains a clipped signal, your final RealMedia file will have high-frequency background noise or static. Lowering the input volume will help reduce clipping.

• When encoding live-source audio, you have less opportunity to manipulate your input signal. Be sure that volume levels are prepared and tested before encoding.

• Cut any unnecessarily long silences from the beginning or end of the output file to conserve space.

Using the Audio Level Meter

While you record RealMedia clips, you can monitor the Audio Level to be sure you are encoding the optimal dynamic range. Green indicates a normal reading. Red warns that you are close to an over-modulated input. The best sound quality will occur when the top red bar is often lit but the clipping indicator (the red light above the meter) is never lit.

The Audio Level Meter

Clear the clipping indicator during recording by clicking on it. This allows you to track if audio clipping is occurring without watching the audio level constantly.

Volume Control

While recording, you can adjust or monitor the volume using the Windows Volume Control window.

To adjust the recording volume:

1. Select Volume Control from the Options menu.

   The Volume Control window opens.

   

2. In the Volume Control window, select Properties from the Options menu.

   The Properties window displays.

   

3. Select Recording to adjust the input recording volume. (Playback adjusts the level of the volume you hear while you are recording, not the volume RealEncoder uses.)

4. Select from the list of volume controls the type of inputs you will be using and click OK.

   The Recording Control window opens.

   

5. Select which recording inputs to use by choosing the Select box for each input.

6. Adjust the sound level by moving the sliders up or down.

   Remember, if the volume is too high, the recorded sound may be clipped and appear distorted. If the volume is too low, it will be difficult to hear. Use the audio level meter in the RealEncoder window to monitor the level during encoding.

7. Close the Recording Control window and return to the RealEncoder.

Producing High-Quality Video

This section describes how to successfully create quality video for RealMedia clips. Follow these tips in order to get the best quality from the different types of video sources.

Recommended Video Types

In order to get high quality output, your video source should meet the following requirements organized by video type.

AVI Files

• AVI files should have a 24-bit color depth.

• The standard video frame size for the Internet is 176 x 144.

• The file should be uncompressed for best results.

• Indeo drivers must be installed on your machine for RealEncoder to be able to open AVI files created with YUV9 format. The Indeo drivers are available from the Intel Web site (http://www.intel.com).

  However, if you captured an AVI file on the same machine as RealEncoder, there is typically no problem.

QuickTime Files

• QuickTime files must be uncompressed.

• Use 24-bit RGB QuickTime video files.

• Use 8-bit or 16-bit mono and stereo audio.

MPEG-1 Files

• Use high audio and video stream rates for best quality.

• MPEG-2 files are not supported.

Video Capture Devices

• When using an external video source, start with the best possible quality. In particular, different video formats yield different qualities when captured (digitized).

  The common video formats in order of quality are:

  • Betacam-SP, also known simply as Beta. This format is common among video production professionals.

  • Laserdisc or DVD

  • S-VHS or Super-VHS

  • VHS

• Video playback devices commonly have two types of video outputs, S-video and composite. S-video produces better results.

Sizing the Image

RealEncoder supports any size image from any video source, but it will automatically crop the height and width to multiples of 4. The most common video image sizes are 160 x 120, 176 x 144 pixels, or 320 x 240 pixels.

Live capture image size is controlled through Set Video Format under the Options menu, and is dependent upon the video capture hardware installed.

Cropping the Image

RealEncoder's cropping feature allows you to record any portion of a video image that you wish. By cropping an image, you can reduce the overall bitrate of your recorded clip while removing unnecessary image space.

The smallest size that you can crop an image to is 32 x 32.

To crop a video image:

1. To edit the image cropping settings, select Crop Settings from the Options menu.

   The Image Cropping window displays a sample image from the session input. Notice the crop lines around part of the image. These lines show the portion of the image that will be recorded.

2. Use Left, Top, Width, and Height buttons to adjust the size and location of crop lines. All dimensions will automatically adjust to a multiple of 4.

3. Click OK to return to the RealEncoder window.

4. Select Crop Enabled from the Options menu.

5. Click the Start button to start the recording process using the crop settings.

   The cropped image appears in the Encoded Output viewer.

Using the Command Line

RealEncoder allows you to use the command line to create RealMedia. Using the MS-DOS prompt, you can use all of RealEncoder's features and bypass the interface.

To use the command line encoder:

1. Open the MS-DOS prompt.

2. Change the directory to the main RealEncoder directory.

   The default main directory is c:\Program Files\Real\Encoder.

3. Type rmbatch <switches> where <switches> are the recording switches you specify to record your RealMedia. See the table below for more details on all necessary switches.

   You must specify an input by using the /I, /D, or /L switches.

4. The command line RealEncoder converts the specified input into RealMedia once you press Enter.

Switches

The following tables describe each switch that you can use on the command line. These switches are divided into Input/Output switches, Encoding switches, and Preferences switches.

Examples

The following example records foo.avi into a RealMedia file for 28 and 56 Kbps audiences, audio set to voice only, video set to normal, file type set to SureStream, and "The Title" as the title of the clip. The output file is foo.rm.

rmbatch /I C:\foo.avi /T 0,1 /A 0 /V 0 /F 1 /B The Title

The next example records from a live source to a RealServer with the same settings as above.

rmbatch /L /S myserver:4040/foo.rm /T 0,1 /A 0 /V 0 /F 1 /B The Title

Settings Configuration File

The Settings Configuration File switch (/M) allows the user to specify a text file that contains the necessary target audience settings for the recording. Using a settings file allows you to save different settings that you use all the time, plus you can specify the exact audio codec used.

The settings file contains a line for each target audience that the user wishes to record for.

The parameters contained used for each target audience are as follows:

A sample configuration settings file for a SureStream recording would be as follows:

TARGET=0,TOTAL_BIT_RATE=20,AUDIO_CODEC=sipr0,MAX_FRAME_RATE=7.5

TARGET=2,TOTAL_BIT_RATE=45,AUDIO_CODEC=sipr1

The RealEncoder then takes these values and creates a RealMedia stream for the target audience specified in each line.

	Warning
	Using a settings configuration file will override the Audio Format switch (/A) and the Target Audience switch (/T).

Target Audience Values

Audio Codec IDs

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This file last updated on 09/25/98 at 14:19:38.