LEAD AC3 Encoder User Interface
The LEAD AC3 Audio Encoder Filter is a DirectShow filter for compressing audio data using the AC3 compression standard (A/52 - Digital Audio Compression Standard (AC-3)). The AC3 compression standard is the sound format for digital television (DTV), digital versatile discs (DVDs), high definition television (HDTV), and digital cable and satellite transmissions. It is a 5.1 format, which means that it provides five full-bandwidth channels:
- Front left
- Front right
- Center
- Surround left
- Surround right
In addition, a low-frequency effect (LFE) channel (the ".1" of the "5.1"), is included for the sound needed for special effects and action sequences in movies. AC3 also has a down-mixing feature that ensures compatibility with devices that do not support the 5.1 format.
Key Features
- Creates Dolby Digital with 6-channel surround sound.
- Creates DVDs with Dolby surround.
- Converts a 2-channel input into a 6-channel output or encodes 6-channels as is.
You can use the encoder with existing converters or DVD creator applications, as long as they allow selection of the audio encoder. The AC3 encoder supports the following output channels:
- Unchanged (the same number as input)
- Force Mono
- Force Stereo
- Force 6 Channels
The AC3 audio encoder is needed in order to create DVDs that have 5.1-channel surround sound.
Options for the LEAD AC3 Audio Encoder can be set manually through the encoder property page, which is shown in the figure below:
Changes will be applied only when the filter's state is stopped with the ability to set them permanently by selecting Apply or OK, or to abandon changes by selecting Cancel. Positioning the mouse pointer over a control displays general information about that control.
The following table shows the controls and their descriptions:
| Control | Description |
|---|---|
| Input channels static text | Shows the number of input channels. |
| Output channels static text | Shows the number of output channels. |
| Output Bit Rate - list box | Sets the output bitrate of the compressed audio data. The bitrate is the average number of bits that one second of audio data will take up in your compressed bitstream. The unit is in kbps. To calculate the number of bytes per second of audio data, divide the bitrate value by eight. Bitrate represents the strength of compression. Also, the bitrate influences quality: the higher the bitrate, the higher the quality.The valid bitrate values are: {32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 , 384, 448, 512, 576, 640}. |
| Output channels - list box | Specifies the number of output channels of compressed data. When Unchanged is selected, the number of the output channels equals the number of input channels. Otherwise, the number of output channels will be forced to be the value selected. |
| Simulate surround check box | When selected, simulates the surround sound of a 5.1 system on a stereo or mono audio source.This feature is available only if Force 6 Channels is selected in the Output Channels list box. |
| Output Sample Rate - list box | Specifies the output sample rate, in samples per second (Hz), of the compressed audio data.The valid sample rate values are: {Input sample rate, 32000, 44100, 48000}. |
