Using the RealAudio Encoder

Using the RealAudio Encoder, you can encode audio files or input from a sound device into a RealAudio format. This chapter describes the encoding procedure.

To encode RealAudio clips:

From the command line, enter the rmenc command, using appropriate options from the following table.

Command Line Options
Option	Description	Default
-A	codec index (format of audio file)	0
-a	the index to an audio input device on the "Capture devices" list
-C	copyright of clip, which is displayed in the RealPlayer window
-H	display all command-line options
-h	display the version of the RealAudio Encoder
-K	enable or disable Mobile Play (Boolean - 0 or 1)	0 (don't enable Mobile Play)
-I	input file name
-O	output file name	If you encode from a file, the output filename is the same as the input filename, except that it has the .`rm` file extension.If you encode from a live source (CD or microphone), the output filename is: `out.rm.`
-R	enable or disable selective record (Boolean - 0 or 1]	0 (don't allow RealPlayer to save the file to the user's disk)
-S	server, port, and URL: server[:port]/resource (The port is optional.)
-T	title of clip, which is displayed in the RealPlayer window
-t	encode for the duration HH:MM:SS, then quit
-U	author of clip, which is displayed in the RealPlayer window
-W	server password
-x	the index to a port on the audio input device (on the "Capture devices" list). Possible ports are: 0 - microphone 1 - line in 2 - CD	2

Encoding Algorithms

To encode an audio file, you use a codec representing an encoding algorithm. The RealAudio Encoder supports several algorithms, and each one is optimized for a particular type of audio and connection speed bandwidth.

Choose a codec that suits your needs. With HTTP streaming, for instance, you should use a codec representing a low frequency response algorithm such as RealAudio 3.0 - 28.8 Stereo. The following table describes each codec.

Note
You specify a codec with the -A command line option.

Audio Codecs
Codec Bits/second Encoding Algorithm Description

0 6500 6.5 Kbps voice

1 8500 8.5 Kbps voice

2 5000 5.0 Kbps voice

3 16000 16 Kbps voice - wideband

4 16000 RealAudio 3.0 - 28.8 Mono, narrow response Can improve clarity for speech-intensive music or noisy signals. Expect a frequency response of 4.0kHz

5 16000 RealAudio 3.0 - 28.8 Mono, medium response Can improve clarity for music with snare drums, cymbals, and vocals. Expect a frequency response of 4.7kHz

6 16000 RealAudio 3.0 - 28.8 Mono, full response Gives the brightest sound for delivery over 28.8 Kbps modems. Expect a frequency response of 5.5kHz.

7 20000 RealAudio 3.0- 28.8 Stereo Use this for general stereo content. Expect a frequency response of 4.0 kHz.

8 40000 RealAudio 3.0 - ISDN Mono Use this for general mono content over ISDN connections. Expect a frequency response of 11.0 kHz.

9 40000 RealAudio 3.0 - ISDN Stereo Use this for stereo content over ISDN connections. Expect a frequency response of 8.0 kHz.

10 80000 RealAudio 3.0 - Dual ISDN Mono Use this for optimal mono quality over ISDN connections. Expect a frequency response of 20.0 kHz (CD quality)

11 80000 RealAudio 3.0 - Dual ISDN Stereo Use this for optimal stereo quality over ISDN connections. Expect a frequency response of 16.0 kHz (broadcast quality).

12 8000 RealMedia 8 Kbps music

13 12000 RealMedia 12 Kbps music

14 32000 RealAudio 5.0 - 32 Kbps mono

15 32000 RealAudio 5.0 - 32 Kbps stereo

16 15200 15.2 Kbps voice

Examples

Consider the following examples of encoding:

Encode sound data from the file myaudio.wav into RealMedia format 3 and save it to the file mynewaudio.rm. (When RealPlayer plays this file, the user will see "My Title" as the title and "My Name" as the author.)
```
rmenc -T `My Title' -U `My Name' -A 3 -O mynewaudio.rm
 -I myaudio.wav
```
Encode from live audio input device 2, port1, using RealMedia format 4, to the RealMedia resource live.rm on machine Sandbox, port 7070. (Access to Sandbox is allowed by the password "veggies." Sandbox must be configured to offer the named resource via RealServer from RealNetworks.)
```
rmenc -a 2 -x 1 -A 4 -S Sandbox:7070/live.rm -W veggies
```