AC3 to M4A: Convert Audio from AC3(Dolby Digital AC-3 Audio) to M4A(MPEG-4 Audio) with River Past Audio Converter, AC32M4A converter, conversion

What is AC3?

Dolby Digital, formerly known as AC-3, is a digital audio compression format. Dolby Digital takes advantage of how the human ear processes sound. When coding noise is close to the frequency of an audio signal, that audio signal masks the noise so that the human ear hears only the intended audio signal.

Dolby Digital is used with digital versatile discs (DVDs), in North America only. European DVD's use MPEG audio instead.

Dolby Digital provides five full-bandwidth channels, front left, front right, center, surround left, and surround right, for true surround sound quality. A low frequency effect (LFE) channel is included that provides the sound needed for special effects and action sequences in movies. The LFE channel is one-tenth of the bandwidth of the other channels and is sometimes erroneously called the subwoofer channel. This multichannel scheme is known as 5.1 channel.

To convert AC-3 audio to other formats in River Past software, please have AC-3 Decoder filter installed.

What is M4A?

Because of its exceptional performance and quality, Advanced Audio Coding (AAC) is at the core of the MPEG-4, 3GPP and 3GPP2 specifications and is the audio codec of choice for Internet, wireless and digital broadcast arenas. AAC provides audio encoding that compresses much more efficiently than older formats, such as MP3, yet delivers quality rivaling that of uncompressed CD audio.

To encode MPEG-4 audio, you need to have River Past MPEG-4 Booster Pack in addition to your audio software.

Additional Requirements

To convert from AC3(Dolby Digital AC-3 Audio) to M4A(MPEG-4 Audio) audio with River Past Audio Converter, you must have River Past MPEG-4 Booster Pack installed.

Launch River Past Audio Converter

Once River Past Audio Converter is installed properly, launch Audio Converter.

Add File

Click on the "Add File" button on the tool bar. The standard file open dialog appears. Select "AC3 - Dolby Digital" in its "Files of type" combo box.

Select the file you want to convert and click "Open". The file will be added to the conversion file list.

Note: To convert from AC-3 files, you must have open source AC-3 decoder installed.

Once the AC-3 Decoder Filter is installed, you will also find a AC-3 Control Panel in your (Windows) Start | Settings | Control Panel area. It allows you to change the settings for the decoder. Often, you may find the default volume from the decoder is lower than desired and it is necessary to adjust the volume in this control panel.

If you cannot add the AC3 file, please verify your AC-3 Decoder filter installation.

River Past Audio Converter

Select output format

Use the setting panel on the bottom of the window to control the output format. Click on the toggle to the left of the "Format" label to expand the panel. Select "M4A - MPEG-4 Audio" as the "Audio Type".

Troubleshoot

If you have MPEG-4 Booster Pack installed, but don't see M4A as an output option, you have a problem with QuickTime installation.

Please make sure you have the latest QuickTime installed. Occasionally, QuickTime may be corrupted due to conflict with some other software. In any case, reinstalling QuickTime should fix this problem.

You can change the sample rate, channel (stereo or mono) and bits/sample, and bitrate.

Note: To convert to MPEG-4 audio, you must have River Past MPEG-4 Booster Pack installed.