Converting media files from one format to another used to be a problem for most people. Today, MPEG-4 is one the most common multimedia formats that offers great audio and video quality (as good as DVDs and CDs), and it is much better than its predecessors MP-2 and MP-3. The problem with the MPEG-4 is that many devices still don’t accept the MPEG-4 format (although it is optimized for combined multimedia playback and web streaming).

The MPEG-4 Standard

MPEG-4 has many features of other standards (such as MPEG-1 and MPEG-2), but it also has other features, like support for VRML objects, video and audio files, 3D rendering, etc.

Although it is becoming more and more popular, this standard is still going through a developing process, and it is divided into many parts. Part 2 (used by DivX, Nero Digital, Xvid, etc), and part 10 are the most commonly used MPEG-4 “parts”.

MPEG-4 offers:

• Mixed media data encoding
• Higher coding efficiency, compared to MPEG-2
• Interaction with the receiver’s audio-visual scene

Common MPEG-4 file extensions are:

Extension Type of Application
.MP4 Audio and Video
.M4A Audio only (typically Audio without copyright protection)
.M4P MPEG-4 files that were encrypted by the FairPlay Digital Rights Management encryption standard through iTunes (now sold without encryption)
.M4B Used for audio books and podcasts. The .M4B file extension permits file bookmarking. Older audio books and podcasts used the .M4A file extension that did not permit bookmarking of the content.
.M4R Used by Apple for iPhone ring tones
.M4V Video Bitstreams
.3GP and .3G2 Special versions of the MPEG-4 Part 12 (Also known as MPEG-4-JPEG2000 media format) that can also store non-MPEG-4 information.

What is the MPEG-3 Format?

MPEG-3 is the most popular audio file format. It can only be used for digital audio encoding.  The format was originally developed by the Moving Picture Experts Group (MPEG) that was comprised of engineers from all around the world. MPEG-3 was formally recognized as the international standard (ISO) in 1991. The advance in the MP-3 audio file format technology was based on the use of a compression algorithm that permitted loss of audio quality in order to achieve smaller file sizes. The acceptable level of quality for an MP-3 to sound as good as a CD is 128 kbits/second. Most users don’t even notice the loss of quality.

MPEG-3 Limitations

Although MP-3 is the most popular digital audio format in the world, it still has a number of limitations. Some of these are:

• Percussion sounds can sound distorted or smeared
• Stereo playback is encoded on a frame-by-frame basis resulting in loss of quality.
• It is difficult for the MP-3 format to handle frequencies over 15.5 kHz
• The MP-3 lacks perceptual noise substitution, spectral band replications, temporal noise shaping and long-term prediction.
• There are significant patent issues for companies that want to create commercial encoding and decoding (playback) products for MP-3. These were partially resolved with MPEG-4.

How to Convert from MPEG-4 to MPEG-3 Format

There are several ways to convert MPEG-4 to MP-3 format. iTunes can be used to convert the audio file formats though it can take time to bulk the files. To convert a large number of MP-4 encoded files, you can use an audio batch conversion software package.

Converting MPEG-4 to MPEG-3 Format Using iTunes

  • Step 1 – Download and install
  • Step 2 – Go to the “Edit->Preferences->General” to change the import setting on iTunes and import music files in MP-3 format. Select the “Import Using” menu option and change the setting to “MP-3 Encoder” from the default .AAC.
  • Step 3– Upload your audio content to iTunes if you don’t already have it in the iTunes library.
  • Step 4 – Create an audio CD with the content to convert to MP-3.
  • Step 5 – Upload the files from the CD to iTunes. This will load non-encrypted audio to the iTunes library.MP3 export utility. If you know the audio is not encrypted, you can skip steps 3 and 4.
  • Step 6 – Right click the file or files you want to convert and select the “Convert to MP-3” Menu option.

The iTunes conversion method is free except for having to burn a real or virtual CD to remove the file-type protection inherent in iTunes for purchased music. Another option for converting MP4 to MP3 file formats is to use a batch converter.

How to Batch Convert MPEG-4 Audio Files to MPEG-3 Format

JHymn software  is an audio batch conversion software application you can use for free in trial mode, or you can pay and use more file modification features. Here is how to batch convert MPEG-4 encoded files to MPEG-3 using JHymn:

    • Step 1 – Download the MP-4 to MP-3 Converterand install it on your computer. It is compatible for both Mac and Windows.
    • Step 2– Select the “Add Files” menu button in the application. Multiple files can be selected in the file open dialog.
    • Step 3– Choose the “Option” button to select the desired conversion format, sample rate, bit rate, channel, and destination file to save the MPEG-3 file.
    • Step 4 – Left Click the “Convert” button in the application to convert all of the selected MPEG-4 files to MP-3 format.

Other Tools to Convert MPEG-4 Files

AVS Audio Converter

Easy CD-DA Extractor 9.0.1 build 2 by Poikosoft

River Past Audio Converter

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