WHAT IS MPEG-4?

MPEG4 is a file format that is commonly used to store media types defined by the ISO/IEC Moving Picture Experts Group, though it can store other media types as well. The files of this format usually have extension .mp4.

The start point design of the *.mp4 file format was Apple's QuickTime file format. Having been improved in many ways, today MPEG-4 differs markedly from its predecessor. MPEG-4 allows each streaming over the internet, multiplexing of multiple video and audio streams in one file, variable frame- and bit-rates, subtitles and still images.

Being quite often used as the alternative to *.mp3 on an Apple iPod and in iTunes, *.mp4 is still not as widely used in computer and hardware players as the *.mp3 in spite of the higher quality of the AAC codec.

The following kinds of data are recommended (for compatibility reasons) to be embedded in MPEG-4:

• Video: MPEG-4, MPEG-2 and MPEG-1
• Audio: MPEG-4 AAC, MP3, MP2, MPEG-1 Part 3, MPEG-2 Part 3, CELP (speech),TwinVQ (very low bitrates), SAOL (midi)
• Pictures: JPEG, PNG
• Subtitles: MPEG-4 Timed Text, and/or xmt/bt text format (means that subtitles have to be translated into xmt/bt)
• Systems: Allows animation, interactivity and DVD-like menus

Here are some file extensions used on files that contain data in the *.mp4 format:

• .mp4: official extension, for audio, video and advanced content (see above) files
• .m4a: for audio-only files; can safely be renamed to *.mp4, though opinions differ on the wisdom of this.
• .m4p: FairPlay protected files
• .mp4v, .m4v: video-only (sometimes also used for raw mpeg-4 video streams not in the *.mp4 container format)
• .3gp, .3g2: used by 3G mobile phones, may also store content not specified directly in the *.mp4 specification (H.263, AMR, TX3G)

Total Audio Converter supports the following conversions with MP4 format files:

MP4 to MP3 MP4 to WMA MP4 to WAV MP4 to OGG MP4 to FLAC MP4 to AAC MP4 to MP4 (change bitrate or frequency) MP4 to MPC MP4 to APE

MP3 to MP4 WMA to MP4 WAV to MP4 OGG to MP4 RA to MP4 CDA to MP4 FLAC to MP4 APE to MP4 APL to MP4 AAC to MP4 MPC to MP4 MPP to MP4 OFR to MP4 SPX to MP4 TTA to MP4 WV to MP4 MOD to MP4

Another supported audio formats

• MPEG Audio Layer format (MP3)
• Windows Media Audio format (WMA)
• WAVE audio format (WAV)
• OGG file format (OGG)
• Real Audio format (RA, RMM, RAM, RAX, RPM, RM, RMVB)
• Audio Tracks format (CDA)
• Free Lossless Audio Codec format (FLAC)
• Monkey's Audio format (APE, APL)
• Advanced audio coding (AAC, M4A)
• Musepack formats (MPP, MPC, MP+)
• MPEG-4 international standard (MP4)
• OptimFROG (OFR)
• Speex (SPX)
• True Audio codec (TTA)
• WavPack (WV)
• MOD music (MOD)