mpeg-4 : What is it?

Discussion of music production, audio, equipment and any related topics, either with or without Ableton Live
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King Frydai
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mpeg-4 : What is it?

Post by King Frydai » Sat Dec 03, 2005 8:08 pm

If I purchase a track from i-tunes it comes in the mpeg-4 format. Is this similar to an mp3 in quality? I plan on converting it to a wav file, but want to make sure I'm not converting a compressed file.

Anyone know what an mpeg-4 is? I know it's originally meant for motion picture use.


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Post by subterFUSE » Sat Dec 03, 2005 9:08 pm

Isn't mp4 the tag for an Apple Lossless file?

Apple Lossless is just a different encoding method, which is higher quality than mp3, but less compression.

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Re: mpeg-4 : What is it?

Post by sweetjesus » Sun Dec 04, 2005 2:39 am

King Frydai wrote:If I purchase a track from i-tunes it comes in the mpeg-4 format. Is this similar to an mp3 in quality? I plan on converting it to a wav file, but want to make sure I'm not converting a compressed file.

Anyone know what an mpeg-4 is? I know it's originally meant for motion picture use.

MP3's can have all kinds of bitrates ranging from very very little upto 320kbps...
I personally wouldnt buy tracks off iTunes for using with Live, check out

they seem to be better priced than iTunes and have more bitrate options available.

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Post by Angstrom » Sun Dec 04, 2005 3:16 am

unfortunatly Mpeg4 is about as descriptive as "vehicle", great for the coders and standards groups to have a set of standards, but for users and customers it is a nightmare.

You can basically implement any part of MPEG4 and it is then mpeg4 compliant, but that might mean you just made a video, some audio, compressed lossless, or lossy, etc.

just dig this groovy and completely transparent list
MPEG-4 consists of several standards—termed "parts"—including the following:

* Part 1 (ISO/IEC 14496-1): Systems: Describes synchronization and multiplexing of video and audio.
* Part 2 (ISO/IEC 14496-2): Visual: A compression codec for visual data (video, still textures, synthetic images, etc.). One of the many "profiles" in Part 2 is the Advanced Simple Profile (ASP).
* Part 3 (ISO/IEC 14496-3): Audio: A set of compression codecs for perceptual coding of audio signals, including some variations of Advanced Audio Coding (AAC) as well as other audio/speech coding tools.
* Part 4 (ISO/IEC 14496-4): Conformance: Describes procedures for testing conformance to other parts of the standard.
* Part 5 (ISO/IEC 14496-5): Reference Software: Provides software for demonstrating and clarifying the other parts of the standard.
* Part 6 (ISO/IEC 14496-6): Delivery Multimedia Integration Framework (DMIF).
* Part 7 (ISO/IEC 14496-7): Optimized Reference Software: Provides examples of how to make improved implementations (e.g., in relation to Part 5).
* Part 8 (ISO/IEC 14496-8 ): Carriage on IP networks: Specifies a method to carry MPEG-4 content on IP networks.
* Part 9 (ISO/IEC 14496-9): Reference Hardware: Provides hardware designs for demonstrating how to implement the other parts of the standard.
* Part 10 (ISO/IEC 14496-10): Advanced Video Coding: A codec for video signals which is also called AVC and is technically identical to the ITU-T H.264 standard.
* Part 11 (ISO/IEC 14496-11): Scene description and Application engine, also called BIFS, can be used for 3D content or subtitles.
* Part 12 (ISO/IEC 14496-12): ISO Base Media File Format: A file format for storing media content.
* Part 13 (ISO/IEC 14496-13): Intellectual Property Management and Protection (IPMP) Extensions.
* Part 14 (ISO/IEC 14496-14): MPEG-4 File Format: The designated container file format for MPEG-4 content, which is based on Part 12.
* Part 15 (ISO/IEC 14496-15): AVC File Format: For storage of Part 10 video based on Part 12.
* Part 16 (ISO/IEC 14496-16): Animation Framework eXtension (AFX).
* Part 17 (ISO/IEC 14496-17): Timed Text subtitle format.
* Part 18 (ISO/IEC 14496-18 ): Font Compression and Streaming (for OpenType fonts).
* Part 19 (ISO/IEC 14496-19): Synthesized Texture Stream.
* Part 20 (ISO/IEC 14496-20): Lightweight Scene Representation (LASeR) (not yet finished - reached "FCD" stage in January 2005).
* Part 21 (ISO/IEC 14496-21): MPEG-J Graphical Framework eXtension (GFX) (not yet finished - at "FCD" stage in July 2005, FDIS January 2006).
* Part 22 (ISO/IEC 14496-22): Open Font Format Specification (OFFS) based on OpenType (not yet finished - reached "CD" stage in July 2005)

Profiles are also defined within the individual "parts", so an implementation of a part is ordinarily not an implementation of an entire part.

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Post by skiptracer » Sun Dec 04, 2005 5:28 am

iTunes actually gives you .m4p files, which are Apple protected files. they are however, a protected version of a .m4a file. .m4a is apple lossless. apple lossless is not a less compressed version of .mp3, it is like a .zip or (more accurately) a .flac. lossless means that no audio data is lost... there is no loss of quality.

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Post by marky » Sun Dec 04, 2005 5:38 am

mp4 = better quality for the same file size.

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Post by pepezabala » Sun Dec 04, 2005 1:09 pm

mp4 = Live & most mp3-players won't play that file.

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Post by grfld » Sun Dec 04, 2005 3:02 pm

You may setup iTunes to create MP3 files, just change your preferences to MP3 and choose your quality. Use the "convert to MP3"-item from the context-menu to convert existing MP4/M4A to MP3.

However, this doesn't work with copyright-protected song from the iTunes-shop.


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