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MP4

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MP4

This page is about MP4 the container format, for MP4 (acronym) the encoding standard see MPEG-4.

Contents

Introduction

There are four primary (and 18 known) competing and semi-compatible/interchangeable container standards that use. For ease of use for most people; this page will cover the four primary formats in general use. A standard MP4 file has three principal parts: Audio, Video, and Subtitle. It may have one, two, or all three streams present.

For the sake of completeness, one must understand that the MP4 container is much like an RAR or ZIP file with 0 compression (container wrap); it can hold virtually anything. Just because it can does not mean it should; however it is not uncommon to find MP4 files on the internet that have other tracks included along with the three principal streams.

MPEG-4 PART 14

The official and original version of the MP4 container it is part of the Moving Picture Experts Group's MPEG-4 standard, and is listed with the World Trade Organization as ISO/IEC 14496.

video

  • MPEG-4 aka H.2xx
  • MPEG-4 AVC
  • MPEG-2
  • MPEG-1

Audio

  • AAC (MPEG-2 Part 7)
  • MPEG-4 Part 3 (MP3)
  • MP3 (MPEG-1 Audio Layer 3)
  • MP2 (MPEG-1 Audio Layer 2)
  • MPEG-1 Audio Layer 1
  • DTS
  • DTS+
  • CELP (speech)
  • TwinVQ
  • SAOL (Sun MIDI)
  • IT (Impulse Tracker XM)
  • MIDI

subtitle/THI

  • SSA (SubStation Alpha)
  • SRT (Subtitle)
  • DCC/CC (Closed Caption)
  • MPEG-4 Timed Text (3GPP Timed Text)

Apple iMedia

As he origin of the MP4 format; Apple chose to maintain their QuickTime basis for MP4, which uses proprietary codecs.

Video

  • Apple iMP4 (QuickTime)
  • Apple iMP4e/MPV (Encrypted MPV files)

Audio

  • Apple M4A (QuickTime Audio) [stereo only]
  • MPEG-4 Part 3 (MP3)

3GP

Developed by the Third Generation Partnership; 3GP is the iteration of MP4 used for multimedia transmissions over Smart-Phones and SmartChip/SmartCard enabled devices (including Mobile Satellite Internet PPV and IPTV). The main difference between 3GP and part 14 is that 3GP files have an entire file bitrate-map at the beginning of each file (the header) to allow the bandwidth provider to properly allocate space for the file if it is 'streamed'.

Video

  • MPEG-4 Part 2 (H.263)
  • MPEG-4 Part 10 (AVC/H.264)

Audio

  • AAC
  • AC3
  • AMR

Subtitle

  • DCC/CC (Closed Caption)
  • MPEG-4 Timed Text (3GPP Timed Text)

Nero Digital/Nero HD

Nero is the wolf-in-sheep's-clothing member of the MP4 group. They have opened up the biggest challenge (and displayed all the flaws of the format) by not only using their own complete proprietary codecs by default, but by also by allowing pass-through conversion to MP4 allowing absolutely anything to be enclosed in the container. Not only that; but the proprietary codecs only work in Nero's software, and no standalone decoders or converters are available. As if that wasn't enough; they also have opened up the container to hold up to 20 separate streams, have eliminated file-size restrictions (allowing raw audio and video, often with file size exceeding 100gb), and have made no attempt to inform users that the output often can not be played outside of Nero ShowTime.

Video

  • NeroDigital MPV/M4V
  • NeroDigital Pro (8MB/S VBR)
  • NeroDigital HD (HD video)
  • Anything else that was in the source file

Audio

  • NeroDigital (M4A)
  • Mp3
  • DTS
  • NeroHD Audio (5.1, 6.1, 7.1 sound)
  • Anything else that was in the source file
  • Nero MP3-Pro

MP3-Pro

An audio file that is partially compressed allowing compatibility with standard MP3 players at lower bitrates, but maintaining the high-quality sound when played back on a computer. A 64Kbs MP3-Pro file has the identical sound quality as a 128Kbs MP3 file when decoded on a computer with the MP3-Pro codec encoder/decoder installed.

Subtitle

  • VOBSub
  • Anything else that was in the source file