MP4, MPEG, and AVI are digital video file container formats used in computers. The MP4 and MPEG are standards developed by the ISO and AVI was developed by Microsoft for the Windows Operating system based on Resource Interchange File Format (RIFF). MPEG and AVI are relatively older file types compared to MP4, which is the current industry standard.
MPEG
MPEG stands for Moving Pictures Experts Group, which is a group established for addressing the issue of standardizing the digital audio/video file formats. Cooperating with ISO, it produces the standards for digital audio and video compression used in computers.
.mpeg is the file extension for media files introduced by the MPEG-1 release. MPEG-1 includes the following components of the releases made in 1998 and afterwards. This extension is used in MPEG-2 too.
1) Systems (synchronization and storage of audio, video, and other media data together)
2) Video (video content compressed)
3) Audio (audio content compression)
4) Conformance and Compliance testing (verifying the correctness of implementations presented in the standard)
5) Reference software (software developed as examples to encode and decode following the methods in the standard)
MPEG-1 allows compression of media down to 1.5 MBits/sec (with compression ratios 26:1 and 6:1), and MPEG -2 allows compression down to 4 MBits/sec. The VCD`s, digital TV and digital audio broadcasting became possible because of the MPEG file type introduced by the MPEG-1 standard. The audio layer III of the MPEG standard, also known as MP3, became widely used in the industry for audio file storage and transfer.
Majority of the software supports this file format; in fact, some of the basic codec features are built on the MPEG platform. .mpg, .mp1, .mp2, .mp3, .m1v, .m1a, .m2a, .mpa, and .mpv are all extensions used in MPEG file format.
MP4
MP4 is a file container format developed by the Moving Pictures Experts Group for the International Standards Organization, and it is based on the QTFF. In fact, the initial release of the format was nearly identical to the QTFF. Still they share the same structure, but MP4 has moved up the timeline and developed into a more advanced container. It is now a major component of the ISO base media file format standards.
Widely used data streams in the MP4 file format are MPEG-4 Part 10 (H.264) and MPEG-4 Part for video and Advanced Audio Coding for audio streams. Subtitles use the MPEG-4 Timed Text data stream.
Since the initial development was based on the QTFF, much of the structure of MPEG-4 is the same. In an Apple environment (MacOS or iOS), these file formats can be used interchangeably. The file format can be changed without actually re-encoding video. The MP4 has the advantage of being able to stream over the internet while QTFF does not support this. Also, MP4 is supported by most of the OS platforms and video editing software. The community around the standard has grown, and contributions from the community have ensured the progress of the standard in the industry; something QTFF does not enjoy due to its proprietary nature.
MPEG4 files use the .mp4 extension in general, but depending on the application extension used may differ. For example, the audio only file can use the .m4a extension. Raw MPEG4 video bit streams are given the .m4v extension. The video file formats used in the mobile phones are also a development from the MPEG4-12, and they use the .3gp and .3g2 extensions. Audio books use the .m4b extension because variation in the code allows bookmarking the audio file.
AVI
AVI stands for Audio Video Interleave, which is a multimedia container format developed by Microsoft for windows operating system environment. AVI was developed from Resource Interchange File Format (RIFF) and allows synchronous play of both audio and video files. AVI can either use compression or not use compression for encoding; therefore, the audio/video quality of the format is higher. Therefore, it uses relatively higher storage space.
In AVI files, the media data is stored in chunks (common in all RIFF derivatives), where AVI file itself is a single chunk, which is further divided into two mandatory “chunks” and one optional “chunk”. The chunks hdrl and movi are mandatory and idx1 chunk is optional. Metadata can be stored in the info chunk of the file.
DV AVI is a compressed form of the AVI that enables the file format, so it is compatible with the DV format. Since the development of the AVI, new features have been developed in digital video technology, and the structure of the AVI file format prevents incorporating these changes into the file format. Therefore, the popularity and usage of the file format has dropped.
MPEG vs MP4 vs AVI
• AVI was developed by Microsoft based on RIFF. MPEG and MP4 are developed by Moving Pictures Experts Group for ISO.
• MP4 is an advancement of the standard from MPEG based on QTFF and supported by multiple platforms and software. AVI is supported in Windows environments.
• AVI can encode with or without compression (initially developed without compression), while MPEG and MP4 use lossy compression. MPEG uses H.261 video compression, and MP4 uses H.264 video compression.
• MPEG is used in VCD`s and DAB (Digital Audio Broadcasting), while MP4 is used in internet media.
• AVI container holds only audio and Video in the file. MPEG also holds audio and video, but MP4 support audio/video and many other media such as text and graphics within the same file.