AVI File Format
By : Jacob, Bab and Conor
Basic operation
Presented By: Conor
What is AVI?
• AVI is a container format that is used for
synchronizing video and audio data for ease of
playback [1]
• Uses RIFF (Resource Interchange File Format)
to segment the different data. [1]
How Does RIFF help?
• By segmenting the data into “chunks” and
each having 2 or 3 “sub-chunks” [2] [3]
• Each Chunk contains both video/audio data
and metadata used by a Codec for playback.
So what Data can AVI contain?
• AVI Format files can hold full-frame, MPEG-4,
indeo, and many more. [1]
• The header chunk contains all the info needed for
media Codecs to read and use the content
segmented and synchronized by AVI.
• Unless the audio/video data is uncompressed
before encapsulation, playback will be lossy. [3]
Quality vs Bit rate
Presented by : Jacob
Three Main factors that determine Bit Rate
of an AVI video are [3] :
• Resolution
• Frame rate
• Variable bit rate vs Constant Bit Rate
Resolution
• Resolution effects the pixel density of an
image [4]
• lower resolution = lower quality images +
lower bit rate
• Higher resolution = higher quality images +
higher bit rate
50 x 58
5548 x 6372
Frame Rate :
• Is the amount of images that appear per second
• Humans generally perceive smooth motion at 24 fps however
most videos follow the ntsc standard at 29
• Kush gauge: pixel count x fps x motion factor (1,2 or 4) x 0.07 ÷
1000 = bit rate in kbps [5]
Example using 1280 x 720 resolution and low motion (factor of 1)
(921,600 x 5) x 1 x 0.07 = 322,560 bps / 1000 = 322 kbps bitrate[5]
(921,600 x 25) x 1 x 0.07 = 1,612,800 bps/ 1000 = 1613 kbps bitrate
VBR Vs CBR
• Variable bit rate is when a file switches from a
minimum to maximum bit rate [3]. Also
usually reduces bit rate by 25% [4]
• Constant bit rate only has one one set rate but
provides smoother playback and less stress to
the video player. [3]
Advantages and Disadvantages
Presented by : Bab
Advantages of AVI
• High compatibility with VirtualDub and Windows
Media Player.
• Advanced DV-AVI standard is compressed to
conform with DV standard.
• Plays in mainstream media players such as
Windows Media Player.[1]
Continue
• Can be used as a starting point to create
playable DVDs.
• Does not require any special hardware or
software.
• Widely used in business such as
advertisement and promo videos. [6]
Disadvantages
• AVI does not provide a standardized way to
encode aspect ratio information, with the result
that players cannot select the right one
automatically .
• Can not hold VBR data such as mp3 below 32khz
sample rate.
• Its ability to enhance sound is bad
• It has limited picture resolution, and it is unable
to do full screen and full motion video. [7]
Current and Future Applications
Presented by : Jacob
Current Applications
• Since being created in 1992 [8] avi has is still
the digital standard for recording and editing
videos
• Avi has influenced other derivatives like xvid
(compressed avi) and dv – avi (lossless avi)[9]
• DV- Avi is used in current video cameras.
Future Applications
• Slowly being replaced by wmv (very slowly) because of
having no ability to maintain aspect ratio information[10]
• Other formats like mpeg 4 and ogg solve this problem. [11]
• Formats like xvid and divx are updated versions of avi and
will continue to be used for pc playback.
End of presentation
References
• [1] Various, "Audio Video Interleave," Wikipedia, 14 March 2014.
[Online]. Available:
http://en.wikipedia.org/wiki/Audio_Video_Interleave. [Accessed 18
March 2014].
• [2] Various, "FourCC," Wikipedia, 15 June 2013. [Online].
Available: http://en.wikipedia.org/wiki/FourCC. [Accessed 18 March
2014].
• [3] Various, "Video Codec," Wikipedia, 7 February 2013. [Online].
Available:
http://en.wikipedia.org/wiki/Video_codec#Lossless_codecs.
[Accessed 18 March 2014].
Continue
• [3] DeskShare, "DeskShare," DeskShare Incorporated, [Online].
Available:
http://www.deskshare.com/resources/articles/dmc_compression_a
vi.aspx. [Accessed 01 april 2014].
•
• [ 4] D. Stanley, "EZS3," Digital Marketing Ltd., 2014. [Online].
Available:
http://www.ezs3.com/public/What_bitrate_should_I_use_when_e
ncoding_my_video_How_do_I_optimize_my_video_for_the_web.cf
m. [Accessed 1 04 2014].
• [5] "Paromita poddar," 2010. [Online]. Available:
http://www.paromitapoddar.com/VideoCompression/kush.html.
[Accessed 02 April 2014].
Continue
• [6 ] K. Zeng, "Articlesbase," 27 October 2010. [Online].
Available: http://www.articlesbase.com/softwarearticles/the-advantages-of-avi-format-3553577.html.
[Accessed 18 March 2014].
• [7] Digiarty Software, "What is AVI - Audio Video Interleave Video Format," January 2014. [Online]. Available:
http://www.winxdvd.com/resource/avi.htm. [Accessed 20
March 2014].
Continue
[8]
E. Team, "Encoding," 2013. [Online]. Available:
http://www.encoding.com/avi-encoding. [Accessed 24 march 2014].
[9]
"Microsoft development center," [Online]. Available:
http://msdn.microsoft.com/enus/library/windows/desktop/dd407250%28v=vs.85%29.aspx.
[Accessed 21 March 2014].
[10]
R. Team, "Real," 22 april 2012. [Online]. Available:
http://www.real.com/resources/digital-video-file-formats/. [Accessed
1 April 2014].
[11]
Digiarty Software, "What is AVI - Audio Video Interleave Video Format," January 2014. [Online]. Available:
http://www.winxdvd.com/resource/avi.htm. [Accessed 20 March
2014].