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 5548 x x 58

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

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] Advantages of AVI

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

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. Current 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. Future Applications

End of presentation

[1] Various, "Audio Video Interleave," Wikipedia, 14 March [Online]. Available: [Accessed 18 March 2014]. [2] Various, "FourCC," Wikipedia, 15 June [Online]. Available: [Accessed 18 March 2014]. [3] Various, "Video Codec," Wikipedia, 7 February [Online]. Available: [Accessed 18 March 2014]. References

Continue [3] DeskShare, "DeskShare," DeskShare Incorporated, [Online]. Available: vi.aspx. [Accessed 01 april 2014]. [ 4] D. Stanley, "EZS3," Digital Marketing Ltd., [Online]. Available: ncoding_my_video_How_do_I_optimize_my_video_for_the_web.cf m. [Accessed ]. [5] "Paromita poddar," [Online]. Available: [Accessed 02 April 2014].

Continue [6 ] K. Zeng, "Articlesbase," 27 October [Online]. Available: articles/the-advantages-of-avi-format html. [Accessed 18 March 2014]. [7] Digiarty Software, "What is AVI - Audio Video Interleave - Video Format," January [Online]. Available: [Accessed 20 March 2014].

[8] E. Team, "Encoding," [Online]. Available: [Accessed 24 march 2014]. [9] "Microsoft development center," [Online]. Available: us/library/windows/desktop/dd407250%28v=vs.85%29.aspx. [Accessed 21 March 2014]. [10] R. Team, "Real," 22 april [Online]. Available: [Accessed 1 April 2014]. [11] Digiarty Software, "What is AVI - Audio Video Interleave - Video Format," January [Online]. Available: [Accessed 20 March 2014]. Continue