Prototyping 2013-11-05 (Lens Based Media): Difference between revisions

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= Compression & Codecs =
= Compression & Codecs in video =
(File)'''Format''' or Container is the shipping box, '''codec''' is the goods inside the box.


== Formats ==
== Format ==
* determines the way audio and video streams (and other metadata(like the codec info)) are stored inside the file
* Examples are :
** .avi (Microsoft -> OLD)
** .wmf (Microsoft -> Unflexible)
** .mov (Apple -> supports a lot of codecs)
** .ogg (Open Source -> but not very well supported by editing software)
** .mkv (Open Source -> but not very well supported by editing software)
** .mp4 (works on virtually all platforms, browsers etc)


== Codec ==


== Glitch Art ==
[[file:interframe.gif|400px|right|thumb|intra- vs. interframe compression]]


=== Data moshing ===
== Encoding/Compressing ==
'''Why do we compress?'''
* Image- and videofile sizes reduced
* More files to store, or longer videos
* Faster to download
* Downside: someone has to decode!
[[File:jpegcompression.png|thumb|right|400px|jpeg compression]]
<br />
 
===Types of compression'===
* '''Intraframe''' or spatial compression
** Compresses each frame (so similar to image compression, with for instance JPG)
** No effective size compression
** High Quality
** Easily readable by edit software
** Apple ProRes, DNxHD (Avid)
 
* '''Interframe''' or temporal Compression
** Compress BETWEEN frames
** effective size compression
** Not easy for edit software
** Use for sharing -> final output
** MPEG-2 (DVD's, hardware players), DivX (downloads), H264 (currently has best quality vs. file ratio)
<br>
[http://en.wikipedia.org/wiki/Comparison_of_video_codecs comparison of video codec]
 
=== encoding techniques ===
* Run length encoding > Looks for identical segments (often lossless)
* [http://www.popmodernism.org/appropirate/delta.html Transform coding] > Most used (jpeg, DCT, wavelet) (selectively removes ‘non-relevant’ detail from the image).
* [http://www.knotless.com/1/post/2012/07/the-mysteries-of-chroma-sub-sampling.html Chroma subsampling] >Selective loss of resolution (4:4:4 vs 4:2:0)
* Reducing bit-depth (reducing colour accuracy)
* Fractal compression (replacing pixels with mathematic approximations)
 
[[file:iframes.jpg|400px]]
 
[http://www.axis.com/products/video/about_networkvideo/compression.htm More Info]<br/>
[http://www.youtube.com/watch?v=ShG1mnHKntg&t=2m2s] <br/>
 
== Encoding Tools ==
* [http://www.ffmpeg.org/download.html ffmpeg (ffmpegX for a Mac gui version)]
* [http://en.wikipedia.org/wiki/MEncoder Mencoder]
* [http://handbrake.fr/ Handbrake]
* [http://www.squared5.com/ Mpegstreamclip]
* Adobe Media Encoder
 
== Bitrate + Framesize ==
 
Most lossy codecs allow you to set a [http://neuron2.net/LVG/ratesandsizes.html bitrate] (the amount of bits per second)
<br>Together with the framesize this determines the quality of the video.
[http://floppyfilms.pleintekst.nl/oscars_2009/slumdog/ Floppy Films]
== Workflow, Archiving & Delivery ==
 
There's no solution to the question 'What is the best setting for my video?". All depends on the platform you will deliver to!
* How do you record? (Camera codec? DSLR)
* How do you edit? (intermediate files?)
* What do you deliver? (Archiving, uploading, DVD?)
<br >
Example, '''for editing/archiving use''':
* ProRes video codec (visually lossless through many iterations)
* Wav/Aiff audio codec
* .mov container
 
'''For (online) delivery use''':
* H.264 codec
* MP3/ACC audio codec
* .mp4 container
 
<br>
* [http://mashable.com/2010/06/03/youtube-i-am-sitting/ what happens when you upload to youtube?]
 
== Glitch Art & Data moshing ==
[[File:downloadfinished.jpg|right|thumb|400px|Download Finished]]
[[File:downloadfinished.jpg|right|thumb|400px|Download Finished]]
* [http://www.youtube.com/watch?v=tYytVzbPky8|How to datamosh]
* [http://www.youtube.com/watch?v=tYytVzbPky8 How to datamosh]
* [http://www.download-finished.com/| Download Finished] by [http://wwwwwwwwwwwwwwwwwwwwww.bitnik.org/d/| Mediengruppe Bitnik]
* [http://www.download-finished.com/ Download Finished] by [http://wwwwwwwwwwwwwwwwwwwwww.bitnik.org/d/| Mediengruppe Bitnik]
* [http://snorpey.github.io/jpg-glitch/| glitch your image, source code]
* [http://snorpey.github.io/jpg-glitch/ glitch your image, source code]
{{#ev:youtube|mvqakws0CeU?version=3&amp;autohide=1&amp;showinfo=0}}
{{#ev:youtube|mvqakws0CeU?version=3&amp;autohide=1&amp;showinfo=0}}

Latest revision as of 10:43, 5 November 2013

Compression & Codecs in video

(File)Format or Container is the shipping box, codec is the goods inside the box.

Format

  • determines the way audio and video streams (and other metadata(like the codec info)) are stored inside the file
  • Examples are :
    • .avi (Microsoft -> OLD)
    • .wmf (Microsoft -> Unflexible)
    • .mov (Apple -> supports a lot of codecs)
    • .ogg (Open Source -> but not very well supported by editing software)
    • .mkv (Open Source -> but not very well supported by editing software)
    • .mp4 (works on virtually all platforms, browsers etc)


intra- vs. interframe compression

Encoding/Compressing

Why do we compress?

  • Image- and videofile sizes reduced
  • More files to store, or longer videos
  • Faster to download
  • Downside: someone has to decode!
jpeg compression


Types of compression'

  • Intraframe or spatial compression
    • Compresses each frame (so similar to image compression, with for instance JPG)
    • No effective size compression
    • High Quality
    • Easily readable by edit software
    • Apple ProRes, DNxHD (Avid)
  • Interframe or temporal Compression
    • Compress BETWEEN frames
    • effective size compression
    • Not easy for edit software
    • Use for sharing -> final output
    • MPEG-2 (DVD's, hardware players), DivX (downloads), H264 (currently has best quality vs. file ratio)


comparison of video codec

encoding techniques

  • Run length encoding > Looks for identical segments (often lossless)
  • Transform coding > Most used (jpeg, DCT, wavelet) (selectively removes ‘non-relevant’ detail from the image).
  • Chroma subsampling >Selective loss of resolution (4:4:4 vs 4:2:0)
  • Reducing bit-depth (reducing colour accuracy)
  • Fractal compression (replacing pixels with mathematic approximations)

Iframes.jpg

More Info
[1]

Encoding Tools

Bitrate + Framesize

Most lossy codecs allow you to set a bitrate (the amount of bits per second)
Together with the framesize this determines the quality of the video. Floppy Films

Workflow, Archiving & Delivery

There's no solution to the question 'What is the best setting for my video?". All depends on the platform you will deliver to!

  • How do you record? (Camera codec? DSLR)
  • How do you edit? (intermediate files?)
  • What do you deliver? (Archiving, uploading, DVD?)


Example, for editing/archiving use:

  • ProRes video codec (visually lossless through many iterations)
  • Wav/Aiff audio codec
  • .mov container

For (online) delivery use:

  • H.264 codec
  • MP3/ACC audio codec
  • .mp4 container


Glitch Art & Data moshing

Download Finished

{{#ev:youtube|mvqakws0CeU?version=3&autohide=1&showinfo=0}}

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