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

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


== Codec != Format ==
== Format ==
 
* determines the way audio and video streams (and other metadata(like the codec info)) are stored inside the file
(File)'''Format''' or Container is the shipping box, '''codec''' is the goods inside the box.
<br >
Format:
* determines the way audio and video (and other metadata) are stored inside the file
* Examples are :
* Examples are :
** .avi (Microsoft -> OLD)
** .avi (Microsoft -> OLD)
Line 13: Line 10:
** .ogg (Open Source -> but not very well supported by editing software)
** .ogg (Open Source -> but not very well supported by editing software)
** .mkv (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)
** .mp4 (works on virtually all platforms, browsers etc)
 
 
[[file:interframe.gif|400px|right|thumb|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!
[[File:jpegcompression.png|thumb|right|400px|jpeg compression]]
<br />


Codec:
===Types of compression'===
* Intraframe compression
* '''Intraframe''' or spatial compression
** Compresses each frame (with for instance JPG compression)
** Compresses each frame (so similar to image compression, with for instance JPG)
** No effective size compression
** No effective size compression
** High Quality
** High Quality
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** Apple ProRes, DNxHD (Avid)
** Apple ProRes, DNxHD (Avid)


* Interframe Compression [http://www.popmodernism.org/appropirate/delta.html| Looking at delta Frames]
* '''Interframe''' or temporal Compression
** Compress BETWEEN frames
** Compress BETWEEN frames
** effective size compression
** effective size compression
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** MPEG-2 (DVD's, hardware players), DivX (downloads), H264 (currently has best quality vs. file ratio)
** MPEG-2 (DVD's, hardware players), DivX (downloads), H264 (currently has best quality vs. file ratio)
<br>
<br>
FYI: Uncompressed HD  video = 400GB per hour
[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]]


== Tools ==
[http://www.axis.com/products/video/about_networkvideo/compression.htm More Info]<br/>
* ffmpeg (ffmpegX for a Mac gui version)
[http://www.youtube.com/watch?v=ShG1mnHKntg&t=2m2s] <br/>
* Mencoder
 
* Mpegstreamclip
== Encoding Tools ==
* Handbrake
* [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
* 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


== Delivery ==
'''For (online) delivery use''':
* [http://mashable.com/2010/06/03/youtube-i-am-sitting/| what happens when you upload to youtube?]
* H.264 codec
* MP3/ACC audio codec
* .mp4 container


== Glitch Art ==
<br>
* [http://mashable.com/2010/06/03/youtube-i-am-sitting/ what happens when you upload to youtube?]


=== Data moshing ===
== 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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