oioiiooixiii: ballet

Showing posts with label ballet. Show all posts

FFmpeg: Extract section of video using MPV screen-shots

An unorthodox, but simple and effective way of accurately extracting a section of video from a larger video file, using MPV screen-shots (with specific file naming scheme) for 'in' and 'out' points.

Bash commands below serve only to demonstrate the general idea. No error handling whatsoever.

#!/bin/bash
# Extract section of video using time-codes taken from MPV screen-shots
# Requires specific MPV screen-shot naming scheme: screenshot-template="%f__%P"
# N.B. Skeleton script demonstrating basic operation

filename="$(ls -1 *.jpg | head -1)"
startTime="$(cut -d. -f-2 <<< "${filename#*__}")"
filename="${filename%__*}"
endTime="$(cut -d_ -f3 <<<"$(ls -1 *.jpg | tail -1)" | cut -d. -f-2)"
ffmpeg \
   -i "$filename" \
   -ss "$startTime" \
   -to "$endTime" \
   "EDIT__${filename}__${startTime}-${endTime}.${filename#*.}"

Another approach to this (and perhaps more sensible) is to script it all through MPV itself. However, that ties the technique down to MPV, whereas, this 'screen-shot' idea allows it to be used with other media players offering timestamps in the filename. Also, it's a little more tangible: you can create a series of screen-shots and later decide which ones are timed better.

video shown in demo: “The Magic of Ballet With Alan and Monica Loughman" DVD (2005)

UPDATE: September 11, 2018

I recently happened upon a MPV lua script created for practical video extraction.

'mpv-webm: Simple WebM maker for mpv, with no external dependencies.' https://github.com/ekisu/mpv-webm Create video clip at selected start/end points, as well as crop coordinates if required. Encoder options, and ability to Preview before output.
— oioiiooixiii (@oioiiooixiii) September 11, 2018

It really works well, and I now find myself using it every time I need to clip a section of video.
link: https://github.com/ekisu/mpv-webm

MacMillan's "The Rite of Spring" + Magma - 'Slag Tanz'.

Music: Magma - 'Slag Tanz'. Dance: MacMillan's "Rite of Spring" - English National Ballet (2012). Principal: Erina Takahashi. pic.twitter.com/p3K2cxETNd
— oioiiooixiii {gifs} (@oioiiooixiii_) March 20, 2017

Listening to Magma often gives me ideas for dance. I dislike sticking things together (spoils both) but gives some idea of what's in my head https://t.co/CvhBEFj0n6
— oioiiooixiii (@oioiiooixiii) March 20, 2017

Costume design by Kinder Aggugini, with additional development by Katya Ryazanskaya https://t.co/a9bV5iD4RL @oioiiooixiii_ pic.twitter.com/ak0cYeA8ul
— oioiiooixiii (@oioiiooixiii) March 20, 2017

source video: https://www.youtube.com/watch?v=GEOi4ZzUud4

FFmpeg: The recursive effects of stacking tblend filters

# Twelve stacked 'tblend=all_mode=difference128' filters.
# Deblocking 'spp' and 'average' filters used to mimimise strobing effects.
# Due to latency issues, the result in ffplay will differ from a ffmpeg rendering.

ffplay \
   -i video.mp4 \
   -vf \
   "
      scale=-2:720,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      spp=4:10,
      tblend=all_mode=average,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      spp=4:10,
      tblend=all_mode=average,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      spp=4:10,
      tblend=all_mode=average,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128 
   "

In the video above, 4 versions of the effect are shown. In order:
- The effects of the tblend filter chain as given
- A tblend fliter chain four-times as long
- The 'mode' alternates between 'difference128' and 'difference'
- A 'average' mode between each 'difference128' tblend filter

Here, the result of the shown tblend filter chain is combined with the original video, using various modes. In order:
- all_mode=difference128
- all_mode=difference
- all_mode=multiply128
- all_mode=multiply
- c0_mode=difference128
- unknown 'average_test.mkv'
- unknown 'all_average_test.mkv'
- unknown 'difference_test.mkv'
- unknown 'difference128_test.mkv'
- Original source material

source video: https://www.youtube.com/watch?v=50lAMbJUXfc

FFmpeg: Display and isolate macroblock motion-vectors in mpeg video

# Isolate motion-vectors using 'difference128' blend filter
# - add brightness, contrast, and scaling, to taste

ffplay \
   -flags2 +export_mvs \
   -i "video.mp4" \
   -vf \
   "
      split[original],
      codecview=mv=pf+bf+bb[vectors],
      [vectors][original]blend=all_mode=difference128,
      eq=contrast=7:brightness=-0.3,
      scale=720:-2
   "

Works best with higher-resolution videos; 4K source used in this case.

more info: https://trac.ffmpeg.org/wiki/Debug/MacroblocksAndMotionVectors
source video: Czech National Ballet - https://www.youtube.com/watch?v=bn12Ffi15Go
shorter alt. version: https://www.youtube.com/watch?v=KN_c4mdBpvg

The Google Juice

A group of beautiful dancers, all yearning forward, towards a mystical bottle of Google Juice.

When is Google integrating Twitter's "fire hose" into search results? My stuff here needs the Google Juice #GiveMeTheGoogleJuice
— oioiiooixiii (@oioiiooixiii) April 6, 2015

My current Twitter banner is a group of beautiful humans, all yearning for something; the Google Juice, perhaps? pic.twitter.com/kkm6KqZXdq
— oioiiooixiii (@oioiiooixiii) April 6, 2015

source image: https://www.flickr.com/photos/royaloperahouse/16637249717/
source image: http://gregladen.com/blog/2015/03/seo-social-networking-blogging/

Comparing mplayer glitching of different MP4 codecs

↖ original ↗ xvid
↙ x264 ↘ x264 (100s of iterations)

more info: http://oioiiooixiii.blogspot.com/2015/03/how-to-progressive-chroma-glitching.html
original video: Aria Alekzander https://youtu.be/ZRnZjTvMaT4?t=1m13s

Igone de Jongh: Bloed, zweet en blaren

source: http://web.avrotros.nl/bloedzweetenblaren/player/20140320_Bloed_zweet_blaren_aflevering_1/

Freddie Mercury was probably responsible for my interest in ballet

Pictured: Freddie Mercury, compared with Brazilian ballet dancer, Francisco Timbó.

original: https://www.flickr.com/photos/festivaldedanca/6254521858/

more info: http://www.vintag.es/2013/09/pictures-of-freddie-mercury-rehearsing.html
more info: http://youtu.be/h3j319l_jyk?t=2m9s

Increasing JPEG degradation over sequential video frames

original: https://www.youtube.com/watch?v=jaGd2lIYYFo

original: https://www.youtube.com/watch?v=FA2nnNspOAo

N.B 1080p viewing necessary.

info: http://oioiiooixiii.blogspot.com/2014/08/jpeg-destruction-via-repeated-rotate.html

Proof that Cadbury Creme Eggs were bigger years ago

info: http://en.wikipedia.org/wiki/Cadbury_Creme_Egg
original: http://www.markronan.com/2012/12/royal-ballet-triple-firebird-in-the-night-raymonda-act-iii-covent-garden-december-2012/

A novel approach to encrypting images in the clear

A novel, but impractical, method of encrypting an image in clear view. Randomising the position of each pixel, and keeping a record of that position, for later decryption. The cypher-key can be a text file or another image [similar to below-left]. The ARGB integer value of each pixel corresponds to the coordinates of where the pixel, in that space, has been moved to. The image below is a RGB key, without an alpha channel. With this RGB key-image, the maximum size of image that can be encoded is 16 megapixels (256*256*256). Adding an alpha channel increases the maximum size to 4 gigapixels.

The reason that this idea, in it's current form, is impractical is because the encrypted image can not be compressed with regular image compression algorithms, like jpeg. If it is saved as a jpeg, chromatic information is lost and what results when the image is decoded, is a monochromatic image [above-right]. To stop this, images can be saved as PNG files, but file size then becomes a problem with larger images [original jpeg image = 47.6KB / encrypted PNG = 278KB]

A solution to this, is to split the image into red, green, and blue components, and save them individually as jpegs. By merging these images together and running the decoding algorithm, the original image reemerges, with just a slight amount of noise added. The problem here is that the three images together still add up to roughly the same size as a single PNG [236KB], and noise has been added, but if we accept the existence of noise, then we can take it to it's logical conclusion.

Applying heavy compression of each of the three images, such that the jpeg quantising matrices can be seen, the total filesize has been reduced to [39.5KB]. Surprisingly, even with so much distortion, a recognisable version of the original can be still created. There is excessive noise but if a secret message were written in the image, it would still be quite legible.

Original image: Igone de Jongh - Dutch ballerina. http://www.operaballet.nl/en/node/2241?destination=peopleoverview/dancers

PNB's Nutcracker: The ever increasing athleticism of ballet

I had never felt inclined to watch an entire version of the Nutcracker ballet, until last December, when I happened upon a Pacific Northwest Ballet GIF animation on tumblr, and decided to source a copy of PNB's 1986 movie version, choreographed and designed by Kent Stowell and Maurice Sendak. And what a wonderful production it is. The Peacock divertissement alone, as danced by Maia Rosal, made it worth watching.

Leah Merchant's arabesque in the GIF of the modern version is stunning. One must comment however, that it does lose the context of the move representing a bird preening it's tail feathers. It is now a show piece, offering the dancer a chance to show off her technical prowess. That's not meant as a criticism by any means, but as an observation of the increasing athleticism of ballet.

I once had a blog post sketched out, which documented the increasing heights of leg extensions and the evolution of the arabesque through the centuries, and ended in a humerous envisioning of what obtuse angles the leg would take in the not too distant future.

notes:
http://oioiiooixiii.tumblr.com/post/69584518064
http://www.imdb.com/title/tt0091658/
http://www.pnb.org/Artists/Corps/LeahMerchant.aspx

oioiiooixiii

Soyuz Ballet #1

Soyuz Ballet #2

Sarah Lamb, Claudio Coviello - 'L'histoire de Manon': Rainbow