The Art of Encoding Flash Video - Derrick Ypenburg
grapefruit through a garden house
video properties that affect encoding
- colour and movement
- edits/transitions/effects - ditch the star wipes
- frame rate
- display size
- sound ranges - 50hz - 18khz
- interlacing
video properties that are affected
- image quality
- smoothness of playback
- audio quality
- transitions and effects
- sound range
how to improve quality
- 2-pass encoding vs single pass - allows compiler to formulate a “plan of attack” for the render
- pre-processing filters
- deinterlacing
- advanced compression settings
- keyframes
- smaller display size
- dropping frame rates - 320×240 - seems small for most applications
third party software
- free flash encoder doesn’t give many of the advanced options
encoding with squeeze 4.5
- endorsed the ON2 VP6 Pro codec in 4.2
- requires a little more processor juice, but worth it
- key features
- 1-pass and 2-pass encoding
- variable data rate - only uses what is needed to properly encode asset
- pre-processing filters /advance compression settings
- batched processing of “watched folders” - automated batching/uploading of assets, like cron
- can share/export settings
- alpha channels
- don’t use just presets, “tweak things out”
compression settings - based off of ON2 VP6 VBR
- crop your video to fit your alpha channels
- set your alpha data rate
- check auto keyframes enabled (on top of your existing preset) - you can set minimum spacing between frames
- compression speed - suck it up, select “best” and go get a cup of coffee
- min/max allowed quality
- VBR variability - 0 creates constant citrate - starts dropping frames if it gets too rough to maintain quality
- Minimum/Maximum VBR datarate - cap thresholds so compressor doesn’t steal from elsewhere
preprocessing filters
- dramatically improves the output quality of your video
- list of filters is similar to Photoshop image effects (color correct/contrast/sharpen)
- DEINTERLACE
- telecine = up-samples from 24fps film
- black/white restore - sets black and white balances for noisey video assets
- white restore can be a little more aggressive than ideal if you aren’t careful
- normalize audio smoothes out levels
alpha channels
- millions of colors
- allows click-through of buttons
- much more processor intensive, so test on slower machines
best practices for video
- whip up an encoding matrix, so you can plot quality vs settings
- the same settings will render wildly different outcomes on a video by video basis
- keep your data rates as low as possible - bandwidth costs money
- categorize your source quality - low/high - movement/image quality/lighting
- build up some rough standards based off of categorizes
creating good video for encoding
- use a tripod
- good lighting
- try to reduce lighting hotspots and high motion shadows
- no pre-compression
- ditch the checkered/tight striped shirts
- use progressive scan cameras if possible
tips pulled from throughout presentation
- hand finagle data rates, just start shifting it up until it looks good enough
- drop your frame rates by even factors (half/third)
- talking heads video can go as low as 10fps
- preprocess filters are global to an entire video, so check to make sure they work throughout and don’t create problem spots
- categorize assets by wide types and create starting points for new assets - high motion, high quality video, bad lighting are based off of custom preset xyz
- “Deep locking” and “Smoothing” options for Flash Video components - lets you blow up video a little bit and not thrash the video quality
