H.264 和 HEVC 编码的最佳实践.pdf

1、BEST PRACTICES FOR ENCODING H.264 AND HEVCJan Ozer,Streaming Learning CenterJBest Practices for H.264 and HEVC EncodingH.264Choosing the optimal GOP sizeBenefits of a variable GOPBitrate controlChoosing a presetChoosing the optimal thread countBest AWS CPU HEVCChoosing the optimal GOP sizeBenefits o

2、f a variable GOPBitrate controlChoosing a presetChoosing the optimal thread countWorking with Wavefront Parallel ProcessingBothOptimizing scaling for lower rung productionFundamentalsTop rung target qualityPremium content 93 95 VMAFUGC 85 92 VMAFGetting there:Choose configuration optionsAdjust bitra

3、te to hit the targetVMAFMeasure harmonic meanAnd low-frame(potential for transient quality problems)Just noticeable difference(how much does a difference matter?)Greater than 50%of viewer notice 3 VMAF point Most differences discussed here will be much lessStill,.4 VMAF here,.6 there,pretty soon you

4、re close to a JNDPlus the target is 95(or whatever)After a few adjustments,you will have to increase the bitrate to achieve the target(boosting your bandwidth costs)H.264 AgendaChoosing the optimal GOP sizeBenefits of a variable GOPBitrate controlChoosing a presetChoosing the optimal thread countBes

5、t AWS CPU Uber Best PracticeContent Adaptive Encoding is the ultimate best practiceNone of the techniques discussed herein can touch CAE as an optimization techniqueBest Practice 1 Choose Longest Possible GOP SizeWhat:GOP size(I-frame interval)is a key config option in all encodesHistoricalVery smal

6、l(like.5 second)for MPEG-2Very long(10-20 seconds)for downloaded videoTypically,2-5 seconds for adaptive bitrate video Must divide evenly into segment sizeQuestionHow does GOP size impact qualityTest 13 files in 4 categoriesEntertainmentSportsAnimationOfficeBest Practice 1:Longer is BetterBenefit si