H.264 baseline

H.264 baseline有一陣子沒用了，因為平均設備的運算都挺強，處理HIgh profile基本沒大問題。然而，在穩定度很critical例如訊號轉接，發現baseline這種低功耗做法，確實讓穩定度提升。

REF: https://trac.ffmpeg.org/wiki/Encode/H.264.

If you want your videos to have highest compatibility with target devices (older iOS versions or all Android devices):

-profile:v baseline -level 3.0

This disables some advanced features but provides for better compatibility. Typically you may not need this setting (and therefore avoid using -profile:vand -level), but if you do use this setting it may increase the bit rate quite a bit compared to what is needed to achieve the same quality in higher profiles.

iOS

iOS Compatability (​source)
Profile	Level	Devices	Options
Baseline	3.0	All devices	-profile:v baseline -level 3.0
Baseline	3.1	iPhone 3G and later, iPod touch 2nd generation and later	-profile:v baseline -level 3.1
Main	3.1	iPad (all versions), Apple TV 2 and later, iPhone 4 and later	-profile:v main -level 3.1
Main	4.0	Apple TV 3 and later, iPad 2 and later, iPhone 4s and later	-profile:v main -level 4.0
High	4.0	Apple TV 3 and later, iPad 2 and later, iPhone 4s and later	-profile:v high -level 4.0
High	4.1	iPad 2 and later, iPhone 4s and later, iPhone 5c and later	-profile:v high -level 4.1
High	4.2	iPad Air and later, iPhone 5s and later	-profile:v high -level 4.2