ffmpeg - Subtitles - Convert a SRT subtitle file to ASS format

ffmpeg -i subtitle.srt subtitle.ass

returns

subtitle.ass

[Script Info]
; Script generated by FFmpeg/Lavc60.31.102
ScriptType: v4.00+
PlayResX: 384
PlayResY: 288
ScaledBorderAndShadow: yes
YCbCr Matrix: None
 
[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,1
 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:02.00,Default,,0,0,0,,This is the first sentence
Dialogue: 0,0:00:02.00,0:00:04.00,Default,,0,0,0,,This is the second sentence
Dialogue: 0,0:00:04.00,0:00:07.00,Default,,0,0,0,,This is the third sentence
Dialogue: 0,0:00:07.00,0:00:10.00,Default,,0,0,0,,This is the forth sentence

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Add this line to prefix of every subtitles{\fade(200,200)\blur5}

{\fade(200,200)\blur5}

---

{\blur5\3c&HFFC000}

This way you do not have to change the Style.

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And via this way you can also let the Outline color transform from one to another:

{\blur5\3c&HFFC000&\t(\3c&HFF00C5&)}