how to support multi pipe input

[cherishman2005]

• u2takey not support multi pipe input

ffmpeg -i pipe:0-i pipe:1-i pipe:2...

such as

	in1 := ffmpeg.Input("pipe:0", inArgs)
	overlay := ffmpeg.Input("pipe:1", inArgs).Filter("scale", ffmpeg.Args{"128:-1"}).WithInput(bytes.NewReader([]byte(testSdp)))
	e := ffmpeg.Filter(
		[]*ffmpeg.Stream{
			in1,
			overlay,
		}, "overlay", ffmpeg.Args{"10:10"}, ffmpeg.KwArgs{"enable": "gte(t,1)"}).
		WithInput(bytes.NewReader([]byte(ffmpegSdp))).
		Output(*output, outArgs).OverWriteOutput().ErrorToStdOut().Run()

pipe:1: Invalid data found when processing input

[cherishman2005]

no way, and try to put content into http-server， and ffmpeg input with http-protocol:

	in1 := ffmpeg.Input("http://xxx", inArgs)
	overlay := ffmpeg.Input("http://yyy", inArgs).Filter("scale", ffmpeg.Args{"128:-1"})
	e := ffmpeg.Filter(
		[]*ffmpeg.Stream{
			in1,
			overlay,
		}, "overlay", ffmpeg.Args{"10:10"}, ffmpeg.KwArgs{"enable": "gte(t,1)"}).
		Output(*output, outArgs).OverWriteOutput().ErrorToStdOut().Run()

• how to support multi pipe input with perfect way?