refactor: new transcoding engine. third (fourth?) time is a charm!

go.sum

@@ -28,6 +28,8 @@ github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumC
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dhowden/tag v0.0.0-20191122115059-7e5c04feccd8 h1:nmFnmD8VZXkjDHIb1Gnfz50cgzUvGN72zLjPRXBW/hU=
 github.com/dhowden/tag v0.0.0-20191122115059-7e5c04feccd8/go.mod h1:SniNVYuaD1jmdEEvi+7ywb1QFR7agjeTdGKyFb0p7Rw=
+github.com/djherbis/fscache v0.10.0 h1:+O3s3LwKL1Jfz7txRHpgKOz8/krh9w+NzfzxtFdbsQg=
+github.com/djherbis/fscache v0.10.0/go.mod h1:yyPYtkNnnPXsW+81lAcQS6yab3G2CRfnPLotBvtbf0c=
 github.com/edsrzf/mmap-go v0.0.0-20170320065105-0bce6a688712 h1:aaQcKT9WumO6JEJcRyTqFVq4XUZiUcKR2/GI31TOcz8=
 github.com/edsrzf/mmap-go v0.0.0-20170320065105-0bce6a688712/go.mod h1:YO35OhQPt3KJa3ryjFM5Bs14WD66h8eGKpfaBNrHW5M=
 github.com/elazarl/go-bindata-assetfs v1.0.0/go.mod h1:v+YaWX3bdea5J/mo8dSETolEo7R71Vk1u8bnjau5yw4=
@@ -174,8 +176,6 @@ gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/djherbis/atime.v1 v1.0.0 h1:eMRqB/JrLKocla2PBPKgQYg/p5UG4L6AUAs92aP7F60=
 gopkg.in/djherbis/atime.v1 v1.0.0/go.mod h1:hQIUStKmJfvf7xdh/wtK84qe+DsTV5LnA9lzxxtPpJ8=
-gopkg.in/djherbis/fscache.v0 v0.9.0 h1:CBmOlHQKg99q0xATpQpSNAR970UN4vECB5SjzkuyLe0=
-gopkg.in/djherbis/fscache.v0 v0.9.0/go.mod h1:izqJMuO+STCEMBEGFiwW5zPlamuiUOxMRpNzHT5cQHc=
 gopkg.in/djherbis/stream.v1 v1.2.0 h1:3tZuXO+RK8opjw8/BJr780h+eAPwOFfLHCKRKyYxk3s=
 gopkg.in/djherbis/stream.v1 v1.2.0/go.mod h1:aEV8CBVRmSpLamVJfM903Npic1IKmb2qS30VAZ+sssg=
 gopkg.in/fsnotify.v1 v1.4.7 h1:xOHLXZwVvI9hhs+cLKq5+I5onOuwQLhQwiu63xxlHs4=