Fix the encoding format spec in the liquidsoap template

The right set of parameters depend on the format, move that logic to a
function in the code and out of the template.

transcoder/liquidsoap.go

@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
+	"strings"
 	"sync"
 	"text/template"
 
@@ -22,8 +23,8 @@ set("log.unix_timestamps", false)
 
 upstream = mksafe(input.http("{{.SourceURL}}", buffer=5.0))
 {{if eq .Channels 1}}upstream = mean(upstream){{end}}
-output.icecast(%{{.Format}}(samplerate={{.SampleRate}}, {{if gt .BitRate 0}}bitrate={{.BitRate}}, {{end}}{{if gt .Quality -1.0}}quality={{.Quality}}, {{end}}{{if .StereoMode}}stereo_mode="{{.StereoMode}}", {{end}}{{if eq .Channels 2}}stereo{{else}}mono{{end}}),
-  mount="{{.TargetMount}}", host="{{.TargetIP}}", port={{.TargetPort}}, user="{{.TargetUsername}}", password="{{.TargetPassword}}",
+output.icecast({{.Format}},
+  mount="{{.TargetMount}}", host="{{.TargetHost}}", port={{.TargetPort}}, user="{{.TargetUsername}}", password="{{.TargetPassword}}",
   upstream)
 `
 
@@ -52,21 +53,14 @@ type liquidsoapParams struct {
 	SourceURL string
 
 	// Target (downstream) connection parameters.
-	TargetIP       string
+	TargetHost     string
 	TargetPort     int
 	TargetMount    string
 	TargetUsername string
 	TargetPassword string
 
-	// Stream encoding parameters. One note on the 'float32'
-	// choice for Quality: text/template can't evaluate the 'gt'
-	// function successfully on a float64 type!
-	Format     string
-	BitRate    int32
-	SampleRate int32
-	Channels   int32
-	StereoMode string
-	Quality    float32
+	Format   string
+	Channels int
 }
 
 // Create new parameters for liquidsoap for a transcoding mount. If
@@ -80,17 +74,13 @@ type liquidsoapParams struct {
 func newLiquidsoapParams(m *pb.Mount) *liquidsoapParams {
 	return &liquidsoapParams{
 		SourceURL:      fmt.Sprintf("http://localhost%s", m.TranscodeParams.SourcePath),
-		TargetIP:       "localhost",
+		TargetHost:     "localhost",
 		TargetPort:     80,
 		TargetMount:    m.Path,
 		TargetUsername: m.SourceUsername,
 		TargetPassword: m.SourcePassword,
-		Format:         m.TranscodeParams.Format,
-		BitRate:        m.TranscodeParams.BitRate,
-		SampleRate:     m.TranscodeParams.SampleRate,
-		Channels:       m.TranscodeParams.Channels,
-		StereoMode:     m.TranscodeParams.StereoMode,
-		Quality:        m.TranscodeParams.Quality,
+		Format:         liquidsoapFormatString(m.TranscodeParams),
+		Channels:       int(m.TranscodeParams.Channels),
 	}
 }
 
@@ -101,3 +91,33 @@ func makeLiquidsoapConfig(m *pb.Mount) ([]byte, error) {
 	}
 	return buf.Bytes(), nil
 }
+
+func liquidsoapFormatString(params *pb.EncodingParams) string {
+	var outp []string
+	switch params.Format {
+	case "mp3", "mp3.cbr", "mp3.vbr", "mp3.abr":
+		if params.Channels == 1 {
+			outp = append(outp, "mono")
+		} else {
+			outp = append(outp, "stereo")
+			outp = append(outp, fmt.Sprintf("stereo_mode=\"%s\"", params.StereoMode))
+		}
+		outp = append(outp, fmt.Sprintf("samplerate=%d", params.SampleRate))
+		switch params.Format {
+		case "mp3", "mp3.cbr", "mp3.abr":
+			outp = append(outp, fmt.Sprintf("bitrate=%d", params.BitRate))
+		case "mp3.vbr":
+			outp = append(outp, fmt.Sprintf("quality=%d", int(params.Quality)))
+		}
+	case "vorbis", "vorbis.cbr", "vorbis.abr":
+		outp = append(outp, fmt.Sprintf("channels=%d", params.Channels))
+		outp = append(outp, fmt.Sprintf("samplerate=%d", params.SampleRate))
+		switch params.Format {
+		case "vorbis":
+			outp = append(outp, fmt.Sprintf("quality=%g", params.Quality))
+		case "vorbis.abr", "vorbis.cbr":
+			outp = append(outp, fmt.Sprintf("bitrate=%d", params.BitRate))
+		}
+	}
+	return fmt.Sprintf("%%%s(%s)", params.Format, strings.Join(outp, ", "))
+}