Merged in audio-order (pull request #419)

revid, alsa: reorder audio setup

Approved-by: Saxon Milton

device/alsa/alsa.go

@@ -116,11 +116,11 @@ func (d *ALSA) Name() string {
 	return "ALSA"
 }
 
-// Set will take a Config struct, check the validity of the relevant fields
-// and then performs any configuration necessary. If fields are not valid,
+// Setup will take a Config struct, check the validity of the relevant fields
+// and then perform any configuration necessary. If fields are not valid,
 // an error is added to the multiError and a default value is used.
 // It then initialises the ALSA device which can then be started, read from, and stopped.
-func (d *ALSA) Set(c config.Config) error {
+func (d *ALSA) Setup(c config.Config) error {
 	var errs device.MultiError
 	if c.SampleRate <= 0 {
 		errs = append(errs, errInvalidSampleRate)
@@ -185,6 +185,14 @@ func (d *ALSA) Set(c config.Config) error {
 	return nil
 }
 
+// Set exists to satisfy the implementation of the Device interface that revid uses.
+// Everything that would usually be in Set is in the Setup function.
+// This is because an ALSA device is different to other devices in that it
+// outputs binary non-packetised data and it requires a different configuration procedure.
+func (d *ALSA) Set(c config.Config) error {
+	return nil
+}
+
 // Start will start recording audio and writing to the ringbuffer.
 // Once an ALSA device has been stopped it cannot be started again. This is likely to change in future.
 func (d *ALSA) Start() error {
@@ -458,6 +466,12 @@ func (d *ALSA) formatBuffer() pcm.Buffer {
 	return formatted
 }
 
+// DataSize returns the size in bytes of the data ALSA device d will
+// output in the duration of a single recording period.
+func (d *ALSA) DataSize() int {
+	return pcm.DataSize(d.SampleRate, d.Channels, d.BitDepth, d.RecPeriod, d.Codec)
+}
+
 // nearestPowerOfTwo finds and returns the nearest power of two to the given integer.
 // If the lower and higher power of two are the same distance, it returns the higher power.
 // For negative values, 1 is returned.

device/alsa/alsa_test.go

@@ -53,7 +53,7 @@ func TestDevice(t *testing.T) {
 	// Create a new ALSA device, start, read/lex, and then stop it.
 	l := logger.New(logger.Debug, os.Stderr, true)
 	ai := New(l)
-	err := ai.Set(c)
+	err := ai.Setup(c)
 	// If there was an error opening the device, skip this test.
 	if _, ok := err.(OpenError); ok {
 		t.Skip(err)
@@ -119,7 +119,7 @@ func TestIsRunning(t *testing.T) {
 	l := logger.New(logger.Debug, &bytes.Buffer{}, true) // Discard logs.
 	d := New(l)
 
-	err := d.Set(config.Config{
+	err := d.Setup(config.Config{
 		SampleRate: sampleRate,
 		Channels:   channels,
 		BitDepth:   bitDepth,

revid/audio_linux.go

@@ -29,13 +29,32 @@ import (
 	"strconv"
 
 	"bitbucket.org/ausocean/av/codec/codecutil"
-	"bitbucket.org/ausocean/av/codec/pcm"
 	"bitbucket.org/ausocean/av/container/mts"
 	"bitbucket.org/ausocean/av/device/alsa"
 	"bitbucket.org/ausocean/utils/logger"
 )
 
 func (r *Revid) setupAudio() error {
+	// Create new ALSA device.
+	d := alsa.New(r.cfg.Logger)
+	r.input = d
+
+	// Configure ALSA device.
+	r.cfg.Logger.Log(logger.Debug, "configuring input device")
+	err := d.Setup(r.cfg)
+	if err != nil {
+		r.cfg.Logger.Log(logger.Warning, "errors from configuring input device", "errors", err)
+	}
+	r.cfg.Logger.Log(logger.Info, "input device configured")
+
+	// Set revid's lexer.
+	l, err := codecutil.NewByteLexer(d.DataSize())
+	if err != nil {
+		return err
+	}
+	r.lexTo = l.Lex
+
+	// Add metadata.
 	mts.Meta.Add("sampleRate", strconv.Itoa(int(r.cfg.SampleRate)))
 	mts.Meta.Add("channels", strconv.Itoa(int(r.cfg.Channels)))
 	mts.Meta.Add("period", fmt.Sprintf("%.6f", r.cfg.RecPeriod))
@@ -50,13 +69,5 @@ func (r *Revid) setupAudio() error {
 		r.cfg.Logger.Log(logger.Fatal, "no audio codec set in config")
 	}
 
-	r.input = alsa.New(r.cfg.Logger)
-
-	l, err := codecutil.NewByteLexer(pcm.DataSize(r.cfg.SampleRate, r.cfg.Channels, r.cfg.BitDepth, r.cfg.RecPeriod, r.cfg.InputCodec))
-	if err != nil {
-		return err
-	}
-	r.lexTo = l.Lex
-
 	return nil
 }