Add rate limit to file descriptor streaming

CONFIGURATION.md

@@ -3,9 +3,11 @@ configuration options and their defaults.
 
 # Options
 
-* **--buffer-size** Audio buffer size (default 500ms)
-* **--fd** Write audio in WAV format to the specified file descriptor. This allows ditty to be used over ssh:
+* **--buffer-size** Audio buffer size, defaults to 500ms.
+* **--restrict-library** Restrict access to a folder and its subfolders.
+* **--fd** Write audio in WAV format to the specified file descriptor instead. This allows ditty to be used over ssh:
   * `ssh ditty.rocketnine.space -t 'ditty --fd=2' 2> >(aplay --quiet)`
+  * Note: Writing to a file descriptor disables pause support.
 
 # Default keybindings
 

audio.go

@@ -30,10 +30,6 @@ var (
 	playingFormat     beep.Format
 	playingSampleRate beep.SampleRate
 
-	nextStreamer beep.StreamSeekCloser
-	nextFormat   beep.Format
-	nextFileName string
-
 	volume *effects.Volume
 	ctrl   *beep.Ctrl
 
@@ -155,8 +151,9 @@ func play(audioFile *audioFile) {
 			streamFd = os.NewFile(uintptr(streamFdInt), "out")
 
 			go func() {
+				rateLimitedStreamer := NewRateLimitedStreamer(ctrl, bufferSize/64)
 				for {
-					_ = wav.Encode(streamFd, ctrl, playingFormat)
+					_ = wav.Encode(streamFd, rateLimitedStreamer, playingFormat)
 					time.Sleep(250 * time.Millisecond)
 				}
 			}()

gui_list.go

@@ -3,8 +3,6 @@ package main
 import (
 	"path"
 	"time"
-
-	"github.com/faiface/beep"
 )
 
 func listPrevious() {
@@ -34,8 +32,6 @@ func listSelect() {
 		browseFolder(path.Join(mainBufferDirectory, ".."))
 		return
 	}
-	nextStreamer = nil
-	nextFormat = beep.Format{}
 
 	entry := selectedEntry()
 	if entry.File.IsDir() {

streamer.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"time"
+
+	"github.com/faiface/beep"
+)
+
+type RateLimitedStreamer struct {
+	streamer beep.Streamer
+	rate     time.Duration
+	last     time.Time
+}
+
+func NewRateLimitedStreamer(streamer beep.Streamer, rate time.Duration) *RateLimitedStreamer {
+	s := RateLimitedStreamer{streamer: streamer, rate: rate}
+	return &s
+}
+
+func (s *RateLimitedStreamer) Stream(samples [][2]float64) (n int, ok bool) {
+	if time.Since(s.last) < s.rate {
+		time.Sleep(time.Until(s.last.Add(s.rate)))
+	}
+	s.last = time.Now()
+
+	return s.streamer.Stream(samples)
+}
+
+func (s *RateLimitedStreamer) Err() error {
+	return s.streamer.Err()
+}