init

2022-09-20 00:54:22 +02:00
commit 4195b20e65
33 changed files with 6397 additions and 0 deletions
--- a/audio/audio.go
+++ b/audio/audio.go
@@ -0,0 +1,167 @@
+package audio
+
+import (
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+
+	"fmt"
+)
+
+const (
+	BufferLength    = 300 // 5min / 3.6MB
+	Channels        = 1   // unfortunately, Discord doesn't seem to support stereo at the time
+	BitRate         = 96000
+	SampleRate      = 48000
+	FrameSize       = 960                                      // 960 samples
+	FrameDuration   = float64(FrameSize) / float64(SampleRate) // 20ms
+	FramesPerSecond = SampleRate / FrameSize
+)
+
+var (
+	ErrNotHttp = errors.New("the requested resource is not an http/https address")
+)
+
+type frameIdx struct {
+	start uint
+	end   uint
+}
+
+// Takes a file path/HTTP(S) stream URL and returns Discord audio frames through
+// audioFrameCh. After audioFrameCh is closed, errCh can be read to get any
+// potential error. Will cleanly kill ffmpeg if a struct{} is sent through
+// killCh (IMPORTANT: only send the kill signal ONCE: there is a chance that
+// this goroutine exits just before you send a kill signal; this will be
+// absorbed by the channel buffer, but your program might get stuck if you try
+// to send two kill signals to a dead stream).
+func StreamToDiscordOpus(ffmpegPath, input string, stdin io.Reader, seekSeconds float64, playbackSpeed float64, inetOnly bool) (audioFrameCh <-chan []byte, errCh <-chan error, killCh chan<- struct{}) {
+	out := make(chan []byte, BufferLength*FramesPerSecond)
+	errch := make(chan error, 1)
+	killch := make(chan struct{}, 1)
+
+	go func() {
+		defer close(out)
+		defer close(errch)
+
+		if inetOnly && !(strings.HasPrefix(input, "http://") || strings.HasPrefix(input, "https://")) {
+			errch <- ErrNotHttp
+			return
+		}
+
+		// Set ffmpeg options
+		var cmdOpts []string
+		cmdOpts = append(cmdOpts,
+			"-vn", // no video
+			"-sn", // no subs
+			"-dn") // no data encoding
+		if seekSeconds != 0.0 {
+			cmdOpts = append(cmdOpts,
+				"-accurate_seek",
+				"-ss", strconv.FormatFloat(seekSeconds, 'f', 5, 64)) // seek duration
+		}
+		cmdOpts = append(cmdOpts,
+			"-i", input)
+		if playbackSpeed != 1.0 {
+			cmdOpts = append(cmdOpts,
+				"-filter:a", "atempo="+strconv.FormatFloat(playbackSpeed, 'f', 5, 64)) // playback speed
+		}
+		cmdOpts = append(cmdOpts,
+			"-ab", strconv.Itoa(BitRate), // audio bit rate
+			"-ac", strconv.Itoa(Channels), // audio channels
+			"-frame_size", strconv.Itoa(int(FrameDuration*1000)), // frame size (in ms)
+			"-f", "opus", // output OPUS audio
+			"pipe:1") // output to stdout
+
+		// Prepare ffmpeg command
+		cmd := exec.Command(ffmpegPath, cmdOpts...)
+		if stdin != nil {
+			cmd.Stdin = stdin
+		}
+		stdout, err := cmd.StdoutPipe()
+		if err != nil {
+			errch <- err
+			return
+		}
+
+		// Start ffmpeg
+		if err := cmd.Start(); err != nil {
+			errch <- err
+			return
+		}
+
+		// We want to let our main loop know if ffmpeg is done
+		donech := make(chan error)
+		go func() {
+			donech <- cmd.Wait()
+		}()
+
+		// Ogg decoder
+		dec := newOggDecoder(stdout)
+		var segDec *oggSegmentDecoder
+		startSegDec := false
+
+		// Avoid dropping frames
+		wantNewFrame := true
+
+		// Main opus encoder loop
+		for {
+			var frame []byte
+
+			for wantNewFrame {
+				if startSegDec && segDec.More() {
+					frame = make([]byte, segDec.SegmentSize())
+					if err := segDec.ReadSegment(frame); err != nil {
+						errch <- err
+						return
+					}
+					wantNewFrame = false
+				} else if dec.More() {
+					var err error
+					var hdr oggPageHeader
+					hdr, segDec, err = dec.Page()
+					if err != nil {
+						errch <- err
+						return
+					}
+					if hdr.GranulePosition != 0 {
+						startSegDec = true
+					}
+				} else {
+					out = nil
+					break
+				}
+			}
+
+			// Channel IO
+			select {
+			case err := <-donech:
+				fmt.Println("Audio done, waiting for read to finish")
+				if err != nil {
+					// Send error and exit
+					errch <- err
+					return
+				}
+				// Process exited normally, wait until all samples are read
+				// before closing the channels
+				for len(out) != 0 {
+					time.Sleep(20 * time.Millisecond)
+				}
+				fmt.Println("Audio read finished")
+				return
+			case <-killch:
+				// Process was killed by user
+				cmd.Process.Signal(os.Interrupt)
+				return
+			case out <- frame:
+				// Output is ready to receive a new frame
+				wantNewFrame = true
+			}
+		}
+	}()
+
+	return out, errch, killch
+}