Add transcoder package with text transcoder

transcoder/text/text.go

@@ -0,0 +1,157 @@
+// Package text transcode a video to text
+package text
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os/exec"
+	"strings"
+	"time"
+
+	"gitlab.crans.org/nounous/ghostream/stream"
+)
+
+// Options holds text package configuration
+type Options struct {
+	Enabled   bool
+	Width     int
+	Height    int
+	Framerate int
+}
+
+// Init text transcoder
+func Init(streams map[string]*stream.Stream, cfg *Options) {
+	if !cfg.Enabled {
+		// Text transcode is not enabled, ignore
+		return
+	}
+
+	// Regulary check existing streams
+	for {
+		for sourceName, sourceStream := range streams {
+			if strings.Contains(sourceName, "@") {
+				// Not a source stream, pass
+				continue
+			}
+
+			// Check that the transcoded stream does not already exist
+			name := sourceName + "@text"
+			_, ok := streams[name]
+			if ok {
+				// Stream is already transcoded
+				continue
+			}
+
+			// Start conversion
+			log.Printf("Starting text transcode '%s'", name)
+			st := stream.New()
+			streams[name] = st
+
+			go transcode(sourceStream, st, cfg)
+		}
+
+		// Regulary pull stream list,
+		// it may be better to tweak the messaging system
+		// to get an event on a new stream.
+		time.Sleep(time.Second)
+	}
+}
+
+// Convert video to ANSI text
+func transcode(input, output *stream.Stream, cfg *Options) {
+	// Start ffmpeg to transcode video to rawvideo
+	videoInput := make(chan []byte)
+	input.Register(videoInput)
+	ffmpeg, rawvideo, err := startFFmpeg(videoInput, cfg)
+	if err != nil {
+		log.Printf("Error while starting ffmpeg: %s", err)
+		return
+	}
+
+	// Transcode rawvideo to ANSI text
+	pixelBuff := make([]byte, cfg.Width*cfg.Height)
+	textBuff := bytes.Buffer{}
+	for {
+		n, err := (*rawvideo).Read(pixelBuff)
+		if err != nil {
+			log.Printf("An error occurred while reading input: %s", err)
+			break
+		}
+		if n == 0 {
+			// Stream is finished
+			break
+		}
+
+		// Header
+		textBuff.Reset()
+		textBuff.Grow((40*cfg.Width+6)*cfg.Height + 47)
+		for i := 0; i < 42; i++ {
+			textBuff.WriteByte('\n')
+		}
+
+		// Convert image to ASCII
+		for i, pixel := range pixelBuff {
+			if i%cfg.Width == 0 {
+				// New line
+				textBuff.WriteString("\033[49m\n")
+			}
+
+			// Print two times the character to make a square
+			text := fmt.Sprintf("\033[48;2;%d;%d;%dm ", pixel, pixel, pixel)
+			textBuff.WriteString(text)
+			textBuff.WriteString(text)
+		}
+		textBuff.WriteString("\033[49m")
+
+		output.Broadcast <- textBuff.Bytes()
+	}
+
+	// Stop transcode
+	ffmpeg.Process.Kill()
+}
+
+// Start a ffmpeg instance to convert stream into rawvideo
+func startFFmpeg(in <-chan []byte, cfg *Options) (*exec.Cmd, *io.ReadCloser, error) {
+	bitrate := fmt.Sprintf("%dk", cfg.Width*cfg.Height*cfg.Framerate)
+	ffmpegArgs := []string{"-hide_banner", "-loglevel", "error", "-i", "pipe:0",
+		"-an", "-vf", fmt.Sprintf("scale=%dx%d", cfg.Width, cfg.Height),
+		"-b:v", bitrate, "-minrate", bitrate, "-maxrate", bitrate, "-bufsize", bitrate,
+		"-q", "42", "-pix_fmt", "gray", "-f", "rawvideo", "pipe:1"}
+	ffmpeg := exec.Command("ffmpeg", ffmpegArgs...)
+
+	// Handle errors output
+	errOutput, err := ffmpeg.StderrPipe()
+	if err != nil {
+		return nil, nil, err
+	}
+	go func() {
+		scanner := bufio.NewScanner(errOutput)
+		for scanner.Scan() {
+			log.Printf("[TELNET FFMPEG %s] %s", "demo", scanner.Text())
+		}
+	}()
+
+	// Handle text output
+	output, err := ffmpeg.StdoutPipe()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Handle stream input
+	input, err := ffmpeg.StdinPipe()
+	if err != nil {
+		return nil, nil, err
+	}
+	go func() {
+		for data := range in {
+			input.Write(data)
+		}
+	}()
+
+	// Start process
+	err = ffmpeg.Start()
+	return ffmpeg, &output, nil
+}

transcoder/text/text_test.go

@@ -0,0 +1 @@
+package text

transcoder/transcoder.go

@@ -0,0 +1,16 @@
+package transcoder
+
+import (
+	"gitlab.crans.org/nounous/ghostream/stream"
+	"gitlab.crans.org/nounous/ghostream/transcoder/text"
+)
+
+// Options holds text package configuration
+type Options struct {
+	Text text.Options
+}
+
+// Init all transcoders
+func Init(streams map[string]*stream.Stream, cfg *Options) {
+	go text.Init(streams, &cfg.Text)
+}