Add support streaming as ascii to terminal

internal/mjpeg/README.md

@@ -0,0 +1,33 @@
+## Stream as ASCII to Terminal
+
+**Tips**
+
+- this feature works only with MJPEG codec (use transcoding)
+- choose a low frame rate (FPS)
+- choose the width and height to fit in your terminal
+- different terminals support different numbers of colours (8, 256, rgb)
+- escape text param with urlencode
+- you can stream any camera or file from a disc
+
+**go2rtc.yaml** - transcoding to MJPEG, terminal size - 210x60, fps - 4
+
+```yaml
+streams:
+  macarena: ffmpeg:macarena.mp4#video=mjpeg#hardware#width=210#height=60#raw=-r 4
+```
+
+**API params**
+
+- `color` - foreground color, values: empty, `8`, `256`, `rgb`
+- `back` - background color, values: empty, `8`, `256`, `rgb`
+- `text` - character set, values: empty, one space, two spaces, anything you like (in order of brightness)
+
+**Examples**
+
+```bash
+% curl "http://192.168.1.123:1984/api/stream.ascii?src=macarena"
+% curl "http://192.168.1.123:1984/api/stream.ascii?src=macarena&color=256"
+% curl "http://192.168.1.123:1984/api/stream.ascii?src=macarena&back=256&text=%20"
+% curl "http://192.168.1.123:1984/api/stream.ascii?src=macarena&back=8&text=%20%20"
+% curl "http://192.168.1.123:1984/api/stream.ascii?src=macarena&text=helloworld"
+```

internal/mjpeg/init.go

@@ -5,12 +5,14 @@ import (
 	"io"
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/AlexxIT/go2rtc/internal/api"
 	"github.com/AlexxIT/go2rtc/internal/api/ws"
 	"github.com/AlexxIT/go2rtc/internal/ffmpeg"
 	"github.com/AlexxIT/go2rtc/internal/streams"
+	"github.com/AlexxIT/go2rtc/pkg/ascii"
 	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/AlexxIT/go2rtc/pkg/magic"
 	"github.com/AlexxIT/go2rtc/pkg/mjpeg"
@@ -21,6 +23,7 @@ import (
 func Init() {
 	api.HandleFunc("api/frame.jpeg", handlerKeyframe)
 	api.HandleFunc("api/stream.mjpeg", handlerStream)
+	api.HandleFunc("api/stream.ascii", handlerStream)
 
 	ws.HandleFunc("mjpeg", handlerWS)
 }
@@ -99,40 +102,24 @@ func outputMjpeg(w http.ResponseWriter, r *http.Request) {
 	}
 
 	h := w.Header()
-	h.Set("Content-Type", "multipart/x-mixed-replace; boundary=frame")
 	h.Set("Cache-Control", "no-cache")
 	h.Set("Connection", "close")
 	h.Set("Pragma", "no-cache")
 
-	wr := &writer{wr: w, buf: []byte(header)}
+	if strings.HasSuffix(r.URL.Path, "mjpeg") {
+		wr := mjpeg.NewWriter(w)
 		_, _ = cons.WriteTo(wr)
+	} else {
+		cons.Type = "ASCII passive consumer "
+
+		query := r.URL.Query()
+		wr := ascii.NewWriter(w, query.Get("color"), query.Get("back"), query.Get("text"))
+		_, _ = cons.WriteTo(wr)
+	}
 
 	stream.RemoveConsumer(cons)
 }
 
-const header = "--frame\r\nContent-Type: image/jpeg\r\nContent-Length: "
-
-type writer struct {
-	wr  io.Writer
-	buf []byte
-}
-
-func (w *writer) Write(p []byte) (n int, err error) {
-	w.buf = w.buf[:len(header)]
-	w.buf = append(w.buf, strconv.Itoa(len(p))...)
-	w.buf = append(w.buf, "\r\n\r\n"...)
-	w.buf = append(w.buf, p...)
-	w.buf = append(w.buf, "\r\n"...)
-
-	// Chrome bug: mjpeg image always shows the second to last image
-	// https://bugs.chromium.org/p/chromium/issues/detail?id=527446
-	if n, err = w.wr.Write(w.buf); err == nil {
-		w.wr.(http.Flusher).Flush()
-	}
-
-	return
-}
-
 func inputMjpeg(w http.ResponseWriter, r *http.Request) {
 	dst := r.URL.Query().Get("dst")
 	stream := streams.Get(dst)

pkg/ascii/README.md

@@ -0,0 +1,6 @@
+## Useful links
+
+- https://en.wikipedia.org/wiki/ANSI_escape_code
+- https://paulbourke.net/dataformats/asciiart/
+- https://github.com/kutuluk/xterm-color-chart
+- https://github.com/hugomd/parrot.live

pkg/ascii/ascii.go

@@ -0,0 +1,140 @@
+package ascii
+
+import (
+	"bytes"
+	"fmt"
+	"image/jpeg"
+	"io"
+	"net/http"
+)
+
+func NewWriter(w io.Writer, foreground, background, text string) io.Writer {
+	a := &writer{wr: w, buf: []byte(clearScreen)}
+
+	var idx0 uint8
+
+	// https://en.wikipedia.org/wiki/ANSI_escape_code
+	switch foreground {
+	case "8":
+		a.color = func(r, g, b uint8) {
+			if idx := xterm256color(r, g, b, 8); idx != idx0 {
+				idx0 = idx
+				a.buf = append(a.buf, fmt.Sprintf("\033[%dm", 30+idx)...)
+			}
+		}
+	case "256":
+		a.color = func(r, g, b uint8) {
+			if idx := xterm256color(r, g, b, 255); idx != idx0 {
+				idx0 = idx
+				a.buf = append(a.buf, fmt.Sprintf("\033[38;5;%dm", idx)...)
+			}
+		}
+	case "rgb":
+		a.color = func(r, g, b uint8) {
+			a.buf = append(a.buf, fmt.Sprintf("\033[38;2;%d;%d;%dm", r, g, b)...)
+		}
+	}
+
+	switch background {
+	case "8":
+		a.color = func(r, g, b uint8) {
+			if idx := xterm256color(r, g, b, 8); idx != idx0 {
+				idx0 = idx
+				a.buf = append(a.buf, fmt.Sprintf("\033[%dm", 40+idx)...)
+			}
+		}
+	case "256":
+		a.color = func(r, g, b uint8) {
+			if idx := xterm256color(r, g, b, 255); idx != idx0 {
+				a.buf = append(a.buf, fmt.Sprintf("\033[48;5;%dm", idx)...)
+			}
+		}
+	case "rgb":
+		a.color = func(r, g, b uint8) {
+			a.buf = append(a.buf, fmt.Sprintf("\033[48;2;%d;%d;%dm", r, g, b)...)
+		}
+	}
+
+	var ascii string
+	switch text {
+	case "":
+		ascii = ` .::--~~==++**##%%$@`
+	case " ":
+		a.text = func(r, g, b uint32) {
+			a.buf = append(a.buf, ' ')
+		}
+	case "  ":
+		a.text = func(r, g, b uint32) {
+			a.buf = append(a.buf, ' ', ' ')
+		}
+	default:
+		ascii = text
+	}
+	if ascii != "" {
+		k := float64(len(ascii)-1) / 255
+		a.text = func(r, g, b uint32) {
+			gray := (19595*r + 38470*g + 7471*b + 1<<15) >> 24 // uint8
+			i := uint8(float64(gray) * k)
+			a.buf = append(a.buf, ascii[i])
+		}
+	}
+
+	return a
+}
+
+type writer struct {
+	wr    io.Writer
+	buf   []byte
+	color func(r, g, b uint8)
+	text  func(r, g, b uint32)
+}
+
+// https://stackoverflow.com/questions/37774983/clearing-the-screen-by-printing-a-character
+const clearScreen = "\033[2J" + "\033[H"
+
+func (a *writer) Write(p []byte) (n int, err error) {
+	img, err := jpeg.Decode(bytes.NewReader(p))
+	if err != nil {
+		return 0, err
+	}
+
+	a.buf = a.buf[:len(clearScreen)]
+
+	w := img.Bounds().Dy()
+	h := img.Bounds().Dx()
+
+	for y := 0; y < w; y++ {
+		for x := 0; x < h; x++ {
+			r, g, b, _ := img.At(x, y).RGBA()
+			if a.color != nil {
+				a.color(uint8(r>>8), uint8(g>>8), uint8(b>>8))
+			}
+			a.text(r, g, b)
+		}
+		a.buf = append(a.buf, '\n')
+	}
+
+	a.buf = append(a.buf, "\033[0m\n"...)
+
+	if n, err = a.wr.Write(a.buf); err == nil {
+		a.wr.(http.Flusher).Flush()
+	}
+
+	return
+}
+
+const x256r = "\x00\x80\x00\x80\x00\x80\x00\xc0\x80\xff\x00\xff\x00\xff\x00\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x08\x12\x1c\x26\x30\x3a\x44\x4e\x58\x60\x66\x76\x80\x8a\x94\x9e\xa8\xb2\xbc\xc6\xd0\xda\xe4\xee"
+const x256g = "\x00\x00\x80\x80\x00\x00\x80\xc0\x80\x00\xff\xff\x00\x00\xff\xff\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x5f\x5f\x5f\x5f\x5f\x5f\x87\x87\x87\x87\x87\x87\xaf\xaf\xaf\xaf\xaf\xaf\xd7\xd7\xd7\xd7\xd7\xd7\xff\xff\xff\xff\xff\xff\x08\x12\x1c\x26\x30\x3a\x44\x4e\x58\x60\x66\x76\x80\x8a\x94\x9e\xa8\xb2\xbc\xc6\xd0\xda\xe4\xee"
+const x256b = "\x00\x00\x00\x00\x80\x80\x80\xc0\x80\x00\x00\x00\xff\xff\xff\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x00\x5f\x87\xaf\xd7\xff\x08\x12\x1c\x26\x30\x3a\x44\x4e\x58\x60\x66\x76\x80\x8a\x94\x9e\xa8\xb2\xbc\xc6\xd0\xda\xe4\xee"
+
+func xterm256color(r, g, b uint8, n int) (index uint8) {
+	best := uint16(0xFFFF)
+	for i := 0; i < n; i++ {
+		diff := uint16(r-x256r[i]) + uint16(g-x256g[i]) + uint16(b-x256b[i])
+		if diff < best {
+			best = diff
+			index = uint8(i)
+		}
+	}
+	return
+}

pkg/mjpeg/writer.go

@@ -0,0 +1,36 @@
+package mjpeg
+
+import (
+	"io"
+	"net/http"
+	"strconv"
+)
+
+func NewWriter(w io.Writer) io.Writer {
+	h := w.(http.ResponseWriter).Header()
+	h.Set("Content-Type", "multipart/x-mixed-replace; boundary=frame")
+	return &writer{wr: w, buf: []byte(header)}
+}
+
+const header = "--frame\r\nContent-Type: image/jpeg\r\nContent-Length: "
+
+type writer struct {
+	wr  io.Writer
+	buf []byte
+}
+
+func (w *writer) Write(p []byte) (n int, err error) {
+	w.buf = w.buf[:len(header)]
+	w.buf = append(w.buf, strconv.Itoa(len(p))...)
+	w.buf = append(w.buf, "\r\n\r\n"...)
+	w.buf = append(w.buf, p...)
+	w.buf = append(w.buf, "\r\n"...)
+
+	// Chrome bug: mjpeg image always shows the second to last image
+	// https://bugs.chromium.org/p/chromium/issues/detail?id=527446
+	if n, err = w.wr.Write(w.buf); err == nil {
+		w.wr.(http.Flusher).Flush()
+	}
+
+	return
+}