install go2rtc on bob

installs_on_host/go2rtc/internal/v4l2/README.md

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+# Video4Linux
+
+[`new in v1.9.9`](https://github.com/AlexxIT/go2rtc/releases/tag/v1.9.9)
+
+What you should to know about [V4L2](https://en.wikipedia.org/wiki/Video4Linux):
+
+- V4L2 (Video for Linux API version 2) works only in Linux
+- supports USB cameras and other similar devices
+- one device can only be connected to one software simultaneously
+- cameras support a fixed list of formats, resolutions and frame rates
+- basic cameras supports only RAW (non-compressed) pixel formats
+- regular cameras supports MJPEG format (series of JPEG frames)
+- advances cameras support H264 format (MSE/MP4, WebRTC compatible)
+- using MJPEG and H264 formats (if the camera supports them) won't cost you the CPU usage
+- transcoding RAW format to MJPEG or H264 - will cost you a significant CPU usage
+- H265 (HEVC) format is also supported (if the camera supports it)
+
+Tests show that the basic Keenetic router with MIPS processor can broadcast three MJPEG cameras in the following resolutions: 1600х1200 + 640х480 + 640х480. The USB bus bandwidth is no more enough for larger resolutions. CPU consumption is no more than 5%.
+
+Supported formats for your camera can be found here: **Go2rtc > WebUI > Add > V4L2**.
+
+## RAW format
+
+Example:
+
+```yaml
+streams:
+  camera1: v4l2:device?video=/dev/video0&input_format=yuyv422&video_size=1280x720&framerate=10
+```
+
+Go2rtc supports built-in transcoding of RAW to MJPEG format. This does not need to be additionally configured.
+
+```
+ffplay http://localhost:1984/api/stream.mjpeg?src=camera1
+```
+
+**Important.** You don't have to transcode the RAW format to transmit it over the network. You can stream it in `y4m` format, which is perfectly supported by ffmpeg. It won't cost you a CPU usage. But will require high network bandwidth.
+
+```
+ffplay http://localhost:1984/api/stream.y4m?src=camera1
+```

installs_on_host/go2rtc/internal/v4l2/v4l2.go

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+//go:build !(linux && (386 || arm || mipsle || amd64 || arm64))
+
+package v4l2
+
+func Init() {
+	// not supported
+}

installs_on_host/go2rtc/internal/v4l2/v4l2_linux.go

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+//go:build linux && (386 || arm || mipsle || amd64 || arm64)
+
+package v4l2
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net/http"
+	"os"
+	"strings"
+
+	"github.com/AlexxIT/go2rtc/internal/api"
+	"github.com/AlexxIT/go2rtc/internal/streams"
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/v4l2"
+	"github.com/AlexxIT/go2rtc/pkg/v4l2/device"
+)
+
+func Init() {
+	streams.HandleFunc("v4l2", func(source string) (core.Producer, error) {
+		return v4l2.Open(source)
+	})
+
+	api.HandleFunc("api/v4l2", apiV4L2)
+}
+
+func apiV4L2(w http.ResponseWriter, r *http.Request) {
+	files, err := os.ReadDir("/dev")
+	if err != nil {
+		return
+	}
+
+	var sources []*api.Source
+
+	for _, file := range files {
+		if !strings.HasPrefix(file.Name(), core.KindVideo) {
+			continue
+		}
+
+		path := "/dev/" + file.Name()
+
+		dev, err := device.Open(path)
+		if err != nil {
+			continue
+		}
+
+		formats, _ := dev.ListFormats()
+		for _, fourCC := range formats {
+			name, ffmpeg := findFormat(fourCC)
+			source := &api.Source{Name: name}
+
+			sizes, _ := dev.ListSizes(fourCC)
+			for _, wh := range sizes {
+				if source.Info != "" {
+					source.Info += " "
+				}
+
+				source.Info += fmt.Sprintf("%dx%d", wh[0], wh[1])
+
+				frameRates, _ := dev.ListFrameRates(fourCC, wh[0], wh[1])
+				for _, fr := range frameRates {
+					source.Info += fmt.Sprintf("@%d", fr)
+
+					if source.URL == "" && ffmpeg != "" {
+						source.URL = fmt.Sprintf(
+							"v4l2:device?video=%s&input_format=%s&video_size=%dx%d&framerate=%d",
+							path, ffmpeg, wh[0], wh[1], fr,
+						)
+					}
+				}
+			}
+
+			if source.Info != "" {
+				sources = append(sources, source)
+			}
+		}
+
+		_ = dev.Close()
+	}
+
+	api.ResponseSources(w, sources)
+}
+
+func findFormat(fourCC uint32) (name, ffmpeg string) {
+	for _, format := range device.Formats {
+		if format.FourCC == fourCC {
+			return format.Name, format.FFmpeg
+		}
+	}
+	return string(binary.LittleEndian.AppendUint32(nil, fourCC)), ""
+}