Add initial implementations for encoder handling and conversion logic

Introduce encoder modules for various codecs and formats (e.g., h264_nvenc, libx264, libmp3lame). Add `Convertor` logic to retrieve supported formats via FFmpeg utilities and manage encoders for audio, video, and image processing.

internal/ffmpeg/ffmpeg.go

@@ -1,6 +1,7 @@
 package ffmpeg
 
 import (
+	"bufio"
 	"errors"
 	"fyne.io/fyne/v2/lang"
 	"git.kor-elf.net/kor-elf/gui-for-ffmpeg/internal/utils"
@@ -10,6 +11,7 @@ import (
 
 type FFmpegContract interface {
 	GetPath() string
+	GetEncoders(scanner func(scanner *bufio.Reader)) error
 }
 
 type ffmpeg struct {
@@ -38,6 +40,26 @@ func (f *ffmpeg) GetPath() string {
 	return f.path
 }
 
+func (f *ffmpeg) GetEncoders(scanner func(scanner *bufio.Reader)) error {
+	cmd := exec.Command(f.path, "-encoders")
+	utils.PrepareBackgroundCommand(cmd)
+
+	stdOut, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+
+	err = cmd.Start()
+	if err != nil {
+		return err
+	}
+
+	scannerErr := bufio.NewReader(stdOut)
+	scanner(scannerErr)
+
+	return cmd.Wait()
+}
+
 func checkFFmpegPath(path string) (bool, error) {
 	cmd := exec.Command(path, "-version")
 	utils.PrepareBackgroundCommand(cmd)