feat: initialise project structure with core encoding queue, database models, and web management API

internal/encoder/audio.go

@@ -0,0 +1,45 @@
+package encoder
+
+import (
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+func (m *FFmpegManager) BuildAudioCmd(inputPath, outputPath, ffmpegFlags string) (*exec.Cmd, error) {
+	args := []string{"-i", inputPath, "-c:a", "libmp3lame", "-b:a", "320k"}
+
+	if ffmpegFlags != "" {
+		userArgs := ShlexSplit(ffmpegFlags)
+		args = append(args, userArgs...)
+	}
+
+	args = append(args, outputPath, "-y")
+
+	return exec.Command(m.BinaryPath, args...), nil
+}
+
+func (m *FFmpegManager) ShouldSkipAudio(inputPath string) bool {
+	// Probe the codec
+	cmd := exec.Command("ffprobe", "-v", "quiet", "-select_streams", "a:0",
+		"-show_entries", "stream=codec_name", "-of", "csv=p=0", inputPath)
+	out, err := cmd.Output()
+	if err != nil {
+		return false
+	}
+	codec := strings.TrimSpace(string(out))
+
+	// If it's already mp3, check bitrate
+	if codec == "mp3" {
+		cmdBr := exec.Command("ffprobe", "-v", "quiet", "-select_streams", "a:0",
+			"-show_entries", "stream=bit_rate", "-of", "csv=p=0", inputPath)
+		outBr, err := cmdBr.Output()
+		if err == nil {
+			br, _ := strconv.Atoi(strings.TrimSpace(string(outBr)))
+			if br >= 300000 {
+				return true // It's ~320k mp3
+			}
+		}
+	}
+	return false
+}