From 5b2896c0325dae7624bb473b3c9c8774de3bbb9a Mon Sep 17 00:00:00 2001
From: Dan Jones <danjones@goodevilgenius.org>
Date: Fri, 8 Sep 2023 09:35:49 -0500
Subject: [PATCH] =?UTF-8?q?=F0=9F=9A=A7=20Trim=20with=20ffmpeg?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 app/run.go       | 16 ++++++++++++++
 config/config.go |  2 ++
 media/ffmpeg.go  | 57 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 media/ffmpeg.go

diff --git a/app/run.go b/app/run.go
index 191b545..dfa6e44 100644
--- a/app/run.go
+++ b/app/run.go
@@ -23,7 +23,23 @@ func quit() {
 	os.Exit(0)
 }
 
+func testTrim() {
+	path := "/home/drj/MyFiles/Videos/WebShows/YouTube/Savannah_Outen/Love_Me_Like_You_Do_-_Ellie_Goulding_Cover_by_Savannah_Outen-tPYfBpRxXfI.mp4"
+	file := SetFile(path)
+	tmp, _ := os.CreateTemp("", "audio.*.mka")
+	tmp.Close()
+	// err := media.TrimWithFade(file, tmp.Name(), 0, 215.84, 0, 3)
+	// err := media.Trim(file, tmp.Name(), 0, 215.84)
+	err := media.TrimWithFade(file, tmp.Name(), 15.2, 70.84, 3.6, 8.4)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(tmp.Name())
+	quit()
+}
+
 func Run(step AppStep) {
+	testTrim()
 	for step < Quit {
 		switch step {
 		case Pick:
diff --git a/config/config.go b/config/config.go
index 3831883..4ca54bc 100644
--- a/config/config.go
+++ b/config/config.go
@@ -16,6 +16,7 @@ type Config struct {
 	SavePath         string            `toml:"save_path"`
 	MusicPath        string            `toml:"music_path"`
 	Codec            string            `toml:"codec"`
+	FfEncoder        string            `toml:"ff_encoder"`
 	AllowedCodecs    []string          `toml:"allowed_codec"`
 	CodecExt         map[string]string `toml:"codec_ext"`
 }
@@ -30,6 +31,7 @@ func newConfig() Config {
 		SavePath:         filepath.Join(xdg.UserDirs.Documents, "StripBeats"),
 		MusicPath:        xdg.UserDirs.Music,
 		Codec:            "opus",
+		FfEncoder:        "libopus",
 		AllowedCodecs:    []string{"aac", "opus"},
 		CodecExt:         map[string]string{"aac": "m4a", "opus": "opus"},
 	}
diff --git a/media/ffmpeg.go b/media/ffmpeg.go
new file mode 100644
index 0000000..9dfa4c2
--- /dev/null
+++ b/media/ffmpeg.go
@@ -0,0 +1,57 @@
+package media
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+
+	"codeberg.org/danjones000/strip-beats/config"
+	ffmpeg "github.com/u2takey/ffmpeg-go"
+)
+
+func TrimWithFade(in Probe, out string, start, stop, up, down float64) error {
+	// -ss (start) -t (end) -af afade=t=in:st=(start):d=(up),afade=t=out:st=(downstart):d=(down)
+	st := in.GetFirstAcceptableAudio()
+	if st == nil {
+		return errors.New("Can't find an audio stream")
+	}
+	args := ffmpeg.KwArgs{"c:a": "copy"}
+	if start != 0 {
+		args["ss"] = start
+	}
+	if stop != 0 {
+		end := stop - start
+		args["t"] = end
+	} else {
+		stop = st.Duration
+	}
+
+	input := ffmpeg.Input(in.Format.Path).Get(strconv.Itoa(st.Index))
+	if up != 0 {
+		args["c:a"] = config.GetConfig().FfEncoder
+		input = input.Filter("afade", ffmpeg.Args{
+			"t=in",
+			fmt.Sprintf("st=%v", start),
+			fmt.Sprintf("d=%v", up)})
+	}
+
+	if down != 0 {
+		args["c:a"] = config.GetConfig().FfEncoder
+		downstart := stop - down
+		input = input.Filter("afade", ffmpeg.Args{
+			"t=out",
+			fmt.Sprintf("st=%v", downstart),
+			fmt.Sprintf("d=%v", down)})
+	}
+	output := input.Output(out, args).GlobalArgs("-y")
+	// @todo out should be stdout
+	return output.Run()
+}
+
+func Trim(in Probe, out string, start, stop float64) error {
+	return TrimWithFade(in, out, start, stop, 0, 0)
+}
+
+func Fade(in Probe, out string, up, down float64) error {
+	return TrimWithFade(in, out, 0, 0, up, down)
+}