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forked from um/cli
cli/internal/ffmpeg/ffmpeg.go

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package ffmpeg
import (
"bytes"
"context"
"fmt"
"io"
"os"
"os/exec"
"strings"
"unlock-music.dev/cli/algo/common"
"unlock-music.dev/cli/internal/utils"
)
func ExtractAlbumArt(ctx context.Context, rd io.Reader) (*bytes.Buffer, error) {
cmd := exec.CommandContext(ctx, "ffmpeg",
"-i", "pipe:0", // input from stdin
"-an", // disable audio
"-codec:v", "copy", // copy video(image) codec
"-f", "image2", // use image2 muxer
"pipe:1", // output to stdout
)
cmd.Stdin = rd
stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}
cmd.Stdout, cmd.Stderr = stdout, stderr
if err := cmd.Run(); err != nil {
return nil, fmt.Errorf("ffmpeg run: %w", err)
}
return stdout, nil
}
type UpdateMetadataParams struct {
Audio string // required
AudioExt string // required
Meta common.AudioMeta // required
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AlbumArt []byte // optional
AlbumArtExt string // required if AlbumArt is not nil
}
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func UpdateMeta(ctx context.Context, outPath string, params *UpdateMetadataParams) error {
if params.AudioExt == ".flac" {
return updateMetaFlac(ctx, outPath, params)
} else {
return updateMetaFFmpeg(ctx, outPath, params)
}
}
func updateMetaFFmpeg(ctx context.Context, outPath string, params *UpdateMetadataParams) error {
builder := newFFmpegBuilder()
out := newOutputBuilder(outPath) // output to file
builder.SetFlag("y") // overwrite output file
builder.AddOutput(out)
// input audio -> output audio
builder.AddInput(newInputBuilder(params.Audio)) // input 0: audio
out.AddOption("map", "0:a")
out.AddOption("codec:a", "copy")
// input cover -> output cover
if params.AlbumArt != nil &&
params.AudioExt != ".wav" /* wav doesn't support attached image */ {
// write cover to temp file
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artPath, err := utils.WriteTempFile(bytes.NewReader(params.AlbumArt), params.AlbumArtExt)
if err != nil {
return fmt.Errorf("updateAudioMeta write temp file: %w", err)
}
defer os.Remove(artPath)
builder.AddInput(newInputBuilder(artPath)) // input 1: cover
out.AddOption("map", "1:v")
switch params.AudioExt {
case ".ogg": // ogg only supports theora codec
out.AddOption("codec:v", "libtheora")
case ".m4a": // .m4a(mp4) requires set codec, disposition, stream metadata
out.AddOption("codec:v", "mjpeg")
out.AddOption("disposition:v", "attached_pic")
out.AddMetadata("s:v", "title", "Album cover")
out.AddMetadata("s:v", "comment", "Cover (front)")
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case ".mp3":
out.AddOption("codec:v", "mjpeg")
out.AddMetadata("s:v", "title", "Album cover")
out.AddMetadata("s:v", "comment", "Cover (front)")
default: // other formats use default behavior
}
}
// set file metadata
album := params.Meta.GetAlbum()
if album != "" {
out.AddMetadata("", "album", album)
}
title := params.Meta.GetTitle()
if album != "" {
out.AddMetadata("", "title", title)
}
artists := params.Meta.GetArtists()
if len(artists) != 0 {
// TODO: it seems that ffmpeg doesn't support multiple artists
out.AddMetadata("", "artist", strings.Join(artists, " / "))
}
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if params.AudioExt == ".mp3" {
out.AddOption("write_id3v1", "true")
out.AddOption("id3v2_version", "3")
}
// execute ffmpeg
cmd := builder.Command(ctx)
if stdout, err := cmd.CombinedOutput(); err != nil {
return fmt.Errorf("ffmpeg run: %w, %s", err, string(stdout))
}
return nil
}