ffmpeg-helper

name	FFmpeg Helper
description	Guidelines for generating valid FFmpeg commands for the mobile FFmpeg Kit.

FFmpeg Helper

Use this skill when working with ffmpeg_kit_flutter_new.

1. Syntax Handling

• Space Escaping: Paths with spaces must be escaped.
  • Incorrect: -i /storage/emulated/0/My Folder/video.mp4
  • Correct: -i "/storage/emulated/0/My Folder/video.mp4"
• Codecs: Mobile devices often prefer aac for audio and libx264 (software) or h264_mediacodec (hardware) for video.

2. Common Recipes

Merge Audio and Video

final command = '-i "$videoPath" -i "$audioPath" -c:v copy -c:a aac "$outputPath"';

Convert to MP3

final command = '-i "$inputPath" -vn -acodec libmp3lame -q:a 2 "$outputPath"';

• -vn: Disable video recording.
• -acodec libmp3lame: Use MP3 codec.
• -q:a 2: Variable bit rate (high quality).

Trim Video

final command = '-ss 00:00:10 -i "$inputPath" -t 00:00:30 -c copy "$outputPath"';

• -ss: Start time.
• -t: Duration.

3. Session Handling

Always check the return code:

FFmpegKit.execute(command).then((session) async {
  final returnCode = await session.getReturnCode();
  if (ReturnCode.isSuccess(returnCode)) {
    // Success
  } else {
    // Failure
    final failStackTrace = await session.getFailStackTrace();
    print("FFmpeg failed: $failStackTrace");
  }
});

4. Permissions

• Ensure Permission.manageExternalStorage (Android 11+) or Permission.storage is granted before running commands involving external files.