Difficulty adding multiple metadata fields to output file

[welpo]

Hello!

First off: thanks for this binding!

I'm trying to add multiple metadata fields to an MP3 file. My goal is to recreate the following FFmpeg command:

ffmpeg -y -i input.mp3 -metadata title="Test Title" -metadata artist="Test Artist" -metadata album="Test Album" -metadata year="2024" -c copy output.mp3

However, I've encountered several issues while attempting to achieve this using the wrapper.

Code

import os
from ffmpeg import FFmpeg, FFmpegError

def add_metadata_to_mp3():
    input_file = os.path.expanduser("~/Desktop/test.mp3")
    output_file = os.path.expanduser("~/Desktop/test_metadata.mp3")

    metadata = {
        "title": "Test Title",
        "artist": "Test Artist",
        "album": "Test Album",
        "year": "2024"
    }

    ffmpeg = (
        FFmpeg()
        .option("y")  # Overwrite output file if it exists
        .input(input_file)
    )

    for key, value in metadata.items():
        ffmpeg = ffmpeg.option(f"metadata", f"{key}={value}")
    ffmpeg = ffmpeg.output(output_file, c="copy")

    try:
        ffmpeg.execute()
        print(f"Metadata added successfully. Output file: {output_file}")
    except FFmpegError as e:
        print(f"An FFmpeg error occurred: {e.message}")
        print(f"FFmpeg arguments: {e.arguments}")

if __name__ == "__main__":
    add_metadata_to_mp3()

Attempts and results

1. Single metadata string:

   metadata_str = ":".join(f"{key}={value}" for key, value in metadata.items())
   ffmpeg.output(url=output_file, metadata=metadata_str, c="copy")

   Result: All metadata fields were concatenated into the "Title" field.

2. Separate metadata options:

   for key, value in metadata.items():
      ffmpeg = ffmpeg.option("metadata", f"{key}={value}")
   ffmpeg = ffmpeg.output(url=output_file, c="copy")

   Result: Error - "Error opening input files: Invalid argument" FFmpeg arguments were ordered incorrectly, with metadata before input file:

   ['ffmpeg', '-y', '-metadata', 'title=Test Title', '-metadata', 'artist=Test Artist', '-metadata', 'album=Test Album', '-metadata', 'year=2024', '-i', '/Users/welpo/Desktop/test.mp3', '-c', 'copy', '/Users/welpo/Desktop/test_metadata.mp3']

3. Output options dictionary:

   output_options = {"c": "copy"}
   for key, value in metadata.items():
      output_options[f"metadata:{key}"] = value
   ffmpeg = ffmpeg.output(output_file, **output_options)

   Result: Error - "Error opening output files: Invalid argument" FFmpeg arguments had incorrect metadata syntax:

   ['ffmpeg', '-y', '-i', '/Users/welpo/Desktop/test.mp3', '-c', 'copy', '-metadata:title', 'Test Title', '-metadata:artist', 'Test Artist', '-metadata:album', 'Test Album', '-metadata:year', '2024', '/Users/welpo/Desktop/test_metadata.mp3']

4. Metadata as separate options:

   for key, value in metadata.items():
      ffmpeg = ffmpeg.option(f"metadata", f"{key}={value}")
   ffmpeg = ffmpeg.output(output_file, c="copy")

   Result: Error - "Error opening input files: Invalid argument" FFmpeg arguments still ordered incorrectly, with metadata before input file:

   ['ffmpeg', '-y', '-metadata', 'title=Test Title', '-metadata', 'artist=Test Artist', '-metadata', 'album=Test Album', '-metadata', 'year=2024', '-i', '/Users/welpo/Desktop/test.mp3', '-c', 'copy', '/Users/welpo/Desktop/test_metadata.mp3']

---

Is there a correct way to add multiple metadata fields to an output file using the wrapper? If so, could you provide an example of how to achieve this?

Thanks!

Additional information

• FFmpeg version: 7.1
• Python version: 3.12.7
• Operating system: macOS Sonoma 14.6.1
• Wrapper version: 2.0.12

[welpo]

I did it!

After a million attempts, Claude came up with the idea to use the metadata:g:n format for passing global metadata options. Here's the working code:

def add_metadata_to_mp3():
    input_file = os.path.expanduser("~/Desktop/test.mp3")
    output_file = os.path.expanduser("~/Desktop/test_metadata.mp3")

    metadata = {
        "metadata:g:0": "title=Test Title",
        "metadata:g:1": "artist=Test Artist",
        "metadata:g:2": "album=Test Album",
        "metadata:g:3": "year=2024"
    }

    ffmpeg = (
        FFmpeg()
        .option("y")
        .input(input_file)
        .output(output_file, c="copy", **metadata)
    )

    try:
        ffmpeg.execute()
        print(f"Metadata added successfully. Output file: {output_file}")
    except FFmpegError as e:
        print(f"An FFmpeg error occurred: {e.message}")
        print(f"FFmpeg arguments: {e.arguments}")

This defines the metadata as a list of tuples, where each tuple contains the metadata:g:n key and the full key=value string for each metadata item.

I searched around and found this comment, which may have been in the training data.