On https://free-av-tools.com you can:

• Convert an audio file to another format - MP3, AAC, WAV, Opus, Vorbis (in the .mka container), FLAC, ALAC, AC3, DTS or CAF.
• Convert a video to an audio-only file (to any of the above formats).
• Convert a video to the MP4 or MKV format.
• Change the audio codec of a video to MP3, AAC, AC3, DTS, WAV, FLAC or ALAC.
• Trim a video or audio file (will not work if using the Safari browser).
• Download a YouTube video or the audio only. The webpage is a youtube-dl wrapper.

[1] Features (audio/video converter)

[2] Features (YouTube downloader)

[3] Supported Filetypes

[4] Audio and Video Decoder

[5] External encoders used

[6] Other tool(s) used

[7] Requirements for developers/running locally

[8] Notes for contributors

• You can see the file upload progress as a percentage and also amount uploaded (MB) in realtime.
• Upload completion time is shown in realtime.
• Whilst the file is being converted, you can see how far into the file the encoder currently is. This information is updated every second.

• Download as an MP3 or MP4 file, or simply the best quality video/audio stream that is available.
• If you choose to download as an MP3, the thumbnail of the video gets embedded as the cover art.
• Download the best quality audio stream without encoding it, so no lossy-to-lossy encoding is done (only applicable if you use the "Audio [best]" button.

Many filetypes are supported, click here for details. Support for other filetypes may be added, feel free to contact me to enquire.

FFmpeg

LAME v3.100 | https://lame.sourceforge.io/

fdk-aac | https://github.com/mstorsjo/fdk-aac

opusenc opus-tools 0.2 (using libopus 1.3.1) | https://github.com/xiph/opus

libvorbis

youtube-dl | https://github.com/ytdl-org/youtube-dl

You can run the Flask app locally for development purposes or if you want audio/video conversion to be quicker as the file(s) will not need to be uploaded to my server.

• Python 3.6+
• FFmpeg

When running locally, you will not be able to convert to AAC unless you compile FFmpeg with --enable-libfdk-aac in the configuration. Or, if you know what you're doing, you can edit the code in converter.py to use FFmpeg's native AAC encoder instead.

• pip install -r requirements.txt

If youtube-dl fails to install when using pip install -r requirements.txt, install it manually. Installation details can be found here.

• Clone this repository.
• Uncomment db.create_all() in main.py and yt.py
• Change the value of youtube_dl_path in yt.py to the correct path.
• cd into the directory that main.py is and enter python3 main.py (or just python if that uses Python 3 for you) in the terminal.
• Enter localhost:5000 in the address bar of your web browser and hit enter.

Run these commands to build and run the Dockerfile. Note sudo is usually required on Linux.

docker build -t audio-and-video-converter .
docker run -p 5000:5000 audio-and-video-converter

Contributors are welcome, simply submit a pull request.

Use f-strings rather than .format() if you know how to do so.