python tool to read and write STEM files. Technically it is just wrapper for ffmpeg that makes it easier to handle multistream MP4 audio files.
stempeg relies on ffmpeg to encode and decode the stems file format.
The Installation if ffmpeg differ among operating systems. If you use Anaconda you can install ffmpeg on Windows/Mac/Linux using the following command:
conda install -c conda-forge ffmpeg
Decoding is supported with any recent build of ffmpeg. For Encoding it is recommended to use the Fraunhofer AAC encoder (libfdk_aac) which is not included in the default ffmpeg builds. Note that the conda version currently does not include fdk-aac. If libfdk_aac is not installed stempeg will use the default aac codec which will result in slightly inferior audio quality.
You can install ffmpeg with libfdk-aac support manually as following:
- Mac: use homebrew:
brew install ffmpeg --with-fdk-aac - Ubuntu Linux: See installation script here.
- Using Docker (Mac, Windows, Linux):
docker pull jrottenberg/ffmpeg
Installation via PyPI using pip
pip install stempeg
There are very few freely available stem files. We included a small test track from the Canadian rock-band The Easton Ellises. The band released them under Creative Commons license CC BY-NC-SA 3.0.
import stempeg
S, rate = stempeg.read_stems("input.stem.mp4")S is the stem tensor that includes the time domain signals scaled to [-1..1]. The shape is (stems, samples, channels).
you can read individual substreams of the stem file by passing the corresponding stem id (starting from 0):
S, rate = stempeg.read_stems("input.stem.mp4", stem_id=[0, 1])
⚠️ Warning: Muxing stems using ffmpeg might lead to non conform stems. Please use MP4Box, if you need a reliable result.
Writing stem files from a numpy tensor
stempeg.write_stems(S, "output.stem.mp4", rate=44100)stem2wav tests/data/The Easton Ellises - Falcon 69.stem.mp4