fork stempeg + add stemsep.py

stempeg/__init__.py

@@ -0,0 +1,59 @@
+"""
+Stempeg is a Python package to read and write [STEM](https://www.native-instruments.com/en/specials/stems/) files.
+Technically, stems are audio containers that combine multiple audio streams and metadata in a single audio file. This makes it ideal to playback multitrack audio, where users can select the audio sub-stream during playback (e.g. supported by VLC). 
+
+Under the hood, _stempeg_ uses [ffmpeg](https://www.ffmpeg.org/) for reading and writing multistream audio, optionally [MP4Box](https://github.com/gpac/gpac) is used to create STEM files that are compatible with Native Instruments hardware and software.
+
+- `stempeg.read`: reading audio tensors and metadata.
+- `stempeg.write`: writing audio tensors.
+
+![stempeg_scheme](https://user-images.githubusercontent.com/72940/102477776-16960a00-405d-11eb-9389-1ea9263cf99d.png)
+
+Please checkout [the Github repository](https://github.com/faroit/stempeg) for more information.
+"""
+
+from .read import read_stems
+from .read import Info
+from .read import StreamsReader, ChannelsReader
+from .write import write_stems
+from .write import write_audio
+from .write import FilesWriter, StreamsWriter, ChannelsWriter, NIStemsWriter
+from .cmds import check_available_aac_encoders
+
+import re
+import subprocess as sp
+import pkg_resources
+
+__version__ = "1.0.0"
+
+
+def default_metadata():
+    """Get the path to included stems metadata.
+
+    Returns
+    -------
+    filename : str
+        Path to the json file
+    """
+    return pkg_resources.resource_filename(__name__, "../metadata.json")
+
+
+def ffmpeg_version():
+    """Returns the available ffmpeg version
+
+    Returns
+    ----------
+    version : str
+        version number as string
+    """
+
+    cmd = ["ffmpeg", "-version"]
+
+    output = sp.check_output(cmd)
+    aac_codecs = [x for x in output.splitlines() if "ffmpeg version " in str(x)][0]
+    hay = aac_codecs.decode("ascii")
+    match = re.findall(r"ffmpeg version \w?(\d+\.)?(\d+\.)?(\*|\d+)", hay)
+    if match:
+        return "".join(match[0])
+    else:
+        return None

stempeg/cmds.py

@@ -0,0 +1,90 @@
+import re
+import subprocess as sp
+import logging
+
+FFMPEG_PATH = None
+FFPROBE_PATH = None
+MP4BOX_PATH = None
+
+
+def find_cmd(cmd):
+    try:
+        from shutil import which
+
+        return which(cmd)
+    except ImportError:
+        import os
+
+        for path in os.environ["PATH"].split(os.pathsep):
+            if os.access(os.path.join(path, cmd), os.X_OK):
+                return path
+
+    return None
+
+
+def ffmpeg_and_ffprobe_exists():
+    global FFMPEG_PATH, FFPROBE_PATH
+    if FFMPEG_PATH is None:
+        FFMPEG_PATH = find_cmd("ffmpeg")
+
+    if FFPROBE_PATH is None:
+        FFPROBE_PATH = find_cmd("ffprobe")
+
+    return FFMPEG_PATH is not None and FFPROBE_PATH is not None
+
+
+def mp4box_exists():
+    global MP4BOX_PATH
+    if MP4BOX_PATH is None:
+        MP4BOX_PATH = find_cmd("MP4Box")
+
+    return MP4BOX_PATH is not None
+
+
+if not ffmpeg_and_ffprobe_exists():
+    raise RuntimeError(
+        "ffmpeg or ffprobe could not be found! "
+        "Please install them before using stempeg. "
+        "See: https://github.com/faroit/stempeg"
+    )
+
+
+def check_available_aac_encoders():
+    """Returns the available AAC encoders
+
+    Returns:
+        list(str): List of available encoder codecs from ffmpeg
+
+    """
+    cmd = [FFMPEG_PATH, "-v", "error", "-codecs"]
+
+    output = sp.check_output(cmd)
+    aac_codecs = [
+        x for x in output.splitlines() if "AAC (Advanced Audio Coding)" in str(x)
+    ][0]
+    hay = aac_codecs.decode("ascii")
+    match = re.findall(r"\(encoders: ([^\)]*) \)", hay)
+    if match:
+        return match[0].split(" ")
+    else:
+        return None
+
+
+def get_aac_codec():
+    """Checks codec and warns if `libfdk_aac` codec
+     is not available.
+
+    Returns:
+        str: ffmpeg aac codec name
+    """
+    avail = check_available_aac_encoders()
+    if avail is not None:
+        if "libfdk_aac" in avail:
+            codec = "libfdk_aac"
+        else:
+            logging.warning("For the better audio quality, install `libfdk_aac` codec.")
+            codec = "aac"
+    else:
+        codec = "aac"
+
+    return codec