import os
import warnings
import numpy as np
from .abstract import _classify_source
from .avconv import LibAVReader
from .avconv import LibAVWriter
from .ffmpeg import FFmpegReader
from .ffmpeg import FFmpegWriter
import skvideo # accessed via attributes so set*Path() updates are seen
from ..utils import *
def _normalize_source(fname):
"""Path-likes go through os.fspath; file-like objects pass through unchanged.
Callers downstream (the Reader/Writer constructors) handle the BytesIO /
file-like case via _classify_source + spool_memory_to_tempfile, so we
must not try to coerce these into strings here.
"""
if _classify_source(fname) == "memory":
return fname
return os.fspath(fname)
def _warn_libav_deprecated():
warnings.warn(
"The libav/avconv backend is deprecated and will be removed in a "
"future release (libav is unmaintained upstream and this backend "
"is not covered by scikit-video's CI). Use the ffmpeg backend "
"instead.", DeprecationWarning, stacklevel=3)
[docs]
def vwrite(fname, videodata, inputdict=None, outputdict=None, backend='ffmpeg', verbosity=0, audiosrc=None):
"""Save a video to file entirely from memory.
Parameters
----------
fname : string
Video file name.
videodata : ndarray
ndarray of dimension (T, M, N, C), (T, M, N), (M, N, C), or (M, N),
where T is the number of frames, M is the height, N is width,
and C is number of channels.
inputdict : dict
Input dictionary parameters, i.e. how to interpret the piped datastream
coming from python to the subprocess.
outputdict : dict
Output dictionary parameters, i.e. how to encode the data to
disk.
backend : string
Program to use for handling video data.
Only 'ffmpeg' and 'libav' are supported at this time.
verbosity : int
Setting to 0 (default) disables all debugging output.
Setting to 1 enables all debugging output.
Useful to see if the backend is behaving properly.
audiosrc : string, optional
Path to a media file whose audio track should be muxed into the
output, allowing audio to be preserved across a ``vread`` /
``vwrite`` round-trip (issues #173, #176). FFmpeg backend only.
Returns
-------
none
"""
fname = _normalize_source(fname)
if not inputdict:
inputdict = {}
if not outputdict:
outputdict = {}
videodata = vshape(videodata)
# check that the appropriate videodata size was passed
T, M, N, C = videodata.shape
if T == 0:
raise ValueError("Cannot write an empty video: videodata has 0 frames.")
if backend == "ffmpeg":
# check if FFMPEG exists in the path
if not skvideo._HAS_FFMPEG:
raise RuntimeError("Cannot find installation of real FFmpeg (which comes with ffprobe).")
writer = FFmpegWriter(fname, inputdict=inputdict, outputdict=outputdict,
audiosrc=audiosrc, verbosity=verbosity)
for t in range(T):
writer.writeFrame(videodata[t])
writer.close()
elif backend == "libav":
_warn_libav_deprecated()
if audiosrc is not None:
raise NotImplementedError("audiosrc passthrough is only supported with backend='ffmpeg'")
# check if FFMPEG exists in the path
if not skvideo._HAS_AVCONV:
raise RuntimeError("Cannot find installation of libav.")
writer = LibAVWriter(fname, inputdict=inputdict, outputdict=outputdict, verbosity=verbosity)
for t in range(T):
writer.writeFrame(videodata[t])
writer.close()
else:
raise ValueError("unknown backend: %r (supported: 'ffmpeg', 'libav')" % (backend,))
[docs]
def vread(fname, height=0, width=0, num_frames=0, as_grey=False, inputdict=None, outputdict=None, backend='ffmpeg', verbosity=0, start_frame=0):
"""Load a video from file entirely into memory.
Parameters
----------
fname : string
Video file name, e.g. ``bickbuckbunny.mp4``
height : int
Set the source video height used for decoding.
Useful for raw inputs when video header does not exist.
width : int
Set the source video width used for decoding.
Useful for raw inputs when video header does not exist.
num_frames : int
Only read the first `num_frames` number of frames from video.
Setting `num_frames` to small numbers can significantly
speed up video loading times.
as_grey : bool
If true, only load the luminance channel of the input video.
inputdict : dict
Input dictionary parameters, i.e. how to interpret the input file.
outputdict : dict
Output dictionary parameters, i.e. how to encode the data
when sending back to the python process.
backend : string
Program to use for handling video data.
Only 'ffmpeg' and 'libav' are supported at this time.
verbosity : int
Setting to 0 (default) disables all debugging output.
Setting to 1 enables all debugging output.
Useful to see if the backend is behaving properly.
start_frame : int
Skip the first ``start_frame`` frames before reading (issue #166).
Combine with ``num_frames`` for a windowed read like
``vread(..., start_frame=1000, num_frames=200)``. Uses FFmpeg's
fast keyframe seek, so the actual first frame returned may snap
to the nearest keyframe at or before the requested position.
Returns
-------
vid_array : ndarray
ndarray of dimension (T, M, N, C), where T
is the number of frames, M is the height, N is
width, and C is depth.
"""
fname = _normalize_source(fname)
if not inputdict:
inputdict = {}
if not outputdict:
outputdict = {}
if backend == "ffmpeg":
# check if FFMPEG exists in the path
if not skvideo._HAS_FFMPEG:
raise RuntimeError("Cannot find installation of real FFmpeg (which comes with ffprobe).")
if ((height != 0) and (width != 0)):
inputdict['-s'] = str(width) + 'x' + str(height)
if num_frames != 0:
outputdict['-vframes'] = str(num_frames)
if as_grey:
outputdict['-pix_fmt'] = 'gray'
reader = FFmpegReader(fname, inputdict=inputdict, outputdict=outputdict, verbosity=verbosity, start_frame=start_frame)
try:
T, M, N, C = reader.getShape()
if T == 0:
# Frame count unknown (URL/stream inputs without nb_frames).
# Collect what the stream yields; preallocation would index
# into an empty array.
frames = list(reader.nextFrame())
if frames:
videodata = np.stack(frames).astype(reader.dtype, copy=False)
else:
videodata = np.empty((0, M, N, C), dtype=reader.dtype)
else:
videodata = np.empty((T, M, N, C), dtype=reader.dtype)
count = 0
for idx, frame in enumerate(reader.nextFrame()):
videodata[idx, :, :, :] = frame
count = idx + 1
# An output filter (e.g. -vf select) can yield fewer frames
# than getShape() predicted from nb_frames; trim so the
# caller never sees uninitialized np.empty rows.
if count < T:
videodata = videodata[:count]
if as_grey:
videodata = vshape(videodata[:, :, :, 0])
finally:
# Always close so a spooled temp file (BytesIO input) is unlinked
# even if reading raises partway through.
reader.close()
return videodata
elif backend == "libav":
_warn_libav_deprecated()
# check if FFMPEG exists in the path
if not skvideo._HAS_AVCONV:
raise RuntimeError("Cannot find installation of libav.")
if ((height != 0) and (width != 0)):
inputdict['-s'] = str(width) + 'x' + str(height)
if num_frames != 0:
outputdict['-vframes'] = str(num_frames)
reader = LibAVReader(fname, inputdict=inputdict, outputdict=outputdict, verbosity=verbosity)
try:
T, M, N, C = reader.getShape()
videodata = np.empty((T, M, N, C), dtype=reader.dtype)
count = 0
for idx, frame in enumerate(reader.nextFrame()):
videodata[idx, :, :, :] = frame
count = idx + 1
if count < T:
videodata = videodata[:count]
finally:
reader.close()
return videodata
else:
raise ValueError("unknown backend: %r (supported: 'ffmpeg', 'libav')" % (backend,))
[docs]
def vreader(fname, height=0, width=0, num_frames=0, as_grey=False, inputdict=None, outputdict=None, backend='ffmpeg', verbosity=0, start_frame=0):
"""Load a video through the use of a generator.
Parameters
----------
fname : string
Video file name, e.g. ``bickbuckbunny.mp4``
height : int
Set the source video height used for decoding.
Useful for raw inputs when video header does not exist.
width : int
Set the source video width used for decoding.
Useful for raw inputs when video header does not exist.
num_frames : int
Only read the first `num_frames` number of frames from video.
Setting `num_frames` to small numbers can significantly speed up video loading times.
If omitted and the container does not expose a frame count, the
generator reads until EOF instead of scanning the whole file up front.
as_grey : bool
If true, only load the luminance channel of the input video.
inputdict : dict
Input dictionary parameters, i.e. how to interpret the input file.
outputdict : dict
Output dictionary parameters, i.e. how to encode the data
between backend and python.
backend : string
Program to use for handling video data.
Only 'ffmpeg' and 'libav' are supported at this time.
verbosity : int
Setting to 0 (default) disables all debugging output.
Setting to 1 enables all debugging output.
Useful to see if the backend is behaving properly.
start_frame : int
Skip the first ``start_frame`` frames before reading (issue #166).
Uses FFmpeg's fast keyframe seek; the first frame returned may
snap to the nearest keyframe at or before the requested position.
Returns
-------
vid_gen : generator
returns ndarrays, shape (M, N, C) where
M is frame height, N is frame width, and
C is number of channels per pixel
"""
fname = _normalize_source(fname)
if not inputdict:
inputdict = {}
if not outputdict:
outputdict = {}
if backend == "ffmpeg":
# check if FFMPEG exists in the path
if not skvideo._HAS_FFMPEG:
raise RuntimeError("Cannot find installation of ffmpeg.")
if ((height != 0) and (width != 0)):
inputdict['-s'] = str(width) + 'x' + str(height)
if num_frames != 0:
outputdict['-vframes'] = str(num_frames)
if as_grey:
outputdict['-pix_fmt'] = 'gray'
reader = FFmpegReader(
fname, inputdict=inputdict, outputdict=outputdict,
verbosity=verbosity, start_frame=start_frame, scan_frames=False)
try:
for frame in reader.nextFrame():
if as_grey:
yield vshape(frame[:, :, 0])
else:
yield frame
finally:
reader.close()
elif backend == "libav":
_warn_libav_deprecated()
# check if FFMPEG exists in the path
if not skvideo._HAS_AVCONV:
raise RuntimeError("Cannot find installation of libav.")
if ((height != 0) and (width != 0)):
inputdict['-s'] = str(width) + 'x' + str(height)
if num_frames != 0:
outputdict['-vframes'] = str(num_frames)
reader = LibAVReader(
fname, inputdict=inputdict, outputdict=outputdict,
verbosity=verbosity, scan_frames=False)
try:
for frame in reader.nextFrame():
yield frame
finally:
reader.close()
else:
raise ValueError("unknown backend: %r (supported: 'ffmpeg', 'libav')" % (backend,))
