# -*- coding: utf-8 -*-
# imageio is distributed under the terms of the (new) BSD License.
"""Read/Write video using FFMPEG
.. note::
We are in the process of (slowly) replacing this plugin with a new one that
is based on `pyav <https://pyav.org/docs/stable/>`_. It is faster and more
flexible than the plugin documented here. Check the :mod:`pyav
plugin's documentation <imageio.plugins.pyav>` for more information about
this plugin.
Backend Library: https://github.com/imageio/imageio-ffmpeg
.. note::
To use this plugin you have to install its backend::
pip install imageio[ffmpeg]
The ffmpeg format provides reading and writing for a wide range of movie formats
such as .avi, .mpeg, .mp4, etc. as well as the ability to read streams from
webcams and USB cameras. It is based on ffmpeg and is inspired by/based `moviepy
<https://github.com/Zulko/moviepy/>`_ by Zulko.
Parameters for reading
----------------------
fps : scalar
The number of frames per second of the input stream. Default None (i.e.
read at the file's native fps). One can use this for files with a
variable fps, or in cases where imageio is unable to correctly detect
the fps. In case of trouble opening camera streams, it may help to set an
explicit fps value matching a framerate supported by the camera.
loop : bool
If True, the video will rewind as soon as a frame is requested
beyond the last frame. Otherwise, IndexError is raised. Default False.
Setting this to True will internally call ``count_frames()``,
and set the reader's length to that value instead of inf.
size : str | tuple
The frame size (i.e. resolution) to read the images, e.g.
(100, 100) or "640x480". For camera streams, this allows setting
the capture resolution. For normal video data, ffmpeg will
rescale the data.
dtype : str | type
The dtype for the output arrays. Determines the bit-depth that
is requested from ffmpeg. Supported dtypes: uint8, uint16.
Default: uint8.
pixelformat : str
The pixel format for the camera to use (e.g. "yuyv422" or
"gray"). The camera needs to support the format in order for
this to take effect. Note that the images produced by this
reader are always RGB.
input_params : list
List additional arguments to ffmpeg for input file options.
(Can also be provided as ``ffmpeg_params`` for backwards compatibility)
Example ffmpeg arguments to use aggressive error handling:
['-err_detect', 'aggressive']
output_params : list
List additional arguments to ffmpeg for output file options (i.e. the
stream being read by imageio).
print_info : bool
Print information about the video file as reported by ffmpeg.
Parameters for writing
----------------------
fps : scalar
The number of frames per second. Default 10.
codec : str
the video codec to use. Default 'libx264', which represents the
widely available mpeg4. Except when saving .wmv files, then the
defaults is 'msmpeg4' which is more commonly supported for windows
quality : float | None
Video output quality. Default is 5. Uses variable bit rate. Highest
quality is 10, lowest is 0. Set to None to prevent variable bitrate
flags to FFMPEG so you can manually specify them using output_params
instead. Specifying a fixed bitrate using 'bitrate' disables this
parameter.
bitrate : int | None
Set a constant bitrate for the video encoding. Default is None causing
'quality' parameter to be used instead. Better quality videos with
smaller file sizes will result from using the 'quality' variable
bitrate parameter rather than specifying a fixed bitrate with this
parameter.
pixelformat: str
The output video pixel format. Default is 'yuv420p' which most widely
supported by video players.
input_params : list
List additional arguments to ffmpeg for input file options (i.e. the
stream that imageio provides).
output_params : list
List additional arguments to ffmpeg for output file options.
(Can also be provided as ``ffmpeg_params`` for backwards compatibility)
Example ffmpeg arguments to use only intra frames and set aspect ratio:
['-intra', '-aspect', '16:9']
ffmpeg_log_level: str
Sets ffmpeg output log level. Default is "warning".
Values can be "quiet", "panic", "fatal", "error", "warning", "info"
"verbose", or "debug". Also prints the FFMPEG command being used by
imageio if "info", "verbose", or "debug".
macro_block_size: int
Size constraint for video. Width and height, must be divisible by this
number. If not divisible by this number imageio will tell ffmpeg to
scale the image up to the next closest size
divisible by this number. Most codecs are compatible with a macroblock
size of 16 (default), some can go smaller (4, 8). To disable this
automatic feature set it to None or 1, however be warned many players
can't decode videos that are odd in size and some codecs will produce
poor results or fail. See https://en.wikipedia.org/wiki/Macroblock.
audio_path : str | None
Audio path of any audio that needs to be written. Defaults to nothing,
so no audio will be written. Please note, when writing shorter video
than the original, ffmpeg will not truncate the audio track; it
will maintain its original length and be longer than the video.
audio_codec : str | None
The audio codec to use. Defaults to nothing, but if an audio_path has
been provided ffmpeg will attempt to set a default codec.
Notes
-----
If you are using anaconda and ``anaconda/ffmpeg`` you will not be able to
encode/decode H.264 (likely due to licensing concerns). If you need this
format on anaconda install ``conda-forge/ffmpeg`` instead.
You can use the ``IMAGEIO_FFMPEG_EXE`` environment variable to force using a
specific ffmpeg executable.
To get the number of frames before having read them all, you can use the
``reader.count_frames()`` method (the reader will then use
``imageio_ffmpeg.count_frames_and_secs()`` to get the exact number of frames,
note that this operation can take a few seconds on large files). Alternatively,
the number of frames can be estimated from the fps and duration in the meta data
(though these values themselves are not always present/reliable).
"""
import re
import sys
import time
import logging
import platform
import threading
import subprocess as sp
import imageio_ffmpeg
import numpy as np
from ..core import Format, image_as_uint
logger = logging.getLogger(__name__)
# Get camera format
if sys.platform.startswith("win"):
CAM_FORMAT = "dshow" # dshow or vfwcap
elif sys.platform.startswith("linux"):
CAM_FORMAT = "video4linux2"
elif sys.platform.startswith("darwin"):
CAM_FORMAT = "avfoundation"
else: # pragma: no cover
CAM_FORMAT = "unknown-cam-format"
def download(directory=None, force_download=False): # pragma: no cover
raise RuntimeError(
"imageio.ffmpeg.download() has been deprecated. "
"Use 'pip install imageio-ffmpeg' instead.'"
)
# For backwards compatibility - we dont use this ourselves
def get_exe(): # pragma: no cover
"""Wrapper for imageio_ffmpeg.get_ffmpeg_exe()"""
return imageio_ffmpeg.get_ffmpeg_exe()
class FfmpegFormat(Format):
"""Read/Write ImageResources using FFMPEG.
See :mod:`imageio.plugins.ffmpeg`
"""
def _can_read(self, request):
# Read from video stream?
# Note that we could write the _video flag here, but a user might
# select this format explicitly (and this code is not run)
if re.match(r"<video(\d+)>", request.filename):
return True
# Read from file that we know?
if request.extension in self.extensions:
return True
def _can_write(self, request):
if request.extension in self.extensions:
return True
# --
class Reader(Format.Reader):
_frame_catcher = None
_read_gen = None
def _get_cam_inputname(self, index):
if sys.platform.startswith("linux"):
return "/dev/" + self.request._video[1:-1]
elif sys.platform.startswith("win"):
# Ask ffmpeg for list of dshow device names
ffmpeg_api = imageio_ffmpeg
cmd = [
ffmpeg_api.get_ffmpeg_exe(),
"-list_devices",
"true",
"-f",
CAM_FORMAT,
"-i",
"dummy",
]
# Set `shell=True` in sp.run to prevent popup of a command
# line window in frozen applications. Note: this would be a
# security vulnerability if user-input goes into the cmd.
# Note that the ffmpeg process returns with exit code 1 when
# using `-list_devices` (or `-list_options`), even if the
# command is successful, so we set `check=False` explicitly.
completed_process = sp.run(
cmd,
stdout=sp.PIPE,
stderr=sp.PIPE,
encoding="utf-8",
shell=True,
check=False,
)
# Return device name at index
try:
name = parse_device_names(completed_process.stderr)[index]
except IndexError:
raise IndexError("No ffdshow camera at index %i." % index)
return "video=%s" % name
elif sys.platform.startswith("darwin"):
# Appears that newer ffmpeg builds don't support -list-devices
# on OS X. But you can directly open the camera by index.
name = str(index)
return name
else: # pragma: no cover
return "??"
def _open(
self,
loop=False,
size=None,
dtype=None,
pixelformat=None,
print_info=False,
ffmpeg_params=None,
input_params=None,
output_params=None,
fps=None,
):
# Get generator functions
self._ffmpeg_api = imageio_ffmpeg
# Process input args
self._arg_loop = bool(loop)
if size is None:
self._arg_size = None
elif isinstance(size, tuple):
self._arg_size = "%ix%i" % size
elif isinstance(size, str) and "x" in size:
self._arg_size = size
else:
raise ValueError('FFMPEG size must be tuple of "NxM"')
if pixelformat is None:
pass
elif not isinstance(pixelformat, str):
raise ValueError("FFMPEG pixelformat must be str")
if dtype is None:
self._dtype = np.dtype("uint8")
else:
self._dtype = np.dtype(dtype)
allowed_dtypes = ["uint8", "uint16"]
if self._dtype.name not in allowed_dtypes:
raise ValueError(
"dtype must be one of: {}".format(", ".join(allowed_dtypes))
)
self._arg_pixelformat = pixelformat
self._arg_input_params = input_params or []
self._arg_output_params = output_params or []
self._arg_input_params += ffmpeg_params or [] # backward compat
# Write "_video"_arg - indicating webcam support
self.request._video = None
regex_match = re.match(r"<video(\d+)>", self.request.filename)
if regex_match:
self.request._video = self.request.filename
# Get local filename
if self.request._video:
index = int(regex_match.group(1))
self._filename = self._get_cam_inputname(index)
else:
self._filename = self.request.get_local_filename()
# When passed to ffmpeg on command line, carets need to be escaped.
self._filename = self._filename.replace("^", "^^")
# Determine pixel format and depth
self._depth = 3
if self._dtype.name == "uint8":
self._pix_fmt = "rgb24"
self._bytes_per_channel = 1
else:
self._pix_fmt = "rgb48le"
self._bytes_per_channel = 2
# Initialize parameters
self._pos = -1
self._meta = {"plugin": "ffmpeg"}
self._lastread = None
# Calculating this from fps and duration is not accurate,
# and calculating it exactly with ffmpeg_api.count_frames_and_secs
# takes too long to do for each video. But we need it for looping.
self._nframes = float("inf")
if self._arg_loop and not self.request._video:
self._nframes = self.count_frames()
self._meta["nframes"] = self._nframes
# Specify input framerate? (only on macOS)
# Ideally we'd get the supported framerate from the metadata, but we get the
# metadata when we boot ffmpeg ... maybe we could refactor this so we can
# get the metadata beforehand, but for now we'll just give it 2 tries on MacOS,
# one with fps 30 and one with fps 15.
need_input_fps = need_output_fps = False
if self.request._video and platform.system().lower() == "darwin":
if "-framerate" not in str(self._arg_input_params):
need_input_fps = True
if not self.request.kwargs.get("fps", None):
need_output_fps = True
if need_input_fps:
self._arg_input_params.extend(["-framerate", str(float(30))])
if need_output_fps:
self._arg_output_params.extend(["-r", str(float(30))])
# Start ffmpeg subprocess and get meta information
try:
self._initialize()
except IndexError:
# Specify input framerate again, this time different.
if need_input_fps:
self._arg_input_params[-1] = str(float(15))
self._initialize()
else:
raise
# For cameras, create thread that keeps reading the images
if self.request._video:
self._frame_catcher = FrameCatcher(self._read_gen)
# For reference - but disabled, because it is inaccurate
# if self._meta["nframes"] == float("inf"):
# if self._meta.get("fps", 0) > 0:
# if self._meta.get("duration", 0) > 0:
# n = round(self._meta["duration"] * self._meta["fps"])
# self._meta["nframes"] = int(n)
def _close(self):
# First close the frame catcher, because we cannot close the gen
# if the frame catcher thread is using it
if self._frame_catcher is not None:
self._frame_catcher.stop_me()
self._frame_catcher = None
if self._read_gen is not None:
self._read_gen.close()
self._read_gen = None
def count_frames(self):
"""Count the number of frames. Note that this can take a few
seconds for large files. Also note that it counts the number
of frames in the original video and does not take a given fps
into account.
"""
# This would have been nice, but this does not work :(
# oargs = []
# if self.request.kwargs.get("fps", None):
# fps = float(self.request.kwargs["fps"])
# oargs += ["-r", "%.02f" % fps]
cf = self._ffmpeg_api.count_frames_and_secs
return cf(self._filename)[0]
def _get_length(self):
return self._nframes # only not inf if loop is True
def _get_data(self, index):
"""Reads a frame at index. Note for coders: getting an
arbitrary frame in the video with ffmpeg can be painfully
slow if some decoding has to be done. This function tries
to avoid fectching arbitrary frames whenever possible, by
moving between adjacent frames."""
# Modulo index (for looping)
if self._arg_loop and self._nframes < float("inf"):
index %= self._nframes
if index == self._pos:
return self._lastread, dict(new=False)
elif index < 0:
raise IndexError("Frame index must be >= 0")
elif index >= self._nframes:
raise IndexError("Reached end of video")
else:
if (index < self._pos) or (index > self._pos + 100):
self._initialize(index)
else:
self._skip_frames(index - self._pos - 1)
result, is_new = self._read_frame()
self._pos = index
return result, dict(new=is_new)
def _get_meta_data(self, index):
return self._meta
def _initialize(self, index=0):
# Close the current generator, and thereby terminate its subprocess
if self._read_gen is not None:
self._read_gen.close()
iargs = []
oargs = []
# Create input args
iargs += self._arg_input_params
if self.request._video:
iargs += ["-f", CAM_FORMAT]
if self._arg_pixelformat:
iargs += ["-pix_fmt", self._arg_pixelformat]
if self._arg_size:
iargs += ["-s", self._arg_size]
elif index > 0: # re-initialize / seek
# Note: only works if we initialized earlier, and now have meta
# Some info here: https://trac.ffmpeg.org/wiki/Seeking
# There are two ways to seek, one before -i (input_params) and
# after (output_params). The former is fast, because it uses
# keyframes, the latter is slow but accurate. According to
# the article above, the fast method should also be accurate
# from ffmpeg version 2.1, however in version 4.1 our tests
# start failing again. Not sure why, but we can solve this
# by combining slow and fast. Seek the long stretch using
# the fast method, and seek the last 10s the slow way.
starttime = index / self._meta["fps"]
seek_slow = min(10, starttime)
seek_fast = starttime - seek_slow
# We used to have this epsilon earlier, when we did not use
# the slow seek. I don't think we need it anymore.
# epsilon = -1 / self._meta["fps"] * 0.1
iargs += ["-ss", "%.06f" % (seek_fast)]
oargs += ["-ss", "%.06f" % (seek_slow)]
# Output args, for writing to pipe
if self._arg_size:
oargs += ["-s", self._arg_size]
if self.request.kwargs.get("fps", None):
fps = float(self.request.kwargs["fps"])
oargs += ["-r", "%.02f" % fps]
oargs += self._arg_output_params
# Get pixelformat and bytes per pixel
pix_fmt = self._pix_fmt
bpp = self._depth * self._bytes_per_channel
# Create generator
rf = self._ffmpeg_api.read_frames
self._read_gen = rf(
self._filename, pix_fmt, bpp, input_params=iargs, output_params=oargs
)
# Read meta data. This start the generator (and ffmpeg subprocess)
if self.request._video:
# With cameras, catch error and turn into IndexError
try:
meta = self._read_gen.__next__()
except IOError as err:
err_text = str(err)
if "darwin" in sys.platform:
if "Unknown input format: 'avfoundation'" in err_text:
err_text += (
"Try installing FFMPEG using "
"home brew to get a version with "
"support for cameras."
)
raise IndexError(
"No (working) camera at {}.\n\n{}".format(
self.request._video, err_text
)
)
else:
self._meta.update(meta)
elif index == 0:
self._meta.update(self._read_gen.__next__())
else:
self._read_gen.__next__() # we already have meta data
def _skip_frames(self, n=1):
"""Reads and throws away n frames"""
for i in range(n):
self._read_gen.__next__()
self._pos += n
def _read_frame(self):
# Read and convert to numpy array
w, h = self._meta["size"]
framesize = w * h * self._depth * self._bytes_per_channel
# t0 = time.time()
# Read frame
if self._frame_catcher: # pragma: no cover - camera thing
s, is_new = self._frame_catcher.get_frame()
else:
s = self._read_gen.__next__()
is_new = True
# Check
if len(s) != framesize:
raise RuntimeError(
"Frame is %i bytes, but expected %i." % (len(s), framesize)
)
result = np.frombuffer(s, dtype=self._dtype).copy()
result = result.reshape((h, w, self._depth))
# t1 = time.time()
# print('etime', t1-t0)
# Store and return
self._lastread = result
return result, is_new
# --
class Writer(Format.Writer):
_write_gen = None
def _open(
self,
fps=10,
codec="libx264",
bitrate=None,
pixelformat="yuv420p",
ffmpeg_params=None,
input_params=None,
output_params=None,
ffmpeg_log_level="quiet",
quality=5,
macro_block_size=16,
audio_path=None,
audio_codec=None,
):
self._ffmpeg_api = imageio_ffmpeg
self._filename = self.request.get_local_filename()
self._pix_fmt = None
self._depth = None
self._size = None
def _close(self):
if self._write_gen is not None:
self._write_gen.close()
self._write_gen = None
def _append_data(self, im, meta):
# Get props of image
h, w = im.shape[:2]
size = w, h
depth = 1 if im.ndim == 2 else im.shape[2]
# Ensure that image is in uint8
im = image_as_uint(im, bitdepth=8)
# To be written efficiently, ie. without creating an immutable
# buffer, by calling im.tobytes() the array must be contiguous.
if not im.flags.c_contiguous:
# checkign the flag is a micro optimization.
# the image will be a numpy subclass. See discussion
# https://github.com/numpy/numpy/issues/11804
im = np.ascontiguousarray(im)
# Set size and initialize if not initialized yet
if self._size is None:
map = {1: "gray", 2: "gray8a", 3: "rgb24", 4: "rgba"}
self._pix_fmt = map.get(depth, None)
if self._pix_fmt is None:
raise ValueError("Image must have 1, 2, 3 or 4 channels")
self._size = size
self._depth = depth
self._initialize()
# Check size of image
if size != self._size:
raise ValueError("All images in a movie should have same size")
if depth != self._depth:
raise ValueError(
"All images in a movie should have same " "number of channels"
)
assert self._write_gen is not None # Check status
# Write. Yes, we can send the data in as a numpy array
self._write_gen.send(im)
def set_meta_data(self, meta):
raise RuntimeError(
"The ffmpeg format does not support setting " "meta data."
)
def _initialize(self):
# Close existing generator
if self._write_gen is not None:
self._write_gen.close()
# Get parameters
# Use None to let imageio-ffmpeg (or ffmpeg) select good results
fps = self.request.kwargs.get("fps", 10)
codec = self.request.kwargs.get("codec", None)
bitrate = self.request.kwargs.get("bitrate", None)
quality = self.request.kwargs.get("quality", None)
input_params = self.request.kwargs.get("input_params") or []
output_params = self.request.kwargs.get("output_params") or []
output_params += self.request.kwargs.get("ffmpeg_params") or []
pixelformat = self.request.kwargs.get("pixelformat", None)
macro_block_size = self.request.kwargs.get("macro_block_size", 16)
ffmpeg_log_level = self.request.kwargs.get("ffmpeg_log_level", None)
audio_path = self.request.kwargs.get("audio_path", None)
audio_codec = self.request.kwargs.get("audio_codec", None)
macro_block_size = macro_block_size or 1 # None -> 1
# Create generator
self._write_gen = self._ffmpeg_api.write_frames(
self._filename,
self._size,
pix_fmt_in=self._pix_fmt,
pix_fmt_out=pixelformat,
fps=fps,
quality=quality,
bitrate=bitrate,
codec=codec,
macro_block_size=macro_block_size,
ffmpeg_log_level=ffmpeg_log_level,
input_params=input_params,
output_params=output_params,
audio_path=audio_path,
audio_codec=audio_codec,
)
# Seed the generator (this is where the ffmpeg subprocess starts)
self._write_gen.send(None)
class FrameCatcher(threading.Thread):
"""Thread to keep reading the frame data from stdout. This is
useful when streaming from a webcam. Otherwise, if the user code
does not grab frames fast enough, the buffer will fill up, leading
to lag, and ffmpeg can also stall (experienced on Linux). The
get_frame() method always returns the last available image.
"""
def __init__(self, gen):
self._gen = gen
self._frame = None
self._frame_is_new = False
self._lock = threading.RLock()
threading.Thread.__init__(self)
self.daemon = True # do not let this thread hold up Python shutdown
self._should_stop = False
self.start()
def stop_me(self):
self._should_stop = True
while self.is_alive():
time.sleep(0.001)
def get_frame(self):
while self._frame is None: # pragma: no cover - an init thing
time.sleep(0.001)
with self._lock:
is_new = self._frame_is_new
self._frame_is_new = False # reset
return self._frame, is_new
def run(self):
# This runs in the worker thread
try:
while not self._should_stop:
time.sleep(0) # give control to other threads
frame = self._gen.__next__()
with self._lock:
self._frame = frame
self._frame_is_new = True
except (StopIteration, EOFError):
pass
def parse_device_names(ffmpeg_output):
"""Parse the output of the ffmpeg -list-devices command"""
# Collect device names - get [friendly_name, alt_name] of each
device_names = []
in_video_devices = False
for line in ffmpeg_output.splitlines():
if line.startswith("[dshow"):
logger.debug(line)
line = line.split("]", 1)[1].strip()
if in_video_devices and line.startswith('"'):
friendly_name = line[1:-1]
device_names.append([friendly_name, ""])
elif in_video_devices and line.lower().startswith("alternative name"):
alt_name = line.split(" name ", 1)[1].strip()[1:-1]
if sys.platform.startswith("win"):
alt_name = alt_name.replace("&", "^&") # Tested to work
else:
alt_name = alt_name.replace("&", "\\&") # Does this work?
device_names[-1][-1] = alt_name
elif "video devices" in line:
in_video_devices = True
elif "devices" in line:
# set False for subsequent "devices" sections
in_video_devices = False
# Post-process, see #441
# prefer friendly names, use alt name if two cams have same friendly name
device_names2 = []
for friendly_name, alt_name in device_names:
if friendly_name not in device_names2:
device_names2.append(friendly_name)
elif alt_name:
device_names2.append(alt_name)
else:
device_names2.append(friendly_name) # duplicate, but not much we can do
return device_names2