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Videoreader

ReadError

Bases: Exception

Base class for file read errors.

mg_videoreader 

mg_videoreader(filename, starttime=0, endtime=0, skip=0, frames=0, rotate=0, contrast=0, brightness=0, crop='None', color=True, keep_all=False, returned_by_process=False)

Reads in a video file, and optionally apply several different processes on it. These include: - trimming, - skipping, - fixing, - rotating, - applying brightness and contrast, - cropping, - converting to grayscale.

Parameters:

Name Type Description Default
filename str

Path to the input video file.

 required
starttime int / float

Trims the video from this start time (s). Defaults to 0.

 0
endtime int / float

Trims the video until this end time (s). Defaults to 0 (which will make the algorithm use the full length of the input video instead).

 0
skip int

Time-shrinks the video by skipping (discarding) every n frames determined by skip. Defaults to 0.

 0
frames int

Specify a fixed target number of frames to extract from the video. Defaults to 0.

 0
rotate int / float

Rotates the video by a rotate degrees. Defaults to 0.

 0
contrast int / float

Applies +/- 100 contrast to video. Defaults to 0.

 0
brightness int / float

Applies +/- 100 brightness to video. Defaults to 0.

 0
crop str

If 'manual', opens a window displaying the first frame of the input video file, where the user can draw a rectangle to which cropping is applied. If 'auto' the cropping function attempts to determine the area of significant motion and applies the cropping to that area. Defaults to 'None'.

 'None'
color bool

If False, converts the video to grayscale and sets every method in grayscale mode. Defaults to True.

 True
keep_all bool

If True, preserves an output video file after each used preprocessing stage. Defaults to False.

 False
returned_by_process bool

This parameter is only for internal use, do not use it. Defaults to False.

 False

Returns:

Name Type Description
int

The number of frames in the output video file.
int

The pixel width of the output video file.
int

The pixel height of the output video file.
int

The FPS (frames per second) of the output video file.
float

The length of the output video file in seconds.
str

The path to the output video file without its extension. The file name gets a suffix for each used process.
str

The file extension of the output video file.
bool

Whether the video has an audio track.
Source code in musicalgestures/_videoreader.py 
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def mg_videoreader(
        filename,
        starttime=0,
        endtime=0,
        skip=0,
        frames=0,
        rotate=0,
        contrast=0,
        brightness=0,
        crop='None',
        color=True,
        keep_all=False,
        returned_by_process=False):
    """
    Reads in a video file, and optionally apply several different processes on it. These include:
    - trimming,
    - skipping,
    - fixing,
    - rotating,
    - applying brightness and contrast,
    - cropping,
    - converting to grayscale.

    Args:
        filename (str): Path to the input video file.
        starttime (int/float, optional): Trims the video from this start time (s). Defaults to 0.
        endtime (int/float, optional): Trims the video until this end time (s). Defaults to 0 (which will make the algorithm use the full length of the input video instead).
        skip (int, optional): Time-shrinks the video by skipping (discarding) every n frames determined by `skip`. Defaults to 0.
        frames (int, optional): Specify a fixed target number of frames to extract from the video. Defaults to 0.
        rotate (int/float, optional): Rotates the video by a `rotate` degrees. Defaults to 0.
        contrast (int/float, optional): Applies +/- 100 contrast to video. Defaults to 0.
        brightness (int/float, optional): Applies +/- 100 brightness to video. Defaults to 0.
        crop (str, optional): If 'manual', opens a window displaying the first frame of the input video file, where the user can draw a rectangle to which cropping is applied. If 'auto' the cropping function attempts to determine the area of significant motion and applies the cropping to that area. Defaults to 'None'.
        color (bool, optional): If False, converts the video to grayscale and sets every method in grayscale mode. Defaults to True.
        keep_all (bool, optional): If True, preserves an output video file after each used preprocessing stage. Defaults to False.
        returned_by_process (bool, optional): This parameter is only for internal use, do not use it. Defaults to False.

    Returns:
        int: The number of frames in the output video file.
        int: The pixel width of the output video file.
        int: The pixel height of the output video file.
        int: The FPS (frames per second) of the output video file.
        float: The length of the output video file in seconds.
        str: The path to the output video file without its extension. The file name gets a suffix for each used process.
        str: The file extension of the output video file.
        bool: Whether the video has an audio track.
    """

    # Separate filename from file extension
    of, fex = os.path.splitext(filename)

    trimming = False
    skipping = False
    fixing = False
    rotating = False
    cbing = False
    cropping = False

    # Cut out relevant bit of video using starttime and endtime
    if starttime != 0 or endtime != 0:
        tmp_path = extract_subclip(filename, starttime, endtime, target_name=of + '_trim' + fex)
        of = os.path.splitext(tmp_path)[0]
        # of = of + '_trim'
        trimming = True

    if skip != 0:
        tmp_path = skip_frames_ffmpeg(of + fex, skip)
        if not keep_all and trimming:
            os.remove(of+fex)

        # of = of + '_skip'
        of, fex = os.path.splitext(tmp_path)
        skipping = True

    if frames != 0:
        tmp_path = fixed_frames_ffmpeg(of + fex, frames)
        if not keep_all and (skipping or trimming):
            os.remove(of+fex)

        # of = of + '_skip'
        of, fex = os.path.splitext(tmp_path)
        fixing = True

    length = get_framecount(of+fex)
    fps = get_fps(of+fex)

    # 0 means full length
    if endtime == 0:
        endtime = length/fps

    if rotate != 0:
        tmp_path = rotate_video(of + fex, rotate)
        if not keep_all and (fixing or skipping or trimming):
            os.remove(of + fex)
        of = os.path.splitext(tmp_path)[0]
        # of = of + '_rot'
        rotating = True

    # Apply contrast/brightness before the motion analysis
    if contrast != 0 or brightness != 0:
        tmp_path = contrast_brightness_ffmpeg(of+fex, contrast=contrast, brightness=brightness)

        if not keep_all and (rotating or fixing or skipping or trimming):
            os.remove(of + fex)
        # of = of + '_cb'
        of = os.path.splitext(tmp_path)[0]
        cbing = True

    # Crops video either manually or automatically
    if crop.lower() != 'none':
        tmp_path = mg_cropvideo_ffmpeg(of+fex, crop_movement=crop)

        if not keep_all and (cbing or rotating or fixing or skipping or trimming):
            os.remove(of + fex)
        of = os.path.splitext(tmp_path)[0]
        # of = of + '_crop'
        cropping = True

    if color == False and returned_by_process == False:
        tmp_path = convert_to_grayscale(of + fex)
        if not keep_all and (cropping or cbing or rotating or fixing or skipping or trimming):
            os.remove(of + fex)
        of = os.path.splitext(tmp_path)[0]

    width, height = get_widthheight(of+fex)
    video_has_audio_track = has_audio(of+fex)

    return length, width, height, fps, endtime, of, fex, video_has_audio_track