In general

Initially, this project aimed to process video lectures.
This program offered the opportunity to separate speech from not-speech and speed up not-speech parts.
But now, you can use it to speed up boring parts using your list of interesting parts of a video and even write a new algorithm to divide video into interesting and boring pieces.

Note

By default, this program doesn't rewrite frames but only changes their timecodes, so it works very fast and generates VFR video. Program skippes (extremely speeds) some parts, so video players don't have time to play video, because of which desynchronization occurs for a while.

Also note, that this program accepts only CFR videos so, if you want to process VFR video or get the resulting CFR video, you have to convert VFR video to CFR.
For this purpose, you can use, for example, FFmpeg. Just run in cmd following command.
ffmpeg -i path/to/your/vfr/video -c:a copy path/to/output/cfr/video
(You don't need to decode audio, because it's in normal format).
Also, if is_result_cfr = True is setted, main functions runs this command on their own.

Instalation

1. Download the FFmpeg from the official website https://ffmpeg.org/download.html.
2. Make FFmpeg seen from the command line.
3. Download the mkvmerge from the official website https://mkvtoolnix.download/.
4. Make mkvmerge seen from the command line.
5. Download or clone this code from Github.
   

Now you are ready to start work with it.

How to use it?

If you want to process video using a built-in project algorithm.

1. Firstly, you have to download your video from the Internet (if it located there). For example, you saved it in input_video_path = input("write path of input video: ")

2. The second step is to choose an algorithm that returns a list of interesting parts. At this moment, there is only two of them.

   • speed_up.VolumeAlgorithm(sound_threshold) accepts float sound_threshold and returns all pieces where volume >= sound_threshold as interesting parts
     For example, speedup_algorithm = VolumeAlgorithm(0.03)
   • speed_up.WebRtcVADAlgorithm(aggressiveness=1) accepts aggressiveness=0, 1, 2 or 3 selects speech from video using voice activity detection algorithm coded by google and returns them as interesting parts
     For example, speedup_algorithm = WebRtcVADAlgorithm(2)

3. Thirdly, you should set some params. The program uses the settings.Settings object to contain them. This class only contains all parameters that the program needs. Description of supported parameters here
   

   • loud_speed - speed of loud parts of video/audio.
   • quiet_speed - speed of quiet parts of video/audio.
   • global_speed - multiplies loud_speed and quiet_speed.
   • min_quiet_time - the program doesn't accelerate the first min_quiet_time seconds in every boring piece.
   • max_quiet_time - in every boring video piece, the program skips part starting from max_quiet_time seconds.

   For example, settings = Settings(min_quiet_time=0.2, quiet_speed=6)

4. The last but not least is to choose path for output mkv video (output video must be mkv, if output file extension isn't mkv process_one_video_in_computer adds ".mkv" to the output_video_path). For example, let be output_video_path = input("write path of output mkv video: ").

5. When you finish all of these steps, run
   process_one_video_in_computer(input_video_path, speedup_algorithm, settings, output_video_path) to process your video.
   Also, process_one_video_in_computer takes some optional kwargs
   

   • working_directory_path = None (str/None) is a directory where this function saves all intermediate files. If working_directory_path is None, process_one_video_in_computer creates a temporary directory for this purpose (and deletes it when it finishes). The name of the temporary directory starts with 'SVA4_' for easy identification.
   • ffmpeg_caller =

     ffmpeg_caller.FFPEG_Caller(
         overwrite_force = None,
         hide_ffmpeg_output = False,
         print_ffmpeg_commands = False
     )
     

     • print_command = None (True/False/None)
       • if the value is None and if this program needs to overwrite a file, this function asks for your acceptance.
       • if the value is True and if this program needs to overwrite a file, this function overwrites it.
       • if the value is False and if this program needs to overwrite a file, this function doesn't overwrite it.
     • hide_output = False (True/False)
       • If this value is True program hides ffmpeg output
       • If this value is False program doesn't hide ffmpeg output
     • print_command = False (True/False)
       • If this parameter is True program prints all ffmpeg commands before executing them .
       • If this parameter is False it doesn't.
   • is_result_cfr = False if this option is True, apply_calculated_interesting_and_boring_parts_to_video and process_one_video_in_computer returns CFR video, but they works much longer.

In total, the code is (tests/process_using_algorithm.py)

"""
Testing process_one_video_in_computer function
"""

from main import process_one_video_in_computer
from settings import Settings
from ffmpeg_caller import FFMPEGCaller
from speed_up import VolumeAlgorithm, WebRtcVADAlgorithm

input_video_path = input("write path of input video: ")
# speedup_algorithm = VolumeAlgorithm(0.0275)
speedup_algorithm = WebRtcVADAlgorithm(3)
settings = Settings(min_quiet_time=0.2, quiet_speed=6)
output_video_path = input("write path of output mkv video path: ")

process_one_video_in_computer(
    input_video_path,
    speedup_algorithm,
    settings,
    output_video_path,
    is_result_cfr=False,
    ffmpeg_caller=FFMPEGCaller(overwrite_force=True, hide_output=True)
)

Using this program to apply interesting parts to the video is the same except for steps 2 and 5.

• 2-th step. Instead of choosing algorithm, you should generate your interesting_parts_list in format
  [[start_of_piece0, end_of_piece0], [start_of_piece1, end_of_piece1], ... [start_of_piecen, end_of_piecen]]
  All values should be positions in video in seconds.
  
• 5-th step. Use apply_calculated_interesting_and_boring_parts_to_video function instead of process_one_video_in_computer
  Syntax
  

apply_calculated_interesting_and_boring_parts_to_video(
    interesting_parts,
    settings,
    input_video_path,
    output_video_path,
    is_result_cfr=True,
    ffmpeg_caller=FFMPEGCaller(overwrite_force=None, hide_output=False)
)

In total, code is (test/set_interesting_parts.py)

"""
Testing apply_calculated_interesting_and_boring_parts_to_video function
"""
import numpy as np

from main import apply_calculated_interesting_and_boring_parts_to_video
from settings import Settings
from ffmpeg_caller import FFMPEGCaller


input_video_path = input("write path of input video: ")
interesting_parts = np.array([[10.0, 20.1], [30.5, 40], [50.5, 60], [70.5, 80]])
settings = Settings(min_quiet_time=0.2, quiet_speed=6)
output_video_path = input("write path of output mkv video: ")

apply_calculated_interesting_and_boring_parts_to_video(
    interesting_parts,
    settings,
    input_video_path,
    output_video_path,
    is_result_cfr=True,
    ffmpeg_caller=FFMPEGCaller(overwrite_force=None, hide_output=False)
)