Custom FFmpeg Commands in WriteGear API⚓

WriteGear API now provides the execute_ffmpeg_cmd Method in Compression Mode that enables the user to pass any custom FFmpeg CLI (Command Line Interface) commands as input to its internal FFmpeg Pipeline by formating it as a list.

This opens endless possibilities of exploiting every FFmpeg params within WriteGear without relying on a third-party API to do the same and while doing that it robustly handles all errors/warnings quietly.

Important Information

This Feature Requires WriteGear's Compression Mode enabled(compression_mode = True). Follow these dedicated Installation Instructions ➶ for its installation.
Only python list is a valid datatype as input for this function, any other value will throw ValueError.
Kindly read FFmpeg Docs carefully, before passing any values to output_param dictionary parameter. Wrong values may result in undesired Errors or no output at all.

Features⚓

Provides the ability to pass any custom command to WriteGear FFmpeg Pipeline.
Compatible with any FFmpeg terminal command.
Standalone On-the-fly functioning.
Can work without interfering with WriteGear API's Writer pipeline.
Minimum hassle and extremely easy to enable and use.

Methods⚓

`execute_ffmpeg_cmd`⚓

This method allows the users to pass the custom FFmpeg terminal commands as a formatted list directly to WriteGear API's FFmpeg pipeline for processing/execution. Its usage is as follows:

# format FFmpeg terminal command `ffmpeg -y -i source_video -acodec copy input_audio.aac` as a list
ffmpeg_command = ["-y", "-i", source_video, "-acodec", "copy", "input_audio.aac"]

# execute this list using this function
execute_ffmpeg_cmd(ffmpeg_command)

Usage Examples⚓

Following usage examples is just an idea of what can be done with this powerful function. So just Tinker with various FFmpeg parameters/commands yourself and see it working. Also, if you're unable to run any terminal FFmpeg command, then report an issue.

Using WriteGear to separate Audio from Video⚓

In this example, we will extract and save audio from a URL stream:

# import required libraries
from vidgear.gears import WriteGear

# define a valid url
url_to_stream = (
    "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"
)

# Define writer with default parameters
writer = WriteGear(output_filename="Output.mp4", logging=True)

# format command to convert stream audio as 'output_audio.aac' as list
ffmpeg_command_to_save_audio = [
    "-y",
    "-i",
    url_to_stream,
    "output_audio.aac",
]  # `-y` parameter is to overwrite outputfile if exists

# execute FFmpeg command
writer.execute_ffmpeg_cmd(ffmpeg_command_to_save_audio)

# safely close writer
writer.close()

After running this script, You will get the final 'output_audio.aac' audio file.

Using WriteGear to merge Audio with Video⚓

In this example, we will merge audio with video:

You can also directly add external audio input to video-frames in WriteGear. For more information, See this FAQ example ➶

Example Assumptions

You already have a separate video(i.e 'input-video.mp4') and audio(i.e 'input-audio.aac') files.
Both these Audio and Video files are compatible.

# import required libraries
from vidgear.gears import VideoGear
from vidgear.gears import WriteGear
import cv2
import time

# Open input video stream
stream = VideoGear(source="input-video.mp4").start()

# set input audio stream path
input_audio = "input-audio.aac"

# define your parameters
output_params = {
    "-input_framerate": stream.framerate
}  # output framerate must match source framerate

# Define writer with defined parameters and suitable output filename for e.g. `Output.mp4`
writer = WriteGear(output_filename="Output.mp4", **output_params)

# loop over
while True:

    # read frames from stream
    frame = stream.read()

    # check for frame if Nonetype
    if frame is None:
        break

    # {do something with the frame here}

    # write frame to writer
    writer.write(frame)

    # Show output window
    cv2.imshow("Output Frame", frame)

    # check for 'q' key if pressed
    key = cv2.waitKey(1) & 0xFF
    if key == ord("q"):
        break

# close output window
cv2.destroyAllWindows()

# safely close video stream
stream.stop()

# safely close writer
writer.close()


# sleep 1 sec as the above video might still be rendering
time.sleep(1)


# format FFmpeg command to generate `Output_with_audio.mp4` by merging input_audio in above rendered `Output.mp4`
ffmpeg_command = [
    "-y",
    "-i",
    "Output.mp4",
    "-i",
    input_audio,
    "-c:v",
    "copy",
    "-c:a",
    "copy",
    "-map",
    "0:v:0",
    "-map",
    "1:a:0",
    "-shortest",
    "Output_with_audio.mp4",
]  # `-y` parameter is to overwrite outputfile if exists

# execute FFmpeg command
writer.execute_ffmpeg_cmd(ffmpeg_command)

After running this script, You will get the final 'Output_with_audio.mp4' file with both video and audio merged.

Last update: October 25, 2021