[ffmpeg] xfade+audio+scale

ffmpeg xfade+audio+scale.py

import itertools
import subprocess

import ffmpeg


def gen_filter(segments):
    """
    https://stackoverflow.com/questions/63553906/merging-multiple-video-files-with-ffmpeg-and-xfade-filter
    """
    video_fades = ""
    audio_fades = ""
    settb = ""
    last_fade_output = "0:v"
    last_audio_output = "0:a"
    fade_duration = 0.3

    video_length = 0
    file_lengths = [0] * len(segments)

    width = "720"
    height = "1280"
    scaler = f",scale=w={width}:h={height}:force_original_aspect_ratio=1,pad={width}:{height}:-1:-1"

    for i in range(len(segments)):
        settb += f"[%d]settb=AVTB,setsar=sar=1,fps=30{scaler}[%d:v];" % (i, i)

    for i in range(len(segments) - 1):
        file_lengths[i] = float(ffmpeg.probe(segments[i])['format']['duration'])

        video_length += file_lengths[i]
        next_fade_output = "v%d%d" % (i, i + 1)
        xfade_offset = video_length - fade_duration * (i + 1)
        video_fades += "[%s][%d:v]xfade=transition=zoomin:duration=%f:offset=%f%s%s" % \
                       (last_fade_output, i + 1, fade_duration, xfade_offset,
                        '[' + next_fade_output + '];' if (i) < len(segments) - 2 else "",
                        "" if (i) < len(segments) - 2 else ",format=yuv420p[video];")
        last_fade_output = next_fade_output

        next_audio_output = "a%d%d" % (i, i + 1)
        afade_offset = (fade_duration * 2)
        audio_fades += "[%s][%d:a]acrossfade=d=%f%s" % \
                       (last_audio_output, i + 1, afade_offset,
                        '[' + next_audio_output + '];' if (i) < len(segments) - 2 else "[audio]")
        last_audio_output = next_audio_output

    setab = ""
    for i in range(len(segments)):
        if i == 0:
            continue
        setab += f"[%d]adelay=delays={int(fade_duration * 1000)}:all=1[%d:a];" % (i, i)

    return settb + setab + video_fades + audio_fades

input_file1 = 'D:\\Users\\WIN11\\Videos\\dd\\1.mp4'
input_file2 = 'D:\\Users\\WIN11\\Videos\\dd\\2.mp4'
input_file3 = 'D:\\Users\\WIN11\\Videos\\dd\\3.mp4'
output_file = 'D:\\Users\\WIN11\\Videos\\output5.mp4'
input_files = [input_file1, input_file2, input_file3]


filter_complex = gen_filter(input_files)
# print(filter_complex)
# exit()

files_input = [['-i', f] for f in input_files]

# Assemble the FFMPEG command arguments
ffmpeg_args = [
    'ffmpeg',
    *itertools.chain(*files_input),
    '-filter_complex', filter_complex,
    '-map', '[video]',
    '-map', '[audio]',
    '-y',
    output_file
]


subprocess.run(ffmpeg_args)

# reference
# https://trac.ffmpeg.org/wiki/Xfade
# https://gist.github.com/royshil/369e175960718b5a03e40f279b131788
# https://stackoverflow.com/questions/63553906/merging-multiple-video-files-with-ffmpeg-and-xfade-filter/63570355#63570355