renderer.py

import os
import subprocess


def render_final_video(
    background,
    audio,
    subtitles,
    output,
    crf=23,
    preset="ultrafast"
):

    if not os.path.exists(background):
        raise FileNotFoundError(
            f"Background file not found: {background}"
        )

    if not os.path.exists(audio):
        raise FileNotFoundError(
            f"Audio file not found: {audio}"
        )

    if not os.path.exists(subtitles):
        raise FileNotFoundError(
            f"Subtitle file not found: {subtitles}"
        )

    print("=" * 60)
    print("AVAILABLE FONTS")
    print("=" * 60)

    if os.path.exists("fonts"):

        for f in os.listdir("fonts"):
            print(f)

    print("=" * 60)
    print("FINAL RENDER START")
    print("=" * 60)

    print("BACKGROUND :", background)
    print("AUDIO      :", audio)
    print("SUBTITLE   :", subtitles)
    print("OUTPUT     :", output)

    vf_filter = (
        #"drawbox="
        #"x=0:y=0:"
        #"w=iw:h=ih:"
        #"color=black@0.20:"
        #"t=fill,"
        f"ass={subtitles}:fontsdir=fonts"
    )

    cmd = [
        "ffmpeg",
        "-y",

        "-stream_loop",
        "-1",

        "-i",
        background,

        "-i",
        audio,

        "-vf",
        vf_filter,

        "-map",
        "0:v",

        "-map",
        "1:a",

        "-c:v",
        "libx264",

        "-preset",
        preset,

        "-crf",
        str(crf),

        "-pix_fmt",
        "yuv420p",

        "-movflags",
        "+faststart",

        "-c:a",
        "aac",

        "-b:a",
        "192k",

        "-shortest",

        output
    ]

    print("\nFFMPEG COMMAND:\n")
    print(" ".join(cmd))
    print()

    result = subprocess.run(
        cmd,
        capture_output=True,
        text=True
    )

    print("=" * 60)
    print("STDOUT")
    print("=" * 60)
    print(result.stdout)

    print("=" * 60)
    print("STDERR")
    print("=" * 60)
    print(result.stderr)

    result.check_returncode()

    if not os.path.exists(output):

        raise Exception(
            "Output video was not generated"
        )

    probe = subprocess.run(
        [
            "ffprobe",
            "-v",
            "error",

            "-show_entries",
            "format=duration",

            "-of",
            "default=noprint_wrappers=1:nokey=1",

            output
        ],
        capture_output=True,
        text=True
    )

    duration = probe.stdout.strip()

    print("=" * 60)
    print("FINAL VIDEO DURATION")
    print("=" * 60)
    print(duration)

    size_mb = (
        os.path.getsize(output)
        / 1024
        / 1024
    )

    print("=" * 60)
    print("FINAL VIDEO SIZE")
    print("=" * 60)

    print(
        f"{size_mb:.2f} MB"
    )

    print("=" * 60)
    print("FINAL RENDER SUCCESS")
    print("=" * 60)

    return output