src/app.py.py

import streamlit as st
import cv2
import numpy as np
from pathlib import Path
import subprocess
import shutil

st.title("🎬 Live Preview + Shader + Logo App (GPU/CPU + Audio)")

# --- Uploads ---
video_file = st.file_uploader("Upload video", type=["mp4", "mov"])
logo_file = st.file_uploader("Upload logo PNG", type=["png"])
logo_size_option = st.selectbox("Logo size", [64, 128, 256])

# --- Shader toggle ---
shader_option = st.radio("Apply Shader?", ["Yes", "No"])
shader_code = """
def shader_frame(width, height, t):
    x = np.linspace(0, 1, width)
    y = np.linspace(0, 1, height)
    xv, yv = np.meshgrid(x, y)
    r = ((xv + 0.5*np.sin(t)) % 1.0 * 255).astype(np.uint8)
    g = ((yv + 0.5*np.cos(t)) % 1.0 * 255).astype(np.uint8)
    b = (0.5*255*np.ones_like(r)).astype(np.uint8)
    frame = np.stack([b, g, r], axis=2)
    return frame
"""
if shader_option == "Yes":
    st.text_area("Current shader code", shader_code, height=200)

# --- Paths ---
video_path = Path("video.mp4")
if video_file:
    video_path.write_bytes(video_file.getbuffer())

status_placeholder = st.empty()

# --- Shader generator ---
def shader_frame(width, height, t):
    x = np.linspace(0, 1, width)
    y = np.linspace(0, 1, height)
    xv, yv = np.meshgrid(x, y)
    r = ((xv + 0.5*np.sin(t)) % 1.0 * 255).astype(np.uint8)
    g = ((yv + 0.5*np.cos(t)) % 1.0 * 255).astype(np.uint8)
    b = (0.5*255*np.ones_like(r)).astype(np.uint8)
    frame = np.stack([b, g, r], axis=2)
    return frame

# --- Logo loader ---
logo = None
has_alpha = False
if logo_file:
    logo_data = np.frombuffer(logo_file.read(), np.uint8)
    logo = cv2.imdecode(logo_data, cv2.IMREAD_UNCHANGED)
    has_alpha = logo.shape[2] == 4 if logo.ndim == 3 else False
    st.text(f"Logo loaded, transparency: {'Yes' if has_alpha else 'No'}")

    # Resize logo
    lh, lw = logo.shape[:2]
    scale = logo_size_option / max(lw, lh)
    new_w = int(lw * scale)
    new_h = int(lh * scale)
    logo = cv2.resize(logo, (new_w, new_h), interpolation=cv2.INTER_AREA)

# --- Logo overlay ---
def overlay_logo(frame, logo, has_alpha):
    height, width = frame.shape[:2]
    lh, lw = logo.shape[:2]
    y1, y2 = height - lh - 10, height - 10
    x1, x2 = width - lw - 10, width - 10
    if has_alpha:
        alpha = logo[:, :, 3] / 255.0
        for c in range(3):
            frame[y1:y2, x1:x2, c] = (
                alpha * logo[:, :, c] + (1 - alpha) * frame[y1:y2, x1:x2, c]
            )
    else:
        frame[y1:y2, x1:x2] = logo[:, :, :3]
    return frame

# --- GPU detection ---
def has_nvenc():
    try:
        result = subprocess.run(["ffmpeg", "-encoders"], capture_output=True, text=True)
        return "h264_nvenc" in result.stdout
    except Exception:
        return False

# --- Preview generator ---
def generate_preview():
    if not video_file:
        status_placeholder.warning("Upload a video first!")
        return

    cap = cv2.VideoCapture(str(video_path))
    fps = cap.get(cv2.CAP_PROP_FPS) or 30
    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
    total_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))

    st.text(f"Preview resolution: {width} x {height} @ {fps:.1f} FPS")

    tmp_out = Path("temp_frames.mp4")
    out = cv2.VideoWriter(str(tmp_out),
                          cv2.VideoWriter_fourcc(*'mp4v'),
                          fps, (width, height))

    t = 0.0
    dt = 1.0 / fps
    frame_idx = 0

    preview_display = st.empty()
    progress_bar = st.progress(0)

    while True:
        ret, frame = cap.read()
        if not ret:
            break

        # Shader
        if shader_option == "Yes":
            shader = shader_frame(width, height, t)
            blended = cv2.addWeighted(frame, 0.7, shader, 0.3, 0)
        else:
            blended = frame.copy()

        # Logo
        if logo is not None:
            blended = overlay_logo(blended, logo, has_alpha)

        out.write(blended)

        # Live preview
        preview_small = cv2.resize(blended, (width // 2, height // 2))
        preview_display.image(preview_small, channels="BGR")

        t += dt
        frame_idx += 1
        progress_bar.progress(min(frame_idx / max(total_frames, 1), 1.0))

    cap.release()
    out.release()

    # --- Merge audio ---
    output_path = Path("preview.mp4")
    encoder = "h264_nvenc" if has_nvenc() else "libx264"
    st.info(f"Encoding with: {encoder}")

    cmd = [
        "ffmpeg", "-y",
        "-i", str(tmp_out),
        "-i", str(video_path),
        "-map", "0:v:0",
        "-map", "1:a:0",
        "-c:v", encoder,
        "-preset", "fast",
        "-b:v", "5M",
        "-c:a", "aac",
        str(output_path)
    ]

    try:
        subprocess.run(cmd, check=True)
        st.success("✅ Preview generated successfully with audio!")
        st.video(str(output_path))
        st.markdown(f"[📥 Download preview](./{output_path})")
    except subprocess.CalledProcessError as e:
        st.error("❌ FFmpeg failed to merge audio.")
        st.text(e)

# --- Buttons ---
if st.button("Generate Preview"):
    generate_preview()

if st.button("Go Live"):
    st.warning("Go Live is not implemented yet.")