feat: add FFmpeg progress parser and output path extraction

app/ffmpeg.py

@@ -1,6 +1,8 @@
 import shlex
 from pathlib import Path
 
+from app.models import Progress
+
 # FFmpeg options that take a value (not exhaustive, covers common ones)
 OPTIONS_WITH_VALUES = {
     "-c", "-c:v", "-c:a", "-b", "-b:v", "-b:a", "-r", "-s", "-ar", "-ac",
@@ -41,3 +43,59 @@ def resolve_paths(args: list[str], data_path: str) -> list[str]:
             resolved.append(arg)
 
     return resolved
+
+
+def parse_progress(output: str, duration_seconds: float | None) -> Progress:
+    """Parse FFmpeg progress output into Progress model."""
+    data: dict[str, str] = {}
+    for line in output.strip().split("\n"):
+        if "=" in line:
+            key, value = line.split("=", 1)
+            data[key.strip()] = value.strip()
+
+    frame = int(data.get("frame", 0))
+    fps = float(data.get("fps", 0.0))
+    out_time_ms = int(data.get("out_time_ms", 0))
+    bitrate = data.get("bitrate", "0kbits/s")
+
+    # Convert out_time_ms to HH:MM:SS.mm format
+    total_seconds = out_time_ms / 1_000_000
+    hours = int(total_seconds // 3600)
+    minutes = int((total_seconds % 3600) // 60)
+    seconds = total_seconds % 60
+    time_str = f"{hours:02d}:{minutes:02d}:{seconds:05.2f}"
+
+    # Calculate percent if duration is known
+    percent = None
+    if duration_seconds and duration_seconds > 0:
+        percent = (total_seconds / duration_seconds) * 100
+        percent = min(percent, 100.0)  # Cap at 100%
+
+    return Progress(
+        frame=frame,
+        fps=fps,
+        time=time_str,
+        bitrate=bitrate,
+        percent=percent,
+    )
+
+
+def extract_output_path(args: list[str]) -> str | None:
+    """Extract output file path from FFmpeg arguments (last non-option argument)."""
+    # Work backwards to find the last argument that isn't an option or option value
+    i = len(args) - 1
+    while i >= 0:
+        arg = args[i]
+        # Skip if it's an option
+        if arg.startswith("-"):
+            i -= 1
+            continue
+        # Check if previous arg is an option that takes a value
+        if i > 0 and args[i - 1] in OPTIONS_WITH_VALUES:
+            i -= 1
+            continue
+        # Check if it looks like a file path (has extension or contains /)
+        if "." in arg or "/" in arg:
+            return arg
+        i -= 1
+    return None