feat: add FFmpeg progress parser and output path extraction

tests/test_ffmpeg.py

@@ -1,6 +1,6 @@
 import pytest
 
-from app.ffmpeg import parse_command, resolve_paths
+from app.ffmpeg import parse_command, resolve_paths, parse_progress, extract_output_path
 
 
 def test_parse_simple_command():
@@ -57,3 +57,45 @@ def test_resolve_paths_skips_options():
 
     # Options and their values should not be resolved as paths
     assert resolved == ["-c:v", "libx264", "-preset", "fast"]
+
+
+def test_parse_progress():
+    output = """frame=1234
+fps=30.24
+total_size=5678900
+out_time_ms=83450000
+bitrate=1250.5kbits/s
+progress=continue
+"""
+    progress = parse_progress(output, duration_seconds=120.0)
+
+    assert progress.frame == 1234
+    assert progress.fps == 30.24
+    assert progress.time == "00:01:23.45"
+    assert progress.bitrate == "1250.5kbits/s"
+    assert progress.percent == pytest.approx(69.54, rel=0.01)
+
+
+def test_parse_progress_no_duration():
+    output = "frame=100\nfps=25.0\nout_time_ms=4000000\nbitrate=500kbits/s\n"
+
+    progress = parse_progress(output, duration_seconds=None)
+
+    assert progress.frame == 100
+    assert progress.percent is None
+
+
+def test_extract_output_path():
+    args = ["-i", "input.mp4", "-c:v", "libx264", "output.mp4"]
+
+    output_path = extract_output_path(args)
+
+    assert output_path == "output.mp4"
+
+
+def test_extract_output_path_complex():
+    args = ["-i", "a.mp4", "-i", "b.mp4", "-filter_complex", "[0:v][1:v]concat", "out.mp4"]
+
+    output_path = extract_output_path(args)
+
+    assert output_path == "out.mp4"