🐛 Stream codec is now honored when picking track file extension (#336)

tiddl/cli/commands/download/downloader.py

@@ -141,7 +141,9 @@ class Downloader:
                     )
                     return None, False
 
-                urls, _ = parse_track_stream(stream)
+                urls, actual_ext = parse_track_stream(stream)
+                if filename.suffix.lower() != actual_ext:
+                    filename = filename.with_suffix(actual_ext)
                 download_path = self.download_path / filename
 
                 quality = track_qualities_color[stream.audioQuality]

tiddl/core/utils/ffmpeg.py

@@ -2,9 +2,18 @@ import subprocess
 from pathlib import Path
 
 
-def run(cmd: list[str]):
-    """Run process without printing to terminal"""
-    subprocess.run(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+class FFmpegError(RuntimeError):
+    pass
+
+
+def run(cmd: list[str]) -> subprocess.CompletedProcess:
+    """Run a process; raise `FFmpegError` on non-zero exit with stderr."""
+    r = subprocess.run(cmd, capture_output=True, text=True)
+    if r.returncode != 0:
+        raise FFmpegError(
+            f"{cmd[0]} failed (rc={r.returncode}): {r.stderr.strip()}"
+        )
+    return r
 
 
 def is_ffmpeg_installed() -> bool:
@@ -13,10 +22,25 @@ def is_ffmpeg_installed() -> bool:
     try:
         run(["ffmpeg", "-version"])
         return True
-    except FileNotFoundError:
+    except (FileNotFoundError, FFmpegError):
         return False
 
 
+def _probe_audio_codec(source: Path) -> str:
+    """Return first audio stream's codec_name, or "" if ffprobe is unavailable."""
+    try:
+        r = run([
+            "ffprobe", "-v", "error",
+            "-select_streams", "a:0",
+            "-show_entries", "stream=codec_name",
+            "-of", "default=noprint_wrappers=1:nokey=1",
+            str(source),
+        ])
+        return r.stdout.strip()
+    except (FileNotFoundError, FFmpegError):
+        return ""
+
+
 def convert_to_mp4(source: Path) -> Path:
     output_path = source.with_suffix(".mp4")
 
@@ -29,13 +53,26 @@ def convert_to_mp4(source: Path) -> Path:
 
 def extract_flac(source: Path) -> Path:
     """
-    Extracts flac audio from mp4 container
+    Extract FLAC audio from an MP4 container.
+
+    Tidal can serve AAC-in-MP4 for tracks without a lossless master, so the
+    input may not actually contain FLAC.
     """
 
+    codec = _probe_audio_codec(source)
+    if codec and codec != "flac":
+        target = source.with_suffix(".m4a")
+        if target != source:
+            source.replace(target)
+        return target
+
+    target = source.with_suffix(".flac")
     tmp = source.with_suffix(".tmp.flac")
 
     run(["ffmpeg", "-y", "-i", str(source), "-c", "copy", str(tmp)])
 
-    tmp.replace(source.with_suffix(".flac"))
+    tmp.replace(target)
+    if source != target and source.exists():
+        source.unlink()
 
-    return source.with_suffix(".flac")
+    return target