audio_splitter/constants.py

@@ -1,53 +1,124 @@
 # audio_splitter/constants.py
-"""Global constants for the audio splitter."""
+"""Global constants for the audio splitter.
+
+This file serves as the single source of truth for:
+- Container formats and their properties
+- Audio codecs and their recommended containers
+- File extensions for each codec/container combination
+
+Codec != Container != File Extension.
+Example: Opus (codec) → Ogg (container) → .opus (extension)
+"""
 
 # ------------------------------------------------------------------------------
-# Container information (used for output format selection)
+# Container information
 # ------------------------------------------------------------------------------
+# Each container entry:
+#   - name: internal identifier used in the code
+#   - ffmpeg: name passed to FFmpeg's -f option
+#   - extension: default file extension
+#   - audio_only: whether the container supports video/subtitle streams
+#   - supports_video: whether video streams can be stored
+#   - supports_subs: whether subtitle streams can be stored
+CONTAINER_INFO = [
+    # Audio-only containers
+    {'name': 'mp3', 'ffmpeg': 'mp3', 'extension': '.mp3', 'audio_only': True, 'supports_video': False, 'supports_subs': False},
+    {'name': 'm4a', 'ffmpeg': 'mp4', 'extension': '.m4a', 'audio_only': True, 'supports_video': False, 'supports_subs': False},  # MP4 container, .m4a extension for audio-only
+    {'name': 'flac', 'ffmpeg': 'flac', 'extension': '.flac', 'audio_only': True, 'supports_video': False, 'supports_subs': False},
+    {'name': 'wav', 'ffmpeg': 'wav', 'extension': '.wav', 'audio_only': True, 'supports_video': False, 'supports_subs': False},
+    {'name': 'aac', 'ffmpeg': 'adts', 'extension': '.aac', 'audio_only': True, 'supports_video': False, 'supports_subs': False},
+
+    # Containers that support video and subtitles
+    {'name': 'mp4', 'ffmpeg': 'mp4', 'extension': '.mp4', 'audio_only': False, 'supports_video': True, 'supports_subs': True},
+    {'name': 'mkv', 'ffmpeg': 'matroska', 'extension': '.mkv', 'audio_only': False, 'supports_video': True, 'supports_subs': True},
+    {'name': 'matroska', 'ffmpeg': 'matroska', 'extension': '.mkv', 'audio_only': False, 'supports_video': True, 'supports_subs': True},
+    {'name': 'ogg', 'ffmpeg': 'ogg', 'extension': '.ogg', 'audio_only': False, 'supports_video': True, 'supports_subs': True},  # Ogg supports video (Theora, Dirac) and subtitles
+    {'name': 'webm', 'ffmpeg': 'webm', 'extension': '.webm', 'audio_only': False, 'supports_video': True, 'supports_subs': False},  # WebM is a subset of Matroska
+]
+
+# Legacy FORMAT_INFO for backward compatibility with existing code
+# Maps container name → FFmpeg format name, extension, and audio_only flag
 FORMAT_INFO = {
-    'mp3':      {'ffmpeg': 'mp3',      'ext': '.mp3',  'audio_only': True},
+    container['name']: {
-    'm4a':      {'ffmpeg': 'mp4',      'ext': '.m4a',  'audio_only': True},
+        'ffmpeg': container['ffmpeg'],
-    'mp4':      {'ffmpeg': 'mp4',      'ext': '.mp4',  'audio_only': False},
+        'ext': container['extension'],
-    'mkv':      {'ffmpeg': 'matroska', 'ext': '.mkv',  'audio_only': False},
+        'audio_only': container['audio_only'],
-    'matroska': {'ffmpeg': 'matroska', 'ext': '.mkv',  'audio_only': False},
+    }
-    'ogg':      {'ffmpeg': 'ogg',      'ext': '.ogg',  'audio_only': True},
+    for container in CONTAINER_INFO
-    'opus':     {'ffmpeg': 'ogg',      'ext': '.opus', 'audio_only': True},
-    'flac':     {'ffmpeg': 'flac',     'ext': '.flac', 'audio_only': True},
-    'wav':      {'ffmpeg': 'wav',      'ext': '.wav',  'audio_only': True},
-    'aac':      {'ffmpeg': 'adts',     'ext': '.aac',  'audio_only': True},
 }
 
 # ------------------------------------------------------------------------------
-# Container list with display names and extensions (for frontend)
+# Codec information
-# ------------------------------------------------------------------------------
-CONTAINER_INFO = [
-    {'name': 'mp3',      'ffmpeg': 'mp3',      'extension': '.mp3',  'audio_only': True},
-    {'name': 'm4a',      'ffmpeg': 'mp4',      'extension': '.m4a',  'audio_only': True},
-    {'name': 'mp4',      'ffmpeg': 'mp4',      'extension': '.mp4',  'audio_only': False},
-    {'name': 'mkv',      'ffmpeg': 'matroska', 'extension': '.mkv',  'audio_only': False},
-    {'name': 'ogg',      'ffmpeg': 'ogg',      'extension': '.ogg',  'audio_only': True},
-    {'name': 'opus',     'ffmpeg': 'ogg',      'extension': '.opus', 'audio_only': True},
-    {'name': 'flac',     'ffmpeg': 'flac',     'extension': '.flac', 'audio_only': True},
-    {'name': 'wav',      'ffmpeg': 'wav',      'extension': '.wav',  'audio_only': True},
-    {'name': 'aac',      'ffmpeg': 'adts',     'extension': '.aac',  'audio_only': True},
-]
-
-# ------------------------------------------------------------------------------
-# Codec information (used for transcoding options)
 # ------------------------------------------------------------------------------
+# Each codec entry:
+#   - name: codec name (used in code)
+#   - ffmpeg: encoder name passed to FFmpeg's -c:a option
+#   - recommended_container: the container format recommended for this codec
+#   - recommended_extension: the recommended file extension for this codec
+#   - supports_transcoding: whether this codec can be used as output via FFmpeg
+#   - supports_video: whether this codec is for video (True) or audio (False)
 CODEC_INFO = [
-    # codec name, ffmpeg encoder name, recommended container, supports transcoding
+    # Audio codecs
-    {'name': 'mp3',      'ffmpeg': 'libmp3lame', 'recommended_container': 'mp3',  'supports_transcoding': True},
+    {'name': 'opus', 'ffmpeg': 'libopus', 'recommended_container': 'ogg', 'recommended_extension': '.opus', 'supports_transcoding': True, 'supports_video': False},
-    {'name': 'aac',      'ffmpeg': 'aac',        'recommended_container': 'm4a',  'supports_transcoding': True},
+    {'name': 'vorbis', 'ffmpeg': 'libvorbis', 'recommended_container': 'ogg', 'recommended_extension': '.ogg', 'supports_transcoding': True, 'supports_video': False},
-    {'name': 'opus',     'ffmpeg': 'libopus',    'recommended_container': 'opus', 'supports_transcoding': True},
+    {'name': 'flac', 'ffmpeg': 'flac', 'recommended_container': 'flac', 'recommended_extension': '.flac', 'supports_transcoding': True, 'supports_video': False},
-    {'name': 'flac',     'ffmpeg': 'flac',       'recommended_container': 'flac', 'supports_transcoding': True},
+    {'name': 'aac', 'ffmpeg': 'aac', 'recommended_container': 'mp4', 'recommended_extension': '.m4a', 'supports_transcoding': True, 'supports_video': False},
-    {'name': 'vorbis',   'ffmpeg': 'libvorbis',  'recommended_container': 'ogg',  'supports_transcoding': True},
+    {'name': 'mp3', 'ffmpeg': 'libmp3lame', 'recommended_container': 'mp3', 'recommended_extension': '.mp3', 'supports_transcoding': True, 'supports_video': False},
-    {'name': 'alac',     'ffmpeg': 'alac',       'recommended_container': 'm4a',  'supports_transcoding': True},
+    {'name': 'alac', 'ffmpeg': 'alac', 'recommended_container': 'mp4', 'recommended_extension': '.m4a', 'supports_transcoding': True, 'supports_video': False},
-    {'name': 'pcm_s16le','ffmpeg': 'pcm_s16le',  'recommended_container': 'wav',  'supports_transcoding': True},
+    {'name': 'pcm_s16le', 'ffmpeg': 'pcm_s16le', 'recommended_container': 'wav', 'recommended_extension': '.wav', 'supports_transcoding': True, 'supports_video': False},
+
+    # Video codecs (for reference, not used for transcoding selection in the UI)
+    {'name': 'theora', 'ffmpeg': 'libtheora', 'recommended_container': 'ogg', 'recommended_extension': '.ogv', 'supports_transcoding': False, 'supports_video': True},
+    {'name': 'vp8', 'ffmpeg': 'libvpx', 'recommended_container': 'webm', 'recommended_extension': '.webm', 'supports_transcoding': False, 'supports_video': True},
+    {'name': 'vp9', 'ffmpeg': 'libvpx-vp9', 'recommended_container': 'webm', 'recommended_extension': '.webm', 'supports_transcoding': False, 'supports_video': True},
+    {'name': 'av1', 'ffmpeg': 'libaom-av1', 'recommended_container': 'mkv', 'recommended_extension': '.mkv', 'supports_transcoding': False, 'supports_video': True},
+    {'name': 'h264', 'ffmpeg': 'libx264', 'recommended_container': 'mp4', 'recommended_extension': '.mp4', 'supports_transcoding': False, 'supports_video': True},
+    {'name': 'h265', 'ffmpeg': 'libx265', 'recommended_container': 'mp4', 'recommended_extension': '.mp4', 'supports_transcoding': False, 'supports_video': True},
 ]
 
-# Map codec name → recommended container
+# ------------------------------------------------------------------------------
+# Video codec support per container
+# ------------------------------------------------------------------------------
+# For each container, list of video codecs it supports.
+# Use '*' to indicate that the container supports all video codecs (e.g., Matroska).
+CONTAINER_VIDEO_CODEC_SUPPORT = {
+    'mp4': ['h264', 'h265', 'vp9', 'av1', 'mpeg4', 'hevc'],  # MP4 supports these via ISO BMFF
+    'mkv': ['*'],   # Matroska supports virtually all video codecs
+    'matroska': ['*'],
+    'ogg': ['theora', 'dirac', 'vp8'],   # Ogg supports Theora, Dirac, VP8
+    'webm': ['vp8', 'vp9', 'av1'],       # WebM is a subset of Matroska with VP8/VP9/AV1
+    'mp3': [],       # Audio-only, no video support
+    'm4a': [],       # Audio-only, no video support
+    'flac': [],      # Audio-only
+    'wav': [],       # Audio-only
+    'aac': [],       # Audio-only
+}
+
+# Map codec name to its type (audio/video)
+# This is used to determine if a stream is audio or video
+CODEC_TYPE_MAP = {
+    'opus': 'audio',
+    'vorbis': 'audio',
+    'flac': 'audio',
+    'aac': 'audio',
+    'mp3': 'audio',
+    'alac': 'audio',
+    'pcm_s16le': 'audio',
+    'theora': 'video',
+    'vp8': 'video',
+    'vp9': 'video',
+    'av1': 'video',
+    'h264': 'video',
+    'h265': 'video',
+    'png': 'video',      # PNG is often used as attached picture (cover art)
+    'mjpeg': 'video',    # MJPEG also used for attached pictures
+}
+
+# Map codec name → recommended container name
 CODEC_TO_CONTAINER_MAP = {codec['name']: codec['recommended_container'] for codec in CODEC_INFO}
 
+# Map codec name → recommended file extension
+CODEC_TO_EXTENSION_MAP = {codec['name']: codec['recommended_extension'] for codec in CODEC_INFO}
+
 # Default bad characters (unchanged)
 DEFAULT_BAD_CHARS = r'!@#№$;:%^&?*(){}[]\/<>+=~`\' '

audio_splitter/core.py

@@ -48,7 +48,7 @@ def split_audio(input_file, output_directory, tracks, args):
     print(f"Output container: {output_format}")
 
     validate_format_compatibility(output_format, stream_info,
-                                  args.drop_video, args.drop_subs)
+                                  args.drop_video, args.drop_subs, input_file)
 
     # Determine file extension.
     extension_info = FORMAT_INFO.get(output_format, {})

audio_splitter/ffmpeg.py

@@ -257,3 +257,24 @@ def build_ffmpeg_command(input_file: str, start_seconds: int, duration_seconds:
 
     cmd.extend(['-y', output_path])
     return cmd
+
+def get_video_codec(input_file: str) -> Optional[str]:
+    """
+    Return the codec name of the first video stream.
+
+    Args:
+        input_file: Path to the media file.
+
+    Returns:
+        Codec name as a lowercase string, or None if no video stream exists.
+    """
+    cmd = [
+        'ffprobe', '-v', 'error',
+        '-select_streams', 'v:0',
+        '-show_entries', 'stream=codec_name',
+        '-of', 'default=noprint_wrappers=1:nokey=1',
+        input_file
+    ]
+    result = subprocess.run(cmd, capture_output=True, text=True, check=False)
+    codec = result.stdout.strip().lower()
+    return codec if codec else None

audio_splitter/formats.py

@@ -3,8 +3,7 @@
 
 from typing import Dict, Optional
 
-from .constants import FORMAT_INFO, CODEC_TO_CONTAINER_MAP, CONTAINER_INFO
+from .constants import FORMAT_INFO, CODEC_TO_CONTAINER_MAP, CONTAINER_INFO, CONTAINER_VIDEO_CODEC_SUPPORT, CODEC_TYPE_MAP
-
 
 def determine_default_format(container: Optional[str], codec: Optional[str]) -> Optional[str]:
     """
@@ -35,60 +34,10 @@ def determine_default_format(container: Optional[str], codec: Optional[str]) ->
     return None
 
 
-def determine_output_format(stream_info: Dict, user_format: Optional[str],
-                            transcode_audio: Optional[str], input_file: Optional[str] = None) -> str:
-    """
-    Decide which container format to use.
-
-    If user_format is provided, use it.
-    Else, try to detect the input file's container and codec, and use the recommended format.
-    If detection fails or format is not supported, fallback to:
-      - MKV if video/subtitles exist
-      - MP3 if the audio codec is MP3
-      - MP4 (M4A) otherwise
-
-    Args:
-        stream_info: Dict from get_stream_info().
-        user_format: User‑requested format (or None).
-        transcode_audio: Audio codec to transcode to (or None) (unused in this function).
-        input_file: Path to the input file (optional, used to detect container and codec).
-
-    Returns:
-        A format name that exists in FORMAT_INFO.
-    """
-    if user_format:
-        return user_format
-
-    # If input_file is provided, try to detect container and codec
-    if input_file:
-        try:
-            from .ffmpeg import get_container_format, get_audio_codec
-            container = get_container_format(input_file)
-            codec = get_audio_codec(input_file)
-            fmt = determine_default_format(container, codec)
-            if fmt in FORMAT_INFO:
-                return fmt
-        except Exception:
-            # If detection fails, fall through to legacy logic
-            pass
-
-    # Fallback: legacy behavior
-    if stream_info.get('has_video') or stream_info.get('has_subtitle'):
-        return 'matroska'
-    audio_codec = stream_info.get('audio_codec', '')
-    if audio_codec == 'mp3':
-        return 'mp3'
-    else:
-        return 'mp4'  # .m4a
-
-
 def validate_format_compatibility(format_name: str, stream_info: Dict,
-                                  drop_video: bool, drop_subs: bool) -> None:
+                                  drop_video: bool, drop_subs: bool, input_file: Optional[str] = None) -> None:
     """
     Ensure the chosen container can accommodate the streams we intend to keep.
-
-    Raises:
-        ValueError: If the format is incompatible with the intended streams.
     """
     info = FORMAT_INFO.get(format_name)
     if not info:
@@ -106,3 +55,80 @@ def validate_format_compatibility(format_name: str, stream_info: Dict,
                 f"Format '{format_name}' does not support subtitle streams. "
                 "Please use --drop-subs or choose a container that supports subtitles."
             )
+    else:
+        # If video is present and not dropped, check if the container supports the video codec
+        if stream_info.get('has_video') and not drop_video and input_file:
+            from .ffmpeg import get_video_codec
+            video_codec = get_video_codec(input_file)
+            if video_codec and not is_video_codec_supported(format_name, video_codec):
+                raise ValueError(
+                    f"Container '{format_name}' does not support video codec '{video_codec}'. "
+                    "Please use --drop-video or choose a container that supports this video codec (e.g., MKV)."
+                )
+
+def is_video_codec_supported(container_name: str, video_codec: str) -> bool:
+    """
+    Check if a given container supports a specific video codec.
+
+    Args:
+        container_name: Name of the container (e.g., 'mkv', 'ogg')
+        video_codec: Video codec name (e.g., 'theora', 'h264', 'png')
+
+    Returns:
+        True if supported, False otherwise.
+    """
+    support = CONTAINER_VIDEO_CODEC_SUPPORT.get(container_name, [])
+    if not support:
+        return False
+    if '*' in support:
+        return True
+    return video_codec in support
+
+
+def determine_output_format(stream_info: Dict, user_format: Optional[str],
+                            transcode_audio: Optional[str], input_file: Optional[str] = None) -> str:
+    """
+    Decide which container format to use.
+
+    If user_format is provided, use it.
+    Else, try to detect the input file's container and codec, and use the recommended format.
+    If detection fails or format is not supported, fallback to:
+      - MKV if video/subtitles exist and the video codec is not supported by the recommended container
+      - MP3 if the audio codec is MP3
+      - MP4 (M4A) otherwise
+    """
+    if user_format:
+        return user_format
+
+    # Try to detect container and codec from input file
+    if input_file:
+        try:
+            from .ffmpeg import get_container_format, get_audio_codec, get_video_codec
+            container = get_container_format(input_file)
+            audio_codec = get_audio_codec(input_file)
+            video_codec = get_video_codec(input_file)  # NEW: get video codec
+
+            # Determine recommended format based on audio codec
+            fmt = determine_default_format(container, audio_codec)
+
+            # If video is present and not dropped, check if the recommended container supports the video codec
+            if stream_info.get('has_video') and not transcode_audio:  # transcode_audio doesn't affect video
+                # If the recommended container doesn't support the video codec, fallback to MKV
+                if fmt and not is_video_codec_supported(fmt, video_codec):
+                    fmt = 'matroska'  # MKV supports virtually all video codecs
+                    # Optionally log a warning
+                    # print(f"Warning: Container '{fmt}' does not support video codec '{video_codec}'. Falling back to MKV.")
+
+            if fmt in FORMAT_INFO:
+                return fmt
+        except Exception:
+            pass
+
+    # Fallback: legacy behavior
+    if stream_info.get('has_video') or stream_info.get('has_subtitle'):
+        return 'matroska'
+    audio_codec = stream_info.get('audio_codec', '')
+    if audio_codec == 'mp3':
+        return 'mp3'
+    else:
+        return 'mp4'  # .m4a