Add fese module for embedded subtitles

1 files changed, 401 insertions, 0 deletions

diff --git a/libs/fese/__init__.py b/libs/fese/__init__.py
new file mode 100755
index 000000000..b1024b8ff
--- /dev/null
+++ b/libs/fese/__init__.py
@@ -0,0 +1,401 @@
+# -*- coding: utf-8 -*-
+# License: GPL
+
+from __future__ import annotations
+
+import json
+import logging
+import os
+import re
+import subprocess
+from typing import List, Optional
+
+from babelfish import Language
+from babelfish.exceptions import LanguageError
+import pysubs2
+
+__version__ = "0.1.0"
+
+logger = logging.getLogger(__name__)
+
+# Paths to executables
+FFPROBE_PATH = os.environ.get("FFPROBE_PATH", "ffprobe")
+FFMPEG_PATH = os.environ.get("FFMPEG_PATH", "ffmpeg")
+
+FFMPEG_STATS = True
+FF_LOG_LEVEL = "quiet"
+
+
+class FeseError(Exception):
+    pass
+
+
+class ExtractionError(FeseError):
+    pass
+
+
+class InvalidFile(FeseError):
+    pass
+
+
+class InvalidStream(FeseError):
+    pass
+
+
+class InvalidSource(FeseError):
+    pass
+
+
+class ConversionError(FeseError):
+    pass
+
+
+class LanguageNotFound(FeseError):
+    pass
+
+
+# Extensions
+
+SRT = "srt"
+ASS = "ass"
+
+
+class FFprobeSubtitleDisposition:
+    def __init__(self, data: dict):
+        self.default = False
+        self.generic = False
+        self.dub = False
+        self.original = False
+        self.comment = False
+        self.lyrics = False
+        self.karaoke = False
+        self.forced = False
+        self.hearing_impaired = False
+        self.visual_impaired = False
+        self.clean_effects = False
+        self.attached_pic = False
+        self.timed_thumbnails = False
+        self._content_type = None
+
+        for key, val in data.items():
+            if hasattr(self, key):
+                setattr(self, key, bool(val))
+
+    def update_from_tags(self, tags):
+        tag_title = tags.get("title")
+        if tag_title is None:
+            logger.debug("Title not found. Marking as generic")
+            self.generic = True
+            return None
+
+        l_tag_title = tag_title.lower()
+
+        for key, val in _content_types.items():
+            if val.search(l_tag_title) is not None:
+                logger.debug("Found %s: %s", key, l_tag_title)
+                self._content_type = key
+                setattr(self, key, True)
+                return None
+
+        logger.debug("Generic disposition title found: %s", l_tag_title)
+        self.generic = True
+        return None
+
+    @property
+    def suffix(self):
+        if self._content_type is not None:
+            return f"-{self._content_type}"
+
+        return ""
+
+    def __str__(self):
+        return self.suffix.lstrip("-").upper() or "GENERIC"
+
+
+class FFprobeSubtitleStream:
+    """Base class for FFprobe (FFmpeg) extractable subtitle streams."""
+
+    def __init__(self, stream: dict):
+        """
+        :raises: LanguageNotFound
+        """
+        self.index = int(stream.get("index", 0))
+        self.codec_name = stream.get("codec_name", "Unknown")
+        self.extension = _subtitle_extensions.get(self.codec_name, self.codec_name)
+        self.r_frame_rate = stream.get("r_frame_rate")
+        self.avg_frame_rate = stream.get("avg_frame_rate")
+        self.time_base = stream.get("time_base")
+        self.tags = stream.get("tags", {})
+        self.duration = float(stream.get("duration", 0))
+        self.start_time = float(stream.get("start_time", 0))
+        self.duration_ts = int(stream.get("duration_ts", 0))
+        self.start_pts = int(stream.get("start_pts", 0))
+
+        self.disposition = FFprobeSubtitleDisposition(stream.get("disposition", {}))
+
+        if self.tags:
+            self.disposition.update_from_tags(self.tags)
+
+        self.language: Language = self._language()
+
+    @property
+    def suffix(self):
+        lang = self.language.alpha2
+        if self.language.country is not None:
+            lang = f"{lang}-{self.language.country}"
+
+        return f"{lang}{self.disposition.suffix}.{self.extension}"
+
+    def _language(self) -> Language:
+        og_lang = self.tags.get("language")
+
+        if og_lang is not None:
+            if og_lang in _extra_languages:
+                extra = _extra_languages[og_lang]
+                title = self.tags.get("title", "n/a").lower()
+                if any(possible in title for possible in extra["matches"]):
+                    logger.debug("Found extra language %s", extra["language_args"])
+                    return Language(*extra["language_args"])
+
+            try:
+                return Language.fromalpha3b(og_lang)
+            except LanguageError as error:
+                logger.debug("Error with '%s' language: %s", og_lang, error)
+
+        raise LanguageNotFound(f"Couldn't detect language for stream: {self.tags}")
+
+    def __repr__(self) -> str:
+        return f"<{self.codec_name.upper()}: {self.language}@{self.disposition}>"
+
+
+# Helpers
+
+
+class FFprobeVideoContainer:
+    def __init__(self, path: str):
+        self.path = path
+
+    @property
+    def extension(self):
+        return os.path.splitext(self.path)[-1].lstrip(".")
+
+    def get_subtitles(self, timeout: int = 600) -> List[FFprobeSubtitleStream]:
+        """Factory function to create subtitle instances from FFprobe.
+
+        :param timeout: subprocess timeout in seconds (default: 600)
+        :raises: InvalidSource"""
+
+        ff_command = [
+            FFPROBE_PATH,
+            "-v",
+            FF_LOG_LEVEL,
+            "-print_format",
+            "json",
+            "-show_format",
+            "-show_streams",
+            self.path,
+        ]
+        try:
+            result = subprocess.run(
+                ff_command, stdout=subprocess.PIPE, check=True, timeout=timeout
+            )
+            streams = json.loads(result.stdout)["streams"]
+        except _ffprobe_exceptions as error:
+            raise InvalidSource(
+                f"{error} trying to get information from {self.path}"
+            ) from error  # We want to see the traceback
+
+        subs = []
+        for stream in streams:
+            if stream.get("codec_type", "n/a") != "subtitle":
+                continue
+            try:
+                subs.append(FFprobeSubtitleStream(stream))
+            except LanguageNotFound:
+                pass
+
+        if not subs:
+            logger.debug("Source doesn't have any subtitle valid streams")
+            return []
+
+        logger.debug("Found subtitle streams: %s", subs)
+        return subs
+
+    def extract_subtitles(
+        self,
+        subtitles: List[FFprobeSubtitleStream],
+        custom_dir=None,
+        overwrite=True,
+        timeout=600,
+    ):
+        """Extracts a list of subtitles. Returns a dictionary of the extracted
+        filenames by index.
+
+        :param subtitles: a list of FFprobeSubtitle instances
+        :param custom_dir: a custom directory to save the subtitles. Defaults to
+        same directory as the media file
+        :param overwrite: overwrite files with the same name (default: True)
+        :param timeout: subprocess timeout in seconds (default: 600)
+        :raises: ExtractionError, OSError
+        """
+        extract_command = [FFMPEG_PATH, "-v", FF_LOG_LEVEL]
+        if FFMPEG_STATS:
+            extract_command.append("-stats")
+        extract_command.extend(["-y", "-i", self.path])
+
+        if custom_dir is not None:
+            # May raise OSError
+            os.makedirs(custom_dir, exist_ok=True)
+
+        items = {}
+        collected_paths = set()
+
+        for subtitle in subtitles:
+            sub_path = f"{os.path.splitext(self.path)[0]}.{subtitle.suffix}"
+            if custom_dir is not None:
+                sub_path = os.path.join(custom_dir, os.path.basename(sub_path))
+
+            if sub_path in collected_paths:
+                sub_path = (
+                    f"{sub_path.rstrip(f'.{subtitle.suffix}')}"
+                    f"-{len(collected_paths)}.{subtitle.suffix}"
+                )
+
+            if not overwrite and os.path.isfile(sub_path):
+                logger.debug("Ignoring path (OVERWRITE TRUE): %s", sub_path)
+                continue
+
+            extract_command.extend(
+                ["-map", f"0:{subtitle.index}", "-c", "copy", sub_path]
+            )
+            logger.debug("Appending subtitle path: %s", sub_path)
+
+            collected_paths.add(sub_path)
+
+            items[subtitle.index] = sub_path
+
+        if not items:
+            logger.debug("No subtitles to extract")
+            return {}
+
+        logger.debug("Extracting subtitle with command %s", " ".join(extract_command))
+
+        try:
+            subprocess.run(extract_command, timeout=timeout, check=True)
+        except (subprocess.SubprocessError, FileNotFoundError) as error:
+            raise ExtractionError(f"Error calling ffmpeg: {error}") from error
+
+        for path in items.values():
+            if not os.path.isfile(path):
+                logger.debug("%s was not extracted", path)
+
+        return items
+
+    def __repr__(self) -> str:
+        return f"<FFprobeVideoContainer {self.extension}: {self.path}>"
+
+
+def check_integrity(
+    subtitle: FFprobeSubtitleStream, path: str, sec_offset_threshold=900
+):
+    """A relative check for the integriy of a file. This can be used to find a failed
+    ffmpeg extraction where the final file might not be complete or might be corrupted.
+    Currently, only ASS and Subrip are supported.
+
+    :param subtitle: FFprobeSubtitle instance
+    :param path: the path of the subtitle file (ass or srt)
+    :param sec_offset_threshold: the maximum seconds offset to determine if the file is complete
+    :raises: InvalidFile
+    """
+    if subtitle.extension not in (ASS, SRT):
+        raise InvalidFile(f"Extension not supported: {subtitle.extension}")
+
+    try:
+        sub = pysubs2.load(path)
+    except (pysubs2.Pysubs2Error, UnicodeError, OSError, FileNotFoundError) as error:
+        raise InvalidFile(error) from error
+    else:
+        off = abs(int(sub[-1].end) - subtitle.duration_ts)
+        if off > abs(sec_offset_threshold) * 1000:
+            raise InvalidFile(
+                f"The last subtitle timestamp ({sub[-1].end/1000} sec) is {off/1000} sec ahead"
+                f" from the subtitle stream total duration ({subtitle.duration} sec)"
+            )
+
+        logger.debug("Integrity check passed (%d sec offset)", off / 1000)
+
+
+def to_srt(
+    source: str, output: Optional[str] = None, remove_source: bool = False
+) -> str:
+    """Convert a subtitle to SubRip. Currently, only ASS is supported. SubRip
+    files will be silently ignored.
+
+    raises: ConversionError, OSError"""
+    if source.endswith(".srt"):
+        return source
+
+    split_path = os.path.splitext(source)
+
+    if split_path[-1] not in (".ass"):
+        raise ConversionError(
+            f"No converter found for extension: {split_path[-1]}"
+        ) from None
+
+    output = output or f"{split_path[0]}.srt"
+
+    try:
+        parsed = pysubs2.load(source)
+        parsed.save(output)
+    except (pysubs2.Pysubs2Error, UnicodeError) as error:
+        raise ConversionError(f"Exception converting {output}: {error}") from error
+
+    logger.debug("Converted: %s", output)
+
+    if remove_source and source != output:
+        try:
+            os.remove(source)
+        except OSError as error:
+            logger.debug("Can't remove source: %s (%s)", source, error)
+
+    return output
+
+
+_subtitle_extensions = {"subrip": "srt", "ass": "ass"}
+
+
+_content_types = {
+    "hearing_impaired": re.compile(r"sdh|hearing impaired"),
+    "forced": re.compile(r"forced"),
+    "comment": re.compile(r"comment"),
+    "visual_impaired": re.compile(r"signs|visual impair"),
+    "karaoke": re.compile(r"karaoke|songs"),
+}
+
+
+_ffprobe_exceptions = (
+    subprocess.SubprocessError,
+    json.JSONDecodeError,
+    FileNotFoundError,
+    KeyError,
+)
+
+_extra_languages = {
+    "spa": {
+        "matches": (
+            "es-la",
+            "spa-la",
+            "spl",
+            "mx",
+            "latin",
+            "mexic",
+            "argent",
+            "latam",
+        ),
+        "language_args": ("spa", "MX"),
+    },
+    "por": {
+        "matches": ("pt-br", "pob", "pb", "brazilian", "brasil", "brazil"),
+        "language_args": ("por", "BR"),
+    },
+}