fix styled ASS and refactor att format

.gitignore

@@ -10,6 +10,8 @@ tools/ansible/inventory/group_vars/all.yml
 ffx_test_report.log
 bin/conversiontest.py
 
+tests/assets/
+
 build/
 dist/
 *.egg-info/

SCRATCHPAD.md

@@ -75,7 +75,9 @@
 
 Detect ffmpeg warning "Timestamps are unset in a packet for stream 0. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly" and try autofix by -fflags +genpts -> Warning if fails -> Error. Check if flags collide with anything.
 
+<!--
 
-## .265 export
+## Source Formats
+
+-->
 
--map 0:v -c:v copy -bsf:v hevc_mp4toannexb out.h265

docs/file_formats.md

@@ -0,0 +1,170 @@
+# File Formats
+
+This document captures source-file-format notes that complement the normative
+requirements in `requirements/source_file_formats.md`.
+
+The first documented format is a Matroska source that carries styled ASS/SSA
+subtitle streams together with embedded font attachments.
+
+## Styled ASS In Matroska With Embedded Fonts
+
+These files are typically `.mkv` releases where subtitle rendering quality
+depends on keeping both parts of the subtitle package together:
+
+- one or more subtitle streams with codec `ass`
+- one or more attachment streams that embed font files used by those subtitles
+
+This matters because ASS subtitles are not plain text subtitles in the narrow
+WebVTT sense. They can carry layout, styling, positioning, karaoke, signs, and
+other typesetting effects. If the matching embedded fonts are lost, consumers
+can still see subtitle text but the intended styling and sometimes glyph
+coverage can be degraded.
+
+For FFX this format is special because the ASS subtitle streams should remain
+normally editable and mappable, while the related font attachments should be
+transported unchanged.
+
+## Observed Sample
+
+Assessment date: `2026-04-17`
+
+Observed sample file:
+
+- `tests/assets/boruto_s01e283_ssa.mkv`
+
+Commands used for assessment:
+
+```bash
+ffprobe tests/assets/boruto_s01e283_ssa.mkv
+ffprobe -hide_banner -show_format -show_streams -of json tests/assets/boruto_s01e283_ssa.mkv
+```
+
+Observed stream layout:
+
+| Stream index | Kind | Key details |
+| --- | --- | --- |
+| `0` | video | `codec_name=h264` |
+| `1` | audio | `codec_name=aac`, `language=jpn` |
+| `2` | subtitle | `codec_name=ass`, `language=ger`, default |
+| `3` | subtitle | `codec_name=ass`, `language=eng` |
+| `4`-`13` | attachment | `tags.mimetype=font/ttf`, `.ttf` filenames |
+
+Observed attachment filenames:
+
+- `AmazonEmberTanuki-Italic.ttf`
+- `AmazonEmberTanuki-Regular.ttf`
+- `Arial.ttf`
+- `Arial Bold.ttf`
+- `Georgia.ttf`
+- `Times New Roman.ttf`
+- `Times New Roman Bold.ttf`
+- `Trebuchet MS.ttf`
+- `Verdana.ttf`
+- `Verdana Bold.ttf`
+
+Important probe behavior from the real sample:
+
+- Plain `ffprobe` lists the font streams as `Attachment: none`.
+- Plain `ffprobe` also prints warnings such as `Could not find codec
+  parameters for stream 4 (Attachment: none): unknown codec` and later
+  `Unsupported codec with id 0 for input stream ...`.
+- The JSON produced by `FileProperties.FFPROBE_COMMAND_TOKENS`
+  (`ffprobe -hide_banner -show_format -show_streams -of json`) still exposes
+  the attachment streams clearly through `codec_type="attachment"` and the
+  attachment tags.
+- In that JSON, the attachment streams do not expose `codec_name`.
+
+This last point is important for FFX: robust detection must not depend on
+attachment `codec_name` being present.
+
+## Detection Guidance
+
+Current known indicators for this format are:
+
+- one or more subtitle streams with `codec_type="subtitle"` and
+  `codec_name="ass"`
+- one or more attachment streams with `codec_type="attachment"`
+- attachment tags that identify embedded fonts, especially
+  `tags.mimetype="font/ttf"`
+- attachment filenames that end in `.ttf`
+
+The pattern can vary. FFX should therefore treat the above as a cluster of
+signals rather than an exact signature tied to one file.
+
+Inference from the observed sample plus FFmpeg documentation:
+
+- MIME matching should not be limited to `font/ttf` alone.
+- The Boruto sample uses `font/ttf`.
+- FFmpeg's Matroska attachment example uses
+  `mimetype=application/x-truetype-font` for a `.ttf` attachment.
+- Detection should therefore normalize multiple TTF-like MIME values rather
+  than depend on a single exact string.
+
+## Processing Expectations In FFX
+
+The format-specific requirements live in
+`requirements/source_file_formats.md`. In practical terms, FFX should:
+
+- recognize the ASS-plus-font-attachment pattern even when attachment probe
+  data is incomplete
+- tell the operator that the pattern was detected and that special handling is
+  being used
+- reject sidecar subtitle import for such sources, because converting or
+  replacing these subtitle tracks with ordinary external text subtitles would
+  break the intended subtitle package
+- continue to allow normal manipulation of the ASS subtitle tracks themselves
+- preserve the font attachment streams unchanged
+
+## FFmpeg Notes
+
+Relevant FFmpeg documentation confirms several behaviors that line up with
+FFX's needs:
+
+- FFmpeg documents `-attach` as adding an attachment stream to the output, and
+  explicitly names Matroska fonts used in subtitle rendering as an example.
+- FFmpeg documents attachment streams as regular streams that are created after
+  the mapped media streams.
+- FFmpeg documents `-dump_attachment` for extracting attachment streams, which
+  is useful for debugging or validating a source file's embedded fonts.
+- FFmpeg's Matroska example requires a `mimetype` metadata tag for attached
+  fonts, which is consistent with using attachment tags as detection signals.
+- FFmpeg also notes that attachments are implemented as codec extradata. That
+  helps explain why probe output for attachment streams can look different from
+  ordinary audio, video, and subtitle streams.
+
+Implication for FFX:
+
+- Attachment preservation is not an optional cosmetic feature for this format.
+  It is part of preserving the subtitle package correctly.
+
+## Jellyfin Notes
+
+Jellyfin's documentation also supports keeping this format intact:
+
+- Jellyfin's subtitle compatibility table lists `ASS/SSA` as supported in
+  `MKV` and not supported in `MP4`.
+- Jellyfin notes that when subtitles must be transcoded, they are either
+  converted to a supported format or burned into the video, and burning them in
+  is the most CPU-intensive path.
+- Jellyfin's subtitle-extraction example for `SSA/ASS` first dumps attachment
+  streams and then extracts the ASS subtitle stream, which reflects the real
+  relationship between ASS subtitles and embedded fonts in MKV releases.
+- Jellyfin's font documentation says text-based subtitles require fonts to
+  render properly.
+- Jellyfin's configuration documentation says the web client uses configured
+  fallback fonts for ASS subtitles when other fonts such as MKV attachments or
+  client-side fonts are not available.
+
+Inference from the Jellyfin compatibility tables:
+
+- Keeping this subtitle format in Matroska is the safest interoperability
+  choice for Jellyfin consumers.
+- Converting the subtitle payload to WebVTT would lose styled ASS behavior.
+- Dropping the attachment streams would force client or fallback font
+  substitution and can change appearance or glyph coverage.
+
+## References
+
+- FFmpeg documentation: https://ffmpeg.org/ffmpeg.html
+- Jellyfin codec support: https://jellyfin.org/docs/general/clients/codec-support/
+- Jellyfin configuration and fonts: https://jellyfin.org/docs/general/administration/configuration/

requirements/source_file_formats.md

@@ -0,0 +1,90 @@
+# Source File Formats
+
+This file defines source-file-format-specific processing requirements for FFX.
+It is intended to grow as additional relevant source file types are identified.
+
+The first covered format is Matroska media that contains styled ASS/SSA
+subtitle streams together with embedded font attachments.
+
+## Scope
+
+- Detecting source files that use ASS subtitle streams together with embedded
+  font attachments needed for correct rendering.
+- Defining the required `ffx convert` behavior when this format is present.
+- Preserving the required attachment streams during conversion.
+- Keeping normal subtitle-track manipulation behavior for the ASS subtitle
+  tracks themselves.
+
+## Out Of Scope
+
+- General subtitle behavior for sources that do not carry this pattern.
+- A complete catalog of all source file formats FFX may support later.
+
+## Terms
+
+- `styled ASS source`: a source media file that contains one or more subtitle
+  streams with `codec_type="subtitle"` and `codec_name="ass"` together with
+  one or more font-bearing attachment streams.
+- `font attachment`: an attachment stream whose metadata identifies a font
+  payload, commonly through `tags.mimetype` and attachment filename metadata.
+- `external subtitle feed`: subtitle tracks supplied from separate subtitle
+  files through the existing subtitle-import path.
+- `special attachment subtracks`: the embedded font attachment streams that
+  belong to the styled ASS source pattern.
+
+## Rules
+
+- `SOURCE_FILE_FORMATS-0001`: The system shall recognize the styled ASS source
+  pattern.
+- `SOURCE_FILE_FORMATS-0002`: Recognition shall not depend on fixed stream
+  counts, fixed stream indices, or one exact attachment count.
+- `SOURCE_FILE_FORMATS-0003`: Recognition shall use the best available ffprobe
+  signals. For known subtitle streams this includes
+  `codec_type="subtitle"` together with `codec_name="ass"`.
+- `SOURCE_FILE_FORMATS-0004`: Recognition of the special attachment subtracks
+  shall use attachment-oriented signals such as `codec_type="attachment"` and
+  font-identifying metadata such as `tags.mimetype="font/ttf"` when present.
+- `SOURCE_FILE_FORMATS-0005`: Recognition shall tolerate known ffprobe
+  variation in attachment reporting, including files where attachment streams
+  do not expose a `codec_name` but do expose `codec_type="attachment"` and
+  font-identifying tags.
+- `SOURCE_FILE_FORMATS-0006`: When attachment metadata varies across files,
+  detection shall not depend on one exact MIME string alone. Detection shall
+  be written so the known pattern can vary while still recognizing font
+  attachments.
+- `SOURCE_FILE_FORMATS-0007`: When the styled ASS source pattern is detected,
+  `ffx convert` shall emit an operator-facing message that reports the
+  detection and hints that special subtitle preservation handling is being
+  applied.
+- `SOURCE_FILE_FORMATS-0008`: When the styled ASS source pattern is present on
+  the source file, `ffx convert` shall not process an external subtitle feed.
+  The command shall stop before conversion and report an error that explains
+  that separate subtitle-file import is incompatible with this source format.
+- `SOURCE_FILE_FORMATS-0009`: Normal manipulation of the ASS subtitle streams
+  themselves shall continue to work through the usual selection, ordering,
+  metadata, language, title, and disposition handling paths.
+- `SOURCE_FILE_FORMATS-0010`: The special attachment subtracks shall be
+  preserved in the target media file as-is rather than transcoded,
+  regenerated, or replaced from external sources.
+- `SOURCE_FILE_FORMATS-0011`: Preserving the special attachment subtracks
+  as-is includes retaining the attachment payload and the attachment metadata
+  required by consumers, especially attachment filename and mimetype
+  information.
+- `SOURCE_FILE_FORMATS-0012`: This file shall remain the extension point for
+  additional source-file-format contracts as FFX adds support for more special
+  source formats.
+
+## Acceptance
+
+- A source file matching the observed pattern of embedded ASS subtitles plus
+  font attachments is recognized even when the attachment streams do not carry
+  a `codec_name`.
+- `ffx convert` output contains a clear detection message before the actual
+  conversion work proceeds.
+- If external subtitle import is requested for such a source file, the command
+  fails fast with an explicit error instead of mixing sidecar subtitles into
+  the job.
+- Existing manipulation of the ASS subtitle tracks still works for metadata,
+  titles, languages, ordering, and dispositions.
+- The output media preserves the required font attachment streams and their
+  identifying metadata needed by downstream media players.

src/ffx/attachment_format.py

@@ -0,0 +1,67 @@
+from enum import Enum
+import os
+
+
+class AttachmentFormat(Enum):
+
+    TTF = {'identifier': 'ttf', 'format': None, 'extension': 'ttf', 'label': 'TTF'}
+    PNG = {'identifier': 'png', 'format': None, 'extension': 'png', 'label': 'PNG'}
+
+    UNKNOWN = {'identifier': 'unknown', 'format': None, 'extension': None, 'label': 'UNKNOWN'}
+
+    def identifier(self):
+        return str(self.value['identifier'])
+
+    def label(self):
+        return str(self.value['label'])
+
+    def format(self):
+        return self.value['format']
+
+    def extension(self):
+        return str(self.value['extension'])
+
+    @staticmethod
+    def identify(identifier: str):
+        formats = [f for f in AttachmentFormat if f.value['identifier'] == str(identifier)]
+        if formats:
+            return formats[0]
+        return AttachmentFormat.UNKNOWN
+
+    @staticmethod
+    def identifyFfprobeStream(streamObj: dict):
+        identifier = streamObj.get("codec_name")
+        identifiedFormat = AttachmentFormat.identify(identifier)
+        if identifiedFormat != AttachmentFormat.UNKNOWN:
+            return identifiedFormat
+
+        if str(streamObj.get("codec_type", "")).strip() != "attachment":
+            return AttachmentFormat.UNKNOWN
+
+        tags = streamObj.get("tags", {}) or {}
+        mimetype = str(tags.get("mimetype", "")).strip().lower()
+        filename = str(tags.get("filename", "")).strip().lower()
+        filenameExtension = os.path.splitext(filename)[1]
+
+        if (
+            mimetype in {
+                "font/ttf",
+                "application/x-truetype-font",
+                "application/x-font-ttf",
+            }
+            or "truetype" in mimetype
+            or filenameExtension == ".ttf"
+        ):
+            return AttachmentFormat.TTF
+
+        if mimetype in {"image/png", "image/x-png"} or filenameExtension == ".png":
+            return AttachmentFormat.PNG
+
+        return AttachmentFormat.UNKNOWN
+
+    @staticmethod
+    def fromTrackCodec(trackCodec):
+        identifier = getattr(trackCodec, "identifier", None)
+        if callable(identifier):
+            return AttachmentFormat.identify(trackCodec.identifier())
+        return AttachmentFormat.UNKNOWN

src/ffx/cli.py

@@ -639,6 +639,7 @@ def getUnmuxSequence(trackDescriptor: TrackDescriptor, sourcePath, targetPrefix,
 
     trackType = trackDescriptor.getType()
     trackCodec = trackDescriptor.getCodec()
+    trackFormat = trackDescriptor.getFormatDescriptor()
 
     targetPathBase = os.path.join(targetDirectory, targetPrefix) if targetDirectory else targetPrefix
 
@@ -651,12 +652,12 @@ def getUnmuxSequence(trackDescriptor: TrackDescriptor, sourcePath, targetPrefix,
         commandTokens += ['-c', 'copy']
 
     # output format
-    codecFormat = trackCodec.format()
+    codecFormat = trackFormat.format()
     if codecFormat is not None:
         commandTokens += ['-f', codecFormat]
 
     # output filename
-    commandTokens += [f"{targetPathBase}.{trackCodec.extension()}"]
+    commandTokens += [f"{targetPathBase}.{trackFormat.extension()}"]
 
     return commandTokens
 
@@ -771,7 +772,7 @@ def unmux(ctx,
                         if not ctx.obj['dry_run']:
 
                             #TODO #425: Codec Enum
-                            ctx.obj['logger'].info(f"Unmuxing stream {trackDescriptor.getIndex()} into file {targetPrefix}.{trackDescriptor.getCodec().extension()}")
+                            ctx.obj['logger'].info(f"Unmuxing stream {trackDescriptor.getIndex()} into file {targetPrefix}.{trackDescriptor.getFormatDescriptor().extension()}")
 
                             ctx.obj['logger'].debug(f"Executing unmuxing sequence")
 
@@ -1313,10 +1314,12 @@ def convert(ctx,
         sourceMediaDescriptor = mediaFileProperties.getMediaDescriptor()
 
 
+        from ffx.attachment_format import AttachmentFormat
+
         if ([smd for smd in sourceMediaDescriptor.getSubtitleTracks()
                     if smd.getCodec() == TrackCodec.ASS]
                 and [amd for amd in sourceMediaDescriptor.getAttachmentTracks()
-                    if amd.getCodec() == TrackCodec.TTF]):
+                    if amd.getAttachmentFormat() == AttachmentFormat.TTF]):
             
             targetFormat = ''
             targetExtension = 'mkv'

src/ffx/media_descriptor.py

@@ -2,6 +2,7 @@ import os, re, click
 
 from typing import List, Self
 
+from ffx.attachment_format import AttachmentFormat
 from ffx.track_type import TrackType
 from ffx.iso_language import IsoLanguage
 
@@ -421,11 +422,11 @@ class MediaDescriptor:
 
         if sourceMediaDescriptor:
             fontDescriptors = [ftd for ftd in sourceMediaDescriptor.getAttachmentTracks()
-                                if ftd.getCodec() == TrackCodec.TTF]
+                                if ftd.getAttachmentFormat() == AttachmentFormat.TTF]
         else:
             fontDescriptors = [ftd for ftd in self.__trackDescriptors
                                 if ftd.getType() == TrackType.ATTACHMENT
-                                and ftd.getCodec() == TrackCodec.TTF]
+                                and ftd.getAttachmentFormat() == AttachmentFormat.TTF]
 
         for ad in sorted(fontDescriptors, key=lambda d: d.getIndex()):
             inputMappingTokens += ["-map", f"0:{ad.getIndex()}"]

src/ffx/media_workflow_screen_base.py

@@ -221,7 +221,7 @@ class MediaWorkflowScreenBase(Screen):
                 trackDescriptor.getIndex(),
                 t(trackType.label()),
                 typeCounter[trackType],
-                trackDescriptor.getCodec().label(),
+                trackDescriptor.getFormatDescriptor().label(),
                 t(audioLayout.label())
                 if trackType == TrackType.AUDIO
                 and audioLayout != AudioLayout.LAYOUT_UNDEFINED

src/ffx/model/track.py

@@ -4,6 +4,7 @@ from sqlalchemy.orm import relationship, declarative_base, sessionmaker
 
 from .show import Base
 
+from ffx.attachment_format import AttachmentFormat
 from ffx.track_type import TrackType
 
 from ffx.iso_language import IsoLanguage
@@ -132,9 +133,16 @@ class Track(Base):
 
         if trackType in [t.label() for t in TrackType]:
 
+            if trackType == TrackType.ATTACHMENT.label():
+                storedFormatIdentifier = AttachmentFormat.identifyFfprobeStream(streamObj).identifier()
+            else:
+                storedFormatIdentifier = TrackCodec.identify(
+                    streamObj.get(TrackDescriptor.FFPROBE_CODEC_KEY)
+                ).identifier()
+
             return cls(pattern_id = patternId,
                         track_type = trackType,
-                        codec_name = streamObj[TrackDescriptor.FFPROBE_CODEC_NAME_KEY],
+                        codec_name = storedFormatIdentifier,
                         disposition_flags = sum([2**t.index() for (k,v) in streamObj[TrackDescriptor.FFPROBE_DISPOSITION_KEY].items()
                                                         if v and (t := TrackDisposition.find(k)) is not None]),
                         audio_layout = AudioLayout.identify(streamObj))
@@ -153,8 +161,20 @@ class Track(Base):
         return TrackType.fromIndex(self.track_type)
 
     def getCodec(self) -> TrackCodec:
+        if self.getType() == TrackType.ATTACHMENT:
+            return TrackCodec.UNKNOWN
         return TrackCodec.identify(self.codec_name)
 
+    def getAttachmentFormat(self) -> AttachmentFormat:
+        if self.getType() != TrackType.ATTACHMENT:
+            return AttachmentFormat.UNKNOWN
+        return AttachmentFormat.identify(self.codec_name)
+
+    def getFormatDescriptor(self):
+        if self.getType() == TrackType.ATTACHMENT:
+            return self.getAttachmentFormat()
+        return self.getCodec()
+
     def getIndex(self):
         return int(self.index) if self.index is not None else -1
 
@@ -206,7 +226,10 @@ class Track(Base):
             kwargs[TrackDescriptor.SUB_INDEX_KEY] = subIndex
 
         kwargs[TrackDescriptor.TRACK_TYPE_KEY] = self.getType()
-        kwargs[TrackDescriptor.CODEC_KEY] = self.getCodec()
+        if self.getType() == TrackType.ATTACHMENT:
+            kwargs[TrackDescriptor.ATTACHMENT_FORMAT_KEY] = self.getAttachmentFormat()
+        else:
+            kwargs[TrackDescriptor.CODEC_KEY] = self.getCodec()
         
         kwargs[TrackDescriptor.DISPOSITION_SET_KEY] = self.getDispositionSet()
         kwargs[TrackDescriptor.TAGS_KEY] = self.getTags()

src/ffx/pattern_controller.py

@@ -134,7 +134,7 @@ class PatternController:
     def _build_track_row(self, trackDescriptor: TrackDescriptor) -> Track:
         track = Track(
             track_type=int(trackDescriptor.getType().index()),
-            codec_name=str(trackDescriptor.getCodec().identifier()),
+            codec_name=str(trackDescriptor.getFormatDescriptor().identifier()),
             index=int(trackDescriptor.getIndex()),
             source_index=int(trackDescriptor.getSourceIndex()),
             disposition_flags=int(

src/ffx/pattern_details_screen.py

@@ -175,7 +175,7 @@ class PatternDetailsScreen(Screen):
                 row = (td.getIndex(),
                         t(trackType.label()),
                         typeCounter[trackType],
-                        td.getCodec().label(),
+                        td.getFormatDescriptor().label(),
                         t(audioLayout.label()) if trackType == TrackType.AUDIO
                             and audioLayout != AudioLayout.LAYOUT_UNDEFINED else ' ',
                         trackLanguage.label() if trackLanguage != IsoLanguage.UNDEFINED else ' ',

src/ffx/track_codec.py

@@ -19,7 +19,6 @@ class TrackCodec(Enum):
     WEBVTT =    {'identifier': 'webvtt',             'format': 'webvtt',     'extension': 'vtt'  , 'label':  'WebVTT'}
     SRT  =      {'identifier': 'subrip',             'format': 'srt',        'extension': 'srt'  , 'label':  'SRT'}
     ASS  =      {'identifier': 'ass',                'format': 'ass',        'extension': 'ass'  , 'label':  'ASS'}
-    TTF  =      {'identifier': 'ttf',                'format': None,         'extension': 'ttf'  , 'label':  'TTF'}
     PGS  =      {'identifier': 'hdmv_pgs_subtitle',  'format': 'sup',        'extension': 'sup'  , 'label':  'PGS'}
     VOBSUB =    {'identifier': 'dvd_subtitle',       'format': None,         'extension': 'mkv'  , 'label':  'VobSub'}
 

src/ffx/track_controller.py

@@ -43,7 +43,7 @@ class TrackController():
             s = self.Session()
             track = Track(pattern_id = patId,
                             track_type = int(trackDescriptor.getType().index()),
-                            codec_name = str(trackDescriptor.getCodec().identifier()),
+                            codec_name = str(trackDescriptor.getFormatDescriptor().identifier()),
                             index = int(trackDescriptor.getIndex()),
                             source_index = int(trackDescriptor.getSourceIndex()),
                             disposition_flags = int(TrackDisposition.toFlags(trackDescriptor.getDispositionSet())),
@@ -82,7 +82,7 @@ class TrackController():
                 track.index = int(trackDescriptor.getIndex())
 
                 track.track_type = int(trackDescriptor.getType().index())
-                track.codec_name = str(trackDescriptor.getCodec().identifier())
+                track.codec_name = str(trackDescriptor.getFormatDescriptor().identifier())
                 track.audio_layout = int(trackDescriptor.getAudioLayout().index())
 
                 track.disposition_flags = int(TrackDisposition.toFlags(trackDescriptor.getDispositionSet()))

src/ffx/track_descriptor.py

@@ -1,5 +1,6 @@
 from typing import Self
 
+from .attachment_format import AttachmentFormat
 from .iso_language import IsoLanguage
 from .track_type import TrackType
 from .audio_layout import AudioLayout
@@ -26,6 +27,7 @@ class TrackDescriptor:
 
     TRACK_TYPE_KEY = "track_type"
     CODEC_KEY = "codec_name"
+    ATTACHMENT_FORMAT_KEY = "attachment_format"
     AUDIO_LAYOUT_KEY = "audio_layout"
 
     FFPROBE_INDEX_KEY = "index"
@@ -110,15 +112,6 @@ class TrackDescriptor:
         else:
             self.__trackType = TrackType.UNKNOWN
 
-        if TrackDescriptor.CODEC_KEY in kwargs.keys():
-            if type(kwargs[TrackDescriptor.CODEC_KEY]) is not TrackCodec:
-                raise TypeError(
-                    f"TrackDesciptor.__init__(): Argument {TrackDescriptor.CODEC_KEY} is required to be of type TrackCodec"
-                )
-            self.__trackCodec = kwargs[TrackDescriptor.CODEC_KEY]
-        else:
-            self.__trackCodec = TrackCodec.UNKNOWN
-
         if TrackDescriptor.TAGS_KEY in kwargs.keys():
             if type(kwargs[TrackDescriptor.TAGS_KEY]) is not dict:
                 raise TypeError(
@@ -151,6 +144,34 @@ class TrackDescriptor:
         else:
             self.__audioLayout = AudioLayout.LAYOUT_UNDEFINED
 
+        self.__trackCodec = TrackCodec.UNKNOWN
+        self.__attachmentFormat = AttachmentFormat.UNKNOWN
+
+        if self.__trackType == TrackType.ATTACHMENT:
+            if TrackDescriptor.ATTACHMENT_FORMAT_KEY in kwargs.keys():
+                if type(kwargs[TrackDescriptor.ATTACHMENT_FORMAT_KEY]) is not AttachmentFormat:
+                    raise TypeError(
+                        f"TrackDesciptor.__init__(): Argument {TrackDescriptor.ATTACHMENT_FORMAT_KEY} is required to be of type AttachmentFormat"
+                    )
+                self.__attachmentFormat = kwargs[TrackDescriptor.ATTACHMENT_FORMAT_KEY]
+            elif TrackDescriptor.CODEC_KEY in kwargs.keys():
+                legacyCodec = kwargs[TrackDescriptor.CODEC_KEY]
+                if type(legacyCodec) is AttachmentFormat:
+                    self.__attachmentFormat = legacyCodec
+                elif type(legacyCodec) is TrackCodec:
+                    self.__attachmentFormat = AttachmentFormat.fromTrackCodec(legacyCodec)
+                else:
+                    raise TypeError(
+                        f"TrackDesciptor.__init__(): Argument {TrackDescriptor.CODEC_KEY} is required to be of type TrackCodec for legacy attachment compatibility"
+                    )
+        else:
+            if TrackDescriptor.CODEC_KEY in kwargs.keys():
+                if type(kwargs[TrackDescriptor.CODEC_KEY]) is not TrackCodec:
+                    raise TypeError(
+                        f"TrackDesciptor.__init__(): Argument {TrackDescriptor.CODEC_KEY} is required to be of type TrackCodec"
+                    )
+                self.__trackCodec = kwargs[TrackDescriptor.CODEC_KEY]
+
     @classmethod
     def fromFfprobe(cls, streamObj, subIndex: int = -1):
         """Processes ffprobe stream data as array with elements according to the following example
@@ -215,7 +236,12 @@ class TrackDescriptor:
 
             kwargs[TrackDescriptor.TRACK_TYPE_KEY] = trackType
 
-            kwargs[TrackDescriptor.CODEC_KEY] = TrackCodec.identify(streamObj[TrackDescriptor.FFPROBE_CODEC_KEY])
+            if trackType == TrackType.ATTACHMENT:
+                kwargs[TrackDescriptor.ATTACHMENT_FORMAT_KEY] = AttachmentFormat.identifyFfprobeStream(streamObj)
+            else:
+                kwargs[TrackDescriptor.CODEC_KEY] = TrackCodec.identify(
+                    streamObj.get(TrackDescriptor.FFPROBE_CODEC_KEY)
+                )
 
             kwargs[TrackDescriptor.DISPOSITION_SET_KEY] = (
                 {
@@ -277,6 +303,14 @@ class TrackDescriptor:
     def getCodec(self) -> TrackCodec:
         return self.__trackCodec
 
+    def getAttachmentFormat(self) -> AttachmentFormat:
+        return self.__attachmentFormat
+
+    def getFormatDescriptor(self):
+        if self.__trackType == TrackType.ATTACHMENT:
+            return self.__attachmentFormat
+        return self.__trackCodec
+
     def getLanguage(self):
         if "language" in self.__trackTags.keys():
             return IsoLanguage.findThreeLetter(self.__trackTags["language"])
@@ -353,12 +387,16 @@ class TrackDescriptor:
             TrackDescriptor.SOURCE_INDEX_KEY: int(self.__sourceIndex),
             TrackDescriptor.SUB_INDEX_KEY: int(self.__subIndex),
             TrackDescriptor.TRACK_TYPE_KEY: self.__trackType,
-            TrackDescriptor.CODEC_KEY: self.__trackCodec,
             TrackDescriptor.TAGS_KEY: dict(self.__trackTags),
             TrackDescriptor.DISPOSITION_SET_KEY: set(self.__dispositionSet),
             TrackDescriptor.AUDIO_LAYOUT_KEY: self.__audioLayout,
         }
 
+        if self.__trackType == TrackType.ATTACHMENT:
+            kwargs[TrackDescriptor.ATTACHMENT_FORMAT_KEY] = self.__attachmentFormat
+        else:
+            kwargs[TrackDescriptor.CODEC_KEY] = self.__trackCodec
+
         if context is not None:
             kwargs[TrackDescriptor.CONTEXT_KEY] = context
         elif self.__context:

src/ffx/track_details_screen.py

@@ -5,6 +5,7 @@ from textual.widgets import Header, Footer, Static, Button, SelectionList, Selec
 from textual.containers import Grid
 from textual.widgets._data_table import CellDoesNotExist
 
+from .attachment_format import AttachmentFormat
 from .audio_layout import AudioLayout
 from .iso_language import IsoLanguage
 from .tag_delete_screen import TagDeleteScreen
@@ -141,6 +142,7 @@ class TrackDetailsScreen(Screen):
         if self.__isNew:
             self.__trackType = trackType
             self.__trackCodec = TrackCodec.UNKNOWN
+            self.__attachmentFormat = AttachmentFormat.UNKNOWN
             self.__audioLayout = AudioLayout.LAYOUT_UNDEFINED
             self.__index = index
             self.__subIndex = subIndex
@@ -150,6 +152,7 @@ class TrackDetailsScreen(Screen):
         else:
             self.__trackType = trackDescriptor.getType()
             self.__trackCodec = trackDescriptor.getCodec()
+            self.__attachmentFormat = trackDescriptor.getAttachmentFormat()
             self.__audioLayout = trackDescriptor.getAudioLayout()
             self.__index = trackDescriptor.getIndex()
             self.__subIndex = trackDescriptor.getSubIndex()
@@ -433,7 +436,10 @@ class TrackDetailsScreen(Screen):
         if not isinstance(selectedTrackType, TrackType):
             selectedTrackType = TrackType.UNKNOWN
         kwargs[TrackDescriptor.TRACK_TYPE_KEY] = selectedTrackType
-        kwargs[TrackDescriptor.CODEC_KEY] = self.__trackCodec
+        if selectedTrackType == TrackType.ATTACHMENT:
+            kwargs[TrackDescriptor.ATTACHMENT_FORMAT_KEY] = self.__attachmentFormat
+        else:
+            kwargs[TrackDescriptor.CODEC_KEY] = self.__trackCodec
 
         if selectedTrackType == TrackType.AUDIO:
             selectedAudioLayout = self.query_one("#audio_layout_select", Select).value

tests/unit/test_tag_table_screen_state.py

@@ -14,6 +14,7 @@ if str(SRC_ROOT) not in sys.path:
 
 
 from ffx.audio_layout import AudioLayout  # noqa: E402
+from ffx.attachment_format import AttachmentFormat  # noqa: E402
 from ffx.helper import DIFF_ADDED_KEY  # noqa: E402
 from ffx.iso_language import IsoLanguage  # noqa: E402
 from ffx.logging_utils import get_ffx_logger  # noqa: E402
@@ -200,6 +201,32 @@ class TagTableScreenStateTests(unittest.TestCase):
         self.assertEqual("German Audio", descriptor.getTitle())
         self.assertEqual("value", descriptor.getTags()["KEEP"])
 
+    def test_track_details_screen_preserves_attachment_format_for_attachment_tracks(self):
+        screen = object.__new__(TrackDetailsScreen)
+        screen.context = {"logger": get_ffx_logger()}
+        screen._TrackDetailsScreen__trackDescriptor = None
+        screen._TrackDetailsScreen__patternId = 5
+        screen._TrackDetailsScreen__index = 4
+        screen._TrackDetailsScreen__subIndex = 0
+        screen._TrackDetailsScreen__trackCodec = TrackCodec.UNKNOWN
+        screen._TrackDetailsScreen__attachmentFormat = AttachmentFormat.TTF
+        screen._TrackDetailsScreen__draftTrackTags = {"filename": "font.ttf", "mimetype": "font/ttf"}
+
+        widgets = {
+            "#type_select": FakeValueWidget(TrackType.ATTACHMENT),
+            "#audio_layout_select": FakeValueWidget(AudioLayout.LAYOUT_UNDEFINED),
+            "#language_select": FakeValueWidget(Select.NULL),
+            "#title_input": FakeInputWidget(""),
+            "#dispositions_selection_list": FakeSelectionListWidget(set()),
+        }
+        screen.query_one = lambda selector, _widget_type=None: widgets[selector]
+
+        descriptor = screen.getTrackDescriptorFromInput()
+
+        self.assertEqual(TrackType.ATTACHMENT, descriptor.getType())
+        self.assertEqual(AttachmentFormat.TTF, descriptor.getAttachmentFormat())
+        self.assertEqual(TrackCodec.UNKNOWN, descriptor.getCodec())
+
     def test_track_details_screen_auto_sets_localized_title_from_selected_language(self):
         set_current_language("de")
         screen = object.__new__(TrackDetailsScreen)

tests/unit/test_track_descriptor_probe.py

@@ -0,0 +1,87 @@
+from __future__ import annotations
+
+import json
+from pathlib import Path
+import sys
+import unittest
+
+
+SRC_ROOT = Path(__file__).resolve().parents[2] / "src"
+
+if str(SRC_ROOT) not in sys.path:
+    sys.path.insert(0, str(SRC_ROOT))
+
+
+from ffx.attachment_format import AttachmentFormat  # noqa: E402
+from ffx.media_descriptor import MediaDescriptor  # noqa: E402
+from ffx.track_codec import TrackCodec  # noqa: E402
+from ffx.track_descriptor import TrackDescriptor  # noqa: E402
+from ffx.track_type import TrackType  # noqa: E402
+
+
+ASSETS_ROOT = Path(__file__).resolve().parents[1] / "assets"
+
+
+class TrackDescriptorProbeTests(unittest.TestCase):
+    def test_attachment_without_codec_name_uses_font_metadata_to_identify_ttf(self):
+        descriptor = TrackDescriptor.fromFfprobe(
+            {
+                "index": 4,
+                "codec_type": "attachment",
+                "disposition": {"default": 0},
+                "tags": {
+                    "filename": "AmazonEmberTanuki-Italic.ttf",
+                    "mimetype": "font/ttf",
+                },
+            },
+            subIndex=0,
+        )
+
+        self.assertIsNotNone(descriptor)
+        self.assertEqual(TrackType.ATTACHMENT, descriptor.getType())
+        self.assertEqual(AttachmentFormat.TTF, descriptor.getAttachmentFormat())
+        self.assertEqual(AttachmentFormat.TTF, descriptor.getFormatDescriptor())
+        self.assertEqual(TrackCodec.UNKNOWN, descriptor.getCodec())
+
+    def test_attachment_without_codec_name_still_probes_as_unknown_when_not_font(self):
+        descriptor = TrackDescriptor.fromFfprobe(
+            {
+                "index": 9,
+                "codec_type": "attachment",
+                "disposition": {"default": 0},
+                "tags": {
+                    "filename": "cover.bin",
+                    "mimetype": "application/octet-stream",
+                },
+            },
+            subIndex=0,
+        )
+
+        self.assertIsNotNone(descriptor)
+        self.assertEqual(TrackType.ATTACHMENT, descriptor.getType())
+        self.assertEqual(AttachmentFormat.UNKNOWN, descriptor.getAttachmentFormat())
+        self.assertEqual(TrackCodec.UNKNOWN, descriptor.getCodec())
+
+    def test_media_descriptor_from_boruto_probe_json_handles_attachment_streams_without_codec_name(self):
+        probe_payload = json.loads(
+            (ASSETS_ROOT / "ffprobe.out.json").read_text(encoding="utf-8")
+        )
+
+        descriptor = MediaDescriptor.fromFfprobe(
+            {"logger": None},
+            probe_payload["format"],
+            probe_payload["streams"],
+        )
+
+        track_descriptors = descriptor.getTrackDescriptors()
+        attachment_tracks = descriptor.getAttachmentTracks()
+
+        self.assertEqual(14, len(track_descriptors))
+        self.assertEqual(10, len(attachment_tracks))
+        self.assertTrue(
+            all(track.getAttachmentFormat() == AttachmentFormat.TTF for track in attachment_tracks)
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()