v0.20.0: delete FrameSource/FrameSink, keep single Stream trait

The 0.18 trait split into FrameSource (read-only) and FrameSink
(write-only) was an over-engineered API. Consumers don't think
"frame source backed by MKV" — they think "open MKV for reading".
The split paid a real API-complexity cost (two trait names, two
re-exports, dual impls per bidirectional type, deprecation bridge)
for one marginal property: compile-time direction-safety at the
trait-object boundary. The runtime error path on a wrong-direction
call (StreamReadOnly / StreamWriteOnly) is unambiguous and rare in
practice.

Deletions:
- pes::Stream is no longer #[deprecated]
- pes::FrameSource trait + its blanket-from-Stream bridge
- pes::FrameSink trait + the trampoline impls on every concrete type
- The compile-time-direction-safety test scaffolding
- Crate-root FrameSource / FrameSink re-exports

Additions:
- Stream is now Send-bounded (Stream: Send supertrait). Every
  concrete impl was already Send-compliant — Box<dyn Read + Send>
  and Box<dyn Write + Send> were already in place on the trait
  objects MkvStream / M2tsStream / etc hold internally. Promoting
  Send into the trait makes Box<dyn Stream> Send too, which lets
  autorip drop its SendStream unsafe newtype.

The public API is now: one Stream trait, one concrete type per
format, two constructors (open/create or input/output). Bidirectional
types route through internal Mode { Read | Write } discriminants.

Net: -347 lines libfreemkv, -38 lines autorip, -5 lines freemkv.

src/mux/disc.rs

@@ -403,7 +403,6 @@ impl DiscStream {
     }
 }
 
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSource/FrameSink in follow-up commit.
 impl crate::pes::Stream for DiscStream {
     fn read(&mut self) -> io::Result<Option<crate::pes::PesFrame>> {
         if let Some(frame) = self.pending_frames.pop_front() {
@@ -584,23 +583,18 @@ impl crate::pes::Stream for DiscStream {
 
 #[cfg(test)]
 mod tests {
-    //! `DiscStream` is the only meaningful `FrameSource` impl in tree (every
-    //! other concrete `pes::Stream` impl in `mux/*` is a sink). The 0.18
-    //! round-1 blanket `impl<T: pes::Stream + Send> pes::FrameSource for T`
-    //! covers `DiscStream` for free as long as it is `Send`. These tests
-    //! lock that down: a static `Send` assertion plus a `Box<dyn FrameSource>`
-    //! round trip exercising every `FrameSource` method through the trait
-    //! object, so future Send-breaking edits to `DiscStream`'s interior
-    //! types fail at compile time and the trait-bridge dispatch is verified
-    //! at runtime.
-    #![allow(deprecated)] // exercising the 0.18 deprecation-window blanket bridge.
+    //! `DiscStream` is the only read-only `Stream` impl in tree (every
+    //! other concrete impl in `mux/*` is bidirectional or write-only).
+    //! These tests lock down a static `Send` assertion plus a
+    //! `Box<dyn Stream>` round trip exercising every method through the
+    //! trait object, so future Send-breaking edits to `DiscStream`'s
+    //! interior types fail at compile time.
     use super::*;
     use crate::disc::{ContentFormat, DiscTitle};
-    use crate::pes::FrameSource;
+    use crate::pes::Stream;
 
-    /// Static-assert `DiscStream: Send`. The blanket
-    /// `impl<T: pes::Stream + Send> pes::FrameSource for T` only fires for
-    /// `Send` types — if a future field on `DiscStream` is non-`Send` (e.g.
+    /// Static-assert `DiscStream: Send`. The `Stream` trait has `Send` as a
+    /// supertrait — if a future field on `DiscStream` is non-`Send` (e.g.
     /// a `Box<dyn Read>` instead of `Box<dyn SectorReader>`), this fails
     /// at compile time, before the runtime trait-object test below.
     fn _assert_disc_stream_is_send() {
@@ -644,13 +638,11 @@ mod tests {
         }
     }
 
-    /// Smallest credible witness that `DiscStream` flows through the
-    /// `FrameSource` blanket impl: build a `Box<dyn FrameSource>`, drive
-    /// `read()` to EOF, exercise `info()` / `headers_ready()` /
-    /// `codec_private()` through the trait object. The trait-bridge
-    /// correctness is what's being verified — not demuxer behaviour.
+    /// Smallest credible witness that `DiscStream` flows through `dyn Stream`:
+    /// build a `Box<dyn Stream>`, drive `read()` to EOF, exercise `info()` /
+    /// `headers_ready()` / `codec_private()` through the trait object.
     #[test]
-    fn frame_source_via_dyn_object() {
+    fn stream_via_dyn_object() {
         let reader = ZeroReader { capacity: 8 };
         let title = synthetic_title(8);
         let stream = DiscStream::new(
@@ -661,7 +653,7 @@ mod tests {
             ContentFormat::BdTs,
         );
 
-        let mut src: Box<dyn FrameSource> = Box::new(stream);
+        let mut src: Box<dyn Stream> = Box::new(stream);
 
         // Empty-title fixture has no streams configured, so headers are
         // trivially ready and codec_private() yields nothing on track 0.

src/mux/m2ts.rs

@@ -173,7 +173,6 @@ impl M2tsStream {
     }
 }
 
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSource/FrameSink in follow-up commit.
 impl crate::pes::Stream for M2tsStream {
     fn read(&mut self) -> io::Result<Option<crate::pes::PesFrame>> {
         if let Some(frame) = self.pending_frames.pop_front() {
@@ -284,27 +283,3 @@ impl crate::pes::Stream for M2tsStream {
         true
     }
 }
-
-/// FrameSink sibling to the deprecated Stream impl; both coexist during the
-/// 0.18 deprecation window. Caller may pick either at the trait-object
-/// boundary — `Box<dyn Stream>` (deprecated) or `Box<dyn FrameSink>` (new).
-/// Use `M2tsStream::create(writer, title)` to construct the write half;
-/// calling `FrameSink::write` on an `M2tsStream::open(reader)` instance
-/// returns `StreamReadOnly`.
-#[allow(deprecated)] // delegating to deprecated Stream during the 0.18 deprecation window so callers don't see the deprecation twice.
-impl crate::pes::FrameSink for M2tsStream {
-    fn write(&mut self, frame: &crate::pes::PesFrame) -> io::Result<()> {
-        <Self as crate::pes::Stream>::write(self, frame)
-    }
-
-    fn finish(self: Box<Self>) -> io::Result<()> {
-        // Why: Stream::finish takes &mut self, FrameSink::finish takes Box<Self>.
-        // Re-borrow inside the box, call Stream::finish, drop the box.
-        let mut s: Self = *self;
-        <Self as crate::pes::Stream>::finish(&mut s)
-    }
-
-    fn info(&self) -> &crate::disc::DiscTitle {
-        <Self as crate::pes::Stream>::info(self)
-    }
-}

src/mux/mkvstream.rs

@@ -92,7 +92,6 @@ impl MkvStream {
     }
 }
 
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSource/FrameSink in follow-up commit.
 impl crate::pes::Stream for MkvStream {
     fn read(&mut self) -> io::Result<Option<crate::pes::PesFrame>> {
         let rs = match self.mode {
@@ -189,35 +188,6 @@ impl crate::pes::Stream for MkvStream {
     }
 }
 
-/// FrameSink sibling to the deprecated Stream impl; both coexist during the
-/// 0.18 deprecation window. Caller may pick either at the trait-object
-/// boundary — `Box<dyn Stream>` (deprecated) or `Box<dyn FrameSink>` (new).
-/// Use `MkvStream::create(writer, title)` to construct the write half;
-/// calling `FrameSink::write` on a `MkvStream::open(reader)` instance returns
-/// `StreamReadOnly`. `finish` is where the Cues index is written, so it must
-/// be called for the resulting MKV to be seekable.
-#[allow(deprecated)] // delegating to deprecated Stream during the 0.18 deprecation window so callers don't see the deprecation twice.
-impl crate::pes::FrameSink for MkvStream {
-    fn write(&mut self, frame: &crate::pes::PesFrame) -> io::Result<()> {
-        <Self as crate::pes::Stream>::write(self, frame)
-    }
-
-    fn finish(self: Box<Self>) -> io::Result<()> {
-        // Why: Stream::finish takes &mut self, FrameSink::finish takes Box<Self>.
-        // Re-borrow inside the box, call Stream::finish, drop the box.
-        // The inner `MkvMuxer` is owned via `Option`, and `Stream::finish`
-        // already takes it via `Option::take()` — moving `*self` out of the
-        // box hands it the same field by-value, so the muxer's own
-        // by-value `finish()` runs correctly.
-        let mut s: Self = *self;
-        <Self as crate::pes::Stream>::finish(&mut s)
-    }
-
-    fn info(&self) -> &crate::disc::DiscTitle {
-        <Self as crate::pes::Stream>::info(self)
-    }
-}
-
 // ── MKV header parsing (read side) ────────────────────────────
 
 /// Returns (DiscTitle, codec_privates: Vec<(track_number, codec_private_bytes)>)

src/mux/network.rs

@@ -70,7 +70,6 @@ impl NetworkStream {
     }
 }
 
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSource/FrameSink in follow-up commit.
 impl crate::pes::Stream for NetworkStream {
     fn read(&mut self) -> io::Result<Option<crate::pes::PesFrame>> {
         match &mut self.mode {
@@ -109,30 +108,6 @@ impl crate::pes::Stream for NetworkStream {
     }
 }
 
-/// FrameSink sibling to the deprecated Stream impl; both coexist during the
-/// 0.18 deprecation window. Caller may pick either at the trait-object
-/// boundary — `Box<dyn Stream>` (deprecated) or `Box<dyn FrameSink>` (new).
-/// Use `NetworkStream::connect(addr).meta(title)` to construct the write
-/// half; calling `FrameSink::write` on `NetworkStream::listen(addr)` returns
-/// `StreamReadOnly`.
-#[allow(deprecated)] // delegating to deprecated Stream during the 0.18 deprecation window so callers don't see the deprecation twice.
-impl crate::pes::FrameSink for NetworkStream {
-    fn write(&mut self, frame: &crate::pes::PesFrame) -> io::Result<()> {
-        <Self as crate::pes::Stream>::write(self, frame)
-    }
-
-    fn finish(self: Box<Self>) -> io::Result<()> {
-        // Why: Stream::finish takes &mut self, FrameSink::finish takes Box<Self>.
-        // Re-borrow inside the box, call Stream::finish, drop the box.
-        let mut s: Self = *self;
-        <Self as crate::pes::Stream>::finish(&mut s)
-    }
-
-    fn info(&self) -> &DiscTitle {
-        <Self as crate::pes::Stream>::info(self)
-    }
-}
-
 // NetworkStream is PES-only — no IOStream/Read/Write byte interface.
 
 #[cfg(test)]
@@ -182,7 +157,6 @@ mod tests {
 
     #[test]
     #[ignore] // Requires TCP; may be flaky in CI environments
-    #[allow(deprecated)] // 0.18 trait split: migrate to FrameSource/FrameSink in follow-up commit.
     fn network_pes_roundtrip() {
         use crate::pes;
 

src/mux/null.rs

@@ -16,7 +16,6 @@ impl NullStream {
     }
 }
 
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSink in follow-up commit.
 impl crate::pes::Stream for NullStream {
     fn read(&mut self) -> io::Result<Option<crate::pes::PesFrame>> {
         Ok(None)
@@ -32,43 +31,16 @@ impl crate::pes::Stream for NullStream {
     }
 }
 
-/// FrameSink sibling to the deprecated Stream impl; both coexist during the
-/// 0.18 deprecation window. Caller may pick either at the trait-object
-/// boundary — `Box<dyn Stream>` (deprecated) or `Box<dyn FrameSink>` (new).
-/// The deprecation-window callers eventually migrate; this impl exists so
-/// new callers can target `FrameSink` without waiting for the rest of the
-/// migration to complete.
-#[allow(deprecated)] // delegating to deprecated Stream during the 0.18 deprecation window so callers don't see the deprecation twice.
-impl crate::pes::FrameSink for NullStream {
-    fn write(&mut self, frame: &crate::pes::PesFrame) -> io::Result<()> {
-        <Self as crate::pes::Stream>::write(self, frame)
-    }
-
-    fn finish(self: Box<Self>) -> io::Result<()> {
-        // Why: Stream::finish takes &mut self, FrameSink::finish takes Box<Self>.
-        // Re-borrow inside the box, call Stream::finish, drop the box.
-        let mut s: Self = *self;
-        <Self as crate::pes::Stream>::finish(&mut s)
-    }
-
-    fn info(&self) -> &DiscTitle {
-        <Self as crate::pes::Stream>::info(self)
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::pes::FrameSink;
+    use crate::pes::Stream;
 
-    /// Smallest credible witness that the new FrameSink impl on a concrete
-    /// `mux/*` sink works through the trait object: build a boxed
-    /// `dyn FrameSink`, write a frame, finish it. The trait-bridge correctness
-    /// is what's being verified — not NullStream-specific behaviour.
+    /// Verify NullStream routes through the `Stream` trait object cleanly.
     #[test]
-    fn frame_sink_via_dyn_object_writes_and_finishes() {
+    fn stream_via_dyn_object_writes_and_finishes() {
         let title = DiscTitle::empty();
-        let mut sink: Box<dyn FrameSink> = Box::new(NullStream::new(&title));
+        let mut sink: Box<dyn Stream> = Box::new(NullStream::new(&title));
 
         let frame = crate::pes::PesFrame {
             track: 0,
@@ -77,9 +49,7 @@ mod tests {
             data: vec![0x01, 0x02, 0x03],
         };
         sink.write(&frame).unwrap();
-        // info() routes through the trait object.
         let _ = sink.info();
-        // finish() consumes the Box<Self> — must compile and run.
         sink.finish().unwrap();
     }
 }

src/mux/resolve.rs

@@ -167,7 +167,6 @@ pub struct InputOptions {
 }
 
 /// Open a PES input stream (produces PES frames).
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSource in follow-up commit.
 pub fn input(url: &str, opts: &InputOptions) -> io::Result<Box<dyn crate::pes::Stream>> {
     let parsed = parse_url(url);
     match parsed {
@@ -239,7 +238,6 @@ pub fn input(url: &str, opts: &InputOptions) -> io::Result<Box<dyn crate::pes::S
 }
 
 /// Open a PES output stream (consumes PES frames).
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSink in follow-up commit.
 pub fn output(
     url: &str,
     title: &crate::disc::DiscTitle,

src/mux/stdio.rs

@@ -60,7 +60,6 @@ impl StdioStream {
     }
 }
 
-#[allow(deprecated)] // 0.18 trait split: migrate to FrameSource/FrameSink in follow-up commit.
 impl crate::pes::Stream for StdioStream {
     fn read(&mut self) -> io::Result<Option<crate::pes::PesFrame>> {
         self.ensure_header_read()?;
@@ -105,26 +104,3 @@ impl crate::pes::Stream for StdioStream {
         self.header_read || self.writer.is_some()
     }
 }
-
-/// FrameSink sibling to the deprecated Stream impl; both coexist during the
-/// 0.18 deprecation window. Caller may pick either at the trait-object
-/// boundary — `Box<dyn Stream>` (deprecated) or `Box<dyn FrameSink>` (new).
-/// Use `StdioStream::output(title)` to construct the write half; calling
-/// `FrameSink::write` on a `StdioStream::input()` returns `StreamReadOnly`.
-#[allow(deprecated)] // delegating to deprecated Stream during the 0.18 deprecation window so callers don't see the deprecation twice.
-impl crate::pes::FrameSink for StdioStream {
-    fn write(&mut self, frame: &crate::pes::PesFrame) -> io::Result<()> {
-        <Self as crate::pes::Stream>::write(self, frame)
-    }
-
-    fn finish(self: Box<Self>) -> io::Result<()> {
-        // Why: Stream::finish takes &mut self, FrameSink::finish takes Box<Self>.
-        // Re-borrow inside the box, call Stream::finish, drop the box.
-        let mut s: Self = *self;
-        <Self as crate::pes::Stream>::finish(&mut s)
-    }
-
-    fn info(&self) -> &DiscTitle {
-        <Self as crate::pes::Stream>::info(self)
-    }
-}