Zero clippy warnings: fix all 32 remaining

- Iterator::find() replaces manual loops (6 sites)
- Index-only loops → iterators (4 sites)
- Identical if-blocks merged
- Box large MkvStream WriteState enum variant
- Vec macro initializers, late init fixes
- Unused fields prefixed with underscore (format spec fields)
- Dead code removed or documented

0 clippy warnings. 319 tests passing.

src/mux/codec/ac3.rs

@@ -101,12 +101,7 @@ impl CodecParser for Ac3Parser {
 
 /// Find AC3/E-AC-3 syncword (0x0B77) in data.
 fn find_ac3_sync(data: &[u8]) -> Option<usize> {
-    for i in 0..data.len().saturating_sub(1) {
-        if data[i] == 0x0B && data[i + 1] == 0x77 {
-            return Some(i);
-        }
-    }
-    None
+    (0..data.len().saturating_sub(1)).find(|&i| data[i] == 0x0B && data[i + 1] == 0x77)
 }
 
 /// Extract bsid from an AC-3/E-AC-3 frame starting at the syncword.

src/mux/codec/dts.rs

@@ -70,16 +70,12 @@ pub fn find_dts_hd_ext_sync(data: &[u8]) -> Option<usize> {
     if data.len() < 4 {
         return None;
     }
-    for i in 0..=data.len() - 4 {
-        if data[i] == DTS_HD_EXT_SYNC[0]
+    (0..=data.len() - 4).find(|&i| {
+        data[i] == DTS_HD_EXT_SYNC[0]
             && data[i + 1] == DTS_HD_EXT_SYNC[1]
             && data[i + 2] == DTS_HD_EXT_SYNC[2]
             && data[i + 3] == DTS_HD_EXT_SYNC[3]
-        {
-            return Some(i);
-        }
-    }
-    None
+    })
 }
 
 /// Calculate DTS-HD extension frame size from the extension header.

src/mux/codec/h264.rs

@@ -110,15 +110,16 @@ impl CodecParser for H264Parser {
         // pictureParameterSetLength = pps.len()
         // pictureParameterSetNALUnit = pps
 
-        let mut record = Vec::new();
-        record.push(1); // configurationVersion
-        record.push(sps[1]); // profile
-        record.push(sps[2]); // compatibility
-        record.push(sps[3]); // level
-        record.push(0xFF); // 6 bits reserved (111111) + 2 bits lengthSizeMinusOne (11 = 3)
-        record.push(0xE1); // 3 bits reserved (111) + 5 bits numSPS (1)
-        record.push((sps.len() >> 8) as u8);
-        record.push(sps.len() as u8);
+        let mut record = vec![
+            1,        // configurationVersion
+            sps[1],   // profile
+            sps[2],   // compatibility
+            sps[3],   // level
+            0xFF,     // 6 bits reserved (111111) + 2 bits lengthSizeMinusOne (11 = 3)
+            0xE1,     // 3 bits reserved (111) + 5 bits numSPS (1)
+            (sps.len() >> 8) as u8,
+            sps.len() as u8,
+        ];
         record.extend_from_slice(sps);
         record.push(1); // numPPS
         record.push((pps.len() >> 8) as u8);
@@ -179,12 +180,7 @@ pub fn find_start_code(data: &[u8], from: usize) -> Option<usize> {
     if data.len() < from + 3 {
         return None;
     }
-    for i in from..data.len() - 2 {
-        if data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01 {
-            return Some(i);
-        }
-    }
-    None
+    (from..data.len() - 2).find(|&i| data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01)
 }
 
 /// Skip past the start code at position `pos`, returning the first byte after it.

src/mux/codec/lpcm.rs

@@ -70,7 +70,7 @@ mod tests {
     fn header_skip_extracts_pcm_data() {
         let mut parser = LpcmParser::new();
         // 4-byte LPCM header + 6 bytes of PCM data
-        let header = vec![0x00, 0x01, 0x00, 0b10_01_0001]; // frame#=1, quant=24bit, rate=48k, ch=1
+        let header = vec![0x00, 0x01, 0x00, 0b1001_0001]; // frame#=1, quant=24bit, rate=48k, ch=1
         let pcm_data = vec![0xDE, 0xAD, 0xBE, 0xEF, 0xCA, 0xFE];
         let mut pes_data = header;
         pes_data.extend_from_slice(&pcm_data);

src/mux/codec/mpeg2.rs

@@ -195,12 +195,7 @@ fn find_start_code(data: &[u8], from: usize) -> Option<usize> {
     if data.len() < from + 3 {
         return None;
     }
-    for i in from..data.len() - 2 {
-        if data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01 {
-            return Some(i);
-        }
-    }
-    None
+    (from..data.len() - 2).find(|&i| data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01)
 }
 
 #[cfg(test)]

src/mux/codec/vc1.rs

@@ -122,12 +122,7 @@ impl CodecParser for Vc1Parser {
 }
 
 fn find_next_sc(data: &[u8], from: usize) -> Option<usize> {
-    for i in from..data.len().saturating_sub(2) {
-        if data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01 {
-            return Some(i);
-        }
-    }
-    None
+    (from..data.len().saturating_sub(2)).find(|&i| data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01)
 }
 
 #[cfg(test)]

src/mux/disc.rs

@@ -359,7 +359,7 @@ mod tests {
     #[test]
     fn state_advances_across_extents() {
         // Simulate two extents of 6 sectors each (2 aligned units each).
-        let extents = vec![
+        let extents = [
             Extent {
                 start_lba: 100,
                 sector_count: 6,
@@ -406,7 +406,7 @@ mod tests {
     /// (moved past) rather than causing an infinite loop.
     #[test]
     fn unaligned_extent_is_skipped() {
-        let extents = vec![
+        let extents = [
             Extent {
                 start_lba: 50,
                 sector_count: 2, // < 3, cannot form an aligned unit
@@ -449,7 +449,7 @@ mod tests {
     /// Verify that multiple reads from the same extent produce advancing offsets.
     #[test]
     fn multiple_batches_within_one_extent() {
-        let extents = vec![Extent {
+        let extents = [Extent {
             start_lba: 1000,
             sector_count: 18, // 6 aligned units = 3 batches of 6 sectors
         }];

src/mux/ebml.rs

@@ -558,7 +558,7 @@ mod tests {
             let mut buf = Vec::new();
             write_uint(&mut buf, test_id, val).unwrap();
             let mut cursor = Cursor::new(&buf);
-            let (id, id_len) = read_id(&mut cursor).unwrap();
+            let (id, _id_len) = read_id(&mut cursor).unwrap();
             assert_eq!(id, test_id);
             let (size, _) = read_size(&mut cursor).unwrap();
             let read_val = read_uint_val(&mut cursor, size as usize).unwrap();
@@ -594,7 +594,7 @@ mod tests {
             0.0,
             1.0,
             -1.0,
-            3.14159265358979,
+            std::f64::consts::PI,
             48000.0,
             7200000.0,
             f64::MIN,

src/mux/isowriter.rs

@@ -490,6 +490,7 @@ mod tests {
     }
 
     /// Read a little-endian u32 from a byte slice at the given offset.
+    #[allow(dead_code)]
     fn le_u32(data: &[u8], off: usize) -> u32 {
         u32::from_le_bytes([data[off], data[off + 1], data[off + 2], data[off + 3]])
     }

src/mux/mkv.rs

@@ -737,7 +737,7 @@ mod tests {
         // (MKV default is 1). When is_default is false, FlagDefault=0 IS written.
         // So we should find at least one FlagDefault element (for the non-default track).
         let flag_default_id = ebml::FLAG_DEFAULT.to_be_bytes();
-        let needle = &[flag_default_id[3]]; // 0x88 is a 1-byte ID
+        let _needle = &[flag_default_id[3]]; // 0x88 is a 1-byte ID
         let count = data.windows(1).filter(|w| w[0] == 0x88).count();
         // 0x88 appears as FlagDefault + as TrackType (also 0x83... no, 0x83 != 0x88)
         // FlagDefault (0x88) should appear for the non-default track

src/mux/mkvstream.rs

@@ -41,7 +41,7 @@ struct ReadState {
 }
 
 enum Mode {
-    Write(WriteState),
+    Write(Box<WriteState>),
     Read(ReadState),
 }
 
@@ -60,7 +60,7 @@ impl MkvStream {
     pub fn new(writer: impl Write + Seek + 'static) -> Self {
         Self {
             disc_title: DiscTitle::empty(),
-            mode: Mode::Write(WriteState {
+            mode: Mode::Write(Box::new(WriteState {
                 demuxer: TsDemuxer::new(&[]),
                 muxer: None,
                 writer: Some(Box::new(writer)),
@@ -70,7 +70,7 @@ impl MkvStream {
                 lookahead: LookaheadBuffer::new(DEFAULT_MAX_BUFFER),
                 phase: WritePhase::Scanning,
                 video_pending: 0,
-            }),
+            })),
             max_buffer: DEFAULT_MAX_BUFFER,
             finished: false,
             file_size: None,
@@ -607,8 +607,8 @@ fn frame_to_ts(out: &mut Vec<u8>, track: u16, pts_ms: i64, data: &[u8]) {
             if pad > 1 {
                 pkt[9] = 0x00;
             }
-            for i in 10..(8 + pad).min(192) {
-                pkt[i] = 0xFF;
+            for byte in pkt.iter_mut().take((8 + pad).min(192)).skip(10) {
+                *byte = 0xFF;
             }
             pkt[8 + pad..8 + pad + n].copy_from_slice(&pes[off..off + n]);
         } else {

src/mux/ps.rs

@@ -81,12 +81,7 @@ impl PsDemuxer {
         let mut packets = Vec::with_capacity(4);
         let mut pos = 0;
 
-        loop {
-            // Find the next start code.
-            let sc = match find_start_code(&self.buffer, pos) {
-                Some(p) => p,
-                None => break,
-            };
+        while let Some(sc) = find_start_code(&self.buffer, pos) {
 
             if sc + 3 >= self.buffer.len() {
                 // Not enough bytes to read the start code ID.
@@ -275,12 +270,7 @@ fn find_start_code(data: &[u8], from: usize) -> Option<usize> {
     if data.len() < from + 3 {
         return None;
     }
-    for i in from..data.len() - 2 {
-        if data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01 {
-            return Some(i);
-        }
-    }
-    None
+    (from..data.len() - 2).find(|&i| data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01)
 }
 
 #[cfg(test)]

src/mux/ts.rs

@@ -125,17 +125,16 @@ impl TsDemuxer {
         let mut completed = Vec::with_capacity(4);
 
         // Prepend any remainder from previous call
-        let work: &[u8];
         let mut combined: Vec<u8> = Vec::new();
-        if !self.remainder.is_empty() {
+        let work: &[u8] = if !self.remainder.is_empty() {
             combined.reserve(self.remainder.len() + data.len());
             combined.extend_from_slice(&self.remainder);
             combined.extend_from_slice(data);
             self.remainder.clear();
-            work = &combined;
+            &combined
         } else {
-            work = data;
-        }
+            data
+        };
 
         let mut offset = 0;