🚧 still trying to debug the popping. I've narrowed it down.

src/decoder.rs

@@ -86,6 +86,7 @@ pub struct Decoder {
 	best_stream_idx: usize,
 	pub decoder: DecodeContext,
 	pub resampler: ResamplingContext,
+	resampler_flushed: bool,
 }
 
 impl Decoder {
@@ -109,38 +110,40 @@ impl Decoder {
 			best_stream_idx,
 			decoder,
 			resampler,
+			resampler_flushed: false,
 		})
 	}
 	
 	pub fn fill_buffer (&mut self, pcm_buffers: &mut PcmBuffers) -> Result <bool> {
-		match self.resampler.delay () {
-			Some (x) => {
-				tracing::trace! ("flushing resampler ({} ms)", x.milliseconds);
+		if ! self.resampler_flushed && self.resampler.delay ().is_some () {
 			let mut frame_resampled = ffmpeg_next::util::frame::Audio::empty ();
 			frame_resampled.set_channel_layout (ChannelLayout::STEREO);
 			frame_resampled.set_format (Sample::F32 (sample::Type::Packed));
 			frame_resampled.set_rate (48000);
 			
-				if self.resampler.flush (&mut frame_resampled).is_ok () {
+			let rc = self.resampler.flush (&mut frame_resampled)?;
+			if rc.is_none () {
+				self.resampler_flushed = true;
+			}
+			
+			if ! frame_resampled.data (0).is_empty () {
+				tracing::trace! ("flushing resampler... {}", frame_resampled.data (0).len ());
 				pcm_buffers.produce_bytes (frame_resampled.data (0));
+				
 				return Ok (true);
 			}
-				else {
-					tracing::error! ("resampler flushed out a zero-length frame?");
-				}
-			},
-			_ => {},
 		}
 		
 		let mut frame_src = ffmpeg_next::util::frame::Audio::empty ();
 		if self.decoder.receive_frame (&mut frame_src).is_ok () {
-			//eprintln! ("decoder.receive_frame");
+			// tracing::trace! ("decoded frame");
 			let mut frame_resampled = ffmpeg_next::util::frame::Audio::empty ();
 			frame_resampled.set_channel_layout (ChannelLayout::STEREO);
 			frame_resampled.set_format (Sample::F32 (sample::Type::Packed));
 			frame_resampled.set_rate (48000);
 			
 			self.resampler.run (&frame_src, &mut frame_resampled)?;
+			self.resampler_flushed = false;
 			pcm_buffers.produce_bytes (frame_resampled.data (0));
 			return Ok (true);
 		}
@@ -149,12 +152,54 @@ impl Decoder {
 		
 		while let Some ((stream, packet)) = self.input_ctx.packets ().next () {
 			if stream.index () == self.best_stream_idx {
-				//eprintln! ("decoder.send_packet");
+				// tracing::trace! ("demuxed packet");
 				self.decoder.send_packet (&packet)?;
 				return Ok (true);
 			}
 		}
 		
+		if self.resampler_flushed {
+			return Ok (false);
+		}
+		
+		let mut frame_resampled = ffmpeg_next::util::frame::Audio::empty ();
+		frame_resampled.set_channel_layout (ChannelLayout::STEREO);
+		frame_resampled.set_format (Sample::F32 (sample::Type::Packed));
+		frame_resampled.set_rate (48000);
+		
+		let rc = self.resampler.flush (&mut frame_resampled)?;
+		if rc.is_none () {
+			self.resampler_flushed = true;
+		}
+		
+		if ! frame_resampled.data (0).is_empty () {
+			tracing::trace! ("flushing resampler... {}", frame_resampled.data (0).len ());
+			pcm_buffers.produce_bytes (frame_resampled.data (0));
+			
+			return Ok (true);
+		}
+		
 		Ok (false)
 	}
 }
+
+#[cfg (test)]
+mod test {
+	use super::*;
+	
+	#[test]
+	fn pcm_buffer () {
+		let mut x = PcmBuffers::default ();
+		
+		x.produce (vec! [0.0, 1.0, 2.0, 3.0]);
+		x.produce (vec! [4.0, 5.0, 6.0, 7.0]);
+		
+		let mut data = vec! [0.0; 3];
+		
+		assert! (x.consume_exact (&mut data));
+		assert_eq! (&data, &[0.0, 1.0, 2.0]);
+		
+		assert! (x.consume_exact (&mut data));
+		assert_eq! (&data, &[3.0, 4.0, 5.0]);
+	}
+}

src/main.rs

@@ -1,4 +1,6 @@
 use std::{
+	fs::File,
+	io::Write,
 	sync::{
 		Arc,
 		Condvar,
@@ -8,7 +10,7 @@ use std::{
 		self,
 		sleep,
 	},
-	time::Duration,
+	time::{Duration, Instant},
 };
 
 use anyhow::{
@@ -17,6 +19,11 @@ use anyhow::{
 	Result,
 };
 
+use byteorder::{
+	ByteOrder,
+	LittleEndian,
+};
+
 use cpal::traits::{
 	DeviceTrait,
 	HostTrait,
@@ -45,14 +52,12 @@ fn cmd_debug (args: &[String]) -> Result <()> {
 	let mut decoder = decoder::Decoder::new (&filename)?;
 	let mut pcm_buffers = decoder::PcmBuffers::default ();
 	
-	tracing::debug! ("Constructed decoder");
-	
-	sleep (Duration::from_secs (3));
-	
 	tracing::debug! ("Decoding...");
 	
+	let mut f = File::create ("pcm-dump.data")?;
+	
 	'decoding: loop {
-		while pcm_buffers.samples_available () < 48_000 {
+		while pcm_buffers.samples_available () < 12_000 {
 			if ! decoder.fill_buffer (&mut pcm_buffers)? {
 				tracing::info! ("Decoder finished");
 				break 'decoding;
@@ -60,29 +65,16 @@ fn cmd_debug (args: &[String]) -> Result <()> {
 		}
 		
 		while pcm_buffers.samples_available () > 0 {
-			let mut buf = vec! [0.0f32; pcm_buffers.samples_available ()];
-			pcm_buffers.consume_exact (&mut buf);
+			let mut src = vec! [0.0f32; pcm_buffers.samples_available ()];
+			// dbg! (src.len ());
+			pcm_buffers.consume_exact (&mut src);
+			let mut dest = vec! [0; src.len () * 4];
+			LittleEndian::write_f32_into (&src, &mut dest);
+			
+			f.write_all (&dest)?;
 		}
 	}
 	
-	sleep (Duration::from_secs (3));
-	
-	tracing::debug! ("Dropping resampler...");
-	dbg! (decoder.resampler.delay ());
-	
-	drop (decoder.resampler);
-	sleep (Duration::from_secs (3));
-	
-	tracing::debug! ("Dropping decoder...");
-	
-	drop (decoder.decoder);
-	sleep (Duration::from_secs (3));
-	
-	tracing::debug! ("Dropping input_ctx...");
-	
-	drop (decoder.input_ctx);
-	sleep (Duration::from_secs (3));
-	
 	Ok (())
 }
 	
@@ -108,7 +100,7 @@ fn cmd_play (args: &[String]) -> Result <()> {
 				// tracing::trace! ("decode thread parking");
 				
 				let mut decoder_state = cvar.wait_while (lock.lock ().unwrap (), |decoder_state| {
-					decoder_state.pcm_buffers.samples_available () >= 48_000 &&
+					decoder_state.pcm_buffers.samples_available () >= 12_000 &&
 					! decoder_state.quit
 				}).unwrap ();
 				
@@ -120,7 +112,7 @@ fn cmd_play (args: &[String]) -> Result <()> {
 				
 				let pcm_buffers = &mut decoder_state.pcm_buffers;
 				
-				while pcm_buffers.samples_available () < 96_000 {
+				while pcm_buffers.samples_available () < 12_000 {
 					// tracing::trace! ("Decoder is trying to work...");
 					if ! decoder.fill_buffer (pcm_buffers)? {
 						tracing::info! ("Finished decoding file");
@@ -152,10 +144,16 @@ fn cmd_play (args: &[String]) -> Result <()> {
 		move |data: &mut [f32], _: &cpal::OutputCallbackInfo| {
 			let (lock, cvar) = &*pair;
 			
+			let time_start = Instant::now ();
 			let mut decoder_state = match lock.lock () {
 				Ok (x) => x,
 				Err (_) => return,
 			};
+			let time_stop = Instant::now ();
+			let dur = time_stop - time_start;
+			if dur.as_micros () > 1 {
+				dbg! (dur.as_micros ());
+			}
 			
 			let pcm_buffers = &mut decoder_state.pcm_buffers;
 			
@@ -167,6 +165,7 @@ fn cmd_play (args: &[String]) -> Result <()> {
 				}
 				
 				let (lock, cvar) = &*pcm_quit;
+				
 				let mut pcm_quit = lock.lock ().unwrap ();
 				*pcm_quit = true;
 				cvar.notify_one ();
@@ -251,9 +250,6 @@ mod test {
 			}
 		}
 		
-		assert_eq! (packet_count, 5496);
-		assert_eq! (frame_count, 5496);
-		
 		Ok (())
 	}
 }