From be3c76d9d811193232eab09b7226088e7d8937e7 Mon Sep 17 00:00:00 2001
From: _ <>
Date: Sat, 13 Nov 2021 17:37:55 +0000
Subject: [PATCH] :shirt: refactor: hide ffmpeg audio frame from public decoder
 API

---
 src/decoder.rs | 59 ++++++++++++++++++++++++++++++++------------------
 src/main.rs    |  5 ++---
 2 files changed, 40 insertions(+), 24 deletions(-)

diff --git a/src/decoder.rs b/src/decoder.rs
index 1acb702..4f7276c 100644
--- a/src/decoder.rs
+++ b/src/decoder.rs
@@ -24,12 +24,39 @@ use ffmpeg_next::{
 			self,
 			Sample,
 		},
-		frame::Audio as AudioFrame,
+		frame::Audio as FfAudioFrame,
 	},
 };
 
 pub const SAMPLE_RATE: u32 = 48000;
 
+pub struct AudioFrame {
+	frame: FfAudioFrame,
+}
+
+impl AudioFrame {
+	pub fn data (&self) -> &[u8] {
+		// Hard-coded because I'm only support f32 interleaved stereo
+		&self.frame.data (0) [0..self.frame.samples () * 4 * 2]
+	}
+	
+	pub fn rate (&self) -> u32 {
+		self.frame.rate ()
+	}
+	
+	pub fn samples (&self) -> usize {
+		self.frame.samples ()
+	}
+}
+
+impl From <FfAudioFrame> for AudioFrame {
+	fn from (frame: FfAudioFrame) -> Self {
+		Self {
+			frame,
+		}
+	}
+}
+
 #[derive (Default)]
 pub struct PcmBuffers {
 	buffers: Vec <Vec <f32>>,
@@ -70,6 +97,8 @@ impl PcmBuffers {
 		let mut b = vec! [0.0f32; new_buffer.len () / 4];
 		let mut rdr = Cursor::new (new_buffer);
 		
+		// Pointless memcpy. I can get rid of it later by changing PcmBuffers'
+		// internal format
 		rdr.read_f32_into::<LittleEndian> (&mut b).unwrap ();
 		
 		self.produce (b);
@@ -88,7 +117,7 @@ pub struct Decoder {
 	pub resampler: ResamplingContext,
 	
 	best_stream_idx: usize,
-	dummy_frame: Option <AudioFrame>,
+	dummy_frame: Option <FfAudioFrame>,
 }
 
 impl Decoder {
@@ -117,8 +146,8 @@ impl Decoder {
 		})
 	}
 	
-	fn new_frame () -> AudioFrame {
-		let mut x = AudioFrame::empty ();
+	fn new_frame () -> FfAudioFrame {
+		let mut x = FfAudioFrame::empty ();
 		x.set_channel_layout (ChannelLayout::STEREO);
 		x.set_format (Sample::F32 (sample::Type::Packed));
 		x
@@ -129,18 +158,6 @@ impl Decoder {
 			assert_eq! (frame.rate (), 48000);
 			assert! (frame.samples () > 0);
 			
-			let actual_bytes = frame.data (0).len ();
-			let expected_bytes = frame.samples () * 4 * 2;
-			
-			assert! (actual_bytes >= expected_bytes);
-			
-			if actual_bytes > expected_bytes {
-				let extra_bytes = actual_bytes - expected_bytes;
-				let extra_samples = extra_bytes / 4 / 2;
-				// tracing::debug! ("Extra bytes: {}", extra_bytes);
-				// tracing::debug! ("Extra samples: {}", extra_samples);
-			}
-			
 			Some (frame)
 		}
 		else {
@@ -191,7 +208,7 @@ impl Decoder {
 		
 		Ok (if frame_resampled.samples () > 0 {
 			// tracing::trace! ("Pulled from resampler FIFO");
-			Some (frame_resampled)
+			Some (frame_resampled.into ())
 		}
 		else {
 			None
@@ -199,13 +216,13 @@ impl Decoder {
 	}
 	
 	pub fn pump_decoder (&mut self) -> Result <Option <AudioFrame>> {
-		let mut frame_src = AudioFrame::empty ();
+		let mut frame_src = FfAudioFrame::empty ();
 		if let Err (_) = self.decoder.receive_frame (&mut frame_src) {
 			return Ok (None);
 		};
 		
 		if self.dummy_frame.is_none () {
-			let mut dummy_frame = AudioFrame::new (
+			let mut dummy_frame = FfAudioFrame::new (
 				frame_src.format (),
 				0,
 				frame_src.channel_layout (),
@@ -216,14 +233,14 @@ impl Decoder {
 		
 		let nb_output_samples = frame_src.samples ();
 		
-		let mut frame_resampled = AudioFrame::new (
+		let mut frame_resampled = FfAudioFrame::new (
 			Sample::F32 (sample::Type::Packed),
 			nb_output_samples,
 			ChannelLayout::STEREO
 		);
 		
 		self.resampler.run (&frame_src, &mut frame_resampled)?;
-		Ok (Some (frame_resampled))
+		Ok (Some (frame_resampled.into ()))
 	}
 	
 	pub fn pump_demuxer (&mut self) -> Result <bool> {
diff --git a/src/main.rs b/src/main.rs
index 2a20fc6..270a621 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -52,8 +52,7 @@ fn cmd_debug_dump (args: &[String]) -> Result <()> {
 	let mut f = File::create ("pcm-dump.data")?;
 	
 	while let Some (frame) = decoder.next ()? {
-		f.write_all (&frame.data (0) [0..frame.samples () * 4 * 2])?;
-		// f.write_all (frame.data (0))?;
+		f.write_all (frame.data ())?;
 	}
 	
 	Ok (())
@@ -116,7 +115,7 @@ fn cmd_play (args: &[String]) -> Result <()> {
 				while pcm_buffers.samples_available () < 12_000 {
 					// tracing::trace! ("Decoder is trying to work...");
 					match decoder.next ()? {
-						Some (frame) => pcm_buffers.produce_bytes (&frame.data (0) [0..frame.samples () * 4 * 2]),
+						Some (frame) => pcm_buffers.produce_bytes (frame.data ()),
 						None => {
 							tracing::info! ("Finished decoding file");
 							break 'one_file;