From b11c4ac0b82535f00fe3975b090d3167c2e9fbdd Mon Sep 17 00:00:00 2001
From: _ <_@_>
Date: Fri, 12 Nov 2021 14:33:38 -0600
Subject: [PATCH] playing audio

---
 .gitignore  |  1 +
 Cargo.lock  |  7 +++++
 Cargo.toml  |  1 +
 src/main.rs | 78 ++++++++++++++++++++++++++++++++++++++++++-----------
 4 files changed, 71 insertions(+), 16 deletions(-)

diff --git a/.gitignore b/.gitignore
index fa4a306..c402bca 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 /target
+*.m4a
 *.opus
diff --git a/Cargo.lock b/Cargo.lock
index 5df42f3..8b4e0a9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -88,6 +88,12 @@ version = "3.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f1e260c3a9040a7c19a12468758f4c16f31a81a1fe087482be9570ec864bb6c"
 
+[[package]]
+name = "byteorder"
+version = "1.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
+
 [[package]]
 name = "bytes"
 version = "1.1.0"
@@ -421,6 +427,7 @@ name = "music_player"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "byteorder",
  "cpal",
  "ffmpeg-next",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 99d484b..4836aee 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,5 +7,6 @@ edition = "2021"
 
 [dependencies]
 anyhow = "1.0.45"
+byteorder = "1.4.3"
 cpal = "0.13.4"
 ffmpeg-next = "4.4.0"
diff --git a/src/main.rs b/src/main.rs
index b0eff56..722274f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,4 +1,5 @@
 use std::{
+	io::Cursor,
 	sync::{
 		Arc,
 		Condvar,
@@ -13,6 +14,11 @@ use anyhow::{
 	Result,
 };
 
+use byteorder::{
+	LittleEndian,
+	ReadBytesExt,
+};
+
 use cpal::traits::{
 	DeviceTrait,
 	HostTrait,
@@ -74,25 +80,35 @@ fn main () -> Result <()> {
 	let pair2 = Arc::clone (&pair);
 	
 	let thread_decoder = thread::spawn (move|| {
+		/*
+		Pipeline:
+		- demuxer
+		- decoder
+		- resampler
+		- cpal
+		*/
+		
 		let (lock, cvar) = &*pair2;
 		
-		let freq = 75;
-		let period = SAMPLE_RATE / freq;
+		let mut input_ctx = ffmpeg_next::format::input (&"test.m4a")?;
+		let stream = input_ctx
+		.streams ()
+		.best (ffmpeg_next::media::Type::Audio)
+		.ok_or_else (|| anyhow! ("can't find good audio stream"))?;
+		let best_stream_idx = stream.index ();
 		
-		let mut saw_counter = 0;
+		let mut decoder = stream.codec ().decoder ().audio ()?;
+		let mut resampler = decoder.resampler (
+			ffmpeg_next::util::format::sample::Sample::F32 (
+				ffmpeg_next::util::format::sample::Type::Packed,
+			),
+			ffmpeg_next::util::channel_layout::ChannelLayout::STEREO,
+			48000,
+		)?;
+		let mut frame = ffmpeg_next::util::frame::Audio::empty ();
+		let mut packets = input_ctx.packets ();
 		
 		loop {
-			let mut buffer = vec! [0.0f32; 4000];
-			
-			for x in &mut buffer {
-				*x = 0.25 * (saw_counter as f32 * 2.0 / period as f32 - 1.0);
-				
-				saw_counter += 1;
-				if saw_counter >= period {
-					saw_counter = 0
-				}
-			}
-			
 			// eprintln! ("decode thread parking");
 			
 			let mut pcm_buffers = cvar.wait_while (lock.lock ().unwrap (), |pcm_buffers| {
@@ -100,8 +116,38 @@ fn main () -> Result <()> {
 				pcm_buffers.samples_available () >= 48_000
 			}).unwrap ();
 			
-			// dbg! (pcm_buffers.samples_available ());
-			pcm_buffers.produce (buffer);
+			let mut did_anything = false;
+			
+			
+			
+			while decoder.receive_frame (&mut frame).is_ok () {
+				did_anything = true;
+				let mut buffer = vec! [0.0f32; frame.plane::<f32> (0).len () * 2];
+				
+				let mut rdr_left = frame.plane::<f32> (0).iter ();
+				let mut rdr_right = frame.plane::<f32> (1).iter ();
+				
+				for x in buffer.chunks_mut (2) {
+					x [0] = *rdr_left.next ().unwrap ();
+					x [1] = *rdr_right.next ().unwrap ();
+				}
+				
+				pcm_buffers.produce (buffer);
+			}
+			
+			match packets.next () {
+				None => {},
+				Some ((stream, packet)) => {
+					did_anything = true;
+					if stream.index () == best_stream_idx {
+						decoder.send_packet (&packet)?;
+					}
+				},
+			}
+			
+			if ! did_anything {
+				break;
+			}
 		}
 		
 		Ok::<_, anyhow::Error> (())