fix: windows, improve audio buffer (#9770) (#9893)

* fix: windows, improve audio buffer (#9770)

* .

* fix statics does not record

and avoid channel changing when drio audio when audio is stero

* add some commence

---------

Co-authored-by: zylthinking <zhaoyulong@qianxin.com>

src/client.rs

@@ -118,7 +118,7 @@ pub const SCRAP_X11_REQUIRED: &str = "x11 expected";
 pub const SCRAP_X11_REF_URL: &str = "https://rustdesk.com/docs/en/manual/linux/#x11-required";
 
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
-pub const AUDIO_BUFFER_MS: usize = 150;
+pub const AUDIO_BUFFER_MS: usize = 3000;
 
 #[cfg(feature = "flutter")]
 #[cfg(not(any(target_os = "android", target_os = "ios")))]
@@ -904,36 +904,123 @@ pub struct AudioHandler {
 }
 
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
-struct AudioBuffer(pub Arc<std::sync::Mutex<ringbuf::HeapRb<f32>>>);
+struct AudioBuffer(
+    pub Arc<std::sync::Mutex<ringbuf::HeapRb<f32>>>,
+    usize,
+    [usize; 30],
+);
 
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
 impl Default for AudioBuffer {
     fn default() -> Self {
-        Self(Arc::new(std::sync::Mutex::new(
+        Self(
+            Arc::new(std::sync::Mutex::new(
                 ringbuf::HeapRb::<f32>::new(48000 * 2 * AUDIO_BUFFER_MS / 1000), // 48000hz, 2 channel
-        )))
+            )),
+            48000 * 2,
+            [0; 30],
+        )
     }
 }
 
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
 impl AudioBuffer {
-    pub fn resize(&self, sample_rate: usize, channels: usize) {
+    pub fn resize(&mut self, sample_rate: usize, channels: usize) {
         let capacity = sample_rate * channels * AUDIO_BUFFER_MS / 1000;
         let old_capacity = self.0.lock().unwrap().capacity();
         if capacity != old_capacity {
             *self.0.lock().unwrap() = ringbuf::HeapRb::<f32>::new(capacity);
+            self.1 = sample_rate * channels;
             log::info!("Audio buffer resized from {old_capacity} to {capacity}");
         }
     }
 
-    // clear when full to avoid long time noise
-    #[inline]
-    pub fn clear_if_full(&self) {
-        let full = self.0.lock().unwrap().is_full();
-        if full {
-            self.0.lock().unwrap().clear();
-            log::trace!("Audio buffer cleared");
+    fn try_shrink(&mut self, having: usize) {
+        extern crate chrono;
+        use chrono::prelude::*;
+
+        let mut i = (having * 10) / self.1;
+        if i > 29 {
+            i = 29;
         }
+        self.2[i] += 1;
+
+        static mut tms: i64 = 0;
+        let dt = Local::now().timestamp_millis();
+        unsafe {
+            if tms == 0 {
+                tms = dt;
+                return;
+            } else if dt < tms + 12000 {
+                return;
+            }
+            tms = dt;
+        }
+
+        // the safer water mark to drop
+        let mut zero = 0;
+        // the water mark taking most of time
+        let mut max = 0;
+        for i in 0..30 {
+            if self.2[i] == 0 && zero == i {
+                zero += 1;
+            }
+
+            if self.2[i] > self.2[max] {
+                self.2[max] = 0;
+                max = i;
+            } else {
+                self.2[i] = 0;
+            }
+        }
+        zero = zero * 2 / 3;
+
+        // how many data can be dropped:
+        // 1. will not drop if buffered data is less than 600ms
+        // 2. choose based on min(zero, max)
+        const N: usize = 4;
+        self.2[max] = 0;
+        if max < 6 {
+            return;
+        } else if max > zero * N {
+            max = zero * N;
+        }
+
+        let mut lock = self.0.lock().unwrap();
+        let cap = lock.capacity();
+        let having = lock.occupied_len();
+        let skip = (cap * max / (30 * N) + 1) & (!1);
+        if (having > skip * 3) && (skip > 0) {
+            lock.skip(skip);
+            log::info!("skip {skip}, based {max} {zero}");
+        }
+    }
+
+    /// append pcm to audio buffer, if buffered data
+    /// exceeds AUDIO_BUFFER_MS,  only AUDIO_BUFFER_MS
+    /// will be kept.
+    fn append_pcm2(&self, buffer: &[f32]) -> usize {
+        let mut lock = self.0.lock().unwrap();
+        let cap = lock.capacity();
+        if buffer.len() > cap {
+            lock.push_slice_overwrite(buffer);
+            return cap;
+        }
+
+        let having = lock.occupied_len() + buffer.len();
+        if having > cap {
+            lock.skip(having - cap);
+        }
+        lock.push_slice_overwrite(buffer);
+        lock.occupied_len()
+    }
+
+    /// append pcm to audio buffer, trying to drop data
+    /// when data is too much (per 12 seconds) based
+    /// statistics.
+    pub fn append_pcm(&mut self, buffer: &[f32]) {
+        let having = self.append_pcm2(buffer);
+        self.try_shrink(having);
     }
 }
 
@@ -993,7 +1080,9 @@ impl AudioHandler {
         let sample_format = config.sample_format();
         log::info!("Default output format: {:?}", config);
         log::info!("Remote input format: {:?}", format0);
-        let config: StreamConfig = config.into();
+        let mut config: StreamConfig = config.into();
+        config.buffer_size = cpal::BufferSize::Fixed(64);
+
         self.sample_rate = (format0.sample_rate, config.sample_rate.0);
         let mut build_output_stream = |config: StreamConfig| match sample_format {
             cpal::SampleFormat::I8 => self.build_output_stream::<i8>(&config, &device),
@@ -1062,7 +1151,6 @@ impl AudioHandler {
                 {
                     let sample_rate0 = self.sample_rate.0;
                     let sample_rate = self.sample_rate.1;
-                    let audio_buffer = self.audio_buffer.0.clone();
                     let mut buffer = buffer[0..n].to_owned();
                     if sample_rate != sample_rate0 {
                         buffer = crate::audio_resample(
@@ -1081,8 +1169,7 @@ impl AudioHandler {
                             self.device_channel,
                         );
                     }
-                    self.audio_buffer.clear_if_full();
-                    audio_buffer.lock().unwrap().push_slice_overwrite(&buffer);
+                    self.audio_buffer.append_pcm(&buffer);
                 }
                 #[cfg(target_os = "android")]
                 {
@@ -1117,18 +1204,40 @@ impl AudioHandler {
         let timeout = None;
         let stream = device.build_output_stream(
             config,
-            move |data: &mut [T], _: &_| {
+            move |data: &mut [T], info: &cpal::OutputCallbackInfo| {
                 if !*ready.lock().unwrap() {
                     *ready.lock().unwrap() = true;
                 }
-                let mut lock = audio_buffer.lock().unwrap();
+
                 let mut n = data.len();
-                if lock.occupied_len() < n {
-                    n = lock.occupied_len();
-                }
-                let mut elems = vec![0.0f32; n];
-                lock.pop_slice(&mut elems);
+                let mut lock = audio_buffer.lock().unwrap();
+                let mut having = lock.occupied_len();
+                if having < n {
+                    let tms = info.timestamp();
+                    let how_long = tms
+                        .playback
+                        .duration_since(&tms.callback)
+                        .unwrap_or(Duration::from_millis(0));
+
+                    // must long enough to fight back scheuler delay
+                    if how_long > Duration::from_millis(6) {
                         drop(lock);
+                        std::thread::sleep(how_long.div_f32(1.2));
+                        lock = audio_buffer.lock().unwrap();
+                        having = lock.occupied_len();
+                    }
+
+                    if having < n {
+                        n = having;
+                    }
+                }
+
+                let mut elems = vec![0.0f32; n];
+                if n > 0 {
+                    lock.pop_slice(&mut elems);
+                }
+                drop(lock);
+
                 let mut input = elems.into_iter();
                 for sample in data.iter_mut() {
                     *sample = match input.next() {