[vlc-commits] [Git][videolan/vlc][master] avsb: fix fast start with airplay devices

[Steve Lhomme (@robUx4)]

Steve Lhomme pushed to branch master at VideoLAN / VLC


Commits:
b0d5b12e by Thomas Guillem at 2024-08-14T13:19:01+00:00
avsb: fix fast start with airplay devices

the setRate atHostTime function can't really be trusted or was used
incorrectly. Start at the given date manually using the whenDataReady
callback.

This fixes the following:
 - Immediate playback with airplay devices (tested with Homepod) on
   iOS/tvOS (don't have to wait 2seconds to hear a sound anymore).
 - Working playback on macOS without the necessity to manually increase
   the pts-delay, but the audio need 2seconds to start (A/V sync OK, but
   video paused for 2 seconds).

- - - - -


1 changed file:

- modules/audio_output/apple/avsamplebuffer.m


Changes:

=====================================
modules/audio_output/apple/avsamplebuffer.m
=====================================
@@ -74,8 +74,10 @@ API_AVAILABLE(macos(MIN_MACOS), ios(MIN_IOS), tvos(MIN_TVOS) VISIONOS_API_AVAILA
 
     int64_t _ptsSamples;
     vlc_tick_t _firstPts;
+    vlc_tick_t _lastDate;
     unsigned _sampleRate;
     BOOL _stopped;
+    BOOL _dateReached;
 }
 @end
 
@@ -229,7 +231,9 @@ customBlock_Free(void *refcon, void *doomedMemoryBlock, size_t sizeInBytes)
         [self stopSyncRenderer];
 
     _ptsSamples = -1;
+    _dateReached = NO;
     _firstPts = VLC_TICK_INVALID;
+    _lastDate = VLC_TICK_INVALID;
 }
 
 - (void)pause:(BOOL)pause date:(vlc_tick_t)date
@@ -252,12 +256,65 @@ customBlock_Free(void *refcon, void *doomedMemoryBlock, size_t sizeInBytes)
     aout_TimingReport(_aout, system_now, pos_ticks);
 }
 
+- (void)startNow:(vlc_tick_t)delta
+{
+    assert(!_dateReached);
+
+    _dateReached = YES;
+    CMTime time = CMTimeMake(0, _sampleRate);
+    [_sync setRate:1.0f time:time];
+
+    const CMTime interval = CMTimeMake(CLOCK_FREQ, CLOCK_FREQ);
+    __weak typeof(self) weakSelf = self;
+    _observer = [_sync addPeriodicTimeObserverForInterval:interval
+                                                    queue:_timeQueue
+                                               usingBlock:^ (CMTime time){
+        [weakSelf whenTimeObserved:time];
+    }];
+}
+
 - (void)whenDataReady
 {
     vlc_mutex_lock(&_bufferLock);
 
-    while (_renderer.readyForMoreMediaData)
+    while (_renderer.readyForMoreMediaData || !_dateReached)
     {
+        if (!_dateReached)
+        {
+            /* Start playback at the requested date */
+
+            CMTime writtenTime = CMTimeMake(_ptsSamples, _sampleRate);
+            vlc_tick_t writtenTicks = [VLCAVSample CMTimeTotick:writtenTime];
+            vlc_tick_t now = vlc_tick_now();
+            vlc_tick_t deadline = _lastDate - writtenTicks;
+            vlc_tick_t delta = deadline - now;
+
+            if (delta <= 0)
+            {
+                msg_Dbg(_aout, "starting late (%"PRId64" us)", delta);
+                [self startNow:delta];
+            }
+            else
+            {
+                msg_Dbg(_aout, "deferring start (%"PRId64" us)", delta);
+
+                int timeout = 0;
+                /* Wait for the start date if there are no buffers to enqueue */
+                while (!_stopped && _outChain == NULL && timeout == 0)
+                {
+                    timeout = vlc_cond_timedwait(&_bufferWait, &_bufferLock,
+                                                 deadline);
+                    deadline = _lastDate - writtenTicks;
+                }
+
+                if (timeout != 0)
+                {
+                    msg_Dbg(_aout, "started");
+                    [self startNow:0];
+                }
+            }
+        }
+
         while (!_stopped && _outChain == NULL)
             vlc_cond_wait(&_bufferWait, &_bufferLock);
 
@@ -296,27 +353,15 @@ customBlock_Free(void *refcon, void *doomedMemoryBlock, size_t sizeInBytes)
     if (_ptsSamples == -1)
     {
         _stopped = NO;
+        _firstPts = block->i_pts;
+        _ptsSamples = 0;
 
         __weak typeof(self) weakSelf = self;
         [_renderer requestMediaDataWhenReadyOnQueue:_dataQueue usingBlock:^{
             [weakSelf whenDataReady];
         }];
-
-        _firstPts = block->i_pts;
-        const CMTime interval = CMTimeMake(CLOCK_FREQ, CLOCK_FREQ);
-        _observer = [_sync addPeriodicTimeObserverForInterval:interval
-                                                        queue:_timeQueue
-                                                   usingBlock:^ (CMTime time){
-            [weakSelf whenTimeObserved:time];
-        }];
-
-        _ptsSamples = 0;
-        vlc_tick_t delta = date - vlc_tick_now();
-        CMTime hostTime = CMTimeAdd(CMClockGetTime(CMClockGetHostTimeClock()),
-                                    CMTimeMake(delta, CLOCK_FREQ));
-        CMTime time = CMTimeMake(_ptsSamples, _sampleRate);
-        [_sync setRate:1.0f time:time atHostTime:hostTime];
     }
+    _lastDate = date;
 
     block_ChainLastAppend(&_outChainLast, block);
 
@@ -334,12 +379,13 @@ customBlock_Free(void *refcon, void *doomedMemoryBlock, size_t sizeInBytes)
 {
     _sync.rate = 0.0f;
 
-    [_sync removeTimeObserver:_observer];
-
     [_renderer stopRequestingMediaData];
     [_renderer flush];
 
     vlc_mutex_lock(&_bufferLock);
+    if (_dateReached)
+        [_sync removeTimeObserver:_observer];
+
     _stopped = YES;
 
     block_ChainRelease(_outChain);
@@ -466,8 +512,12 @@ customBlock_Free(void *refcon, void *doomedMemoryBlock, size_t sizeInBytes)
     _sync.delaysRateChangeUntilHasSufficientMediaData = NO;
     [_sync addRenderer:_renderer];
 
+    _stopped = NO;
+    _dateReached = NO;
+
     _ptsSamples = -1;
     _firstPts = VLC_TICK_INVALID;
+    _lastDate = VLC_TICK_INVALID;
     _sampleRate = fmt->i_rate;
     _bytesPerFrame = desc.mBytesPerFrame;
 



View it on GitLab: https://code.videolan.org/videolan/vlc/-/commit/b0d5b12e07daa41b8d17d32107c11dad4e694cec

-- 
View it on GitLab: https://code.videolan.org/videolan/vlc/-/commit/b0d5b12e07daa41b8d17d32107c11dad4e694cec
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