[vlc-devel] [PATCH] pulse: calculate the start time from the last date played

[Rémi Denis-Courmont]

You need to start with the PTS of the first block in queue, not the last block. This does not look right.

Le 2 juillet 2018 17:31:59 GMT+03:00, Thomas Guillem <thomas at gllm.fr> a écrit :
>If I understand correctly, stream_latency_cb() is needed to
>re-calculate the
>new derrered time (or start late in the worst case scenario) when the
>audio
>device latency changes.
>
>This callback called stream_start() with the first played system date.
>The
>problem is that the delta calculated from stream_start was always late.
>Using
>the last system date seems more logical. Indeed, the delta need to be
>calculated from values using the same reference point (and
>vlc_pa_get_latency()
>is calculated from the amount of buffers played).
>
>This issue can be reproduced when the first played date is more than
>100ms in
>the future.
>---
> modules/audio_output/pulse.c | 22 +++++++++-------------
> 1 file changed, 9 insertions(+), 13 deletions(-)
>
>diff --git a/modules/audio_output/pulse.c
>b/modules/audio_output/pulse.c
>index f999eb534b..a275c9f5e6 100644
>--- a/modules/audio_output/pulse.c
>+++ b/modules/audio_output/pulse.c
>@@ -68,8 +68,7 @@ typedef struct
>     pa_threaded_mainloop *mainloop; /**< PulseAudio thread */
>     pa_time_event *trigger; /**< Deferred stream trigger */
>     pa_cvolume cvolume; /**< actual sink input volume */
>-    vlc_tick_t first_pts; /**< Play stream timestamp of buffer start
>*/
>-    vlc_tick_t first_date; /**< Play system timestamp of buffer start
>*/
>+    vlc_tick_t last_date; /**< Play system timestamp of last buffer */
> 
>  pa_volume_t volume_force; /**< Forced volume (stream must be NULL) */
>pa_stream_flags_t flags_force; /**< Forced flags (stream must be NULL)
>*/
>@@ -227,7 +226,7 @@ static void stream_start(pa_stream *s,
>audio_output_t *aout, vlc_tick_t date)
>     aout_sys_t *sys = aout->sys;
>     vlc_tick_t delta;
> 
>-    assert (sys->first_pts != VLC_TS_INVALID);
>+    assert (sys->last_date != VLC_TS_INVALID);
> 
>     if (sys->trigger != NULL) {
>         vlc_pa_rttime_free(sys->mainloop, sys->trigger);
>@@ -258,10 +257,10 @@ static void stream_latency_cb(pa_stream *s, void
>*userdata)
>     aout_sys_t *sys = aout->sys;
> 
>     /* This callback is _never_ called while paused. */
>-    if (sys->first_pts == VLC_TS_INVALID)
>+    if (sys->last_date == VLC_TS_INVALID)
>         return; /* nothing to do if buffers are (still) empty */
>     if (pa_stream_is_corked(s) > 0)
>-        stream_start(s, aout, sys->first_date);
>+        stream_start(s, aout, sys->last_date);
> }
> 
> 
>@@ -331,7 +330,7 @@ static void stream_overflow_cb(pa_stream *s, void
>*userdata)
>     if (unlikely(op == NULL))
>         return;
>     pa_operation_unref(op);
>-    sys->first_pts = VLC_TS_INVALID;
>+    sys->last_date = VLC_TS_INVALID;
> }
> 
> static void stream_started_cb(pa_stream *s, void *userdata)
>@@ -504,10 +503,7 @@ static void Play(audio_output_t *aout, block_t
>*block, vlc_tick_t date)
>      * will take place, and sooner or later a deadlock. */
>     pa_threaded_mainloop_lock(sys->mainloop);
> 
>-    if (sys->first_pts == VLC_TS_INVALID) {
>-        sys->first_pts = block->i_pts;
>-        sys->first_date = date;
>-    }
>+    sys->last_date = date;
> 
>     if (pa_stream_is_corked(s) > 0)
>         stream_start(s, aout, date);
>@@ -543,7 +539,7 @@ static void Pause(audio_output_t *aout, bool
>paused, vlc_tick_t date)
>         stream_stop(s, aout);
>     } else {
>     pa_stream_set_latency_update_callback(s, stream_latency_cb, aout);
>-        if (likely(sys->first_pts != VLC_TS_INVALID))
>+        if (likely(sys->last_date != VLC_TS_INVALID))
>             stream_start_now(s, aout);
>     }
> 
>@@ -576,7 +572,7 @@ static void Flush(audio_output_t *aout, bool wait)
>         op = pa_stream_flush(s, NULL, NULL);
>     if (op != NULL)
>         pa_operation_unref(op);
>-    sys->first_pts = VLC_TS_INVALID;
>+    sys->last_date = VLC_TS_INVALID;
>     stream_stop(s, aout);
> 
>     pa_threaded_mainloop_unlock(sys->mainloop);
>@@ -807,7 +803,7 @@ static int Start(audio_output_t *aout,
>audio_sample_format_t *restrict fmt)
> 
>     sys->trigger = NULL;
>     pa_cvolume_init(&sys->cvolume);
>-    sys->first_pts = VLC_TS_INVALID;
>+    sys->last_date = VLC_TS_INVALID;
> 
>     pa_format_info *formatv = pa_format_info_new();
>     formatv->encoding = encoding;
>-- 
>2.18.0
>
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