[vlc-devel] [vlc-commits] pulse: follow PulseAudio write requests

[Thomas Guillem]

On Tue, Mar 19, 2019, at 17:22, Thomas Guillem wrote:
> Reverted with a force push, this cause an underflow on startup (just 
> after a flush).

OK, it was a small problem: when 2 flush were called in a row, the second one reseted the write_request count to 0.

> 
> On Tue, Mar 19, 2019, at 16:03, Thomas Guillem wrote:
> > vlc | branch: master | Thomas Guillem <thomas at gllm.fr> | Tue Mar 19 
> > 13:51:15 2019 +0100| [e8633b41c86516e2f5c91b2eec05f99e1d3ecd8a] | 
> > committer: Thomas Guillem
> > 
> > pulse: follow PulseAudio write requests
> > 
> > Wait from Play() if the server don't ask for more data (like every other aout
> > modules).
> > 
> > Note: tlength (target length of the buffer) is increased from 120ms to 2s.
> > Before this commit, the average audio delay (time_get) was around 500ms (file
> > caching and input dependant). If we don't increase it, the delay of the stream
> > will be arround 120ms (since we now follow PulseAudio write requests). Setting
> > tlength to 2sec will restore the previous time_get behavior: delay of arround
> > 500ms, and always lower than 2sec (when file-caching is increased). This fixes
> > potential overflow.
> > 
> > > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=e8633b41c86516e2f5c91b2eec05f99e1d3ecd8a
> > ---
> > 
> >  modules/audio_output/pulse.c | 27 ++++++++++++++++++++++++++-
> >  1 file changed, 26 insertions(+), 1 deletion(-)
> > 
> > diff --git a/modules/audio_output/pulse.c b/modules/audio_output/pulse.c
> > index cc4af1e8c0..961fa7129a 100644
> > --- a/modules/audio_output/pulse.c
> > +++ b/modules/audio_output/pulse.c
> > @@ -69,6 +69,7 @@ typedef struct
> >      pa_time_event *trigger; /**< Deferred stream trigger */
> >      pa_cvolume cvolume; /**< actual sink input volume */
> >      vlc_tick_t last_date; /**< Play system timestamp of last buffer */
> > +    size_t write_request; /**< Write request from PulseAudio */
> >  
> >      pa_volume_t volume_force; /**< Forced volume (stream must be NULL) 
> > */
> >      pa_stream_flags_t flags_force; /**< Forced flags (stream must be 
> > NULL) */
> > @@ -357,6 +358,15 @@ static void stream_underflow_cb(pa_stream *s, void 
> > *userdata)
> >      (void) s;
> >  }
> >  
> > +static void stream_request_cb(pa_stream *s, size_t nbytes, void 
> > *userdata)
> > +{
> > +    audio_output_t *aout = userdata;
> > +    aout_sys_t *sys = aout->sys;
> > +
> > +    sys->write_request = nbytes;
> > +    pa_threaded_mainloop_signal(sys->mainloop, 0);
> > +}
> > +
> >  static int stream_wait(pa_stream *stream, pa_threaded_mainloop 
> > *mainloop)
> >  {
> >      pa_stream_state_t state;
> > @@ -491,6 +501,13 @@ static void Play(audio_output_t *aout, block_t 
> > *block, vlc_tick_t date)
> >          void *ptr;
> >          size_t len = block->i_buffer;
> >  
> > +        while (sys->write_request == 0)
> > +            pa_threaded_mainloop_wait(sys->mainloop);
> > +
> > +        if (len > sys->write_request)
> > +            len = sys->write_request;
> > +        sys->write_request -= len;
> > +
> >          if (pa_stream_begin_write(s, &ptr, &len))
> >              vlc_pa_error(aout, "cannot begin write", sys->context);
> >  
> > @@ -540,6 +557,8 @@ static void Flush(audio_output_t *aout)
> >  
> >      pa_threaded_mainloop_lock(sys->mainloop);
> >  
> > +    sys->write_request = 0;
> > +
> >      pa_operation *op = pa_stream_flush(s, NULL, NULL);
> >      if (op != NULL)
> >          pa_operation_unref(op);
> > @@ -555,6 +574,9 @@ static void Drain(audio_output_t *aout)
> >      pa_stream *s = sys->stream;
> >  
> >      pa_threaded_mainloop_lock(sys->mainloop);
> > +
> > +    sys->write_request = 0;
> > +
> >      pa_operation *op = pa_stream_drain(s, NULL, NULL);
> >      if (op != NULL)
> >          pa_operation_unref(op);
> > @@ -778,7 +800,7 @@ static int Start(audio_output_t *aout, 
> > audio_sample_format_t *restrict fmt)
> >      /* PulseAudio goes berserk if the target length (tlength) is not
> >       * significantly longer than 2 periods (minreq), or when the 
> > period length
> >       * is unspecified and the target length is short. */
> > -    attr.tlength = pa_usec_to_bytes(3 * AOUT_MIN_PREPARE_TIME, &ss);
> > +    attr.tlength = pa_usec_to_bytes(AOUT_MAX_PREPARE_TIME, &ss);
> >      attr.prebuf = 0; /* trigger manually */
> >      attr.minreq = pa_usec_to_bytes(AOUT_MIN_PREPARE_TIME, &ss);
> >      attr.fragsize = 0; /* not used for output */
> > @@ -790,6 +812,7 @@ static int Start(audio_output_t *aout, 
> > audio_sample_format_t *restrict fmt)
> >          pa_cvolume_set(cvolume, ss.channels, sys->volume_force);
> >      }
> >  
> > +    sys->write_request = 0;
> >      sys->trigger = NULL;
> >      pa_cvolume_init(&sys->cvolume);
> >      sys->last_date = VLC_TICK_INVALID;
> > @@ -919,6 +942,7 @@ static int Start(audio_output_t *aout, 
> > audio_sample_format_t *restrict fmt)
> >      pa_stream_set_started_callback(s, stream_started_cb, aout);
> >      pa_stream_set_suspended_callback(s, stream_suspended_cb, aout);
> >      pa_stream_set_underflow_callback(s, stream_underflow_cb, aout);
> > +    pa_stream_set_write_callback(s, stream_request_cb, aout);
> >  
> >      if (pa_stream_connect_playback(s, sys->sink_force, &attr, flags,
> >                                     cvolume, NULL) < 0
> > @@ -976,6 +1000,7 @@ static void Stop(audio_output_t *aout)
> >      pa_stream_set_started_callback(s, NULL, NULL);
> >      pa_stream_set_suspended_callback(s, NULL, NULL);
> >      pa_stream_set_underflow_callback(s, NULL, NULL);
> > +    pa_stream_set_write_callback(s, NULL, NULL);
> >  
> >      pa_stream_unref(s);
> >      sys->stream = NULL;
> > 
> > _______________________________________________
> > vlc-commits mailing list
> > vlc-commits at videolan.org
> > https://mailman.videolan.org/listinfo/vlc-commits
> >
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