[vlc-devel] [PATCH] RFC: output_clock: respect first pts delay (FIXUP)

[Denis Charmet]

On 2019-02-13 13:23, Thomas Guillem wrote:
> Commit on top of the 
> https://code.videolan.org/jbk/vlc/tree/clock-core/25
> branch, will be fixup.
> 
> This commit fixes underrun when the first audio pts is too far in the 
> future.
> This happened with .ogg, .ts and live streams.
> 
> Without this commit, the first vlc_clock_ConvertToSystem() from 
> aout/dec.c will
> return a first play date that only take the jitter into account. So we 
> ended
> with an invalid first system date: likely to be vlc_tick_now() + 
> clock->jitter,
> ignoring the delay between the first audio pts and the PCR.
> ---
>  src/clock/clock.c  | 15 ++++++++++++++-
>  src/clock/clock.h  |  2 ++
>  src/input/es_out.c |  4 ++++
>  3 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/src/clock/clock.c b/src/clock/clock.c
> index 8308c0ffc4..5bdc6c174e 100644
> --- a/src/clock/clock.c
> +++ b/src/clock/clock.c
> @@ -47,6 +47,7 @@ struct vlc_clock_main_t
>      vlc_tick_t delay;
> 
>      vlc_tick_t pause_date;
> +    vlc_tick_t first_pts;
> 
>      clock_point_t wait_sync_ref; /* When the master */
>      vlc_tick_t dejitter; /* Delay used to absorb the clock jitter */
> @@ -276,8 +277,12 @@ static vlc_tick_t
> vlc_clock_main_to_system_locked(vlc_clock_main_t * main_clock,
>          if (main_clock->wait_sync_ref.stream == VLC_TICK_INVALID ||
>              main_clock->wait_sync_ref.system == VLC_TICK_INVALID)
>          {
> +            const vlc_tick_t initial_delay = pts - 
> main_clock->first_pts;

Check if first_pts is valid or prepare for trouble and make it double 
:)

> +            const vlc_tick_t system_delay =
> +                __MAX(main_clock->dejitter, initial_delay);
> +
>              main_clock->wait_sync_ref =
> -                clock_point_Create(pts, now + main_clock->dejitter);
> +                clock_point_Create(pts, now + system_delay);
>          }
>          system = (pts - main_clock->wait_sync_ref.stream) / 
> main_clock->rate;
>          system += main_clock->wait_sync_ref.system;
> @@ -423,6 +428,14 @@ void vlc_clock_main_Reset(vlc_clock_main_t * 
> main_clock)
>  {
>      vlc_mutex_lock(&main_clock->lock);
>      vlc_clock_main_reset(main_clock);
> +    main_clock->first_pts = VLC_TICK_INVALID;
> +    vlc_mutex_unlock(&main_clock->lock);
> +}
> +
> +void vlc_clock_main_SetFirstPts(vlc_clock_main_t * main_clock, 
> vlc_tick_t pts)
> +{
> +    vlc_mutex_lock(&main_clock->lock);
> +    main_clock->first_pts = pts;
>      vlc_mutex_unlock(&main_clock->lock);
>  }
> 
> diff --git a/src/clock/clock.h b/src/clock/clock.h
> index e079440af6..8bd5adb40d 100644
> --- a/src/clock/clock.h
> +++ b/src/clock/clock.h
> @@ -51,6 +51,8 @@ void vlc_clock_main_Abort(vlc_clock_main_t * main);
>   */
>  void vlc_clock_main_Reset(vlc_clock_main_t * main);
> 
> +void vlc_clock_main_SetFirstPts(vlc_clock_main_t * main, vlc_tick_t 
> pts);
> +
>  /**
>   * This function set the allocated interface as the master making the 
> current
>   * master if any a slave.
> diff --git a/src/input/es_out.c b/src/input/es_out.c
> index 5d8be99f9f..773c825a2d 100644
> --- a/src/input/es_out.c
> +++ b/src/input/es_out.c
> @@ -798,6 +798,10 @@ static void EsOutDecodersStopBuffering( es_out_t
> *out, bool b_forced )
>      p_sys->i_preroll_end = -1;
>      p_sys->i_prev_stream_level = -1;
> 
> +    /* Send the first PCR to the output clock. This will be used as a 
> reference
> +     * point for the sync point. */
> +    vlc_clock_main_SetFirstPts(p_sys->p_pgrm->p_main_clock, 
> i_stream_start);


PCR is more related to DTS than PTS... beware of out of order pictures.


> +
>      if( p_sys->i_buffering_extra_initial > 0 )
>      {
>          /* FIXME wrong ? */