[vlc-devel] [PATCH v3 2/6] clock: add vlc_clock_main_SetInputDrift

[Denis Charmet]

On 2021-03-12 16:08, Thomas Guillem wrote:
> ---
>  src/clock/clock.c | 15 +++++++++++++--
>  src/clock/clock.h |  8 ++++++++
>  2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/src/clock/clock.c b/src/clock/clock.c
> index cfbb5eb6f6d..0bb2a9fe375 100644
> --- a/src/clock/clock.c
> +++ b/src/clock/clock.c
> @@ -45,6 +45,7 @@ struct vlc_clock_main_t
>      average_t coeff_avg; /* Moving average to smooth out the instant 
> coeff */
>      double rate;
>      double coeff;
> +    vlc_tick_t input_drift;
>      vlc_tick_t offset;
>      vlc_tick_t delay;
> 
> @@ -88,6 +89,7 @@ static vlc_tick_t
> main_stream_to_system(vlc_clock_main_t *main_clock,
>  static void vlc_clock_main_reset(vlc_clock_main_t *main_clock)
>  {
>      AvgReset(&main_clock->coeff_avg);
> +    main_clock->input_drift = 0;
>      main_clock->coeff = 1.0f;
>      main_clock->rate = 1.0f;
>      main_clock->offset = VLC_TICK_INVALID;
> @@ -266,7 +268,8 @@ static vlc_tick_t
> vlc_clock_slave_to_system_locked(vlc_clock_t *clock,
>          system = vlc_clock_monotonic_to_system_locked(clock, now, ts, 
> rate);
>      }
> 
> -    return system + (clock->delay - main_clock->delay) * rate;
> +    return system + main_clock->input_drift +

You cannot do that. The whole point of the main clock is to be the 
reference used to calculate the different drifts of other clocks. The 
main clock cannot drift it's the monotonic clock if you start doing that 
you are basically going back to the PCR master of the previous versions.


> +        (clock->delay - main_clock->delay) * rate;
>  }
> 
>  static vlc_tick_t vlc_clock_master_to_system_locked(vlc_clock_t 
> *clock,
> @@ -282,7 +285,7 @@ static vlc_tick_t
> vlc_clock_master_to_system_locked(vlc_clock_t *clock,
>          system = vlc_clock_monotonic_to_system_locked(clock, now, ts, 
> rate);
>      }
> 
> -    return system + clock->delay * rate;
> +    return system + main_clock->input_drift + clock->delay * rate;
>  }
> 
>  static vlc_tick_t vlc_clock_slave_update(vlc_clock_t *clock,
> @@ -370,6 +373,7 @@ vlc_clock_main_t *vlc_clock_main_New(void)
>      main_clock->master = NULL;
>      main_clock->rc = 1;
> 
> +    main_clock->input_drift = 0;
>      main_clock->coeff = 1.0f;
>      main_clock->rate = 1.0f;
>      main_clock->offset = VLC_TICK_INVALID;
> @@ -439,6 +443,13 @@ void vlc_clock_main_SetDejitter(vlc_clock_main_t
> *main_clock,
>      vlc_mutex_unlock(&main_clock->lock);
>  }
> 
> +void vlc_clock_main_SetInputDrift(vlc_clock_main_t *main_clock, 
> double drift)
> +{
> +    vlc_mutex_lock(&main_clock->lock);
> +    main_clock->input_drift = drift;
> +    vlc_mutex_unlock(&main_clock->lock);
> +}
> +
>  void vlc_clock_main_ChangePause(vlc_clock_main_t *main_clock, 
> vlc_tick_t now,
>                                  bool paused)
>  {
> diff --git a/src/clock/clock.h b/src/clock/clock.h
> index f780d448bcc..f628024e057 100644
> --- a/src/clock/clock.h
> +++ b/src/clock/clock.h
> @@ -90,6 +90,14 @@ void vlc_clock_main_SetFirstPcr(vlc_clock_main_t 
> *main_clock,
>  void vlc_clock_main_SetInputDejitter(vlc_clock_main_t *main_clock,
>                                       vlc_tick_t delay);
> 
> +/**
> + * Set the input drift
> + *
> + * Set the average drift calculted by the input_clock, it is used to 
> delay all
> + * output clocks according to this drift.
> + **/
> +void vlc_clock_main_SetInputDrift(vlc_clock_main_t *main_clock, 
> double drift);
> +
>  /**
>   * This function sets the dejitter delay to absorb the clock jitter
>   *

Regards,
-- 
Denis Charmet - TypX
Le mauvais esprit est un art de vivre