[vlc-devel] Question of pts delay and clock jitter testing

David R. Robison david.robison at openroadsconsulting.com
Tue Jan 20 20:19:08 CET 2015

In the EsOutControlLocked funtion in src/input/es_out.c there is a check 
to see if the pts delay is greater than a configured clock jitter amount:

const mtime_t i_jitter_max = INT64_C(1000) * var_InheritInteger( 
p_sys->p_input, "clock-jitter" );
if( i_pts_delay > __MIN( i_pts_delay_base + i_jitter_max, 
     msg_Err( p_sys->p_input,
              "ES_OUT_SET_(GROUP_)PCR  is called too late (jitter of %d 
ms ignored)",
              (int)(i_pts_delay - i_pts_delay_base) / 1000 );
     i_pts_delay = p_sys->i_pts_delay;

      /* reset clock */
     for( int i = 0; i < p_sys->i_pgrm; i++ )
       input_clock_Reset( p_sys->pgrm[i]->p_clock );
     msg_Err( p_sys->p_input,
              "ES_OUT_SET_(GROUP_)PCR  is called too late (pts_delay 
increased to %d ms)",
               (int)(i_pts_delay/1000) );

    /* Force a rebufferization when we are too late */

    /* It is not really good, as we throw away already buffered data
     * TODO have a mean to correctly reenter bufferization */
    es_out_Control( out, ES_OUT_RESET_PCR );

I may be confused, but should the conditional be reversed? Should the 
jitter be ignored if the i_pts_delay is less than __MIN( 
i_pts_delay_base + i_jitter_max, INPUT_PTS_DELAY_MAX ) rather than 
greater than?


David R Robison

*Principal Systems Engineer*

+1 757 546 3401 (o)

+1 757 286 0022 (m)

david.robison at openroadsconsulting.com 
<mailto:david.robison at openroadsconsulting.com>



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