new-implementation.c

static int DecoderPrerollBlock( decoder_t * p_dec,
  uint32_t i_flags, mtime_t i_pts, mtime_t i_pts_stop, void(*pf_prerolled)(decoder_t*) )
{
    bool b_flag_preroll = i_flags & BLOCK_FLAG_PREROLL;
    bool b_flag_forced  = i_flags & BLOCK_FLAG_DISPLAY_FORCED;

    if( b_flag_preroll && !b_flag_forced )
        return 1;

    decoder_owner_sys_t * p_owner = p_dec->p_owner;

    vlc_mutex_lock( &p_owner->lock );

    mtime_t i_preroll_end = p_owner->i_preroll_end;

    if( i_preroll_end <= VLC_TS_INVALID )
    {    
        vlc_mutex_unlock( &p_owner->lock );
        return 0;
    }    

    if( i_pts < i_preroll_end && i_pts_stop < i_preroll_end )
    {    
        vlc_mutex_unlock( &p_owner->lock );
        return !b_flag_forced;
    }    

    p_owner->i_preroll_end = VLC_TS_INVALID;

    if( pf_prerolled )
        pf_prerolled( p_dec );

    vlc_mutex_unlock( &p_owner->lock );
    return 0;
}

old-implementation.c

static int DecoderPrerollBlock( decoder_t * p_dec,
  uint32_t i_flags, mtime_t i_pts, mtime_t i_pts_stop, void(*pf_prerolled)(decoder_t*) )
{
    bool b_flag_preroll = i_flags & BLOCK_FLAG_PREROLL;
    bool b_flag_forced  = i_flags & BLOCK_FLAG_DISPLAY_FORCED;

    if( b_flag_preroll && !b_flag_forced )
        return 1;

    mtime_t i_preroll_end = input_DecoderGetPrerollEnd( p_dec );

    if( i_preroll_end <= VLC_TS_INVALID )
        return 0;

    if( i_pts < i_preroll_end && i_pts_stop < i_preroll_end )
        return !b_flag_forced;

    input_DecoderSetPrerollEnd( p_dec, VLC_TS_INVALID );

    if( pf_prerolled )
        pf_prerolled( p_dec );

    return 0;
}