yarpdataplayer speed not consistent with real data

[vvasco]

Describe the bug
yarpdataplayer seems to reproduce data faster than the real data.
This seems related to #2049.

To Reproduce

• Record a dataset using yarpdatadumper --rxTime --txTime;
• Replay the dataset through yarpdataplayer --withExtraTimeCol 2;
• Record the same dataset from yarpdataplayer using yarpdatadumper --rxTime --txTime;
• Compare the receiver times.

Expected behavior
I expect yarpdataplayer to use the recorded times for playing the data, while it seems to reproduce data faster.

Screenshots
I recorded a dataset with the options --rxTime --txTime and re-dumped the data from the dataplayer with the same options. When plotting the receiver times of both datasets, it seems that yarpdataplayer (red line) reproduces the data faster than the real data (blue line), while I would expect times to be equal:

The delay accumulates and at the end of my dataset (which is ~20mins long), it reaches ~158s.
yarpdataplayer seems to apply a warping factor of ~0.8 to time, which seems consistent across different datasets.

Configuration (please complete the following information):

• OS: Ubuntu 18.04.2 LTS
• yarp version: v3.1.0 commit 96123316f36edd00db68b46b2a6240d1d5ab11ba

Additional context
I spotted the problem because I was trying to synchronize a command (black dashed line in the plot) using the recorded time, and it was given ~20s later than expected.

[pattacini]

Hi @vvasco

Could you attach here in a zip containing the minimum dataset with which we can reproduce the problem?

[vvasco]

Hi @pattacini

Unfortunately I can't because the dataset contains sensitive data.
But I can provide @vtikha with it.

[vtikha]

@vvasco & @lrapetti First of all I apologise for the delay but was not able to work on this any sooner. I managed to replicate the problem with your dataset and instructions. There was clearly an issue with the virtual virtual time of the yarpdataplayer and I have been working on a solution.

Behaviour

I have used @vvasco 20 minutes dataset to:

• Replay the dataset through yarpdataplayer --withExtraTimeCol 2; (also --withExtraTimeCol 1)

• Record the same dataset from yarpdataplayer using yarpdatadumper --rxTime --txTime;

• Compare the receiver times (several times)

Screenshot

I plotted the receiver times of both datasets, it seems that the yarpdataplayer (red line) now manages to reproduce correctly the real data (blue line):

Configuration:

OS: MacOS 10.14.6
YARP version 3.2.0+20190710.4+git291925cd2

update

I also tested the datasets from @lrapetti and all is working as expected. PR created.

[Nicogene]

Fixed by #2074