Fix ivf timestamps

[xdrudis]

Description

IVFwriter produces incorrect timestamps leading to unplayable video with the changes introduced in #2853.

The confusion lies in the different timestamps.
The RTP timestamp refects the sampling clock for the media stream. This timestamp increments based on the sampling rate.
The PTS of a media stream represents the presentation time in the time base units.

Example

v3 first captured packets from examples/save-to-disk (ffprobe -select_streams v -show_packets -show_entries packet=pts,pts_time,dts,dts_time,duration,duration_time,size,pos -of default output.ivf)

[PACKET]
pts=0
pts_time=0.000000
dts=0
dts_time=0.000000
duration=1
duration_time=0.033333
size=2749
pos=32
[/PACKET]
[PACKET]
pts=1
pts_time=0.033333
dts=1
dts_time=0.033333
duration=1
duration_time=0.033333
size=61
pos=2793
[/PACKET]
[PACKET]
pts=2
pts_time=0.066667
dts=2
dts_time=0.066667
duration=1
duration_time=0.033333
size=46
pos=2866
[/PACKET]
[PACKET]
pts=3
pts_time=0.100000
dts=3
dts_time=0.100000
duration=1
duration_time=0.033333
size=222
pos=2924
[/PACKET]

v4 first captured packets from examples/save-to-disk (prior to this PR)

[PACKET]
pts=556350009
pts_time=18545000.300000
dts=556350009
dts_time=18545000.300000
duration=1
duration_time=0.033333
size=2712
pos=32
[/PACKET]
[PACKET]
pts=556353159
pts_time=18545105.300000
dts=556353159
dts_time=18545105.300000
duration=1
duration_time=0.033333
size=64
pos=2756
[/PACKET]
[PACKET]
pts=556356129
pts_time=18545204.300000
dts=556356129
dts_time=18545204.300000
duration=1
duration_time=0.033333
size=229
pos=2832
[/PACKET]

v4 first captured packets with this PR

pts=0
pts_time=0.000000
dts=0
dts_time=0.000000
duration=1
duration_time=0.033333
size=2851
pos=32
[/PACKET]
[PACKET]
pts=1
pts_time=0.033333
dts=1
dts_time=0.033333
duration=1
duration_time=0.033333
size=61
pos=2895
[/PACKET]
[PACKET]
pts=2
pts_time=0.066667
dts=2
dts_time=0.066667
duration=1
duration_time=0.033333
size=232
pos=2968
[/PACKET]

[xdrudis]

cc @radekg, @edaniels

[codecov]

Codecov Report

Attention: Patch coverage is 76.47059% with 8 lines in your changes missing coverage. Please review.

Project coverage is 79.38%. Comparing base (92fce5f) to head (803fd08).
Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/media/ivfwriter/ivfwriter.go	80.00%	2 Missing and 3 partials ⚠️
pkg/media/ivfreader/ivfreader.go	66.66%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2987      +/-   ##
==========================================
+ Coverage   77.84%   79.38%   +1.54%     
==========================================
  Files          89       78      -11     
  Lines       10524     9649     -875     
==========================================
- Hits         8192     7660     -532     
+ Misses       1842     1541     -301     
+ Partials      490      448      -42     

Flag	Coverage Δ
go	79.38% <76.47%> (-0.03%)	⬇️
wasm	?

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[xdrudis]

The changes in this test just undo https://github.com/pion/webrtc/pull/2853/files

[edaniels]

LGTM

[edaniels]

Just need to fix the lint and we're good to go

[xdrudis]

Just need to fix the lint and we're good to go

The problem lies in the two Revert commits , which take the message just a bit over 50 characters. Do you have the power to overwrite this check? Ideally the linter would be able to account for this particular case.

[edaniels]

Just need to fix the lint and we're good to go

The problem lies in the two Revert commits , which take the message just a bit over 50 characters. Do you have the power to overwrite this check? Ideally the linter would be able to account for this particular case.

I do :)

[edaniels]

Done!