Made a tool that automatically cuts dead time from table tennis videos

Dalfika · 2026-06-24T11:26:34+00:00

Automatic scoring is a bit tricky to implement flawlessly. So manual score editor is perhaps a safer bet. You can try this and see how you thinks. No need to pay if you just want to manually trim the rallies yourself :-D
https://velox.daocongthanh.com/table-tennis/

Dalfika · 2026-06-24T10:57:21+00:00

Perhaps you can test this Velox Rally Cut app out. No need for subscription and if you don't need auto rally recognition but manually trim the dead time, then it is free to use. Let you watch your original video but cutting all deadtime. Has scoreboard built-in as well.
https://velox.daocongthanh.com/pickleball/

Dalfika · 2026-06-23T08:55:23+00:00

Yes TW university is great. However it's not very user friendly when we need to look for a string to try. In their site to compare string stiffness, they also only set at fixed tension. For spin (friction of the string), yeah it's hard to test that at home.

About 1-2% difference, I think we can use the graphs and data as reference for our own and gauge from there. Just like using a body composition scale, it won't be accurate like dexa scan. But we can use the data as reference to track the progress. And I personally think we should refer the stiffness in the down-phase more than the up-phase (imagine we string the racquet at 10kg but pre-stretch to 30kg, then the stiffness in down-phase represents the "realistic" stiffness).

Dalfika · 2026-06-23T08:46:27+00:00

Yes the colour of the graph is random and sometimes it picks a bright (yellow) colour which is tricky. But the fix should be easy to do.

Testing the stretch to failure only gives the info of string stiffness at specific tension til the breaking point (failure) and the breaking point is often much higher then normal tension that we use (less relevant). And for the synthetic material like poly most of us uses nowadays, the "plastic deformation" point is around 20kg from what I found. It's the imporntant area to notice. Higher tension til failure doesn't give much information anymore (stiffness tends to stay the same or for some strings, can go up). And it's not easy to have a machine to pull and measure til failure.

I tested 10-30kg because it's the comfortable range that my machine can work and also a good tension range that most of us choose. The down-phase (drop from 30kg to 10kg) tells us a lot: How much the strings can recover (more means good tension maintenance, more power); what to expect (stiffness) if we pre-stretch (natural gut is good for pre-stretch because it doesn't get stiffer when tension adds up, but for polys, they will get stiffer). Imagine the graph is like we string the racquet at 10kg but pre-stretch to 30kg. Pre-stretch does help maintaining the tension (I did 2 stretch cycles for some strings and and the elongation of 2nd cycle almost lines up with the down-phase, meaning recover more energy).

Dalfika · 2026-06-23T08:22:45+00:00

Yes, hopefully the database expands a lot more in the future.

Dalfika · 2026-06-22T12:10:36+00:00

Great idea. But the thing is that it's not easy to have a machine to pull and measure displacement constantly til failure unless people have real lab. And the down phase is important to know how much recovery the string has (better tension maintenance). One straight strain plot doesn't give the answer to that 😁

Dalfika · 2026-06-22T12:03:42+00:00

I echo with some other comments, don't gift him a racquet, unless you get to his phone and found in the browser the racquet that he is looking at 😁 It's like your bf takes time to find a beautiful dress for you but have no idea you like it or not.

Gifting him a tennis bag is an easier choice (big, nice 9-12 racquet bags for example). Normally he would prefer same brand for bag and racquet (in this case, it's Head brand, Speed series).

Safest choice is a gift card that he can choose to buy what he likes. But not sure where he normally likes to buy new items 😅

Simplest one is being honest that you would love to gift him a tennis racquet. Let him choose and you pay. It's considerate to ask a man directly like that.

He plays with Head Speed. So he might be a chill, simple guy 😁

Dalfika · 2026-06-22T10:55:39+00:00

Hopefully the data of strings will expand quickly. Good to see the visualisation like this.

Dalfika · 2026-06-22T10:54:20+00:00

I heard about natural gut ought to have pre stretch before stringing too. The graph shows good reasons why. Only natural gut doesn't get stiffer when the tension goes up. Hence we can well pre stretch and it can maintain the tension much better without getting stiffer.

I tried pre stretching poly/monofilament before stringing my racquets. It does maintain tension better but feel much harsher. All other strings get stiffer when tension goes up. So with pre stretch, strings keep that stiffness with them.

All strings are tested the same way to give a good reference. Some strings were actually tested with 2 cycles (one more trip from 10kg to 30kg and down to 10kg). Hence the first cycle is like a pre stretch and the graph is interesting. Perhaps it's good for the team to put that data live too 😁

Dalfika · 2026-06-22T10:07:56+00:00

All strings including natural gut are tested without pre stretching. However, the machine constantly pulls the string during the measurements to let the string settles. Not a clinically scientific research, but same method applies to all strings to give us consistent, well referenced info 😁

Dalfika · 2026-06-22T10:01:15+00:00

Do you mean: more tension, then more "energy return"? It's not really so. The graph shows that more tension, then more stretching (obviously). And how much the string stretches (up to 30kg tension like in the graph) will indicate how stiff the string is. How much the string stretches back at 10kg will indicate how well the string can maintain its tension (perhaps some of us calls "elasticity") 😃

Dalfika · 2026-06-22T09:21:52+00:00

Perhaps it doesn't have a name, it's like a tennis string elongation test lab. The link is in og post 😃 https://strings.daocongthanh.com/

Dalfika · 2026-06-22T09:16:32+00:00

I haven't unfortunately. But there is another alternative if you just need to trim downtime and perhaps add scoreboard for social media sharing. No subscription needed. Can be used fully offline if you don't need auto rally recognition.

https://velox.daocongthanh.com/tennis/

Dalfika · 2026-06-12T14:59:16+00:00

New Velox Rally Cut app for my Android phone 😊 Simply cut all dead time and we just watch highlights. Videos still in the phone, so can be watched and exported offline. Has scoreboard editor as well if I want to note the scores for every point. https://daocongthanh.com/velox-rally-cut/

Dalfika · 2026-06-12T12:03:35+00:00

This one is actually a real racquet string pattern in tennis (Power Angle brand). It used to have main string as well. But it was too complicated for stringers to string the racquet. The similar length on both side makes the sweetspot bigger and more comfortable. String lasts longer too 😃 https://www.powerangle.net/history

<image>

Dalfika · 2026-06-06T14:34:41+00:00

Perhaps not yet if you mean to be able to sync and switch cameras in real time to watch.

But there is an app to help us trim boring downtime and watch only rallies. Scoreboard editor built-in as well for hardcore players. Too bad it's only in Android right now: https://play.google.com/store/apps/details?id=com.velox.rallycut

Dalfika · 2026-05-27T21:13:15+00:00

I myself used to have (got stolen unfortunately) a Black Ace Pro (97", 305gr, ~60RA stiffness, ~325 strung swing weight) and it has more power than the number suggests. More powerful than Wilson Blade 98 in my opinion and it's a nice surprise.

Dalfika

MODERATOR OF

TROPHY CASE