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Author Topic: Peg a video timeline to the blockchain  (Read 961 times)
findftp
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February 14, 2015, 08:33:10 AM
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There are so many fake videos in this world.
I even think that a good load of videos on MSM are fake.

One way to prove that videos are real would be to peg the video timeline to the blockchain, right?

For example; A video could be proven authentic when every few frames there is a timestamp made on the blockchain which could prove there was no time in between several frames which indicate that CGI or cuts were not done afterwards.
You could for example sha256sum every few frames and use them as an address. I think it might even allow for some re-encoding for the video while keeping the sha256sum intact.

I think this idea is feasible.
I would even want to pay for such service to prevent bullshit from entering my head.

If someone is going to develop such a service, you could later donate a few thousand BTC to my address in my profile page when you sell this idea to youtube. Wink

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DannyHamilton
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February 14, 2015, 10:01:42 AM
 #2

There are so many fake videos in this world.
I even think that a good load of videos on MSM are fake.

One way to prove that videos are real would be to peg the video timeline to the blockchain, right?

For example; A video could be proven authentic when every few frames there is a timestamp made on the blockchain which could prove there was no time in between several frames which indicate that CGI or cuts were not done afterwards.
You could for example sha256sum every few frames and use them as an address. I think it might even allow for some re-encoding for the video while keeping the sha256sum intact.

I think this idea is feasible.
I would even want to pay for such service to prevent bullshit from entering my head.

If someone is going to develop such a service, you could later donate a few thousand BTC to my address in my profile page when you sell this idea to youtube. Wink

Unfortunately, since the bitcoin blockchain strives for a block every 10 minutes, and there are typically many frames per second in video, you would have large gaps between timestamps for your video frames.

There are no timestamps on transactions or addresses, and the timestamps in the blockchain are allowed to drift by a few hours, so you can't really even count on the timestamps being accurate.  There are many situations in the blockchain where a later block has an earlier timestamp than its previous block.  There would be no guarantee that your timestamp transaction would even make it into the next block.

Timestamping with the blockchain is reasonable when you want to know when something happened with an accuracy of "within a few hours of this timestamp", and it is great for setting what order some events occurred if the actual time itself doesn't matter, but I don't think it's going to fit your desire of a permanent bitcoin blockchain timestamp every few frames of video.

findftp
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February 15, 2015, 08:57:31 AM
 #3

Unfortunately, since the bitcoin blockchain strives for a block every 10 minutes, and there are typically many frames per second in video, you would have large gaps between timestamps for your video frames.

Well, I don't mean that live video has be proven live. I mean that you can say prove that recorded video was recorded in one take without alteration like cuts.

Quote
There are no timestamps on transactions or addresses, and the timestamps in the blockchain are allowed to drift by a few hours, so you can't really even count on the timestamps being accurate. 

But if I look at some transactions at blockchain.info I clearly see date and time. Is this done outside the blockchain and only on their website?

Quote
There are many situations in the blockchain where a later block has an earlier timestamp than its previous block.  There would be no guarantee that your timestamp transaction would even make it into the next block.

So basically there is no accurate timeline built into the blockchain is what you say.

Quote
Timestamping with the blockchain is reasonable when you want to know when something happened with an accuracy of "within a few hours of this timestamp", and it is great for setting what order some events occurred if the actual time itself doesn't matter, but I don't think it's going to fit your desire of a permanent bitcoin blockchain timestamp every few frames of video.

I think it would fit my purpose if the drift is less than an hour.

I don't understand why the drift is allowed to be so much. What's the benefit? Or is this just something not thought about before?

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DannyHamilton
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February 15, 2015, 02:27:31 PM
 #4

Quote
There are no timestamps on transactions or addresses, and the timestamps in the blockchain are allowed to drift by a few hours, so you can't really even count on the timestamps being accurate.

But if I look at some transactions at blockchain.info I clearly see date and time. Is this done outside the blockchain and only on their website?

Correct.

Quote
There are many situations in the blockchain where a later block has an earlier timestamp than its previous block.  There would be no guarantee that your timestamp transaction would even make it into the next block.

So basically there is no accurate timeline built into the blockchain is what you say.

Correct.

The blockchain provides an accurate ordering of transactions (transaction A occurred before transaction B), but it does not provide an accurate time of when those transactions occurred.  The reason that a timestamp is included in the block is so that once every 2016 blocks the software can check and see if it took more time or less time than 20160 minutes (that's 336 hours) for those blocks to occur.  If it took more time, then the blocks are too slow and difficulty is decreased.  If it took less time, then blocks are too fast and difficulty is increased.  That's it.  The timestamps don't serve any other purpose.  Since the time per block is being averaged over approximately 336 hours, a couple of hours for any given block isn't very significant, and if coincidence results in many more blocks drifting in one direction than the other the only effect is to cause the difficulty for the next 2016 blocks to be slightly higher or slightly lower than it should be.  It will correct itself the next adjustment.

Quote
Timestamping with the blockchain is reasonable when you want to know when something happened with an accuracy of "within a few hours of this timestamp", and it is great for setting what order some events occurred if the actual time itself doesn't matter, but I don't think it's going to fit your desire of a permanent bitcoin blockchain timestamp every few frames of video.

I think it would fit my purpose if the drift is less than an hour.

You mentioned earlier that you didn't mean that live video has to be proven live, but unless at least one timestamp can be proven to be tied to some trusted live event, the video could be edited first and then timestamped.

Example:
  • We invent some new blockchain system that provides a trustworthy public timestamp every second and allows us to add hashes to the blocks
  • I record some video over the next 20 minutes at 24 frames per second.
  • I spend the next 24 hours editing and altering the video
  • At this time tomorrow (after I'm all done modifying the video) I start adding hashes of every 24th frame to the blockchain.
  • Anyone that checks the blockchain will find that from start frame to end frame there is a hash in the block chain every second.


I don't understand why the drift is allowed to be so much. What's the benefit?

Accurate timestamps aren't very important to the operation of bitcoin.  The purpose of the blockchain is to prove that transactions occurred and to provide an ordering of the transactions, not to provide a time that they occurred.

Or is this just something not thought about before?

By most of those that are familiar with the technical details of bitcoins it is well understood that block timestamps can only be assumed to be within a few hours of the block.

findftp
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February 15, 2015, 03:04:58 PM
 #5

Quote
There are no timestamps on transactions or addresses, and the timestamps in the blockchain are allowed to drift by a few hours, so you can't really even count on the timestamps being accurate.

But if I look at some transactions at blockchain.info I clearly see date and time. Is this done outside the blockchain and only on their website?

Correct.

Quote
There are many situations in the blockchain where a later block has an earlier timestamp than its previous block.  There would be no guarantee that your timestamp transaction would even make it into the next block.

So basically there is no accurate timeline built into the blockchain is what you say.

Correct.

The blockchain provides an accurate ordering of transactions (transaction A occurred before transaction B), but it does not provide an accurate time of when those transactions occurred.  The reason that a timestamp is included in the block is so that once every 2016 blocks the software can check and see if it took more time or less time than 20160 minutes (that's 336 hours) for those blocks to occur.  If it took more time, then the blocks are too slow and difficulty is decreased.  If it took less time, then blocks are too fast and difficulty is increased.  That's it.  The timestamps don't serve any other purpose.  Since the time per block is being averaged over approximately 336 hours, a couple of hours for any given block isn't very significant, and if coincidence results in many more blocks drifting in one direction than the other the only effect is to cause the difficulty for the next 2016 blocks to be slightly higher or slightly lower than it should be.  It will correct itself the next adjustment.

Quote
Timestamping with the blockchain is reasonable when you want to know when something happened with an accuracy of "within a few hours of this timestamp", and it is great for setting what order some events occurred if the actual time itself doesn't matter, but I don't think it's going to fit your desire of a permanent bitcoin blockchain timestamp every few frames of video.

I think it would fit my purpose if the drift is less than an hour.

You mentioned earlier that you didn't mean that live video has to be proven live, but unless at least one timestamp can be proven to be tied to some trusted live event, the video could be edited first and then timestamped.

Example:
  • We invent some new blockchain system that provides a trustworthy public timestamp every second and allows us to add hashes to the blocks
  • I record some video over the next 20 minutes at 24 frames per second.
  • I spend the next 24 hours editing and altering the video
  • At this time tomorrow (after I'm all done modifying the video) I start adding hashes of every 24th frame to the blockchain.
  • Anyone that checks the blockchain will find that from start frame to end frame there is a hash in the block chain every second.


I don't understand why the drift is allowed to be so much. What's the benefit?

Accurate timestamps aren't very important to the operation of bitcoin.  The purpose of the blockchain is to prove that transactions occurred and to provide an ordering of the transactions, not to provide a time that they occurred.

Or is this just something not thought about before?

By most of those that are familiar with the technical details of bitcoins it is well understood that block timestamps can only be assumed to be within a few hours of the block.


I now understand that although the blockchain provides an unchangeable history of events, these event cannot follow each other too quickly.
Adjustment of the difficulty would be most accurate time-stamp moment I guess.

I assume that sidechains would also not be suitable for this feature since they would be pegged to the blockchain anyway (with its limits)
To 'solve' this you would probably need an alt coin with much faster blocks or difficulty adjustments or something else built into it.

Thank you for your detailed answer on my questions.

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