Binary check differences on some video files - MTP transfer

[Am30]

Hi

I have been running a binary comparison between files on my Android phone and the same files which I have copied across to my PC using MTP. The files are photos and videos.

436 photos and 71 videos are identical however 4 videos are not.

The results for one of those video comparisons are below



I decided to try copying the 4 videos from my Android phone over to another folder on my PC – the binary comparison shows differences.

I then decided to compare the two videos which had now been transferred to my PC – they were identical.

It seems something is different in those 4 files after they get transferred from my phone to my PC. Whatever the differences are, they are not random as the exact same differences happen to the files when retransferring them.

I have restarted my phone and restarted my PC a number of times in between the initial transfer and todays test.
I run a quick test and everything matches, the CRC check shows differences

Phone – Sony Z2 with Lollipop
PC – Windows 8.1 fully updated.
Latest version of Beyond Compare.

[Am30]

Update - still using the trial version

Tried the following:

Test 1 - Re-create original copy
Create a new folder on PC
Copy all files from Android phone to PC using Windows copy and paste
Result – BC4 still highlights the same 4 videos as having different values on the PC compared to the phone, using binary comparison.

Test 2 – Use SyncBack (latest version) MTP Profile - copy the 4 files that are causing the problem (settings checked to copy everything)
Result – Exactly the same, BC4 shows errors on the 4 files

Test 3 – Use SyncBack (latest version) Touch profile with the Touch app to transfer over WIFI - to copy the 4 files that are causing the problem
Result – Exactly the same, BC4 shows errors on the 4 files

Test 4 – Compare the files copied across on Test 1 with those copied on Test 2 and Test 3
Result - All copied files are identical. It’s definitely something on the Android Sony Z2 that’s causing the comparison difference.

I've watched each video - they all play fine.

I really want to add BC4 to my backup routine but I can't if its highlighting issues that I cant yet explain. Really happy to do more tests, just let me know :-)

[Dave_L]

Wild guess: Maybe the phone is doing some type of compression and/or format conversion. That would cause a difference when doing a binary comparison.

[Zoë]

Given that two different programs are producing the same output when you copy it locally, and that the changed data is just extra bytes at the end, I'm guessing it's a bug in BC's MTP support. Do you have any other MTP devices you could copy the file to to test against? Assuming it repeats there, would it be possible for us to acquire a copy of one of them for testing?

[Am30]

Given that two different programs are producing the same output when you copy it locally, and that the changed data is just extra bytes at the end, I'm guessing it's a bug in BC's MTP support. Do you have any other MTP devices you could copy the file to to test against? Assuming it repeats there, would it be possible for us to acquire a copy of one of them for testing?

Hi

Sorry for the late reply, I've had problems with my internet connection this week and finally had a visit from an engineer today.

I can try copying the file to my Samsung Galaxy Tablet. I don't have that knowledge about binary information, the data that's shown as different - is it not that significant?

[Zoë]

In your screenshot it shows the file on the left has data at the end which isn't in the file in the right, but it doesn't appear there's a difference between them prior to that. That tells me that BC is reading/writing more data than it should be. It's probably just not handling the last block of data correctly.

[Am30]

In your screenshot it shows the file on the left has data at the end which isn't in the file in the right, but it doesn't appear there's a difference between them prior to that. That tells me that BC is reading/writing more data than it should be. It's probably just not handling the last block of data correctly.

Thanks Zoë. I tried another test today:
I tried using the 'USB connection mode' menu under 'USB Connectivity' on my Xperia Z2. I changed the connection mode from MTP to Mass Storage Mode (MSC)'.
This type of connection only works with the SD card but luckily that's what all my files are on. I copied the files across to my PC using Windows Explorer and then run BC, the files on the phone and the PC matched!

I switched back to MTP and used BC to compare the files again and this time they didn't. It definitely seems to be something that BC doesn't like about the MTP connection but its strange that it only effects 4 files.

Happy to share one of the files - how do you want me to send it? Only have a couple days left of my trial so eager to get this done so I can do some actual testing once I know why this happens :-)

[Aaron]

Hello,

Thanks. If we could get one of those files that would be helpful for testing. If you can email us at [email protected] with:
- a link back to this forum thread
- the file, perhaps hosted as a private link on a share service like Dropbox or Onedrive. Would this transfer protocol work for you?

that would be great.

[Am30]

Sent :-)

[Aaron]

As a quick follow up here for users finding this thread, it seems like BC4 is copying a larger file (more of the movie) than Explorer. So files that were copied with Explorer then detected as different, since the Explorer copied file is truncated. We're still troubleshooting over email, but does not appear to be a Beyond Compare issue.