Friday, April 05, 2019

creating an AppImage to distribute Linux binaries

Some notes of my AppImage creation process.


  1. First tried creating manually, using
    https://github.com/AppImage/docs.appimage.org/blob/master/source/packaging-guide/manual.rst and the AppRunx86-64 from https://github.com/AppImage/AppImageKit/releases
  2. Found and copied the libs it uses by doing the following to copy all shared libraries -https://www.commandlinefu.com/commands/view/10238/copy-all-shared-libraries-for-a-binary-to-directory
    ldd file | grep "=> /" | awk '{print $3}' | xargs -I '{}' cp -v '{}' /destination
  3. Need to use the environment variable $OWD (Original Working Directory) to get files from the OWD, like our ini file. This code snippet was a good template, https://stackoverflow.com/questions/40306012/c-using-environment-variables-for-paths
        char* pPath;
        pPath = getenv("PATH");
        if (pPath)
          std::cout << "Path =" << pPath << std::endl;
        return 0;
  4. Many libs copied with the manual method had to be excluded using the excludelist at
    https://github.com/AppImage/pkg2appimage/blob/master/excludelist
  5. Still did not work on newer distros. In this thread, probono recommended using trusty on TravisCI for building, and linuxdeployqt instead of manual creation of AppDir. Did that, and it worked. Far fewer libs are bundled by linuxdeployqt. Lists of the two bundles are available at this issue thread.
  6. The download link from transfer.sh can be seen if the entire log is downloaded from TravisCI.
  7. The travis yml file gives the outline of the build and bundling process.

Thursday, April 04, 2019

USB drive reported as read only - solution

Found my USB drive reported as read-only on Linux Mint 18.1.

Corruption could cause this, so tried
sudo dosfsck -a /dev/sdc1

That did not help. Though the CLI is able to write to it, Nemo still complains it is read-only.

Apaprently the fix is at https://forums.linuxmint.com/viewtopic.php?t=176546

So everything needed to fix the issue is to execute:
sudo chmod 777 /media/USERNAME

And/or maybe a reboot?

When I faced this issue today, I rebooted the system, and then the USB drive was mounted read/write.

Wednesday, April 03, 2019

transparent proxy over ssh - sshuttle

Sometimes the network to which I am connected fails, while the LAN over fiber to Studio is active, and Studio's backup network is functional. Then, an elegant way to use the Studio network, without having to install any proxy server software, is using sshuttle.

sshuttle --dns -r username@ip.address.of.machine 0.0.0.0/0

will transparently proxy all dns requests as well as all traffic through the remote machine. Only python needs to be installed on the remote machine. 

Tuesday, March 19, 2019

Fedex (India) - expectation vs reality

Documenting my experience with Fedex. Plenty of lessons here for everyone, I think. My takeaway was, avoid Fedex (at least in India) whenever possible, if you are an individual, and not a corporate with a Fedex account. Perhaps they treat corporates better - who knows. But the level of miscommunication and lack of communication would indicate otherwise. Even our University had requested us a couple of years ago to avoid Fedex when importing.

1. I get a phone call on Saturday, 23 Feb 2019, that my shipment is due to arrive the next day, and I need to submit the required documents. Since I had already submitted my "one time only" Know Your Customer (KYC) documents last year, I thought this would be a breeze. I was wrong.

2. The form I had to fill in this year was different from last year's. (My printer was on the blink, so I had to trek all the way to another office, 15 minutes away, in order to print all the new documentation that had been requested.) The documents requested would probably change again, so it may not be worthwhile documenting them, but just for completeness:


·        KYC Form along with supporting documents – DULY SELF ATTESTED {signed & stamped}  (KYC is mandatory and is a 1 time requirement)

·         PAN copy,

·         Aadhar Card & Voter ID card

·         Address proof. (Telephone /Electricity Bill/Bank Statement/ Rental Agreement )

·         AD code ( Authorized dealer code from Bank)

·         DUMMY IEC LETTER

·         Gatt and DGFT declaration ( Attached )

·         Technical write up & INDIVIDUAL NET WEIGHT FOR ALL ITEM to prepare Advance checklist

3. At first, the Fedex rep on the phone told me that "since the item has come in cargo mode" it was mandatory that I have an IEC code - which is an Import-Export code for importers. She told me to find out from my organisation if I can import under their IEC, saying that individuals cannot import. Though I tried telling her that I had imported items in the past, she said it was impossible. Luckily, as it turns out, there was a delay in getting hold of the head of operations at our institution. In the meantime, Fedex called me again, saying that it would be possible, using something known as a dummy IEC, the request for which was listed in the above list.

4. Then there was Sunday - a day of rest - and no communications from Fedex.

5. On Monday, there were a flurry of 17 emails. Fedex did not accept my Voter ID as address proof. Only one of the items listed above. And AD code - I thought that since I am not an authorized dealer, I need not submit. But I was wrong. Apparently this is the AD code of the forex section of the bank. Even the bank manager did not know this, and this led to another day of delays.
Expectation - if someone from Fedex had explained this to me, I would have done it immediately.
Reality - I got the same "form" email from Fedex which I received earlier, so I just wrote back saying that I have already submitted the documents. So, this led to a one-day delay in filing the Bill of Entry (BoE) and thus a Rs. 5000 fine. Which has to be paid by me, of course. And even after receiving the AD code, there was some confusion - I got an email saying that the AD code is not valid. I again contacted the bank. The bank said it was valid. Then Fedex confirmed that the AD code was valid, it was the wait for permission to use dummy IEC which was causing the delay.

6. On Tuesday, I got an email with approval list for BoE filing, from jeena.co.in, Fedex India's clearing agents. I filled it up and returned it within 15 minutes. Then came the long wait, 26 Feb to 1 Mar. No intimation from Fedex or Jeena as to what is happening. I tried calling all the numbers available. No one picks up. Calling the toll-free numbers gets me an agent who speaks very soothingly, saying that Mr. (name) is in charge of clearing this package, they will inform him to get in touch with me. But Mr. (name) does not contact me. At all. Ever.
Expectation - if someone from Fedex or Jeena had explained that it would take a week or two for customs to clear it, I would have waited patiently. At the very least, someone should pick up the phone.
Reality - Either the staff are so over-worked and harassed by customers that they cannot bear to pick up calls, or they just stopped caring long ago.

7. On 1st March, I was asked to submit any or all of the following, for value evidence:
1) Internet price
2) Supplier price list
3) Previous BOE,which cleared earlier with same Item
4) If payment is made Bank remittance.

I did so.

8. Again a looong silence. On Mar 7, late in the evening, I get an email, asking for technical writeup. Technical writeup had been submitted in the first batch of documents. Anyway, I again edit that writeup, add a couple of lines, and submit along with all the SLED documentation in the supplier's website.

9. Silence again, till 13 Mar. Now, I am asked to pay the customs duty directly using the ICEGATE website, and to provide "E-way bill". Since I am an individual and not a company, I was not sure if I could do these things. Called up the toll-free. They said they will ask their people to call me and guide me. They never called. I googled, found the ICEGATE website, paid using the details like Challan number supplied by Jeena. But according to various internet sources, individuals need not file E-way bill unless they are transporting high-value goods in their own vehicle. Again write to Fedex, no reply. Again call toll-free. Again they tell me that they will ask their rep to contact me. They do not do so.
Expectation - when the customer asks for help, someone tries to help.
Reality - The toll-free operators either are not allowed to, or not able to, help. The customs clearance people are either overworked or not bothered.

10. 14 Mar - called up Jeena - the executive picked up! That itself was half the battle won. I mentioned that I'm an individual, not a company. Immediately he said, in that case, just send me a letter saying so, no E-way bill required. So, again I sent an email saying just that. And that evening, I get the automated Fedex tracking email, shipment released for delivery.

11. I thought I had paid all that was necessary, but wanted to make sure. Called Fedex toll-free to check. On 15th morning, they said please call back by 15th evening, because some documents may take time to be uploaded into their system. On 15th evening, I call, they say nothing to be paid. On 16th morning, I get a call from Fedex delivery agent, saying I need to pay Rs. 7000 for delivery. Again I call the toll-free number. They tell me that though it is not yet mentioned on their system, it is possible that the clearance charges are what I am expected to pay.
Expectation - clear intimation of what is to be paid, with an emailed invoice in advance.
Reality - confused signals. Nobody knows anything.

12. Part of the problem is the expectation. With services like India Post, you know that there is no one to call to ask for updates, you expect delays, you don't expect any email updates. But then Fedex is more than twice as expensive, so maybe the expectations are warranted. Especially when they put up pages like
http://www.fedex.com/in/why-ship-with-fedex/money-back-guarantee.html
and then completely renege on the delivery date. Like what happened last night - item still not delivered, so delivery status was shifted from "by 8.00 pm" to "pending".

Edit: The item was finally delivered on 20th March, after being shipped on 22 Feb. Even if you discount all the customs clearance delays, it took 8 days. With "Fedex International Priority" shipping. Now compare this with another similar package, sent via Royal Mail and India Post, which took a total of 10 days to reach me from Aberdeen, Scotland.  

Monday, March 18, 2019

different kinds of hash verifications, and writing boot disk iso to USB

Fedora - the hash is in a file called NameofISO-CHECKSUM:
sha256sum -c *CHECKSUM
OpenSuse is similar - the hash is in a file called NameofISO.iso.sha256:

Ubuntu - has sha sums as well as  md5sums, so can use
md5sum -c MD5SUMS 
also.

Then, writing - for Ubuntu based distros, can use the "make startup disk" tool. If the iso is from a different distro, and it is known to be compatible with usb boot, then something like (after verifying the device name - sdd or whatever - very important!)

sudo umount /dev/sdd*
sudo dd if=Fedora-Workstation-Live-x86_64-24-1.2.iso of=/dev/sdd bs=8M status=progress oflag=direct

The above method is known to work for Fedora 24 to 29, and OpenSuse 13.2.

If it is a DVD iso and not meant for USB boot, maybe unetbootin is required. 

Friday, March 15, 2019

burning in subtitles with VLC

From https://www.youtube.com/watch?v=G0NzMlhnzQQ -

Burning in subtitles with VLC needs a bit of tweaking -

1. Media -> Stream, choose the video file. Don't enable the subtitle checkbox on that screen. Click the Stream button.
2. In the Stream Media Wizard, choose the destination as File. Click Add and choose a filename for the destination.
3. In the next Wizard screen, make sure activate transcoding is checked. Click on the settings button, in the subtitles tab, make sure the 'enable subtitles', and 'overlay subtitles on the video' are checked. Codec can remain T.140.
4. In the next screen, in the Generated Stream Output String, we need to edit out (delete) the part of the string which says scodec=t140,
5. Click stream to transcode. 

Saturday, March 02, 2019

F&D smart TV - removing the ads from home screen

We wanted the F&D smart TVs in our lobby to start up with "last selected input" instead of the Home screen with all the youtube "recommendations" or ads. I tried out
Setting -> Common -> System Recovery

(To be updated.)

For Sony TVs, https://www.sony.com/electronics/support/articles/00257833 - Quick settings - Power on behaviour - Last input

There are many posts about using third-party home screen apps etc, but I'd rather use "Last input". Will check on this later. 

Monday, February 25, 2019

Sunday, February 24, 2019

easy way to copy ssh keys to remote machines

ssh-keygen -t rsa
ssh-copy-id -i ~/.ssh/id_rsa.pub user@host


This copies the public key to the authorized_keys file on the remote machine.

Saturday, February 23, 2019

stabilizing cycling videos

In the process of making videos of my morning cycling jaunts, wanted to stabilize the video and also speed it up. Found that Microsoft Hyperlapse Mobile was doing a reasonable job, though it is limited to saving in 720p on my LG Q6 mobile. Very blocky output (probably a low-bitrate codec?) and the video goes blurry once in a while, but stability is good. Compared to kdenlive's vidstab stabilization in the video below.

Bugs and workarounds -

1. My phone doesn't show all the videos all the time, either to Hyperlapse when importing video, or via MTP to Linux Mint 18.1 on USB for taking backups. Workaround, as suggested here, was to just restart the phone.

2. Initially, I was working with kdenlive 15 which came with Linux Mint 18.1, and faced the problem of tooltips being unreadable, having white text on yellow background as mentioned in this post. Then I started using the version 18.12 appimage - that does not have this issue, and also is less prone to random crashes.

3. My equipment is the LG Q6 mobile mounted on the handlebar using a cheap mount from Amazon,


The bracket is not tight enough, and I keep needing to push it up 5-6 times per ride (if the ride is not very smooth) to prevent the phone from tilting down and capturing only the ground right in front of me. Maybe a different way of mounting the phone may solve this - will try out different orientations. 

Time taken for processing

Hyperlapse took around 10 minutes per video to import, and 2 minutes to export as 4x sped up 720p video. Input videos were 1080p 30 fps captured by OpenCamera with the phone's default bitrate and codec, 17 Mbps mp4, file size limited to 1 GB. The 1 GB had around 8 minutes of footage. So, overall speed of Hyperlapse was 12 minutes for 8 minutes of footage, 1.5x real-time.

Kdenlive + vidstab was much slower. Around 2.5x real-time for just rendering mp4 to mp4. This is at a higher bitrate, but on an i7 Macbook. And around 50 minutes for an 8 minute clip stabilization. So, for speeding up 4x and then stabilizing, it would take around 35 minutes in a two-step process, or 4.4x real-time.  

So, I'm going with Hyperlapse. Maybe my colleagues with better stabilization software would prefer the raw footage, so I'm archiving the raw footage separately. 

Finally, here's the comparison video






Friday, February 22, 2019

options when running out of space in legacy GSuite free

Copy-pasting from an email I wrote to a colleague - Regarding email - currently, our domain uses GSuite legacy free plan and does not allow expansion of the existing amount of space. So, the only way is to delete large attachments. In many cases, the attachments are required and cannot be deleted. This can be handled in many ways.


1. Forward them themewise to specially created gmail ids and then delete
2. archive them locally by storing on a local hard disk and then delete
3. automate the local archiving using some tool like

Wednesday, February 20, 2019

videos for waiting area

We did a first test of a video screening solution for our waiting area at the planetarium. The idea is to have videos playing on the screen, with some onscreen text indicating the probable time of the next show. Raspberry Pis to play out on old surplus VGA or TV screens. After a bit of trial and error, the method used was to play videos using VLC called from a script,
cvlc -I http --http-port 43210 --http-password MyPassword  --fullscreen --no-video-title --sub-source="marq{file=/pathto/marq.txt,position=10}" /home/pi/playlist.xspf

Documentation for the marq subfilter is at https://wiki.videolan.org/Documentation:Modules/marq
and the idea came from this discussion.

Auto starting using a .desktop file put in .config/autostart directory as described at
https://www.raspberrypi.org/forums/viewtopic.php?t=17051
with the contents of the .desktop file being
[Desktop Entry] 
Type=Application
Exec=/path/to/my/shellscript.sh

Modifying the marq.txt is currently by ssh, need to make some better solution, perhaps using a web server and PHP or something like that. Some images below of our test setup -


Saturday, February 16, 2019

making a flower timelapse

Timelapses shot on 13 and 16 Feb 2019
using OpenCamera app on an LG Q6 mobile phone.

Settings:
Repeat - Unlimited
Repeat Mode Interval - 10 seconds.

So, playback at 30 fps made it 300x real-time.

Imported into kdenlive as an image sequence and then exported with pan and zoom effect applied.
Bug and workaround - kdenlive 15.12.3 which comes with Linux Mint 18.1 has an issue with importing image sequences when the numbering is not sequential, or jumps. For example, the image sequence shot by OpenCamera had filenames like
Although kdenlive would see all 463 files in the folder, the images after 85953 would be ignored, and 85953 would be repeated for those frames. Workaround was to put the 8xxx sequence in one folder, 9xxx sequence in a separate folder, etc, and then import as image sequence.

kdenlive 18.12.1 64 bit appimage seems to have mitigated this bug by just importing those frames in the sequence it recognizes, without causing any of the repeat frames. But in the clip properties, it still erroneously shows the larger number of frames found etc. So, the workaround above is recommended.


https://www.youtube.com/watch?v=tD0L7H1jbWo




Thursday, February 14, 2019

TVS MSP345 printer with Epson drivers

Using the TVS MSP345 printer with Epson 24-pin generic drivers on Linux, we need to use the resolution 360x180 - lower than that, the print quality is terrible, and higher than that, it just prints the print codes.

Monday, February 11, 2019

sending and receiving emails with domain aliases on GSuite

One of our units had two domains, longname.tld and shortname.tld - they asked if they would receive emails sent to user@shortname.tld which had been set up as a domain alias in GSuite. My reply - 

The above holds good for receiving emails from username@shortname.tld

If you wish to send emails from username@shortname.tld (as against username@longname.tld), you need to follow the procedure below by logging on to username@longname.tld 


  1. On your computer, open Gmail logged in as username@longname.tld .
  2. In the top right, click Settings Settings and then Settings.
  3. Click the Accounts and import or Accounts tab.
  4. In the "Send mail as" section, click Add another email address.
  5. There, enter username@sssvv.org
You also have an option to make whichever email you wish to have as the default sending email, just below that section.

Tuesday, February 05, 2019

modus operandi for processing audio files for rebroadcast

Made this list for the people at Studio, since I would no longer be processing mandir audio for rebroadcast -

1. Listen to the whole thing (if feasible at 2x speed, or at mandir itself, while the program is going on), mark problematic parts with markers.
2. If the program is a drama that contains copyrighted songs, edit out those songs within only 10-20 seconds.
3. If the program is of poor quality, like songs which are completely out of tune, do not process for broadcast.
4. If the program has speeches which are not of general interest, or which are not suitable for broadcast due to poor delivery, do not process for broadcast. If the speech is good, but marred by repetitive words like Ummmm / Aaaah / "You know" / "Like" etc, edit those out. Also edit out any gaps like speaker turning pages, speaker drinking water, etc. 
5. If it is a music program, try to cut into individual songs/announcements if possible. Filenames similar to historical filenames which you can see under MSV* and SV* in our local cdsearch page.
6. For speeches, I have been processing to remove noise as per this:
http://hnsws.blogspot.com/2010/01/tips-for-clean-audio.html or
http://hnsws.blogspot.com/2013/11/another-audio-cleanup-tool-chain-reaper.html

7. I have been skipping processing Telugu dramas for AsiaStream once TeluguStream started, so that if the Telugu team is interested, they can use for TeluguStream. Similarly now with Hindi team. 

Sunday, January 27, 2019

paying income tax on tax demand

I had made a mistake in income tax calculation and payment, and in the intimation sent by the Income Tax department, there was a demand to pay Rs. 230 as tax. The clickable link on the pdf did not work for me (since I was using Linux) with pdf readers Xreader and Google Chrome. So, googled and got the website
where there is a Pay Taxes online link.

The next links were deciphered using the Challan included in the pdf. Challan No. 280, so the relevant link for 280. Address as per PAN. Details of payment as per the Challan again, (no surcharges or penalties for me.) And as soon as the confirmation link is clicked, we get a downloadable receipt. Done. Painless.

Friday, January 11, 2019

malware/adware on our home page with BSNL router

When I opened our home page now from my room, I got an advertisement popup. 

Whichever link on our website I click, a pop-up appears.

No such popup on other sites. No such popup if I click on direct links, popups only if I click on javascript links like on our home page.

Also, no such popups when I use my phone as a hotspot and don't use the BSNL router.

There was recently an email from a user who also experienced this.

According to this blog post, this is some issue with BSNL?
As mentioned by this person, I put off and put on the BSNL router (reset the router), and the popups stopped.

Apparently, this malware/adware is being injected into any and all non-encrypted traffic. So, a good solution would be to upgrade to https.

Monday, December 24, 2018

low cost desktops for billing counter etc

An idea for low cost desktops for applications like billing counter etc - Found this,
https://eltechs.com/product/exagear-desktop/
for running Windows software on the Pi.

Cost of full fledged Pi system would be < Rs. 4000 including software and HDMI to VGA convertor which would enable use of old monitors.

Sunday, December 23, 2018

building Matlab-like gui programs on GNU Octave

I did not know about the gui capabilities of Octave - some old gui programs I had made with GUIDE on Matlab more than a decade ago had refused to run, so I thought it did not have that capability. But now I see that I only have to avoid nested functions - ie. sub-functions inside another function.

https://stackoverflow.com/questions/47298509/how-to-manually-convert-matlab-guide-gui-code-to-octave-ui-components

https://stackoverflow.com/questions/43519040/how-to-code-a-slider-in-octave-to-have-interactive-plot/43536882#43536882

A nice example -
https://github.com/octave-de/macgyver_utils/blob/master/demo_uicontrol.m

On Matlab, gui creation guide,
https://in.mathworks.com/videos/creating-a-gui-with-guide-68979.html



Tuesday, December 18, 2018

issue with server-hosted mp3 played on Android app

There was a query from one of our sister institutions about their Android app having issues playing audio from server1 but playing audio from server2 without problems.

For Audio files that are present in server2 we are able to download/stream, for all the android devices (including Android 4.4 version devices also) . But Audio files present in server1 is not downloading/streaming for few android devices (like Android 4.4 version devices etc). 

Links from both the servers are mentioned for your reference.
http://server1/path/1.mp3 (not working in all the devices) Same links we have tested for https also. 
http://server2/path/1.mp3  (working in all the devices)
Kindly suggest us how to go about this issue.

Excerpts from my reply:

The only difference I can see is that server1 is auto-redirecting to https
So, if the devices are not capable of handling https, [Edit: or http to https redirects] they will fail with server1.
 
server2 is not doing the auto-redirect to https - so, http works as-is on that server.

If the devices are capable of https, perhaps you can just give the https link instead of http link, so that the redirection is not required - in case the redirection is what is causing the failure.

Saturday, December 15, 2018

incomplete instructions - SBI debit card

SBI is updating their debit cards as per RBI mandate to chip-based cards, and I received a mailer with my updated card. Getting it to work was a bit of a struggle. 

1. First tried the 'send SMS, get one time PIN' method. Did not get any response. So, tried the next - Netbanking method. 

2. Set the first two digits of the PIN, AA, and then the next two digits BB are sent via SMS. Then AABB would be the PIN. 

Then, I received the one time PIN from step 1. So, that was probably the reason the card was declined when I tried to use it at the Canara bank ATM. 

Then, tried

3. Changing the PIN from SBI ATM - went to the SBI ATM early in the morning to avoid crowds. Used the Generate PIN from the first screen. That sent me a one time PIN. But apparently, that was for one-time use only. "You must change the PIN before use." But the change PIN menu item is not immediately obvious. For that,

4. Again swiped the card, used the one time PIN, went into Banking menu, and there, found the Change PIN option. Changed, now the card works. 

OpenCV CUDA performance comparisons

This query thread about slow CUDA performance
had an answer pointing to this interesting speed comparison post -


Wednesday, October 31, 2018

Google Apps error report and workaround

S sent me the following:

FYI, for future reference. 

Was trying to create a new email Id in Google Apps. 

Clicking on the 'Users' menu item in the Admin panel of Google Apps, repeatedly gave "Error 400, URL is not available error" described here. Tried the steps described there.  

Finally, I could get there and create the same only through the Plain-HTML Gmail interface. Nothing else worked.

Friday, October 26, 2018

google group permissions for Google Apps domain

Reply to a query from one of my colleagues, who had an issue with some users on a domain getting the message: "You only have read-only access to groups outside of your domain. Contact your domain administrator for more information."

(The actual domain names have been changed :)

Whoever is the admin for your whateveritwas.extension domain in Google Apps, has to enable access.

I believe that whateveritwas.extension was set as a domain alias for anotherdomain.com in Google Apps? I see an email thread where I suggested that this was a possibility. In that case, webmaster@anotherdomain.com would be the admin.

After logging on to webmaster@anotherdomain.com , go to the administrative console at
https://admin.google.com/Dashboard

According to this page,
https://productforums.google.com/forum/#!msg/apps/6wYszBdjuaI/W1cJcvxAf50J

"From the administrative console select the Organizations& Users tab, then click on Services. Scroll down to Google Groups and turn it on."

Wednesday, October 24, 2018

install EOS utility without CD

I seem to have misplaced the EOS Utility CD for the Canon 1100D camera I used in the lab. Tried this method to install for a student -

https://www.youtube.com/watch?v=VTLISryqbSc

Creating a registry key under
HKEY_LOCAL_MACHINE ->  Software ->  WOW6432Node
(Right-click, New -> Key)
Canon
(Right-click, New -> Key)
EOS Utility

This did not work for the latest version of EOS Utility, but did work for an earlier version. 

Thursday, October 04, 2018

flashing a custom ROM on a Samsung Galaxy Grand Quattro - i8552

A gave me a Samsung Galaxy Grand Quattro - model i8552, also known by many other names like Win Duos and so on -
https://www.gsmarena.com/samsung_galaxy_win_i8550-5392.php

This was for use at our exhibit of Universe2go.

The stock Samsung had Android 4.1, and Universe2go needed at least 4.2. So, I started on the journey to flash a custom ROM on the device. It took me 3-5 hours over 3-5 days because of conflicting instructions and things not going as planned. The things which delayed me turned out to be

  1. loose USB cable. A good fit for the USB cable, and a good cable, is a must before doing any flashing.
  2. lack of clear instructions on how exactly the buttons need to be pressed to go into download mode on this particular model, and terribly written instructions in general,
  3. and many broken links and links to paid file hosts. Downloaded files from androidfilehost.com instead, using the filenames given. 
Finally after I finished the process, found that universe2go is laggy on this device, so I won't be using this device after all. Documenting the method which worked - took less than fifteen minutes excluding time taken to download the ROM images - 

1. Downloaded TWRP recovery image,    

2. Downloaded the custom ROM, saved on the phone's SD card by moved it to the phone SD card using Airdroid. Can be either internal memory or extra SD card, doesn't matter. Could have downloaded on the phone directly also. (I tried these ROMs below - 
https://forum.xda-developers.com/grand-quattro/development/rom-trans-k-rom-transwin-v4-rom-t2912032
which is actually just a skin on the existing 4.1 kernel and wrongly reports as 4.4 - so universe2go does not run ...
and also lineageOS 13,
https://forum.xda-developers.com/grand-quattro/orig-development/rom-lineage-os-13-grand-quattro-t3541777
which crashes a lot. This one ran universe2go, but the screen refreshes were at 5 fps or so, not usable. Also tried this one,
https://forum.xda-developers.com/grand-quattro/orig-development/rom-carbon-rom-gt-i8552-delos3geur-t3628076
which says that the sensors work. But installing GApps causes crashes. GApps is supposed to be the version of the OS and ARM pico version - ie ARM 4.4 pico for this carbon, etc from opengapps.org . Also, it does not shut down cleanly. And universe2go crashes.)


3. Installed heimdall with
sudo apt-get install heimdall-flash heimdall-flash-frontend
On Windows, Odin is supposed to do the job, but was stumped by not seeing the device. Probably some driver install issue. 

4. Download the PIT file from the phone using heimdall, following the instructions at

Utilities tab, Download PIT, choose save as destination, Download. 

5. Power down the phone, wait 10-15 seconds to allow it to power down completely. Then boot into Download mode by continuously pressing Home + Vol Down + Power buttons, and when the phone vibrates, after it finishes vibrating, releasing the Power button, keeping the other two buttons pressed until the warning screen appears. (This part in bold is the technique which stumped me.) As the warning screen says, press Vol Up to go into Download mode. 

6.  Following the instructions in this link,
flash the TWRP img file downloaded in step 1 - 
Flash tab - choose the PIT file downloaded in the previous step - click Add - choose Recovery in the dropdown menu, choose No Reboot. Then start. 

7. A blue progress bar on the phone shows when the flashing is done - should take only 10 seconds or so once it starts. Then remove the battery, put it back. This would have installed the TWRP - Team Win Recovery Project - custom recovery software which would allow the flashing of custom (unsigned) ROMs. 

8. Now boot into Recovery by continuously pressing Home + Vol Up + Power buttons, and when the phone vibrates, after it finishes vibrating, releasing the Power button, keeping the other two buttons pressed until the TWRP screen appears. TWRP is easy to use, and has a touch interface.

9. Choose to Wipe (factory reset - this is generally safer, though not always necessary) and then Install - choosing the ROM downloaded in step 2. After the installer says it is done, remove the battery, put it back, and reboot. Done.

Will try to restore the stock ROM -
https://forum.xda-developers.com/showthread.php?t=2433941
and then maybe unroot etc,
https://forum.xda-developers.com/showthread.php?t=2494471

Edit: Finally restored stock ROM from

TransK ROM had play store and other apps crashes, maybe since it reports it is Android 4.4 in spite of being 4.1.

The actual sequence of steps I followed, with many missteps, was something like this -

(Samsung Galaxy Quattro 18552

1. Root with Framaroot

2. Update downloaded from

3. ADB all in one from

4. TWRP install via 

5. TWRP via recovery flashable link at

6. Installed TWRP Manager, then copied over recovery.img using airdroid, then using TWRP Manager, "recovered". 

7. Manager did not install TWRP, so using Flashify,
But Flashify not responding.

8. Installed CWM instead

9. Downloaded files from androidhost via google instead of the links in above.

10. (I was continuing to press the vol + power + home buttons after the vibrate also, hence phone was booting into normal mode)

11. Finally entered download mode with adb

12. Loose contact USB, problems. 

13. Driver issues on Windows with fastboot, so Linux.

14. just sudo apt-get install android-tools-adb android-tools-fastboot

15. lsusb shows Samsung

16.  adb devices showed
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
List of devices attached
71ba1f19    device

17. Then did via
adb method.
But again, waiting for device at fastboot flash

18. So, trying 

lsusb gave
Bus 002 Device 008: ID 04e8:6860 Samsung Electronics Co., Ltd Galaxy (MTP)

But still no fastboot.

19, Tried adding as per

adb works, fastboot waiting for device.

20. Try with android sdk install. Downloaded tools.

21. Trying this, 

lsusb in download mode gave different id
Bus 002 Device 011: ID 04e8:685d Samsung Electronics Co., Ltd GT-I9100 Phone [Galaxy S II] (Download mode)
Bus 002 Device 003: ID 046

Apparently, Samsung devices need heimdall and do not work with the fastboot tool.  

method worked to get into download mode, and get pit file.

23. heimdall

24. To boot into recovery, vol up + pow + home, leave pow when vibrates

25. from Twrp, selected install, and chose the trans-k rom. 

26/. Wipe cache/dalvik, as per

27. pull out battery, put it back, boot as normal. )

Edit: Some more trial and error in getting back to Stock ROM. See main section above for
assert error

downloaded stock from
But did not work with TWRP. Will probably need to use an external removable sdcard since I formatted the system partition and the device does not boot. 


Wednesday, August 29, 2018

correcting browser fonts on Ubuntu and related distros

On Linux Mint, Hindi fonts were not being displayed correctly by Chrome as well as Firefox. Apparently this was the solution -

https://askubuntu.com/questions/1008661/incorrect-rendering-display-of-devanagari-fonts-in-browsers-chrome-firefox-etc

On Firefox, in Preferences, Language and Appearance, changed default font to Lohit Devanagari

Friday, August 03, 2018

ease of use of Word vs LaTEX

I am now officially a convert to LaTEX. Using overleaf in particular. Pretty equations, citation management and changing of templates is really easy using bibtex.
https://blog.mendeley.com/2012/03/24/how-to-series-generate-bibtex-files-for-your-collections-for-use-in-latex-part-3-of-12/

Can easily get bibtex entries using Google scholar too.
https://texblog.org/2014/04/22/using-google-scholar-to-download-bibtex-citations/

Some manual corrections are needed.

With Microsoft Word, equations, citations, and almost everything else needs tweaks. There is a tendency to get mangled as the document goes from one collaborator to another with different versions of Word. For example, here is the long procedure for copy-pasting an equation!
https://answers.microsoft.com/en-us/msoffice/forum/msoffice_word-mso_other-mso_2010/copy-and-pasting-equations-between-word-2010-files/d3b3ab43-886b-e011-8dfc-68b599b31bf5

1. Select the equation > click on the dark bar on the right side with the little down-arrow at the bottom > Save as New Equation...

2. Name the equation > OK

3. Switch to the other document > click where you want to insert the equation

4. tab: Insert Equation v (click on the down-arrow!) > scroll to the bottom > click on your equation


To delete the equation from your list of frequently used equations when you no longer need it:

1. tab: Insert Equation v (click on the down-arrow!) > scroll to the bottom > right-click on your equation > Organize and Delete...

2. Building Blocks Organizer appears with your equation selected > DeleteYes Close.



Thursday, July 19, 2018

loudness with reaper - dB and RMS and LUFS

Found an interesting discussion on Reaper forums regarding RMS normalization to particular presets - https://forum.cockos.com/showthread.php?t=165331

In particular, the advice given by Michal is, "use actions from SWS.

SWS: Set RMS analysis/normalize options
Here you can set your RMS level target, it is one time operation..

SWS: Normalize items to overall peak RMS
You can select all items on the track and run this action for RMS normalization to predefined level.."

Of course, right now I'm not likely to try any of these...

Monday, July 09, 2018

troubleshooting streaming delay on Google Home device

While testing our Google Assistant action for our audio streams, SC reported that
 I'm still seeing ~100 second delays even on this stream on the Home device. On my phone/browser, it plays instantly.

I tried changing the burst-size but initially did not find any difference - 

64 kB  = 65535   = 100 sec delay - this is the default burst-size for icecast
128 kB = 131072  = 100 sec delay
256 kB = 262144  = 100 sec delay
512 kB = 524288  = 100 sec delay
1 MB   = 1048576 = 100 sec delay

Then it turned out that I was using a relay for testing, and on-demand was set to 1. After setting the relay's on-demand parameter to 0 (so that the relay is always ready and doesn't have to start after a new connection is made),  

128000 = started within 4 seconds!
64000  = 100 sec delay

Repeated this three times, waiting 100 sec + each time after restarting the server. Seems to work well with 128000. So, set this as the burst-size for all our streams. 

Sunday, July 08, 2018

Google Home Mini - a mini review

As long as you don't have inflated expectations, this device does a pretty good job. But my initial problem was that I had higher expectations from Google :)

Expectation - I thought "Google Home" should be able to do a google search, like
OK google, do a google search for callisthenics
Sorry, I don't understand.

Reality - the device needs the prompt "tell me about", or "what is" - like
OK google, tell me about callisthenics.
According to wikipedia, callisthenics is.... (the first sentence only.)

OK google, what is a meteorite?
etc.

OK google, tell me more about callisthenics.
Sorry, I don't know how to help with that yet.

So, it can't read more than the first sentence.

It can tell jokes and do trivia etc, as described in various posts elsewhere.

OK google, tell me a joke.
(it tells a different one-liner every time.)

It needs an exact match for playing radio stations. For example,
OK google, play all india radio on tunein
Sorry, artists aren't available on tunein.

OK google, play All India Radio Classical on tunein
Sure, here's All India Radio Classical on tunein - (plays immediately).

Unfortunately, the music player in the API seems to buffer for quite a while, so currently, if we do
OK google, ask Radiosai to play bhajans
Playing radiosai bhajanstream - (plays after 100 seconds!)
We will try to fix this. It appears this is fixed now, by increasing the burst-size to 128000 on our server.

The radiosai action is a work in progress, but currently, things like this work -
OK google, talk to Radiosai
Sairam, welcome to radiosai etc...
Search for Climate Change
It appears your current device does not have a screen, so here's the first result... etc
(plays immediately).

OK google, increase volume to 50%
works when radiosai or some other agent is not having context.

The touch interface on the device has recently been enabled. So, long touch on either side makes it pause or resume, a tap on the left side makes it reduce volume, and a tap on the right side makes it increase volume. This was not immediately obvious.

It can do more complicated things, but within a limited repertoire. For example,
OK google, tell me how to make idlis
(reads out ingredients and steps one by one, saying let me know when you want to continue, etc.)
OK google, continue
Nothing is playing at the moment
OK google, next ingredient
(reads out the next ingredient.)
OK google, next.
(reads out the next ingredient.)
OK google, next.
(Reads instructions one step at a time, we have to say next for the next step.)
OK google, previous step
(Reads the previous instruction)
(Asks if we want an alarm to be set for required time, etc.)

Apparently there's a 640 character limit for each interaction from the device. So, reading out a large page would need user interaction like the above series of steps for the recipe. Wikihow works in a similar way.

OK google, wikihow
Hi, how's it going?
Bake a cake.
Hi, how's it going?
Wiki how to bake a cake.
I didn't get that, can you tell me what you were looking to do one more time?
(never got it to work.)

It can play news, weather forecast etc. - OK google, how is my day?

And for those with home automation systems, it can be set up to put on lights, play something on the TV with Chromecast, and so on.

So, some people will like it, especially if they memorize the phrases needed for the device to do the required action. But others will be frustrated by it. Examples can be seen in the comments in the article below,


Edit - and here is a "comprehensive list which is periodically updated" from CNET, of all Google Home commands - https://www.cnet.com/how-to/google-home-complete-list-of-commands/

Tuesday, July 03, 2018

packet sniffing wifi

Packet sniffing on a wifi network is a bit more complicated than using a wired network and a hub. Promiscuous mode alone is not enough -

https://osqa-ask.wireshark.org/questions/61656/promiscuous-mode-not-working

https://wiki.wireshark.org/CaptureSetup/WLAN#Monitor_mode

Then the packets have to be decrypted.

https://wiki.wireshark.org/HowToDecrypt802.11

For that, if using WEP, the WEP password has to be converted to the Hexadecimal key -
http://corecoding.com/utilities/wep2hex.php

change Google Home mini wifi settings without Google Assistant app

Trying out a Google Home Mini device. For setup, it needs the Google Home App on an Android or iOS device. For changing certain settings, it needs Google Assistant to be enabled on your phone. Since my current phone runs an earlier Android version than 5.0 which is the least required for Google Assistant, I am unable to change language of the device, unable to change the voice, and so on. Even changing the wifi network needs a different procedure than the one listed on google support.

So, my procedure, found by trial and error, was:

1. Open the Google Home app
2. Tap on the devices icon on top right corner.
3. If there is a card which says "your speaker name" speaker needs setup, and a setup link, you can use that.
4. Else, click on your device name, if it is listed, and the three dots on top right.
5. Choose reboot.
6. From the list of linked devices, unlink the device for which wifi needs to be set up.
7. Tap the back button to go to the home screen of the Home app.
7. Then the app would say that it has found one device which is ready for setup.
8. Click through to set up, including linking to an account and wifi settings.
9. When using a wifi network which was previously configured, it does not ask for the wifi password again.


Friday, June 29, 2018

ITR2 - paying income tax

1. Using the java based ITR2 utility needs openjfx in addition to installing java etc - on Mint/Ubuntu, sudo apt-get install openjfx

2. PAN / TAN of deductor = PAN/TAN of employer

3. importing - pre-filling the form - takes longer than a minute on the Acer laptop, takes 10 seconds on the i7 machine.

4. The re-calculate button of the java utility is not the same as validation. On clicking Save, validation errors pop up. So, use 'Save' to validate, and 'Save draft' to save partially completed form.

5. For the first time, I needed to pay tax. Payment is via https://onlineservices.tin.egov-nsdl.com/etaxnew/tdsnontds.jsp , Challan 280 at the bottom of the page. Netbanking and Debit cards are accepted. The type of payment is Self Assessment Tax.

6. The Challan serial number and other details like date are available in the pdf made available to download from the SBI post-payment screen. These have to be entered in the ITR2 form under self assessment tax payment made, and then submitted.

5. The Aadhaar based verification of return did not work for me - said that service is not registered with UIDAI. The bank account based verification worked.

Friday, June 22, 2018

blender z axis flip

Just a quick recipe for flipping an object in Blender -

  • Select object
  • Ctrl A (for Apply)
  • Choose Scale
  • Enter Z scale as -1
  • Ensure that scale checkbox is ticked under apply.