ffmpeg spacial cropping troubleshooting

ffmpeg is invoked to crop a .mp4 video of resolution 720X1366. Specifically the goal is crop out the first 212 rows of the video’s pixels:

ffmpeg -i Dwell-2019-09-19_13.23.14.mp4 -filter:v "crop=1366:556:1:213" Dwell_out.mp4 

An .mp4 file of zero bytes is returned along with

ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609 configuration: –prefix=/usr –extra-version=0ubuntu0.16.04.1 –build-suffix=-ffmpeg –toolchain=hardened –libdir=/usr/lib/x86_64-linux-gnu –incdir=/usr/include/x86_64-linux-gnu –cc=cc –cxx=g++ –enable-gpl –enable-shared –disable-stripping –disable-decoder=libopenjpeg –disable-decoder=libschroedinger –enable-avresample –enable-avisynth –enable-gnutls –enable-ladspa –enable-libass –enable-libbluray –enable-libbs2b –enable-libcaca –enable-libcdio –enable-libflite –enable-libfontconfig –enable-libfreetype –enable-libfribidi –enable-libgme –enable-libgsm –enable-libmodplug –enable-libmp3lame –enable-libopenjpeg –enable-libopus –enable-libpulse –enable-librtmp –enable-libschroedinger –enable-libshine –enable-libsnappy –enable-libsoxr –enable-libspeex –enable-libssh –enable-libtheora –enable-libtwolame –enable-libvorbis –enable-libvpx –enable-libwavpack –enable-libwebp –enable-libx265 –enable-libxvid –enable-libzvbi –enable-openal –enable-opengl –enable-x11grab –enable-libdc1394 –enable-libiec61883 –enable-libzmq –enable-frei0r –enable-libx264 –enable-libopencv libavutil 54. 31.100 / 54. 31.100 libavcodec 56. 60.100 / 56. 60.100 libavformat 56. 40.101 / 56. 40.101 libavdevice 56. 4.100 / 56. 4.100 libavfilter 5. 40.101 / 5. 40.101 libavresample 2. 1. 0 / 2. 1. 0 libswscale 3. 1.101 / 3. 1.101 libswresample 1. 2.101 / 1. 2.101 libpostproc 53. 3.100 / 53. 3.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from ‘Dwell-2019-09-19_13.23.14.mp4’: Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf56.40.101 Duration: 00:00:33.94, start: 0.001333, bitrate: 526 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1366×768 [SAR 1:1 DAR 683:384], 518 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: vorbis (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 0 kb/s (default) Metadata: handler_name : SoundHandler File ‘Dwell_out.mp4’ already exists. Overwrite ? [y/N] y [libx264 @ 0x1cd1600] using SAR=1/1 [libx264 @ 0x1cd1600] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 [libx264 @ 0x1cd1600] profile High, level 3.1 [libx264 @ 0x1cd1600] 264 – core 148 r2643 5c65704 – H.264/MPEG-4 AVC codec – Copyleft 2003-2015 – http://www.videolan.org/x264.html – options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00 [aac @ 0x1cd2560] The encoder ‘aac’ is experimental but experimental codecs are not enabled, add ‘-strict -2’ if you want to use it.

Where to begin troubleshooting?

sshfs troubleshooting: what would cause openssl to fail?

I believe sshfs requires an sftp server on the remote computer (router):

ipkg list_installed | grep -i sftp openssh-sftp-server - 5.9p1-1 - sftp-server only from a FREE version of the SSH protocol suite of network connectivity tools. 

The goal is to invoke sshfs to mount a remote directory:

sshfs user@mydomain.asuscomm.com:/mnt/CRUZERFIT16/directory/ /home/user/Documents/scpbox/ 

This sshfs setup was working correctly in May, however, a family member reset the router. sshfs returns an error:

remote host has disconnected total 0 

Attempt to remote sftp into router returned:

/opt/libexec/sftp-server: can't load library 'libcrypto.so.0.9.8' Connection closed 

ipkg list_installed | grep openssl returned:

openssl – 0.9.8v-2 – Openssl provides the ssl implementation in libraries libcrypto and libssl, and is needed by many other applications and librari

openssl successfully reinstalled on router:

ipkg -force-reinstall install  openssl 

and am now able to sftp & sshfs into target router. Not sure why openssl was unavailable before reinstalling. Is there a test command to determine if openssl is available for the sftp server?

Troubleshooting Firefox


I am suddenly unable to access websites from Firefox 68.0 on 16.04.

Chromium is able to access websites as the local router. Firefox is not able elicit a response from the router’s LAN IP address.


What additional tests can be performed to find the root cause of the problem?

Can one conclude the problem is isolated to Firefox?

Any good website or book for iOS troubleshooting? [on hold]

I’m a repair technician still learning iOS.

I know this question may seem improper, but I’m so fed up with having to research and test myself iOS to learn how it works that here it goes:

I’d be immensely grateful if anyone suggested to me a good book or website explaining iOS for technicians, illuminating on the secrets such as how to fix software or hardware issues of any kind a customer-facing technician may need. Something not to advanced please, I’m a just a repair tech not a developer.

Any help much welcome

Repeated Installation Failure on 19.04 and 18.04.2 – Troubleshooting advice?

For the first time in several years of using Ubuntu I’m completely failing to install on a couple of desktop PCs. They have identical specs, and both fail in similar ways so its highly unlikely its hardware failure. I’ve tried 19.04 and 18.04.2 LTS.

The installer fails on both from Live USB boot and from direct install. It fails due to random parts crashing at any point during the installer – the timezone picker crashes, the part which is making partitions fails, it fails with a random unknown error later in the process and tries to make an error report but crashes out completely during that phase. I can’t get any debugging information out.

I’ve tried disabling UEFI Secure Boot from BIOS and have gone through looking for any weird looking power savingfeatures in BIOS but I’m not really sure I’m looking for? I’ve formatted the disks with long format i.e. writing 0s just to make sure no weird partition problems from all the failed install attempts.

I’ve also tried two different USB sticks.

Any advice for where to look for errors or what to try switching off? Here is the hardware spec. Again I have two identical PCs both with this issue.

Processor (CPU) Intel® CoreTM i5 Six Core Processor i5-8500 (3.0GHz) 9MB Cache

Motherboard ASUS® H310M-A R2.0: Micro-ATX, DDR4, LGA1151, USB 3.1, SATA 6GBs

Memory (RAM) 16GB Corsair VENGEANCE DDR4 2400MHz

Graphics Card 2GB NVIDIA GEFORCE GT 1030

Troubleshooting X11 Forwarding after an SSH tunnel to an EC2 Instance

I am doing an SSH tunnel to an EC2 instance with the eventual goal of getting a working GUI of Stata.

I’ve done the SSH connection both through PuTTY and through just my CLI (Git Bash).

When I run xstata through my CLI I get an error message to define the Unix environment variable DISPLAY. I fix this error message by doing

export DISPLAY='IP:0.0' 

where IP is the IP address of my local computer.

Then, when I run xstata, nothing pops up and nothing is returned in my CLI. I get the same result after doing the SSH tunnel through PuTTY. With PuTTY, I set the display location to be localhost:0 (shown in the screenshot below). The screenshot below shows my PuTTY X11 Forwarding configuration.

PuTTY Configuration

I do have Xming and XLaunch installed on my local computer.

Any suggestions? I think the display location I am providing may be incorrect. All the different configurations I have tried based off docs and also feedback from others on the internet, such as localhost:0, IP:0, etc have not worked.

Troubleshooting 500 Internal Server Errors on IIS 8.5?

How does one tell the difference between an HTTP / HTTPS request that is failing in an ASP .NET Core application, and one that’s failing from an IIS mis-configuration?

Most of the time IIS and the ASP .NET Core have different logs, and the solution is often just to turn off HTTPS to figure out which is returning the error, but the error messages from IIS just seem to be along the lines of HTTP 500 Internal Server Error in the output of a W3C formatted log message, and they don’t specify anything deeper than that.

As far as I can tell, ASP .NET Core applications just sit behind IIS and requests/responses are kind of reverse proxied to the actual application.

I came across the following IIS configuration setting in which you can enable the tracing of failed requests, and it seems to specify that it will gladly log the deeper error messages as HTTP 500 Internal Server Error is mentioned at the bottom of that documentation, but I’m uncertain of this.

In-depth php script troubleshooting

Pardon, but I’m a bit of a programming noob.

I tweak my php script, then upload it to the web, then try testing it.

I include in my script a fopen command to open a log file, then I use a smattering of fwrite commands to check the contents of some variables after the script has run.

Is there a single command I can use in my script that will provide a comprehensive insight as to what my script is doing? I’m getting tired of writing dozens of fwrite’s… there’s got to be an easier way!


I need help troubleshooting my code for MergeSort and Merge

So I’ve been working on MergeSort for an Algorithm project, but I’ve ran into various problems when it comes to getting the code to sort the arrays. Whenever I generate a string and put it into MergeSort, it seems to just come out exactly the same. I want some help in finding where the mistake in my code is, why is it giving me this, and a solution with a simple, but good explanation.

Here’s what I’ve tried in the past: 1. I’ve tried to use return arr[0] instead of arr, but it throws me an error with it being unable to convert from int to int[]. 2. I’ve looked in my merge class and everything seems to be ok there. 3. I’ve discussed the issue with my teacher and he says that everything looks fine, but I know that there must be something wrong somewhere. 4. I’ve tried to remove return merge(arr1, arr2) but the system throws an error telling me I have to return something. 5. I’ve tried to print out the arrays individually, but it still shows no changes and is the exact same as the original string.

Merge Class:

private static int[] merge(int[] a, int[] b) {     int[] c = new int[a.length + b.length];     int counterA = 0;     int counterB = 0;     int counterC = 0;      while(counterA != a.length && counterB != b.length)     {       if(a[counterA] < b[counterB])       {         c[counterC] = a[counterA];         counterA++;         counterC++;       }        else       {         c[counterC] = b[counterB];         counterB++;         counterC++;       }     }      while(counterB == b.length && counterA != a.length)     {       c[counterC] = a[counterA];       counterA++;       counterC++;     }      while(counterA == a.length && counterB != b.length)     {       c[counterC] = b[counterB];       counterB++;       counterC++;     }      return c; } 

MergeSort Class:

public static int[] mergeSort(int[] arr) {      if(arr.length == 1)     {       return arr[0];     }      int[] arr1 = new int[arr.length / 2];     int[] arr2 = new int[arr.length - arr1.length];      for(int i = 0; i < arr1.length; i++)     {       arr1[i] = arr[i];     }      for(int i = 0; i < arr2.length; i++)     {       arr2[i] = arr[i + arr1.length];     }      arr1 = mergeSort(arr1);     arr2 = mergeSort(arr2);      return merge(arr1, arr2); } 

Because the array is randomly generated, an example would be this: 9, 1, 7, 5, 7, 2, 2, 9, 8, 9

The intended result should be this: 1, 2, 2, 5, 7, 7, 8, 9, 9, 9

However, this is what the output is instead: 9, 1, 7, 5, 7, 2, 2, 9, 8, 9 (The array comes out unchanged)

Pfsense OpenVPN Troubleshooting

I’m trying to setup a Pfsense OpenVPN tunnel and am running into issues. I’ve set these up several times without issue but this environment has unique constraints.

Currently I connect to the firewall and get an IP but am unable to ping across the tunnel. (Firewall rules are in place – here).

dev tun persist-tun persist-key cipher AES-128-CBC (HAVE TRIED WITH MULTIPLE CIPHERS) auth SHA256 tls-client client resolv-retry infinite remote XX.XX.XX.XX 1194 udp lport 0 verify-x509-name "Open-VPN-ServerCert" name auth-user-pass remote-cert-tls server 

The modem has 5 static IP’s and the OpenVPN will be running on one static IP, however, there is an existing Ubiquiti firewall running a l2tp VPN on another of the static IP’s. Is this a viable scenarios’s or will it interfere with Open-Vpn tunnel ? Do I need to to add sometime of special rule for routing or nat ?