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• Split video with ffmpeg with specific conditions

  15 juin 2023, par Mahdi

  I have some videos and I want to split them into 15 min each with FFmpeg with the following conditions :

  


  

  1. Final videos should be less than 15 min

  


  2. Script should cut the video somewhere that speaker is not talking. For example, script should cut video on the following point :

  


  


  

  


  And it should not cut videos like the following :


  


  This article could working for the first condition, but the second option is missed.

  


  python ffmpeg-split.py -f big_video_file.mp4 -s 10


  


• My SBC Collection

  31 décembre 2023, par Multimedia Mike — General

  Like many computer nerds in the last decade, I have accumulated more than a few single-board computers, or “SBCs”, which are small computers based around a system-on-a-chip (SoC) that nearly always features an ARM CPU at its core. Surprisingly few of these units are Raspberry Pi units, though that brand has come to exemplify and dominate the product category.

  Also, as is the case for many computer nerds, most of these SBCs lay fallow for years at a time. Equipped with an inexpensive lightbox that I procured in the last year, I decided I could at least create glamour shots of various units and catalog them in a blog post.

  While Raspberry Pi still enjoys the most mindshare far and away, and while I do have a few Raspberry Pi units in my inventory, I have always been a bigger fan of the ODROID brand, which works with convenient importers around the world (in the USA, I can vouch for Ameridroid, to whom I’ve forked over a fair amount of cash for these computing toys).

  As mentioned, Raspberry Pi undisputedly has the most mindshare of all these SBC brands and I often wonder why… and then I immediately remind myself that it has the biggest ecosystem, and has a variety of turnkey projects and applications (such as Pi-hole and PiVPN) that promise a lower barrier to entry — as well as a slightly lower price point — than some of these other options. ODROID had a decent ecosystem for awhile, especially considering the monthly ODROID Magazine, though that ceased publication in July 2020. The Raspberry Pi and its variants were famously difficult to come by due to the global chip shortage from 2021-2023. Meanwhile, I had no trouble procuring these boards during the same timeframe.

  So let’s delve into the collection…
  

  Cubieboard
  The Raspberry Pi came out in 2012 and by 2013 I was somewhat coveting one to hack on. Finally ! An accessible ARM platform to play with. I had heard of the BeagleBoard for years but never tried to get my hands on one. I was thinking about taking the plunge on a new Raspberry Pi, but a colleague told me I should skip that and go with this new hotness called the Cubieboard, based on an Allwinner SoC. The big value-add that this board had vs. a Raspberry Pi was that it had a SATA adapter. Although now that it has been a decade, it only now occurs to me to quander whether it was true SATA or a USB-to-SATA bridge. Looking it up now, I’m led to believe that the SoC supported the functionality natively.

  Anyway, I did get it up and running but never did much with it, thus setting the tone for future SBC endeavors. No photos because I gave it to another tech enthusiast years ago, whose SBC collection dwarfs my own.

  ODROID-XU4
  I can’t recall exactly when or how I first encountered the ODROID brand. I probably read about it on some enthusiast page or another circa 2014 and decided to try one out. I eventually acquired a total of 3 of these ODROID-XU4 units, each with a different case, 1 with a fan and 2 passively-cooled :

  

  Collection of ODROID-XU4 SBCs

  This is based on the Samsung Exynos 5422 SoC, the same series as was used in their Note 3 phone released in 2013. It has been a fun chip to play with. The XU4 was also my first introduction to the eMMC storage solution that is commonly supported on the ODROID SBCs (alongside micro-SD). eMMC offers many benefits over SD in terms of read/write speed as well as well as longevity/write cycles. That’s getting less relevant these days, however, as more and more SBCs are being released with direct NVMe SSD support.

  I had initially wanted to make a retro-gaming device built on this platform (see the handheld section later for more meditations on that). In support of this common hobbyist goal, there is this nifty case XU4 case which apes the aesthetic of the Nintendo N64 :

  

  ODROID-XU4 N64-style case

  It even has a cool programmable LCD screen. Maybe one day I’ll find a use for it.

  For awhile, one of these XU4 units (likely the noisy, fan-cooled one) was contributing results to the FFmpeg FATE system.

  While it features gigabit ethernet and a USB3 port, I once tried to see if I could get 2 Gbps throughput with the unit using a USB3-gigabit dongle. I had curious results in that the total amount of traffic throughput could never exceed 1 Gbps across both interfaces. I.e., if 1 interface was dealing with 1 Gbps and the other interface tried to run at 1 Gbps, they would both only run at 500 Mbps. That remains a mystery to me since I don’t see that limitation with Intel chips.

  Still, the XU4 has been useful for a variety of projects and prototyping over the years.

  ODROID-HC2 NAS
  I find that a lot of my fellow nerds massively overengineer their homelab NAS setups. I’ll explore this in a future post. For my part, people tend to find my homelab NAS solution slightly underengineered. This is the ODROID-HC2 (the “HC” stands for “Home Cloud”) :

  

  ODROID-HC2 NAS

  It has the same guts as the ODROID-XU4 except no video output and the USB3 function is leveraged for a SATA bridge. This allows you to plug a SATA hard drive directly into the unit :

  

  ODROID-HC2 NAS uncovered

  Believe it or not, this has been my home NAS solution for something like 6 or 7 years now– I don’t clearly remember when I purchased it and put it into service.

  But isn’t this sort of irresponsible ? What about a failure of the main drive ? That’s why I have an external drive connected for backing up the most important data via rsync :

  

  ODROID-HC2 NAS backup enclosure

  The power consumption can’t be beat– Profiling for a few weeks of average usage worked out to 4.5 kWh for the ODROID-HC2… per month.

  ODROID-C2
  I was on a kick of ordering more SBCs at one point. This is the ODROID-C2, equipped with a 64-bit Amlogic SoC :

  

  ODROID-C2

  I had this on the FATE farm for awhile, performing 64-bit ARM builds (vs. the XU4’s 32-bit builds). As memory serves, it was unreliable and would occasionally freeze up.

  Here is a view of the eMMC storage through the bottom of the translucent case :

  

  Bottom of ODROID-C2 with view of eMMC storage

  ODROID-N2+
  Out of all my ODROID SBCs, this is the unit that I long to “get back to” the most– the ODROID-N2+ :

  

  ODROID-N2+

  Very capable unit that makes a great little desktop. I have some projects I want to develop using it so that it will force me to have a focused development environment.

  Raspberry Pi
  Eventually, I did break down and get a Raspberry Pi. I had a specific purpose in mind and, much to my surprise, I have stuck to it :

  

  Original Raspberry Pi

  I was using one of the ODROID-XU4 units as a VPN gateway. Eventually, I wanted to convert the XU4 to something else and I decided to run the VPN gateway as an appliance on the simplest device I could. So I procured this complete hand-me-down unit from eBay and went to work. This was also the first time I discovered the DietPi distribution and this box has been in service running Wireguard via PiVPN for many years.

  I also have a Raspberry Pi 3B+ kicking around somewhere. I used it as a Steam Link device for awhile.

  SOPINE + Baseboard
  Also procured when I was on this “let’s buy random SBCs” kick. The Pine64 SOPINE is actually a compute module that comes in the form factor of a memory module.

  

  Pine64 SOPINE Compute Module

  Back to using Allwinner SoCs. In order to make this thing useful, you need to place it in something. It’s possible to get a mini-ITX form factor board that can accommodate 7 of these modules. Before going to that extreme, there is this much simpler baseboard which can also use eMMC for storage.

  

  Baseboard with SOPINE, eMMC, and heat sinks

  I really need to find an appropriate case for this one as it currently performs its duty while sitting on an anti-static bag.

  NanoPi NEO3
  I enjoy running the DietPi distribution on many of these SBCs (as it’s developed not just for Raspberry Pi). I have also found their website to be a useful resource for discovering new SBCs. That’s how I found the NanoPi series and zeroed in on this NEO3 unit, sporting a Rockchip SoC, and photographed here with some American currency in order to illustrate its relative size :

  

  NanoPi NEO3

  I often forget about this computer because it’s off in another room, just quietly performing its assigned duty.

  MangoPi MQ-Pro
  So far, I’ve heard of these fruits prepending the Greek letter pi for naming small computing products :

  • Raspberry – the O.G.
  • Banana – seems to be popular for hobbyist router/switches
  • Orange
  • Atomic
  • Nano
  • Mango

  Okay, so the AtomicPi and NanoPi names don’t really make sense considering the fruit convention.

  Anyway, the newest entry is the MangoPi. These showed up on Ameridroid a few months ago. There are 2 variants : the MQ-Pro and the MQ-Quad. I picked one and rolled with it.

  

  MangoPi MQ-Pro pieces arrive

  When it arrived, I unpacked it, assembled the pieces, downloaded a distro, tossed that on a micro-SD card, connected a monitor and keyboard to it via its USB-C port, got the distro up and running, configured the wireless networking with a static IP address and installed sshd, and it was ready to go as a headless server for an edge application.

  

  MangoPi MQ-Pro components, ready for assembly

  The unit came with no instructions that I can recall. After I got it set up, I remember thinking, “What is wrong with me ? Why is it that I just know how to do all of this without any documentation ?”

  

  MangoPi MQ-Pro in first test

  Only after I got it up and running and poked around a bit did I realize that this SBC doesn’t have an ARM SoC– it’s a RISC-V SoC. It uses the Allwinner D1, so it looks like I came full circle back to Allwinner.

  

  MangoPi MQ-Pro with more US coinage for scale

  So I now have my first piece of RISC-V hobbyist kit, although I learned recently from Kostya that it’s not that great for multimedia.

  Handheld Gaming Units
  The folks at Hardkernel have also produced a series of handheld retro-gaming devices called ODROID-GO. The first one resembled the original Nintendo Game Boy, came as a kit to be assembled, and emulated 5 classic consoles. It also had some hackability to it. Quite a cool little device, and inexpensive too. I have since passed it along to another gaming enthusiast.

  Later came the ODROID-GO Advance, also a kit, but emulating more devices. I was extremely eager to get my hands on this since it could emulate SNES in addition to NES. It also features a headphone jack, unlike the earlier model. True to form, after I received mine, it took me about 13 months before I got around to assembling it. After that, the biggest challenge I had was trying to find an appropriate case for it.

  

  ODROID-GO Advance with case and headphones

  Even though it may try to copy the general aesthetic and form factor of the Game Boy Advance, cases for the GBA don’t fit this correctly.

  Further, Hardkernel have also released the ODROID-GO Super and Ultra models that do more and more. The Advance, Super, and Ultra models have powerful SoCs and feature much more hackability than the first ODROID-GO model.

  I know that the guts of the Advance have been used in other products as well. The same is likely true for the Super and Ultra.

  Ultimately, the ODROID-GO Advance was just another project I assembled and then set aside since I like the idea of playing old games much more than actually doing it. Plus, the fact has finally crystalized in my mind over the past few years that I have never enjoyed handheld gaming and likely will never enjoy handheld gaming, even after I started wearing glasses. Not that I’m averse to old Game Boy / Color / Advance games, but if I’m going to play them, I’d rather emulate them on a large display.

  The Future
  In some of my weaker moments, I consider ordering up certain Banana Pi products (like the Banana Pi BPI-R2) with a case and doing my own router tricks using some open source router/firewall solution. And then I remind myself that my existing prosumer-type home router is doing just fine. But maybe one day…

  The post My SBC Collection first appeared on Breaking Eggs And Making Omelettes.

• Reverse Engineering Italian Literature

  1er juillet 2014, par Multimedia Mike — Reverse Engineering

  Some time ago, Diego “Flameeyes” Pettenò tried his hand at reverse engineering a set of really old CD-ROMs containing even older Italian literature. The goal of this RE endeavor would be to extract the useful literature along with any structural metadata (chapters, etc.) and convert it to a more open format suitable for publication at, e.g., Project Gutenberg or Archive.org.

  Unfortunately, the structure of the data thwarted the more simplistic analysis attempts (like inspecting for blocks of textual data). This will require deeper RE techniques. Further frustrating the effort, however, is the fact that the binaries that implement the reading program are written for the now-archaic Windows 3.1 operating system.

  In pursuit of this RE goal, I recently thought of a way to glean more intelligence using DOSBox.

  Prior Work
  There are 6 discs in the full set (distributed along with 6 sequential issues of a print magazine named L’Espresso). Analysis of the contents of the various discs reveals that many of the files are the same on each disc. It was straightforward to identify the set of files which are unique on each disc. This set of files all end with the extension “LZn”, where n = 1..6 depending on the disc number. Further, the root directory of each disc has a file indicating the sequence number (1..6) of the CD. Obviously, these are the interesting targets.

  The LZ file extensions stand out to an individual skilled in the art of compression– could it be a variation of the venerable LZ compression ? That’s actually unlikely because LZ — also seen as LIZ — stands for Letteratura Italiana Zanichelli (Zanichelli’s Italian Literature).

  The Unix ‘file’ command was of limited utility, unable to plausibly identify any of the files.

  Progress was stalled.

  Saying Hello To An Old Frenemy
  I have been showing this screenshot to younger coworkers to see if any of them recognize it :

  
  
  

  Not a single one has seen it before. Senior computer citizen status : Confirmed.

  I recently watched an Ancient DOS Games video about Windows 3.1 games. This episode showed Windows 3.1 running under DOSBox. I had heard this was possible but that it took a little work to get running. I had a hunch that someone else had probably already done the hard stuff so I took to the BitTorrent networks and quickly found a download that had the goods ready to go– a directory of Windows 3.1 files that just had to be dropped into a DOSBox directory and they would be ready to run.

  Aside : Running OS software procured from a BitTorrent network ? Isn’t that an insane security nightmare ? I’m not too worried since it effectively runs under a sandboxed virtual machine, courtesy of DOSBox. I suppose there’s the risk of trojan’d OS software infecting binaries that eventually leave the sandbox.

  Using DOSBox Like ‘strace’
  strace is a tool available on some Unix systems, including Linux, which is able to monitor the system calls that a program makes. In reverse engineering contexts, it can be useful to monitor an opaque, binary program to see the names of the files it opens and how many bytes it reads, and from which locations. I have written examples of this before (wow, almost 10 years ago to the day ; now I feel old for the second time in this post).

  Here’s the pitch : Make DOSBox perform as strace in order to serve as a platform for reverse engineering Windows 3.1 applications. I formed a mental model about how DOSBox operates — abstracted file system classes with methods for opening and reading files — and then jumped into the source code. Sure enough, the code was exactly as I suspected and a few strategic print statements gave me the data I was looking for.

  Eventually, I even took to running DOSBox under the GNU Debugger (GDB). This hasn’t proven especially useful yet, but it has led to an absurd level of nesting :

  
  
  

  The target application runs under Windows 3.1, which is running under DOSBox, which is running under GDB. This led to a crazy situation in which DOSBox had the mouse focus when a GDB breakpoint was triggered. At this point, DOSBox had all desktop input focus and couldn’t surrender it because it wasn’t running. I had no way to interact with the Linux desktop and had to reboot the computer. The next time, I took care to only use the keyboard to navigate the application and trigger the breakpoint and not allow DOSBox to consume the mouse focus.

  New Intelligence
  
  By instrumenting the local file class (virtual HD files) and the ISO file class (CD-ROM files), I was able to watch which programs and dynamic libraries are loaded and which data files the code cares about. I was able to narrow down the fact that the most interesting programs are called LEGGENDO.EXE (‘reading’) and LEGGENDA.EXE (‘legend’ ; this has been a great Italian lesson as well as RE puzzle). The first calls the latter, which displays this view of the data we are trying to get at :

  
  
  

  When first run, the program takes an interest in a file called DBBIBLIO (‘database library’, I suspect) :

  === Read(’LIZ98\DBBIBLIO.LZ1’) : req 337 bytes ; read 337 bytes from pos 0x0
  === Read(’LIZ98\DBBIBLIO.LZ1’) : req 337 bytes ; read 337 bytes from pos 0x151
  === Read(’LIZ98\DBBIBLIO.LZ1’) : req 337 bytes ; read 337 bytes from pos 0x2A2
  [...]
  

  While we were unable to sort out all of the data files in our cursory investigation, a few things were obvious. The structure of this file looked to contain 336-byte records. Turns out I was off by 1– the records are actually 337 bytes each. The count of records read from disc is equal to the number of items shown in the UI.

  Next, the program is interested in a few more files :

  *** isoFile() : ’DEPOSITO\BLOKCTC.LZ1’, offset 0x27D6000, 2911488 bytes large
  === Read(’DEPOSITO\BLOKCTC.LZ1’) : req 96 bytes ; read 96 bytes from pos 0x0
  *** isoFile() : ’DEPOSITO\BLOKCTX0.LZ1’, offset 0x2A9D000, 17152 bytes large
  === Read(’DEPOSITO\BLOKCTX0.LZ1’) : req 128 bytes ; read 128 bytes from pos 0x0
  === Seek(’DEPOSITO\BLOKCTX0.LZ1’) : seek 384 (0x180) bytes, type 0
  === Read(’DEPOSITO\BLOKCTX0.LZ1’) : req 256 bytes ; read 256 bytes from pos 0x180
  === Seek(’DEPOSITO\BLOKCTC.LZ1’) : seek 1152 (0x480) bytes, type 0
  === Read(’DEPOSITO\BLOKCTC.LZ1’) : req 32 bytes ; read 32 bytes from pos 0x480
  === Read(’DEPOSITO\BLOKCTC.LZ1’) : req 1504 bytes ; read 1504 bytes from pos 0x4A0
  [...]

  Eventually, it becomes obvious that BLOKCTC has the juicy meat. There are 32-byte records followed by variable-length encoded text sections. Since there is no text to be found in these files, the text is either compressed, encrypted, or both. Some rough counting (the program seems to disable copy/paste, which thwarts more precise counting), indicates that the text size is larger than the data chunks being read from disc, so compression seems likely. Encryption isn’t out of the question (especially since the program deems it necessary to disable copy and pasting of this public domain literary data), and if it’s in use, that means the key is being read from one of these files.

  Blocked On Disassembly
  So I’m a bit blocked right now. I know exactly where the data lives, but it’s clear that I need to reverse engineer some binary code. The big problem is that I have no idea how to disassemble Windows 3.1 binaries. These are NE-type executable files. Disassemblers abound for MZ files (MS-DOS executables) and PE files (executables for Windows 95 and beyond). NE files get no respect. It’s difficult (but not impossible) to even find data about the format anymore, and details are incomplete. It should be noted, however, the DOSBox-as-strace method described here lends insight into how Windows 3.1 processes NE-type EXEs. You can’t get any more authoritative than that.

  So far, I have tried the freeware version of IDA Pro. Unfortunately, I haven’t been able to get the program to work on my Windows machine for a long time. Even if I could, I can’t find any evidence that it actually supports NE files (the free version specifically mentions MZ and PE, but does not mention NE or LE).

  I found an old copy of Borland’s beloved Turbo Assembler and Debugger package. It has Turbo Debugger for Windows, both regular and 32-bit versions. Unfortunately, the normal version just hangs Windows 3.1 in DOSBox. The 32-bit Turbo Debugger loads just fine but can’t load the NE file.

  I’ve also wondered if DOSBox contains any advanced features for trapping program execution and disassembling. I haven’t looked too deeply into this yet.

  Future Work
  NE files seem to be the executable format that time forgot. I have a crazy brainstorm about repacking NE files as MZ executables so that they could be taken apart with an MZ disassembler. But this will take some experimenting.

  If anyone else has any ideas about ripping open these binaries, I would appreciate hearing them.

  And I guess I shouldn’t be too surprised to learn that all the literature in this corpus is already freely available and easily downloadable anyway. But you shouldn’t be too surprised if that doesn’t discourage me from trying to crack the format that’s keeping this particular copy of the data locked up.