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• ffmpeg can't recognize an UDP stream

  30 décembre 2014, par yaapelsinko

  When executing

  ffmpeg -i udp://239.192.1.2:3456

  kind of command, ffmpeg seems not being able to read such stream. No metadata info, and no transcoding if appropriate commands given.

  My network layout is the following :

  Ubuntu Server (ffmpeg) <---> Windows Server (Wowza) <---> Multicast subnet

  Stream must come from Multicast subnet through Window Server. Windows is configured to route IGMP via RRAS service. When I launching ffmpeg on Ubuntu, I can monitor that appropriate reports are received by RRAS and UDP stream starts to flow from Windows-to-Multicast network interface. I wasn’t able to monitor Ubuntu-to-Windows network interface, though, because Ubuntu is actually a Hyper-V VM on that Windows Server. Something is preventing Wireshark from listening on virtual NICs. Windows Server also has third NIC to the Internet, but it doesn’t matter here. Stream itself is okay, it can be successfully played with VLC or transcoded by Wowza (all on Windows Server). It is encoded with MPEG2/MP3 codecs.

  If I restream the stream through Wowza (passing through or transcoding), then ffmpeg is able to ingest it from rstp ://windows-server-ip:1935/LiveApp/myStream.stream so that I see metadata report and can transcode it. But I want to get it directly from multicast.

  Is it ffmpeg can’t read directly from udp ? Or maybe I missed something in configuration ? How can I investigate it further and localize the problem ?

  Update : Well, when restreaming the stream via VLC right into Ubuntu server NIC, ffmpeg can grab it. There are another problems, though, but at least I see that ffmpeg receives something. So, IGMP routing is not working correctly.

  Here is what I’ve done when configuring it : Enabled RRAS service. Added IGMP protocol to IPv4 routing. Added pNIC and vNIC as interfaces. pNIC is in Proxy mode, vNIC is in Router mode.

  That way I can at least see : 1) new records in IGMP group table when someone is requesting IGMP membership, 2) UDP packets flooding pNIC multicast interface when request from vNIC is received. However, I can’t listen vNIC interface with Wireshark from guest or host by some reason so I don’t know if packets are actually reaching the player on VM. I assume they aren’t, because I can’t play it with VLC or ingest the stream by ffmpeg (but who knows, maybe it just can’t be played in Hyper-V ?).

  If both interfaces are in IGMP router mode, no UDP traffic can be detected.

• Vedanti and Max Sound vs. Google

  14 août 2014, par Multimedia Mike — Legal/Ethical

  Vedanti Systems Limited (VSL) and Max Sound Coporation filed a lawsuit against Google recently. Ordinarily, I wouldn’t care about corporate legal battles. However, this one interests me because it’s multimedia-related. I’m curious to know how coding technology patents might hold up in a real court case.

  Here’s the most entertaining complaint in the lawsuit :

  Despite Google’s well-publicized Code of Conduct — “Don’t be Evil” — which it explains is “about doing the right thing,” “following the law,” and “acting honorably,” Google, in fact, has an established pattern of conduct which is the exact opposite of its claimed piety.

  I wonder if this is the first known case in which Google has been sued over its long-obsoleted “Don’t be evil” mantra ?

  Researching The Plaintiffs
  
  I think I made a mistake by assuming this lawsuit might have merit. My first order of business was to see what the plaintiff organizations have produced. I have a strong feeling that these might be run of the mill patent trolls.

  VSL currently has a blank web page. Further, the Wayback Machine only has pages reaching back to 2011. The earliest page lists these claims against a plain black background (I’ve highlighted some of the more boisterous claims and the passages that make it appear that Vedanti doesn’t actually produce anything but is strictly an IP organization) :

  The inventions key :
  The patent and software reduced any data content, without compressing, up to a 97% total reduction of the data which also produces a lossless result. This physics based invention is often called the Holy Grail.

  Vedanti Systems Intellectual Property
  Our strategic IP portfolio is granted in all of the world’s largest technology development and use countries. A major value indemnification of our licensee products is the early date of invention filing and subsequent Issue. Vedanti IP has an intrinsic 20 year patent protection and valuation in royalties and licensing. The original data transmission art has no prior art against it.

  Vedanti Systems invented among other firsts, The Slice and Partitioning of Macroblocks within a RGB Tri level region in a frame to select or not, the pixel.

  Vedanti Systems invention is used in nearly every wireless chipset and handset in the world

  Our original pixel selection system revolutionized wireless handset communications. An example of this system “Slice” and “Macroblock Partitioning” is used throughout Satellite channel expansion, Wireless partitioning, Telecom – Video Conferencing, Surveillance Cameras, and 2010 developing Media applications.

  Vedanti Systems is a Semiconductor based software, applications, and IP Continuations Intellectual Property company.

  Let’s move onto the other plaintiff, Max Sound. They have a significantly more substantive website. They also have an Android app named Spins HD Audio, which appears to be little more than a music player based on the screenshots.

  Max Sound also has a stock ticker symbol : MAXD. Something clicked into place when I looked up their ticker symbol : While worth only a few pennies, it was worth a few more pennies after this lawsuit was announced, which might be one of the motivations behind the lawsuit.

  Here’s a trick I learned when I was looking for a new tech job last year : When I first look at a company’s website and am trying to figure out what they really do, I head straight to their jobs/careers page. A lot of corporate websites have way too much blathering corporatese that can be tough to cut through. But when I see what mix of talent and specific skills they are hoping to hire, that gives me a much better portrait of what the company does.

  The reason I bring this up is because this tech company doesn’t seem to have jobs/careers page.

  The Lawsuit
  The core complaint centers around Patent 7974339 : Optimized data transmission system and method. It was filed in July 2004 (or possibly as early as January 2002), issued in July 2011, and assigned (purchased ?) by Vedanti in May 2012. The lawsuit alleges that nearly everything Google has ever produced (or, more accurately, purchased) leverages the patented technology.

  The patent itself has 5 drawings. If you’ve ever seen a multimedia codec patent, or any whitepaper on a multimedia codec, you’ve seen these graphs before. E.g., “Raw pixels come in here -> some analysis happens here -> more analysis happens over here -> entropy coding -> final bitstream”. The text of a patent document isn’t meant to be particularly useful. I’ve tried to understand this stuff before and it never goes well. Skimming the text, I just see a blur of the words data, transmission, pixel, and matrix.

  So I read the complaint to try to figure out what this is all about. To summarize the storyline as narrated by the lawsuit, some inventors were unhappy with the state of video compression in 2001 and endeavored to create something better. So they did, and called it the VSL codec. This codec is so far undocumented on the MultimediaWiki, so it probably has yet to be seen “in the wild”. Good luck finding hard technical data on it now since searches for “VSL codec” are overwhelmed by articles about this lawsuit. Also, the original codec probably wasn’t called VSL because VSL is apparently an IP organization formed much later.

  Then, the protagonists of the lawsuit patented the codec. Then, years later, Google wanted to purchase a video codec that they could open source and use to supplant H.264.

  The complaint goes on to allege that in 2010, Google specifically contacted VSL to possibly license or acquire this mysterious VSL technology. Google was allegedly allowed to study the technology, eventually decided not to continue discussions, and shipped back the proprietary materials.

  Here’s where things get weird. When Google shipped back the materials, they allegedly shipped back a bunch of Post-It notes. The notes are alleged to contain a ton of incriminating evidence. The lawsuit claims that the notes contained such tidbits as :

  • Google was concerned that its infringement could be considered “recklessness” (the standard applicable to willful infringement) ;
  • Google personnel should “try” to destroy incriminating emails ;
  • Google should consider a “design around” because it was facing a “risk of litigation.”

  Actually, given Google’s acquisition of On2, I can totally believe that last one (On2’s codecs have famously contained a lot of weirdness which is commonly suspected to be attributable to designing around known patents).

  Anyway, a lot of this case seems to hinge on the authenticity of these Post-It notes :

  “65. The Post-It notes are unequivocal evidence of Google’s knowledge of the ’339 Patent and infringement by Defendants”

  I wish I could find a stock photo of a stack of Post-It notes in an evidence bag.

  I’ve worked at big technology companies. Big tech companies these days are very diligent about indoctrinating employees about IP liability issues. The reason this Post-It situation strikes me as odd is because the alleged contents of the notes basically outline everything the corporate lawyers tell you NOT to do.

  Analysis
  I’m trying to determine what specific algorithms and coding techniques. I guess I was expecting to see a specific claim that, “Our patent outlines this specific coding technique and here is unequivocal proof that Google A) uses the same technique, and B) specifically did so after looking at our patent.” I didn’t find that (well, a bit of part B, c.f., the Post-It note debacle), but maybe that’s not how these patent lawsuits operate. I’ve never kept up before.

  Maybe it’s just a patent troll. Maybe it’s for the stock bump. I’m expecting to see pump-n-dump stock spam featuring the stock symbol MAXD anytime now.

  I’ve never been interested in following a lawsuit case carefully before. I suddenly find myself wondering if I can subscribe to the RSS feed for this case ? Too much to hope for. But I found this item through Pando and maybe they’ll stay on top of it.

• Building ffmpeg libraries for third party usage

  23 mars 2023, par mikeProgrammer

  I am trying to create bindings for FFmpeg in Elixir programming language and would love to handle FFmpeg binaries for users of my library.

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  The whole flow is as follows :

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  1. Write some function definition in Elixir

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  2. Implement it in in C using ffmpeg libs

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  3. Compile C code as shared library

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  4. When running application, Erlang Virtual Machine will load my dynamic library

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  The question is how to compile and include ffmpeg libs in my shared lib so that users of my Elixir lib don't have to install any native dependencies.

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  Here is what I was trying :

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  1. Compile ffmpeg libs as shared ones. When my Elixir lib is compiling, it downloads precompiled ffmpeg archive, extracts its content and links to it when compiling native functions. I realized that this still won't work as ffmpeg shared libs depend on other shared libs that user has to install on their own.

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  2. Compile ffmpeg libs as static ones and include them in my native shared library using —whole-archive linker option. Here I am getting

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  /usr/bin/ld : ffmpeg_build/lib/libavcodec.a(vp9lpf_16bpp.o) : warning : relocation against ff_pw_1' in read-only section .text'&#xA;/usr/bin/ld : ffmpeg_build/lib/libavcodec.a(cavsdsp.o) : relocation R_X86_64_PC32 against symbol `ff_pw_5' can not be used when making a shared object ; recompile with -fPIC&#xA;/usr/bin/ld : final link failed : bad value&#xA;collect2 : error : ld returned 1 exit status

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  The command I am using

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  cc -fPIC -I/home/michal/.asdf/installs/erlang/25.1/erts-13.1/include -Iffmpeg_build/include -Ic_src/xav -shared -DXAV_DEBUG=1 c_src/xav/xav_nif.c c_src/xav/reader.c c_src/xav/utils.c -o /home/michal/Repos/xav/_build/test/lib/xav/priv/libxav.so -Lffmpeg_build/lib -Wl,--whole-archive -lavcodec -lswscale -lavutil -lavformat -Wl,--no-whole-archive


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  FFmpeg configuration

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  ./configure \
--prefix="$PWD/ffmpeg_build" \
--extra-cflags="-fPIC -I$PWD/ffmpeg_build/include" \
--extra-ldflags="-L$PWD/ffmpeg_build/lib" \
--enable-pic
--disable-programs


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  Does anything that I am trying to do make sense to you ?

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  When I am installing ffmpeg-libs package on Fedora, it depends on other shared libs that are automatically downlaoded but what I would love to achieve is to provide self-contained ffmpeg build that can be used in other shared libraries.

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