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• Using ffmpeg to pipe Logitech C920 video to two outputs : re-encoded to RTMP stream and hardware-encoded to file

  18 décembre 2018, par Maros Hluska

  I’m trying to use ffmpeg to accept video from a Logitech C920 and broadcast it to an RTMP stream (e.g. Twitch). But there’s a twist : I would like to also save to file the original 1080p hardware-encoded video.

  So I would like to do both of these :

  1. Re-encode the input to 852x480 resolution and upload to an RTMP url with 1500 bitrate
  2. Save the original input to a file without re-encoding (C920 does hardware encoding with the h.264 codec)

  I’ve tried saving the video to file without re-encoding using the following :

  ffmpeg -s 1920x1080 -framerate 30 -pixel_format uyvy422 -vcodec h264 -f avfoundation -i 'HD Pro' -copyinkf -vcodec copy out.mp4

  This seems to almost work. The webcam light turns on and a few seconds of running this produces a massive file (1GB or so). However, I can’t seem to open the file with VLC. I do see a warning from ffmpeg :

  [AVBSFContext @ 0x7fbd4fc3e9c0] No start code is found.
  
  HD Pro: could not find codec parameters

  I’m on a Mac using ffmpeg 4.1.

  Edit :

  It seems the file that ffmpeg produces is not h264 encoded but rather raw pixel data. I’m starting to think that it’s not possible to set the webcam into the h264 mode with Mac (most other cases do it in Linux with v4l2).

  To anyone answering the question, I’d be happy with a solution that involves Linux as well. Especially if I can use a bootable live USB.

• Can you insert text from a file in real time with ffmpeg streaming ?

  6 décembre 2020, par Fight Fire With Fire

  I have this code i use to stream a file and place the name of the show of the video at a certain time of the video ( name_of_show ) at the top of the screen, and the bottom of the screen it take the name of the show from video_title.txt and places it on the bottom of the screen.

  


  What I want to do is find a way at a interval say 1 or 2 minutes, pull whatever text is currently in video_title.txt and place it in the video for a few seconds.

  


  I would update video_title.txt from another python program. Here's my current code below.

  


             command = [
        "ffmpeg" , "-re" , "-i" , video[0] ,
        "-vf" ,  "[in]drawtext=fontsize=40:fontcolor=white:box=1:boxcolor=black@0.8:boxborderw=5:fontfile=/home/fonts/timeless.ttf: text='" + name_of_show + "':x='W-(W+tw)*mod(t\,10)/10':y='H/20':enable='between(t,50,70)',drawtext=fontsize=20:fontfile=/home/fonts/timeless.ttf:textfile=/video_title.txt:fontcolor=white:box=1:boxcolor=black@0.8:boxborderw=5:x=W-w+5:y=h-th-50:enable='1'[out]"
        "-vcodec" , "libx264", "-pix_fmt", "yuv420p",
        "-preset" , "medium" , "-r" , "30" , "-g" , "48" , "-b:v" , "2500k" ,
        "-acodec" , "libmp3lame" , "-ar" , "44100", "-threads" , "6" ,
        "-q:a" , "3" , "-b:a" , "712000" ,"-bufsize", "512k" , "-f" ,
        "flv" , STREAM_URL,


  


  Ultimately the effect I am trying to achieve is a long stream of lets say 1 hour on twitch/youtube where someone could send a text message and it would appear in the stream.

  


• 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.