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• Play Raspberry Pi h264 stream in C# app

  29 octobre 2016, par CoreMeltdown

  I have a Raspberry Pi board with dedicated camera that records video only in h264. I am looking for the best method to stream and play recorded video in real-time (as in, less than 1 sec delay) in c# windows forms app. The additional requirement is that such stream can be easily processed before displaying, for example for searching for objects on the image.

  Stuff I tried :

  - VLC server on raspi and VLC control in c# forms app <- simple solution, with RTSP, but has a serious flaw, which is a 3sec delay in image displayed. I couldn’t fix it with buffor size/options etc.

  - creating a socket on raspi with nc, receiving raw h264 data in c# and passing it to mplayer frontend <- If I simply start raspivid | nc and on the laptop nc | mplayer, i get exactly the results i want, the video i get is pretty much realtime, but the problem arises when i try to create mplayer frontend in c# and simulate the nc.exe. Maybe I’m passing the h264 data wrong (simply write them to stdin) or maybe something else.

  - using https://github.com/cisco/openh264 <- I compiled everything, but i can’t even get to decode sample vid.h264 i recorded on raspi with h264dec.exe, not to mention using it in c#.

  h264dec.exe vid.h264 out.yuv

  This produces 0bytes out.yuv file, while :

  h264dec.exe  vid.h264

  Gives me error message : "No input file specified in configuration file."

  - ffmpeg <- I implemented ffplay.exe playback in c# app but the lack of easy method to take screencaps etc. discouraged me to further investigate and develop.

  I’m not even sure whether I’m properly approaching the subject, so I’d be really thankful for every piece of advice I can get.

  EDIT
  Here is my ’working’ solution I am trying to implement in c#

  raspivid --width 400 --height 300 -t 9999999 --framerate 25 --output - | nc -l 5884
  
  
  
  nc ip_addr 5884 | mplayer -nosound -fps 100 -demuxer +h264es -cache 1024 -

  The key here is FPS 100, becuase then mplayer skips lag and plays the video it immediately receives with normal speed.
  The issue here is that I don’t know how to pass video data from socket into mplayer via c#, because I guess it is not done via stdin (already tried that).

• The First Problem

  19 janvier 2011, par Multimedia Mike — HTML5

  A few years ago, The Linux Hater made the following poignant observation regarding Linux driver support :

  Drivers are only just the beginning... But for some reason y’all like to focus on the drivers. You know why lusers do that ? Because it just happens to be the problem that people notice first.

  And so it is with the HTML5 video codec debate, re-invigorated in the past week by Google’s announcement of dropping native H.264 support in their own HTML5 video tag implementation. As I read up on the fiery debate, I kept wondering why people are so obsessed with this issue. Then I remembered the Linux Hater’s post and realized that the video codec issue is simply the first problem that most people notice regarding HTML5 video.

  I appreciate that the video codec debate has prompted Niedermayer to post on his blog once more. Otherwise, I’m just munching popcorn on the sidelines, amused and mildly relieved that the various factions are vociferously attacking each other rather than that little project I help with at work.

  Getting back to the "first problem" aspect— there’s so much emphasis on the video codec ; I wonder why no one ever, ever mentions word one about an audio codec. AAC is typically the codec that pairs with H.264 in the MPEG stack. Dark Shikari once mentioned that "AAC’s licensing terms are exponentially more onerous than H.264′s. If Google didn’t want to use H.264, they would sure as hell not want to use AAC." Most people are probably using "H.264" to refer to the entire MPEG/H.264/AAC stack, even if they probably don’t understand what all of those pieces mean.

  Anyway, The Linux Hater’s driver piece continues :

  Once y’all have drivers, the fight will move to the next layer up. And like I said, it’s a lot harder at that layer.

  A few months ago, when I wanted to post the WebM output of my new VP8 encoder and thought it would be a nice touch to deliver it via a video tag, I ignored the video codec problem (just encoded a VP8/WebM file) only to immediately discover a problem at a different layer— specifically, embedding a file using a video tag triggers a full file download when the page is loaded, which is unacceptable from end user and web hosting perspectives. This is a known issue but doesn’t get as much attention, I guess because there are bigger problems to solve first (c.f. video codec issue).

  For other issues, check out the YouTube blog’s HTML5 post or Hulu’s post that also commented on HTML5. Issues such as video streaming flexibility, content protection, fullscreen video, webcam/microphone input, and numerous others are rarely mentioned in the debates. Only "video codec" is of paramount importance.

  But I’m lending too much weight to the cacophony of a largely uninformed internet debate. Realistically, I know there are many talented engineers down in the trenches working to solve at least some of these problems. To tie this in with the Linux driver example, I’m consistently stunned these days regarding how simple it is to get Linux working on a new computer— most commodity consumer hardware really does just work right out of the box. Maybe one day, we’ll wake up and find that HTML5 video has advanced to the point that it solves all of the relevant problems to make it the simple and obvious choice for delivering web video in nearly all situations.

  It won’t be this year.

• Concatenate / Join MP4 files using ffmpeg and windows command line batch NOT LINUX

  17 juillet 2014, par julesverne

  I’ve written a batch script that attempts to take a generic introductory title video (MP4) that runs for 12 seconds and attaches it to the beginning of 4 other MP4 videos (same video but each has a different language audio track)

  According to ffmpeg syntax here : http://ffmpeg.org/trac/ffmpeg/wiki/How%20to%20concatenate%20%28join,%20merge%29%20media%20files the concat demuxer needs to be run from a text file that looks like this :

  # this is a comment
  
  file '/path/to/file1'
  
  file '/path/to/file2'
  
  file '/path/to/file3'

  I believe everything in my script up until the point of joining the files appears to be working correctly. But I get this error :

  [concat @ 04177d00] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\frenchfile.mp4'
  
  filelistFrench.txt: Invalid data found when processing input
  
  [concat @ 03b70a80] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\spanishfile.mp4'
  
  filelistSpanish.txt: Invalid data found when processing input
  
  [concat @ 0211b960] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\basquefile.mp4'
  
  filelistBasque.txt: Invalid data found when processing input
  
  [concat @ 03a20a80] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\Englishfile.mp4'
  
  filelistEnglish.txt: Invalid data found when processing input

  I believe the issue lies in the text file I’m creating. Please excuse my n00b ignorance, but sometimes new script makers like myself get confused about developer jargon and may take things literally.

  So when I look at that example text file they gave, am I correct in thinking THIS is what my text file should look like ?

  # this is a comment
  
  Titlefile.mp4 'C:\Users\Joe\1May\session3\readyforfinalconversion\Titlefile.mp4'
  
  Englishfile.mp4 'C:\Users\Joe\1May\session3\readyforfinalconversion\Englishfile.mp4'

  Again, am I being too literal ? are the quotations correct ? Are the slashes correct ? In the example they provide the slashes in the path are / instead of normal windows \ . I’ll provide the entire script in case it helps.

  @echo off
  
  
  
  setlocal EnableDelayedExpansion
  
  
  
  rem Create an array of languages
  
  set i=0
  
  for %%a in (French Spanish Basque English) do (
  
     set /A i+=1
  
     set term[!i!]=%%a
  
  )
  
  
  
  rem Get the title video file name from user
  
  
  
  set /p titlevideofilename=What is the title video file 
  
  
  
  name?
  
  
  
  rem create a path variable for the title video file
  
  
  
  set pathtotitlevideo=%~dp0%titlevideofilename%
  
  
  
  rem Get the names of the different language video files to append to the title video
  
  rem create a path variable for each different language video files
  
  
  
  for /L %%i in (1,1,4) do (
  
     set /p language[%%i]=what is the name of the !term
  
  
  
  [%%i]! file you want to append after the title video?
  
     set pathtofile[%%i]=%~dp0!language[%%i]!
  
  )
  
  
  
  rem create data file for ffmpeg based on variable data
  
  
  
  for /L %%i in (1,1,4) do (
  
      echo # this is a comment>>filelist!term[%
  
  
  
  %i]!.txt
  
      echo file '%pathtotitlevideo%'>>filelist!term[%
  
  
  
  %i]!.txt
  
      echo file '!pathtofile[%%i]!'>>filelist!term[%
  
  
  
  %i]!.txt
  
  )
  
  
  
  cls
  
  
  
  rem join files using ffmpeg concat option
  
  
  
  for /L %%i in (1,1,4) do (
  
     c:\ffmpeg\ffmpeg\bin\ffmpeg.exe -loglevel error -f 
  
  
  
  concat -i filelist!term[%%i]!.txt -c copy !language[%
  
  
  
  %i]!.!term[%%i]!.withtitle.mp4
  
  )
  
  
  
  endlocal
  
  
  
  :eof
  
  exit

  EDIT
  Thanks to @foxidrive making me look at the simplicity of it... it occurred to me that Apparently I wasn’t being literal enough. I made these 3 changes and script works perfectly now
  1 : "file" in there example literally meant the word "file"
  2 : needed the use of single quotes not double quotes as it shows in there example.
  3 : Used "\" instead of "/" as they have in there example.

  So NOW my code to create the text files looks like this :

  rem create data file for ffmpeg based on variable data
  
  
  
  for /L %%i in (1,1,4) do (
  
      echo # this is a comment>>filelist!term[%
  
  
  
  %i]!.txt
  
      echo file '%pathtotitlevideo%'>>filelist!term[%
  
  
  
  %i]!.txt
  
      echo file '!pathtofile[%%i]!'>>filelist!term[%
  
  
  
  %i]!.txt
  
  )

  So NOW my text file looks like this :

  # this is a comment    
  
  file 'C:\Users\Joe\1May\session3\readyforfinalconversion\Titlefile.mp4'
  
  file 'C:\Users\Joe\1May\session3\readyforfinalconversion\Englishfile.mp4'