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• multithreaded client/server listener using ffmpeg to record video

  29 janvier 2014, par user1895639

  I've got a python project where I need to trigger start/stop of two Axis IP cameras using ffmpeg. I've gotten bits and pieces of this to work but can't put the whole thing together. A "listener" program runs on one machine that can accept messages from other machines to start and stop recordings.

  The listener responds to two commands only :

  START v :/video_dir/myvideo.mov
  STOP

  The START command is followed by the full path of a video file that it will record.
  When receiving a STOP command, the video recording should stop.

  I am using ffmpeg to attach to cameras, and manually doing this works :

  ffmpeg.exe -i rtsp ://cameraip/blah/blah -vcodec copy -acodec copy -y c :\temp\output.mov

  I can attach to the stream and upon hitting 'q' I can stop the recording.

  What I'd like to be able to do is relatively simple, I just can't wrap my head around it :

  Listener listens
  When it receives a START signal, it spawns two processes to start recording from each camera
  When it receives a STOP signal, it sends the 'q' keystroke to each process to tell ffmpeg to stop recording.

  I've got the listener part, but I'm just not sure how to get the multithreaded part down :

  while True:
  
      client,address = s.accept()
  
      data = client.recv( size )
  
      if data:
  
          if data.startswith('START'):
  
              # start threads here
  
          elif data.startswith('STOP'):
  
              # how to send a stop to the newly-created processes?

  In the thread code I'm doing this (which may be very incorrect) :

  subprocess.call('ffmpeg.exe -i "rtsp://cameraipstuff -vcodec copy -acodec copy -t 3600 -y '+filename)  

  I can get this process to spawn off and I see it recording, but how can I send it a "q" message ? I can use a Queue to pass a stop message and then do something like

  win32com.client.Dispatch('WScript.Shell').SendKeys('q')

  but that seems awkward. Perhaps a pipe and sending q to stdin ? Regardless, I'm pretty sure using threads is the right approach (as opposed to calling subprocess.call('ffmpeg.exe ...') twice in a row), but I just don't know how to tie things together.

• Embedding SMPTE timecode into mpeg1/2 video (no audio)

  6 janvier 2014, par user3164141

  I am working on a task which a client requires smpte drop frame timecode to be embedded into an mpeg1/2 video that my software will capture and encode. I have had success with encoding using both openCV and ffmpeg (windows). What I am having trouble with is embedding timecode.

  I've spent about a month researching this and have not been able to come up with a solution.
  Is there software available that can do what I need ?

  In my head, I picture a video file without timecode and I open with a player. It displays time in hh:mm:ss:ms. Then I imagine a video with timecode would display time information as hh:mm:ss:ff. This is not the case. Many video players don't even support displaying timecode.

  How is timecode stored in mpeg1/2 files ? I had thought it was stored on a per frame basis and would be as simple as :

  frameToEncode->setTimecode(SMPTE_DROPFRAME, framenum);
  
  MPEGEncoder::encodeFrame(frameToEncode);

  I have scoured the internet for an answer to this. Maybe I'm searching with the wrong terms, but I cannot find a clear cut solution to simply embed timecode to my video file.

  I have tried to use ffmpeg for this but have not been able to confirm/deny my attempts. Is there software I can use that will tell me I have embedded timecode in my video file ? I have tried using adobe premiere pro and roxio creator pro with no success.

  Lastly, is what my client asking even possible ? Is it possible to embed timecode. I am stunned by the lack of information I have been able to find on this and am beginning to think what is required isn't even possible. If it is possible, is there a commercial or free sdk/library capable of this ?

  TL ;DR : I need to embed timecode into an mpeg1/2 video file which I am capturing and encoding on the fly. How is timecode stored in mpeg1/2 files ? As a global header ? Per frame ? Something else ? I need software that can verify embedded timecode exists. Is what the client asking even possible ? If so, is there a commercial or free SDK available that can accomplish my task ?

  Note : I would need a c/c++ library capable of embedding the timecode.

• "An attempt was made to load a program with an incorrect format"

  31 janvier 2014, par user2922938

  I work in visual studio 2008, when run the program this error is shown :

  $exception "Could not load file or assembly 'AForge.Video.FFMPEG,
  Version=2.2.5.0, Culture=neutral, PublicKeyToken=03563089b1be05dd' or one of its dependencies. An attempt was made to load a program with an incorrect format."

  using System;
  
  using System.Collections.Generic;
  
  using System.ComponentModel;
  
  using System.Data;
  
  using System.Drawing;
  
  using System.Linq;
  
  using System.Text;
  
  using System.Windows.Forms;
  
  using AForge.Video.FFMPEG;
  
  
  
  namespace WindowsFormsApplication9
  
  {
  
      public partial class Form1 : Form
  
      {        
  
          public Form1()
  
          {
  
              InitializeComponent();
  
          }
  
  
  
          private void button1_Click(object sender, EventArgs e)
  
          {
  
              VideoFileReader video = new VideoFileReader();
  
          }
  
      }
  
  }

  What is wrong with my program ?