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• tls : Add options for verifying the peer certificate

  22 février 2011, par Martin Storsjö

  tls : Add options for verifying the peer certificate
  A file containing the trusted CA certificates needs to be
  
  supplied via the ca_file AVOption, unless the TLS library
  
  has got a system default file/database set up.
  This doesn’t check the hostname of the peer certificate with
  
  openssl, which requires a non-trivial piece of code for
  
  manually matching the desired hostname to the string provided
  
  by the certificate, not provided as a library function.
  That is, with openssl, this only validates that the received
  
  certificate is signed with the right CA, but not that it is
  
  the actual server we think we’re talking to.
  Verification is still disabled by default since we can’t count
  
  on a proper CA database existing at all times.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] doc/protocols.texi
  • [DH] libavformat/tls.c
  • [DH] libavformat/version.h

• How to synchronize audio and video using ffmpeg libraries ?

  21 octobre 2013, par jsp99

  Stuck writing a very basic media player in C, using SDL and ffmpeg libraries. Initially, followed the theory in this page to get an idea about the entire program and the usage of libraries. After coding from scratch, thanks to that tutorial and many other resources, finally I made my code work, using the latest libraries of ffmpeg and SDL (2.0). But my code lacks a proper synchronization mechanism (actually it lacks a sync mechanism !).

  I still don't have a clear idea on how to synchronize the audio and video together as the theory provided in the link is only very partially correct (atleast when it comes to using the latest dev libraries).
  For example, a sentence in this page is as follows :

  However, ffmpeg reorders the packets so that the DTS of the packet being processed by avcodec_decode_video() will always be the same as the PTS of the frame it returns.

  I am using avcodec_decode_video2() and the DTS of the packet is definitely not the same as pts of the frame it decodes (in general).

  I read this very informative BBC report and it makes complete sense. I have a clear idea about PTS and DTS. But the PTS and DTS values that ffmpeg is using for packets and decoded frames is confusing. I wish there were some documentation on that aspect.

  Can someone explain the steps to synchronize audio and video ? I only need the steps. I am quite comfortable implementing them. Any help is greatly appreciated. Thanks !

  PS : Here's a screenshot of what I am talking about :

  

  The huge negative value is, I assume AV_NOPTS_VALUE.

• Adding and reading timestamp to an image using ffmpeg

  17 novembre 2013, par Andrew Simpson

  I am not sure if i should be posting this type of question here and I have not uploaded any code as I am talking about concepts.

  I have a C# winform desktop application.

  It produces a flow of jpegs that have derived from a motion detection algorithm.

  I use the Graphics.DrawText to add a time stamp directly onto the image when it was created.

  I then use ffmpeg to produce a ogg video file.

  When i play the video file back I obviously see the image with the time stamp.

  What I would like to be able to do is read in code the time stamp that is on every image. I had thought of using some sort of OCR to do this but it seems overkill to me. I also have considered creating a separate text file that acts as the 'index' of the video file. But then I have to manage the 'transaction' between 2 different files.

  Corruption to the text file could happen.

  I would like a way of encapsulating this information to be easily read by my C# code.

  Has anyone had any experience doing this ? Any recommendations pls ?

  Many Thanks