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• Why my App cannot decode the RTSP stream ?

  25 septembre 2015, par MathxH Chen

  I use live555 to receive RTP video frame (frame encoded in H264). I use Live555 open my local .sdp file to receive frame data. I just saw DummySink::afterGettingFrame was called ceaselessly。 if fReceiveBuffer in DummySink is correct, Why FFMPEG cannot decode the frame ? My code is wrong ?

  Here is my Code Snippet :
  http://paste.ubuntu.com/12529740/

  the function avcodec_decode_video2 is always return failed , its value less than zero

  fReceiveBuffer is present one video frame？

  Oh, Here is my FFMPEG init code need to open related video decoder :
  http://paste.ubuntu.com/12529760/

• Tools to determine video orientation

  6 avril 2014, par JayLev

  I receive videos from different devices and want to encode them using the correct orientation.

  I've seen some of examples of how to determine the orientation of a video from a iPhone.

  With exiftool and mediainfo I can indeed tell if an iPhone video has to be rotated.

  However, for android videos, both portrait and landscape videos have the same rotation and matrix structure as each other.

  Maybe this is just with my phone, I'm trying to find videos taken from newer droid phones.

  My question however is whether there's other tools or a different way to determine the orientation that'll work with all devices.

  EDIT :
  I just checked a video from a Samsung Galaxy S II, and I can get the orientation from exiftool. So it's not a problem with all android phones.
  My android phone is a HTC Desire running on android 2.2.

  And actually (I didn't even notice before) a portrait video will not be correctly oriented even when playing on the phone. So I guess it's not about the tools, the orientation data just doesn't seem to be correct at all.

• Connect external cameras to iOS and decompress to a usable form

  27 septembre 2017, par Ping Chen

  I want to create a 2 camera setup which can send 1 of the camera views out as an RTMP stream depending on the motion intensity detected. The chosen camera view can change if motion intensity on the views changes.

  I imagine that I could use an iPhone/iPad as encoding/streaming hub as well as 1 of the cameras. And connect a WiFi camera to the iPad/iPhone to feed the 2nd camera view.

  My goals for the iOS side are :

  1. Connect with a WiFi camera on the local network
  2. Decode the data and run motion intensity detection on the WiFi camera feed AND the iPhone/iPad’s own camera feed with Brad Larson’s GPUImage framework https://github.com/BradLarson/GPUImage
  3. Stream out the chosen camera view. depending on motion detected

  Larson’s GPUImage framework works with an AVCaptureSession subclass. I’m only familiar with AVFoundation objects, but am a complete noob with it comes to VideoToolbox and some of the lower level iOS video stuff. Through googling, I kind of know that VTDecompressionSession is what I’d get from the WiFi camera. I have no clue how I can manipulate that to a usable form for my purposes.

  I’ve dug through stackoverflow answers such as : https://stackoverflow.com/a/29525001/7097455

  Very informative, but maybe I don’t even know to ask the correct questions