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• Flutter ffmpeg kit : Invalid size error when trying to scale video

  27 juillet 2023, par veryepicdude

  I'm trying to resize a video to match instagram's video format requirements. I'm using the ffmpeg_kit_flutter_full_gpl: ^5.1.0 package to do so and this is the function I'm calling :

  


  Future<void> resizeVideo(String input, String output) async {&#xA;&#xA;  final command = &#x27;-i $input -c:v libx264 -aspect 16:9 -crf 18 -vf "scale=iw*min(1280/iw\,720/ih):ih*min(1280/iw\,720/ih),pad=1280:720:(1280-iw)/2:(720-ih)/2" -fpsmax 60 -preset ultrafast -c:a aac -b:a 128k -ac 1 -use_editlist false -ar 48000 -pix_fmt yuv420p -movflags &#x2B;faststart -t 59 -y $output&#x27;;&#xA;  final session = await FFmpegKit.execute(command);&#xA;  print("resize done with ${await session.getReturnCode()}");&#xA;}&#xA;</void>

  


  However I get this error every time :

  


   Stream #0:0[0x1](und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 60 kb/s (default)
    Metadata:
      creation_time   : 2023-07-27T15:30:28.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Video: hevc (hvc1 / 0x31637668), yuv420p(tv, smpte170m/bt709/bt709), 720x1280, 2085 kb/s, 30 fps, 30 tbr, 600 tbn (default)
    Metadata:
      creation_time   : 2023-07-27T15:30:28.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:1 -> #0:0 (hevc (native) -> h264 (libx264))
  Stream #0:0 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[Parsed_scale_0 @ 0x2834a53f0] Invalid size 'iw*min(1280/iw'
[AVFilterGraph @ 0x28278e3a0] Error initializing filter 'scale'[AVFilterGraph @ 0x28278e3a0]  with args 'iw*min(1280/iw'[AVFilterGraph @ 0x28278e3a0] 
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #0:1
[aac @ 0x105334290] Qavg: 461.613
[aac @ 0x105334290] 2 frames left in the queue on closing


  


  Removing the scale filter makes the function work fine, but it fails the instagram video requirements listed here.
Any help will be greatly appreciated.

  


• problem with changing the frames in an video with opencv

  5 septembre 2023, par Avizipi

  I have a code that runs in the last few months without any problem. The code shows an image from a video with extra data from the relevant db. using the keyboard you can jump around some frames and get better insights. However, in the last week changing the frame of the video stopped working.

  


  I built a small script that show the problem.

  


  import cv2

vid_cap_reader_path = "vid_230830_122746_C.avi"
cap_rgb = cv2.VideoCapture(vid_cap_reader_path)

k = 0
while 1:
    if k == ord("q"):
        break
    if k == ord("b"):
        before = cap_rgb.get(cv2.CAP_PROP_POS_FRAMES)
        cap_rgb.set(cv2.CAP_PROP_POS_FRAMES, before + 30.0)
        after = cap_rgb.get(cv2.CAP_PROP_POS_FRAMES)
        print(f"before = {before} after = {after}")
    ret, img = cap_rgb.read()
    if ret:
        cv2.imshow("bla", img)
        k = cv2.waitKey(0)
    else:
        break


  


  This is what is printed to the terminal :

  


  [mpeg4 @ 0x1d87400] warning: first frame is no keyframe
before = 36.0 after = 0.0
before = 67.0 after = 0.0
[mpeg4 @ 0x1d87400] warning: first frame is no keyframe
before = 40.0 after = 0.0
[mpeg4 @ 0x1d87400] warning: first frame is no keyframe


  


  The video itself doesn't "jump" for the next frame as expected and also most of the properties that opencv have return 0. I tested also CAP_PROP_FRAME_COUNT, and CAP_PROP_POS_MSEC without any lack, although the msec flag did give non-zero results which make no sense.

  


  It is also important to mention that I am building this application in a docker file and I am not using a specific version for my requirements. The tests here are with opencv-python==4.7.0.68. Also, the videos are working fine while playing them on VLC.

  


  I was looking around the net for a similar problem from the recent time and didn't find much except this github issue that may be similar. I started to downgrade opencv one by one without any luck.

  


  Maybe someone here can help with this issue, or give me a lead to doing something different.

  


• Implementing Live Streaming Webinar Architecture - Need Guidance

  21 septembre 2023, par vishnugpl

  Question : I'm working on a project to implement a live streaming webinar platform, and I'm looking for guidance on the architecture and technologies to use. I have some specific requirements and constraints, and I'd appreciate any advice or pointers on how to get started.

  


  Context :
I'm tasked with building a live streaming webinar platform from scratch for our organization. Here are some key requirements and constraints :

  


  


  1. Live Video Streaming : We need to support live video streaming for
webinars, workshops, and conferences. Low latency is crucial for
real-time interaction between presenters and attendees.

     


  


  2. Scalability : The platform should be able to handle a large number of concurrent attendees, potentially thousands or more,
without compromising performance.

     


  


  3. Security : Security is a top priority. We need to ensure that only authorized users can access the webinars, and we must protect
against unauthorized recording or distribution of the content.

     


  


  4. User Interaction : Attendees should be able to ask questions, participate in polls, and interact with presenters in real-time.

     


  


  5. Recording and Playback : We also want to provide recorded versions of past webinars for on-demand viewing (HLS).

     


  


  


  Current Tech Stack :

  


  

  • Frontend : React

  


  • Backend : Node.js with Express

  


  • Database : MongoDB

  


  • Cloud Hosting : AWS

  


  


  Questions :

  


  


  • What technologies or services are best suited for handling live video streaming with low latency ?

    


  


  • How can I ensure scalability in terms of both video streaming and handling a large number of users ?

    


  


  • What security measures should I consider to protect the content and user data ?

    


  


  • Are there any recommended frameworks or libraries for building interactive features like real-time chat and polling ?

    


  


  • What's the best approach for recording and serving on-demand webinar content ?

    


  


  


  Additional Information :

  


  


  • Budget is a consideration, so cost-effective solutions are preferred.

    


  


  • Any open-source or third-party tools that can simplify development are welcome.

    


  


  • I have experience with AWS, but I'm open to other cloud providers if they offer advantages for this project.