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• stream usb webcam via http using vlc without transcoding using mjpeg signal from webcam

  10 novembre 2020, par Peter Nußreiner

  I wanna stream my (Microsoft live) USB webcam using vlc from a raspberry.
While it works perfectely fine with transcoding my raspberry does not have enough power.

  


  So I checked the output formats of my webcam using :

  


  ffmpeg -f v4l2 -list_formats all -i /dev/video0


  


  wich gives me the following output :

  


  [video4linux2,v4l2 @ 0x559d5aee36c0] Raw       :     yuyv422 :           YUYV 4:2:2 : 640x480 1280x720 960x544 800x448 640x360 424x240 352x288 320x240 800x600 176x144 160x120 1280x800
[video4linux2,v4l2 @ 0x559d5aee36c0] Compressed:       mjpeg :          Motion-JPEG : 640x480 1280x720 960x544 800x448 640x360 800x600 416x240 352x288 176x144 320x240 160x120
/dev/video0: Immediate exit requested


  


  when running my streaming command :

  


  cvlc v4l2:///dev/video0:chroma=h264:width=1280:height=720 --sout '#standard{access=http,mux=ts,dst=192.168.178.27:8080,name=stream,mime=video/ts}' -vvv


  


  I get the following error :

  


  mux_ts mux warning: rejecting stream with unsupported codec YUY2
main mux error: cannot add this stream
main decoder error: cannot create packetizer output (YUY2)


  


  along with many other lines of information.
As far as I can interpret the error, vlc wants to use the YUY2 RAW signal of my webcam.
Is there any way I can force vlc to use the mjpg output of my camera ?

  


  I've already tried to use 'chroma=mjpg' without success.
Transcoding is not an alternative as my raspi has by far not enough power.

  


  I've also read about using ffmpeg for streaming, maybe someone has an alternative solution since I'm very new to the whole topic of websites and stuff

  


  It will (or should) be used as a live webcam for a windsurfing spot.
Therefore I need a fluent video with at least 10fps to judge the situation. A delay of a minute or so is no problem.
The basic idea was to stream the video to a webserver and embed the image in a website. I've got good internet connection at the spot.

  


  But for now I want to try it locally on my pc.

  


• movenc : Timecode in MP4 Although MP4 does not have a concrete specification to store...

  21 janvier 2016, par Syed Andaleeb Roomy

  movenc : Timecode in MP4 Although MP4 does not have a concrete specification to store timecode information, the following technical note from Apple describes a way to achieve this via timecode track, similar to how it is done for MOV files.
  https://developer.apple.com/library/mac/technotes/tn2174/_index.html
   Enabled creation of timecode tracks for MP4 in the same way as MOV.
  
   Used nmhd as media information header of timecode track of MP4 instead
  
    of gmhd used in MOV, thus avoiding tcmi also, as recommended above.
  
   Bypassed adding source reference field for MP4, as suggested above.
  Issue : https://trac.ffmpeg.org/ticket/4704
  Signed-off-by : Syed Andaleeb Roomy <andaleebcse@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/movenc.c

• App Intents FFmpeg-iOS operation not permitted

  2 octobre 2023, par apo_p9

  Using latest iOS and Xcode, I have an AppIntent to which Im passing a video file from iOS Shortcuts, Im using an IntentFile parameter to read that in the intent. Then Im using FFmpeg-iOS to generate a single frame from the video.

  


  ...
@Parameter(title: "Media", supportedTypeIdentifiers: ["public.image", "public.video"], inputConnectionBehavior: .connectToPreviousIntentResult)
var media: IntentFile
...
let mediaPath = media.fileURL!.absoluteString;
let posterPath = mediaPath.replacingOccurrences(of: media.filename, with: "poster.jpg")
_ = ffmpeg(["FFmpeg-iOS", "-i", mediaPath, "-frames:v", "1", posterPath])


  


  Here is the output :

  


  ffmpeg(_:) ["FFmpeg-iOS", "-i", "file:///var/mobile/tmp/com.apple.WorkflowKit.BackgroundShortcutRunner/IMG_2751.mov", "-frames:v", "1", "file:///var/mobile/tmp/com.apple.WorkflowKit.BackgroundShortcutRunner/poster.jpg"]
ffmpeg version N-109970-g7dc0944ce2 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 14.0.0 (clang-1400.0.29.202)
  configuration: --prefix=/Users/changbeomahn/Projects/FFmpeg-iOS/build/install/FFmpeg/arm64 --enable-cross-compile --disable-debug --disable-doc --enable-pic --disable-audiotoolbox --disable-sdl2 --disable-libxcb --target-os=darwin --arch=arm64 --cc='xcrun -sdk iphoneos clang' --as='gas-preprocessor.pl -arch aarch64 -- xcrun -sdk iphoneos clang' --extra-cflags='-arch arm64 -mios-version-min=13.0 -I/Users/changbeomahn/Projects/FFmpeg-iOS/build/install/FFmpeg/arm64/include' --extra-ldflags='-arch arm64 -mios-version-min=13.0 -L/Users/changbeomahn/Projects/FFmpeg-iOS/build/install/FFmpeg/arm64/lib'
HookMain: setjmp=0
FFmpeg_exit=1, will longjmp
HookMain: setjmp=1
  libavutil      58.  3.100 / 58.  3.100
  libavcodec     60.  6.100 / 60.  6.100
  libavformat    60.  4.100 / 60.  4.100
  libavdevice    60.  2.100 / 60.  2.100
  libavfilter     9.  4.100 /  9.  4.100
  libswscale      7.  2.100 /  7.  2.100
  libswresample   4. 11.100 /  4. 11.100
file:///var/mobile/tmp/com.apple.WorkflowKit.BackgroundShortcutRunner/IMG_2751.mov: Operation not permitted


  


  The issue is in the last line : Operation not permitted

  


  I also tried just writing a file to the same directory as the media file :

  


  let str = "Super long string here"
let filename = media.fileURL!.absoluteString.replacingOccurrences(of: media.filename, with: "asd.txt")

do {
    try str.write(to: URL(string: filename)!, atomically: true, encoding: String.Encoding.utf8)
} catch {
    print(error)
}


  


  But got the error :

  


  Error Domain=NSCocoaErrorDomain Code=513 "You don’t have permission to save the file “asd.txt” in the folder “com.apple.WorkflowKit.BackgroundShortcutRunner”." UserInfo={NSFilePath=/var/mobile/tmp/com.apple.WorkflowKit.BackgroundShortcutRunner/asd.txt, NSUnderlyingError=0x280f09aa0 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}}


  


  Apparently there is a permission issue, I tried googling about "AppIntents file permissions"/"shortcut permissions"/etc but found nothing. Im not a mobile developer so Im totally clueless. The same code though works fine in the simulator, it gets the permission issue only on device.