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• Trying to grab video stream from a 802W device

  1er juin 2015, par brentil

  A group of us in the RC hobby forums had started trying to use a device called the 802W, it takes RCA in and then broadcasts it back out over a WiFi you connect to via an Android or iOS device. They’re typically used for backup camera addon systems for vehicles. We want to use it to do FPV (First Person Video/View) with using smartphones instead of buying more expensive FPV goggles.

  802W device example (plenty of clones online)

  http://www.amazon.com/Wireless-Backup-Camera-Transmitter-Android/dp/B00LJPTJSY

  The problem is you can only use their application WIFI_AVIN or WIFI_AVIN2 from the app stores to connect to it because they don’t publish the information about how to grab the stream data. We want to write our own apps that can use the stream to better show the information. We’ve tried using VLC to grab the stream from an Android phone or a Windows PC but we’ve had no success so far. I was hoping someone could look at the Wireshark outputs and might understand what they’re looking at better than I am. I "think" it’s a UDP multicast being broadcasted but I just don’t know enough to be sure. We’ve tried using VLC to connect to network streams directly on the device or from udp ://@ type addresses but I think part of the issue too might be we’re missing the file path of the stream file.

  Attempting to reverse engineer their code for learning purposes showed that ffmpeg is inside a compiled .so library which also seems to be where the actual connection code happens which we were unable to dig into.

  In the images 192.168.72.33 is my phone and 192.168.72.173 is the 802W device.

  Image of what I believe is a UDP broadcast of the video information.
  

  This is what the stream turns into when the device connects using the WIFI_AVIN application.
  

• Using FFMPEG to convert .mov to mp4 with Blob Urls (NodeJS)

  31 juillet 2020, par Mick Marsden

  I'm trying to convert my .mov files to .mp4 in nodeJS. I'm using fluent-ffmpeg, and my users are capturing live video on their mobile phones that come in a variety of file formats. But the API I'm sending these files to only accepts .mp4. As these videos are being captured live, I am using blobs to capture them. I'm trying to convert it to .mp4, but fluent-ffmpeg does not recognize the blob:url format.

  


  Do I have to turn the blob into buffer first ? What should I be doing when trying to convert a blob's format ?

  


• Can ffmpeg transcode an audio track and add it as a second audio track at the same time, or if not, how to do it as separate commands ?

  31 mai 2020, par wb6vpm

  A bit of history. I am using Plex as my media server, but for reasons unknown, it has issues transcoding the DTS-HD MA 7.1 audio to EAC3 stereo and keeps buffering (the server has plenty of horsepower on all fronts, CPU/RAM/drive space & speed, gigabit networks connections for all devices. The playback device (TCL Roku TV, with a 3rd party soundbar connected via HDMI ARC) doesn't support the built-in 7.1 audio, so I get silence if I play it back directly by putting the file on a USB stick.

  



  Also, I am by no means a ffmpeg guru, I figured out what I do know by Google University and asking questions, so please be kind and forgive me if I ask follow-up questions that may seem n00b-ish, and please provide example commands (preferably in the context of my command below so that I can have a known point of reference to start with).

  



  I have a movie with 4K (HEVC Main 10 HDR) video and DTS-HD MA 7.1 audio that I am looking to leave the video and audio untouched, but to add a 2nd audio track in either EAC3 or if necessary, just AC3 in stereo

  



  So what I am looking for is as follows :

  



  video.mkv

  



  

  • Existing->4k video file (no change)

  


  • Existing->7.1 audio (no change)

  


  • Convert and add->stereo audio as a 2nd audio track to the output.mkv file

  


  



  Below is the command I've historically used with ffmpeg to convert and replace the audio file with the stereo audio, but since I'd prefer to leave the 7.1 audio in place, this doesn't work :
ffmpeg -i "D:\video.mkv" -c:v copy -c:a aac -b:a 128k "D:\output.mkv"

  



  And if this cannot be done as a single command, please also let me know what steps I do need to take to be able to do it.

  



  Thanks in advace,
Mike