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• very low latency streaminig with ffmpeg using a webcam

  22 mars 2017, par userDtrm

  I’m trying to configure ffmpeg to do a real-time video streaming using a webcam. The ffmpeg encoder command I use is as follows.

  ffmpeg -f v4l2 -input_format yuyv422 -s 640x480 -i /dev/video0 -c:v libx264 -profile:v baseline -trellis 0 -subq 1 -level 32 -preset superfast -tune zerolatency -me_method epzs -crf 30 -threads 0 -bufsize 1 -refs 4 -coder 0 -b_strategy 0 -bf 0 -sc_threshold 0 -x264-params vbv-maxrate=2000:slice-max-size=1500:keyint=30:min-keyint=10: -pix_fmt yuv420p -an -f mpegts udp://192.168.1.8:5001

  The ffplay command used to display the video feed is,

  ffplay -analyzeduration 1 -fflags -nobuffer -i udp://192.168.1.8:5001

  However, I’m experiencing a latency of 0.5 - 1.0s latency in the video stream. Is there a way to reduce this to a number less than 100ms. Also, when I replace the v4l2 camera capture with a screen capture using x11grab, the stream is almost real-time and I experience no noticeable delays. Moreover, changing the encoder from x264 to mpeg2 had no effect on the latency. In addition, the statistics from the ffmpeg shows that the encoder is performing at a 30fps rate, which I believe indicates that the encoding is real-time. This leaves me with only one reason for the experienced delay.

  • Is there a significant delay in buffers when using v4l2 during video capturing in a webcam ?
  • I don’t think the transmission delay is in effect in this case as I see no latencies when screen capture is used under the same conditions.
  • Can this latency be further reduced ?. Can someone think of a different encoder configuration to be used instead of the one that I’ve been using ?.

  Any suggestions or assistance is highly appreciated.

  Thank You.

• Nginx VOD Transcoding

  21 décembre 2015, par nicb19

  I’m trying to setup MPEG-DASH video on demand streaming using nginx. I came across the nginx vod module which works great with dash.js but am wondering if anyone has managed to get real-time transcoding working.

  I’ve currently got it setup to play H264 MP4 local files, producing a MPD manifest for a single MP4. I know I can transcode multiple versions of the video and store them on the server, creating a multi URL manifest, but I only have limited space on the server so am not able to do this. Instead, I’m trying to find a way to transcode in real-time to allow more adaptive bitrate streaming like is possible with the nginx rtmp module and ffmpeg (however with MPEG-DASH instead of RTMP since I don’t want to use flash).

  Does anyone know of a way to do this ? Thanks in advanced.

• Youtube live stream with dynamic content

  6 octobre 2019, par Arturek

  I’m trying to create a live stream with changing data in real-time on youtube.

  Let’s say I want to show the current Bitcoin price in real-time. For instance, using python and sending requests to some public APIs, I can very easily get current prices of Bitcoin. But I have no idea how to create such a live stream, which will be automatically updated with fresh data.

  I know that I can use ffmpeg to stream on youtube, but how would I change the content of my stream ?

  # To make sure you know what I mean, I created a basic sample.
  
  
  
  import requests
  
  import json
  
  import time
  
  
  
  createYtLiveStream()
  
  
  
  while(True):
  
    response = requests.get('https://api.coindesk.com/v1/bpi/currentprice.json').json()
  
    price = response['bpi']['USD']['rate']
  
  
  
    updateYtLiveStream(price)
  
  
  
    time.sleep(20)

  I want to do it on Ubuntu. Can you tell me how can I do it, please ?
  Thanks.