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• Invalid data found when processing input on ffmpeg m4s to mp4 transfer

  1er mars 2020, par keith scott

  The result of the power shell window

  I saw a post on here about converting m4s to mp4 and I have followed the steps of concatenating all the files into another m4s file that I called all.m4s and when I use the command ffmpeg -i allm4s.m4s -c copy video.mp4. I made the combined m4s file by coding an exe to add all the m4s files that have the word video in them to the m4s file. Here is the source code written in c# if you compile the code then that is the code I have used to make the m4s

  using System;
  
  using System.Collections.Generic;
  
  using System.Linq;
  
  using System.Text;
  
  using System.Threading.Tasks;
  
  using System.IO;
  
  
  
  namespace files
  
  {
  
      class Program
  
      {
  
          static void Main(string[] args)
  
          {
  
              string dir = Directory.GetCurrentDirectory();
  
              string[] info = Directory.GetFiles(dir);
  
              Console.WriteLine(dir + "\\allm4s.m4s");
  
              Console.ReadKey();
  
              foreach (string name in info)
  
              {
  
                  if (Path.GetFileName(name).Contains(".m4s") && Path.GetFileName(name).Contains("video"))
  
                  {
  
                      using (Stream srcStream = File.OpenRead(name))
  
                      {
  
                          using (Stream destStream = File.OpenWrite(dir+"\\allm4s.m4s"))
  
                          {
  
                              srcStream.CopyTo(destStream);
  
                              Console.WriteLine(destStream+name);
  
                          }
  
                      }
  
                  }
  
              }
  
              Console.ReadKey();
  
          }
  
      }
  
  }

  I think if there is to be an issue it is to do with this allm4s.m4s file as the file size is about 1.5mb even though each segment m4s is about 750kb each and there are quite a lot.If anyone has a way of adding concatenating lots of files together through a program/application that would be useful.

• ffmpeg lags when streaming video+audio from RPi Zero W with Logitech C920

  7 janvier 2021, par Ema

  I've been trying to setup a baby monitor with a Raspberry Pi Zero and a Logitech C920 webcam. I does work with VLC (cvlc) but it lags too much and gets worse over time.

  


  So I am playing around with ffmpeg and I am getting some better results. This is what I've done so far.

  


  First I set the webcam to output h264 1080p natively (the Pi Zero W can't afford to do any transcoding).

  


  v4l2-ctl --set-fmt-video=width=1920,height=1080,pixelformat=1


  


  Now, if I stream audio only with

  


  ffmpeg \
-f alsa \
-i hw:1,0 \
-vn \
-flags +global_header \
-acodec aac \
-ac 1 \
-ar 16000 \
-ab 16k \
-f rtp rtp://192.168.0.10:5002 > audio.sdp


  


  it works great and the lag is about 1 second (definitely acceptable).

  


  If I stream video only with

  


  ffmpeg \
-f v4l2 \
-vcodec h264 \
-i /dev/video0 \
-an \
-vcodec copy \
-pix_fmt yuv420p \
-r 30 \
-b:v 512k \
-flags +global_header \
-f rtp rtp://192.168.0.10:5000 > video.sdp


  


  same result, very little lag (for some reason the first -vcodec is necessary to force the webcam to output h264).

  


  However, when I stream both with

  


  ffmpeg \
-f v4l2 \
-vcodec h264 \
-i /dev/video0 \
-f alsa \
-i hw:1,0 \
-an \
-preset ultrafast \
-tune zerolatency \
-vcodec copy \
-pix_fmt yuv420p \
-r 30 \
-b:v 512k \
-flags +global_header \
-f rtp rtp://192.168.0.10:5000 \
-vn \
-flags +global_header \
-acodec aac \
-ac 1 \
-ar 16000 \
-ab 16k \
-f rtp rtp://192.168.0.10:5002 > both.sdp


  


  the lag ramps up to 10 seconds and audio and video are out of sync. Does anybody know why ?

  


  I've tried UDP and TCP instead of RTP but then the lag is always high, even with audio/video only.

  


  Any suggestion is much appreciated.

  


  P.S. On the client side (MacOS) I'm receiving with

  


  ffplay -protocol_whitelist file,rtp,udp -i file.sdp


  


• avcodec/vc2enc : Don't use bitcount when byte-aligned

  6 octobre 2022, par Andreas Rheinhardt

  avcodec/vc2enc : Don't use bitcount when byte-aligned
  (There is a small issue that is now being treated differently :
  
  The earlier code would record a position in a buffer that
  
  is being written to via put_bits(), then write data,
  
  then overwrite the byte at the position recorded earlier
  
  and only then flush the PutBitContext. In case there was
  
  no writeout in the meantime, said flush would overwrite
  
  what one has just written. This never happened in my tests,
  
  but maybe it can happen. In this case this commit fixes
  
  this issue by flushing before overwriting the old data.)
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/vc2enc.c