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• ffmpeg correct audio ( stretch or shrink)

  9 septembre 2014, par mido22

  I am not familiar with ffmpeg or video processing in general, but i am developing a web app, where people can record videos. I have been able to send chunks of audio n video to server successfully, where I am trying to combine them and return as single proper file.

  my problem is if the recording is for one hour, after merging the chunks

  video length : 1:00:00 , audio length : 00:59:30,

  now, this is not a issue of audio not getting recorded( I have checked that), the problem is, somehow, when i merge the chunks of audio, it shrinks,

  I find that it is progressive sync issue where it gets worse and worse as time increases.

  I have searched the net for the solution, most places say async, I have tried using it, but to no avail, is the below usage correct ?

  ffmpeg  -i audio.wav -async 1 -i video.webm -y -strict -2 v.mp4

  (v.mp4 is the final file that I provide to the users.)

• ffmpeg command leads to audio stream lost in conversion

  3 janvier 2023, par Sebastien Boulnois

  I have been exploring at a high level the concept of 360 videos for VR purposes and have been searching how to compress them in a way that my Oculus Quest 2 likes.

  


  I have been advised to use ffmpeg to do these kind of conversion. My initial file is a .mov file that I exported using ProRes422. My desired output is a compressed, optimized mp4 file for Oculus purposes.

  


  Here is the command line I used (simple copy paste from a person who was doing what I wanted to achieve) :

  


  ffmpeg -i input.mov -c:v libx264 -preset slow -crf 18 -maxrate 100M -bufsize 200M -pix_fmt yuv420p -an -movflags faststart output.mp4

  


  The compression works, the video quality is amazing. However, I lose the audio stream, which I really need.

  


  Here is the version of ffmpeg I currently have on my Mac :
ffmpeg current version on my mac

  


  Do you people know how to fix this issue ?

  


  I am just not sure how to proceed from here. I did not try anything specific.

  


• How to create a script on a Raspberry to run ffmpeg at boot and restart itself if/when ffmpeg fails ?

  5 février 2021, par Mycelium

  I'm using a Raspberry Pi Zero to stream to YouTube using FFMPEG. It works great so far and now I'd like to set it up to run the stream/FFMPEG daily and automatically from 6am to 7pm and restart itself in case it fails.

  


  I've heard/read of people doing so with Python, but I haven't been able to find examples to try. I've never used Python (or any other) before, I'm a complete beginner. All I know is how/where to place the script file to make it run at boot.

  


  Could anyone point me in the right direction on how to achieve this ? The FFMPEG command is as follows :

  


  v4l2-ctl --set-fmt-video=width=1280,height=720,pixelformat=4 
v4l2-ctl --set-ctrl=rotate=180
v4l2-ctl --overlay=1
v4l2-ctl -p 30
v4l2-ctl --set-ctrl=video_bitrate=2000000
ffmpeg -ar 44100 -ac 2 -acodec pcm_s16le -f s16le -i /dev/zero -f h264 -framerate 30 -i /dev/video0 -vcodec copy -acodec aac -ab 128k -g 60 -f flv -r 30 rtmp://a.rtmp.youtube.com/live2/SECRET-KEY