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• react native app doesn't load my video which is made by ffmpeg

  10 mars 2023, par yabbee

  I'm working on react native expo project and using expo-av to play video.I'm experimenting on my iphone and it's working almost fine. I copy and paste the sample code on expo av doc and Big Buck Bunny video is loaded successfully and able to play. But, there is a video that can't be played on my app. I have a video which is stored on s3 server. This is the mp4 video made by ffmpeg command on my computer and manually uploaded it on s3. I can download it and play on my machine. But when I try to load that video on my expo app, the video doesn't show up on the component at all. I write video source correctly including https:// but doesn't show up anything. How can i solve this problem ? I'm using expo 48.0.0 , expo-av 13.2.1 and expo-dev-client 2.1.5 now.

  


  Here is the ffmpeg code that I've used to make video. As you can see, I'm making a retro video by overlaying grain effect mp4 video which I downloaded.

  


  ffmpeg -i /Users/yosuke/Desktop/ffmpeg_playground/effects/grainAndFlash.mp4 -i 
{inputFilePath} -filter_complex "[0:a][1:a]amerge[mixedAudio];
[0]format=rgba,colorchannelmixer=aa=0.25[fg];[1][fg]overlay[out];
[out]trim=0:32,setpts=PTS-STARTPTS[video]" -map "[video]" -map "[mixedAudio]" -
pix_fmt yuv420p -c:v libx264 -crf 18 -shortest {outputFilePath}


  


  Here is the Expo app code

  


  import React, { useState, useEffect, useContext, useRef } from &#x27;react&#x27;;&#xA;import { View, Text, ScrollView, TouchableOpacity, Dimensions } from &#x27;react-native&#x27;;&#xA;&#xA;const Container = () => {&#xA;    const vidRef = useRef(null);&#xA;return (&#xA;    <scrollview style="{{" 1="1">&#xA;      &#xA;    </scrollview>&#xA;  );&#xA;};&#xA;&#xA;export default Container;&#xA;

  


• How do you make a modern bleep censor ? (With ffmpeg or other ready-made software)

  1er août 2023, par nick carraway

  I have always been a fan of live caller radio shows. These (sports) shows allow callers to call a hotline and talk to the radio host directly.

  


  One of the oldest problems with this show format is what if the caller curses, or says something highly inappropriate ? To keep the show clean (and legal), the radio shows broadcast with a 7 second delay. They also use a "bleep" censor, which historically allowed them to wipe the incriminating phrase with a "Beeeeeep" sound. These days, however, they completely cut out the caller's sentence before it even begins. ("Ah, we had to let you go there pal. Can't say that on the radio"). In the modern method, the transition is seamless, almost like they shorten the 7 second delay to a 4 second delay as they remove the start of the caller's reply entirely, and overwrite it with the host's explanations. The caller does not appear to be "interrupted" at all, the start of their sentence leading to the bad phrase is never even broadcasted.

  


  I've been thinking about how to do this in software. I found a project that looked promising. It adds a 7 second delay to your streams, and allows you to convert X amount of those seconds into silence assuming a caller says something inappropriate. While not ideal (since it's a few seconds of dead silence and would interrupt the caller mid-sentence), how can you do something like this in ffmpeg ? It is a good starting point before implementing the more modern features.

  


  


  1. How do you use ffmpeg to livestream a video/audio stream with a delay ?

     


  


  2. How do you overwrite the last 3 seconds of that stream with silence or a "bleep", when you need to ?

     


  


  3. Are you able to easily switch your stream to overwrite those 3 seconds with new audio (e.g. the host's explanation for why the caller was hung-up on) ? And how can you go back from a 4 second delay to a 7 second delay ?

     


  


  4. OR, is there a ready-made way to get flawless "radio-like" hang-ups on bad callers ?

     


  


  


• Video made from images using ffmpeg is not seekable in some players

  14 avril 2017, par Satya

  I’m trying to make video from images, used the following command

  ffmpeg -framerate 1/5 -i img%03d.png -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4

  as explained in the link https://trac.ffmpeg.org/wiki/Slideshow. But the problem is in some popular players if I try to seek the video, it plays from the beginning(video restarts from 0:00). How can I make a seeklable video ?