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• ffmpeg : is it nessesary to create a copy of original AVCodecContext to call avcodec_decode_video2 ?

  8 décembre 2015, par cgwic

  Should i use copy :

  videoCodecCtx = avcodec_alloc_context3(videoDecoder);
  
  avcodec_copy_context(videoCodecCtx, formatContext->streams[videoStreamIndex]->codec);
  
  ret = avcodec_open2(videoCodecCtx, videoDecoder, NULL);
  
  if (videoStreamIndex < 0) {
  
      avErrorMsg("Error opening video codec context", ret);
  
      goto exit;
  
  }

  or simply use existing codec context from AVFormatContext :

  videoCodecCtx = formatContext->streams[videoStreamIndex]->codec;
  
  ret = avcodec_open2(videoCodecCtx, videoDecoder, NULL);
  
  if (videoStreamIndex < 0) {
  
      avErrorMsg("Error opening video codec context", ret);
  
      goto exit;
  
  }

  In my case both works fine, but in old Dranger tutorial he creates a copy.
  And updated code uses existing AVCodecContext.

• How do I combine PyTube audio and video streams in a Flask app and let the user download as one file without storing on the web server ?

  10 avril 2022, par AJB9384

  I'm building a YouTube downloader as a side project in Flask. It allows users to input a url and download the video without storing anything on the server I'm hosting on

  


  Lower quality videos can be sent to the user easily as they from PyTube as one file. I use the code below :

  


  import os
import flask
from flask import redirect, url_for, session, send_file
import requests

import pytube
from pytube import YouTube
from io import BytesIO

@app.route('/pull_videos', methods = ['GET', 'POST'])
def pull_videos(): 
  buffer=BytesIO()
  yt_test=YouTube('https://www.youtube.com/watch?v=NNNPgIfK2YE')
  video = yt_test.streams.get_by_itag(251)

  video.stream_to_buffer(buffer)
  buffer.seek(0)

  return send_file(buffer, as_attachment=True, download_name="Test video")


  


  However, I struggle when trying to pull in higher quality videos as they come in as separate audio and videos streams (see documentation here : https://pytube.io/en/latest/user/streams.html#)

  


  I am trying to use ffmpeg to combine the two and then send to the user, but the code below isn't working as expected and throws an error :

  


  Code :

  


  import os
import flask
from flask import redirect, url_for, session, send_file
import requests
import ffmpeg

import pytube
from pytube import YouTube
from io import BytesIO

@app.route('/pull_videos', methods = ['GET', 'POST'])
def pull_videos(): 
  buffer=BytesIO()
  
  video = yt_test.streams.get_by_itag(137)
  input_video = ffmpeg.input(video)
  
  audio = yt_test.streams.get_by_itag(137)
  input_audio = ffmpeg.input(audio)
  
  combined = ffmpeg.concat(input_video, input_audio, v=1, a=1)
  combined.stream_to_buffer(buffer)
  buffer.seek(0)

  return send_file(buffer, as_attachment=True, download_name="Test video")


  


  Error : AttributeError : 'FilterableStream' object has no attribute 'stream_to_buffer'

  


  How could I combine these audio and video streams from PyTube into one file for the user to download without storing on the server ?

  


• How do I use gpg to verify an ffmpeg source snapshot download ? [closed]

  2 novembre 2024, par Neddie

  I downloaded two files :

  


  ffmpeg-snapshot.tar.bz2
ffmpeg-devel.asc


  


  The .asc file looks like this :

  


  -----BEGIN PGP PUBLIC KEY BLOCK-----

  


  mQENBE22rV0BCAC3DzRmA2XlhrqYv9HKoEvNHHf+PzosmCTHmYhWHDqvBxPkSvCl
...
+x8ETJgPoNK3kQoDagApj4qAt83Ayac3HzNIuEJ7LdvfINIOprujnJ9vH4n04XLg
I4EZ
=Rjbw
-----END PGP PUBLIC KEY BLOCK-----

  


  The command

  


  gpg --show-keys ffmpeg-devel.asc


  


  gives

  


  pub   rsa2048 2011-04-26 [SC]
      FCF986EA15E6E293A5644F10B4322F04D67658D8
uid                      FFmpeg release signing key <ffmpeg-devel@ffmpeg.org>
sub   rsa2048 2011-04-26 [E]


  


  The command

  


  gpg --verify ffmpeg-devel.asc ffmpeg-snapshot.tar.bz2


  


  gives output

  


  gpg: verify signatures failed: Unexpected error


  


  I tried decompressing the bz2 file and then

  


  gpg --verify ffmpeg-devel.asc ffmpeg-snapshot.tar


  


  and got the same error.

  


  What am I missing ?