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• doc/muxers/image2 : drop unmatched quote in example

  11 mai 2023, par Andriy Utkin

  doc/muxers/image2 : drop unmatched quote in example
  Percent sign is not a special character in popular shells, so the
  
  quoting isn't necessary.
  

  • [DH] doc/muxers.texi

• How to add Qt to an existing C program and compile ?

  26 juin 2015, par El Sampsa

  I have a small Qt program I have compiled with qmake and make. When I launch make, I get the following commands for compilation :

  g++ -c -m64 -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++-64 -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I/usr/lib/x86_64-linux-gnu -I/usr/include/SDL -I. -o simpleqt.o simpleqt.cpp

  (.. lets call that (**)) and

  g++ -m64 -Wl,-O1 -o qt simpleqt.o -L/usr/lib/x86_64-linux-gnu -lSDL -lX11 -lQtGui -lQtCore -lpthread

  .. and the program is compiled without problems.

  On the other hand, I have the ffmpeg library which has the "ffplay" program. I want to put some Qt things into ffplay. In the ffmpeg config files I tell to the make process (using "common.mak") that it should be verbose and when issuing "make ffplay", it gives me the following monster :

  gcc -I. -I./ -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 -DZLIB_CONST -I/home/sampsa/ffmpeg/build/include -std=c99 -fomit-frame-pointer -pthread -I/usr/include/freetype2 -I/usr/include/fribidi -I/usr/include/freetype2 -D_GNU_SOURCE=1 -D_REENTRANT -I/usr/include/SDL -g -Wdeclaration-after-statement -Wall -Wdisabled-optimization -Wpointer-arith -Wredundant-decls -Wwrite-strings -Wtype-limits -Wundef -Wmissing-prototypes -Wno-pointer-to-int-cast -Wstrict-prototypes -Wempty-body -Wno-parentheses -Wno-switch -Wno-format-zero-length -Wno-pointer-sign -O3 -fno-math-errno -fno-signed-zeros -fno-tree-vectorize -Werror=format-security -Werror=implicit-function-declaration -Werror=missing-prototypes -Werror=return-type -Werror=vla -Wformat -Wno-maybe-uninitialized -D_GNU_SOURCE=1 -D_REENTRANT -I/usr/include/SDL -MMD -MF ffplay.d -MT ffplay.o -c -o ffplay.o ffplay.c

  (lets call that monster (++)).

  So far, so good, I have two commands, one (**) for compiling Qt programs and another one (++) for another project (in this case, ffmpeg’s ffplay)

  How do I combine these two ?

  I have tried merging the flags in (**) into command (++). It compiles OK, but the moment I am adding

  #include <qtgui> 
  
  </qtgui>

  into "ffplay.c", all hell breaks loose and the compiler tells me (among many other things) :

  In file included from /usr/include/qt4/QtCore/qobjectdefs.h:45:0,
  from /usr/include/qt4/QtCore/qobject.h:47,
  from /usr/include/qt4/QtCore/qabstracteventdispatcher.h:45,
  from /usr/include/qt4/QtCore/QtCore:3,
  from /usr/include/qt4/QtGui/QtGui:3,
  from ffplay2.c:61 :
  /usr/include/qt4/QtCore/qnamespace.h:51:1 : warning : return type defaults to ‘int’ [enabled by default]
  QT_MODULE(Core)
  ^
  /usr/include/qt4/QtCore/qnamespace.h:51:1 : warning : function declaration isn’t a prototype [-Wstrict-prototypes]
  /usr/include/qt4/QtCore/qnamespace.h : In function ‘QT_MODULE’ :
  /usr/include/qt4/QtCore/qnamespace.h:54:1 : error : unknown type name ‘namespace’
  namespace
  ^
  ...
  ...

  If I combine flags in (**) to (++) and change the compiler from "gcc" to "g++", I get all kinds of errors, this time related to the "ffplay.c" source code.

  What is going on ?

• Nodejs youtube-dl ffmpeg audio stream

  19 septembre 2015, par Majster

  I have an issue with streaming video from YouTube. I have a http server which attempts to grab the raw video url, pull out the audio, convert it to mp3 and stream it to clients. The issue is that I’m not getting any audio on my client. Code is below (it’s all work in progress so there’s a lot of hardcoded stuff in there).

  // The obvious stuff
  
  var exec = require('child_process').exec;
  
  var spawn = require('child_process').spawn;
  
  var request = require('request');
  
  var http = require('http');
  
  
  
  //Listen for requests
  
  var server = http.createServer(function(req, response) {
  
     //This command runs youtube-dl and gets the video url
  
     var command = './node_modules/youtube-dl/bin/youtube-dl --simulate --get-url http://www.youtube.com/watch?v=5qF_qbaWt3Q';
  
     var exc = exec(command, function(error, stdout, stderr) {
  
        var downloadUrl = stdout.toString(); //Convert the buffer to string
  
        downloadUrl = downloadUrl.substring(0, downloadUrl.length - 1); //And strip the '\n' sign at the end
  
        console.log("This thing is: '" + downloadUrl + "'");
  
        response.writeHead(200, {
  
           'Content-Type': 'audio/mpeg'
  
        }); //When this is mpeg3 browser will download a blank .mp3 file now it tries to stream it
  
  
  
        //Spawn the ffmpeg child process
  
        var child = spawn('ffmpeg', ['-i', 'pipe:0', '-acodec', 'libmp3lame','-f', 'mp3', '-']);
  
        child.stdout.pipe(response); //Pipe it so it writes to our response
  
  
  
        // fs.createReadStream(filePath).pipe(child.stdin); - this is a testing thing ---> fs is filesystem and filePath is a link to a file - works
  
        request({url: downloadUrl, headers: {'Youtubedl-no-compression': 'True'}}).pipe(child.stdin); //Request the data and pipe it to ffmpeg for processing
  
     });
  
  });

  I can provide any additional info if needed. But the thing works if I try to use a file instead of request call so there is no problem with ffmpeg and other settings. Is it possible that YouTube has a protection against downloading videos this way ? I tried to paste the URL of console.log into my browser and nothing happens - no video. How can I fix this ?