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• Adding AY Files To The Game Music Website

  1er décembre 2013, par Multimedia Mike — General

  For the first time since I launched the site in the summer of last year, I finally added support for new systems for my Game Music Appreciation site : A set of chiptune music files which bear the file extension AY. These files come from games that were on the ZX Spectrum and Amstrad CPC computer systems.

  
   
  

  Right now, there are over 650 ZX Spectrum games in the site while there are all of 20 Amstrad CPC games. The latter system seems a bit short-changed, but I read that a lot of Amstrad games were straight ports from the Spectrum anyway since the systems possessed assorted similarities. This might help explain the discrepancy.

  Technically
  The AY corpus has always been low hanging fruit due to the fact that the site already supports the format courtesy of the game-music-emu backend. The thing that blocked me was that I didn’t know much about these systems. I knew that there were 2 systems (and possibly more) that shared the same chiptune format. Apparently, these machines were big in Europe (I was only vaguely aware of them before I started this project).

  Both the Spectrum and the Amstrad used Zilog Z-80 CPUs for computing and created music using a General Instruments synthesizer chip designated AY-3-8912, hence the chiptune file extension AY. This has 3 channels similar to the C64 SID chip. Additionally, there’s a fourth channel that game music emu calls “beeper” (and which Wikipedia describes as “one channel with 10 octaves”). Per my listening, it seems similar to the old PC speaker/honker. The metadata for a lot of the songs will specify either (AY) or (Beeper).

  Wrangling Metadata
  Large collections of AY files are easy to find ; as is typical for pure chiptunes, the files are incredibly small.

  As usual, the hardest part of the whole process was munging metadata. There seems to be 2 slightly different conventions for AY metadata, likely from 2 different people doing the bulk of the work and releasing the fruits of their labor into the wild. After I recognized the subtle differences between the 2 formats, it was straightforward to craft a tool to perform most of the work, leaving only a minimum of cleanup effort required afterwards.

  (As an aside, I think this process is called extract – transform – load, or ETL. Sounds fancy and complicated, yet it’s technically one of the first computer programming tasks I was ever paid to perform.)

  Collateral Damage
  While pushing this feature, I managed to break the site’s search engine. The search solution I developed was always sketchy (involving compiling a C program as a static binary CGI script and trusting it to run on the server). I will probably need to find a better approach, preferably sooner than later.

• Qt 5.2 / OpenCV 2.4.8 - Can’t open video files via VideoCapture

  21 février 2014, par Zamahra

  I have a big problem that i can’t solve by myself. OpenCV itself works fine, but i’m not able to load videos. Here’s my code :

  PRO- File

  QT       += core gui
  
  
  
  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
  
  
  
  TARGET = videoredux
  
  TEMPLATE = app
  
  
  
  INCLUDEPATH += C:/OpenCV/opencv_bin/install/include
  
  LIBS += -LC:\\OpenCV\\opencv_bin\\bin \
  
      libopencv_core248d \
  
      libopencv_highgui248d \
  
      libopencv_imgproc248d \
  
      libopencv_features2d248d \
  
      libopencv_calib3d248d \
  
      libopencv_video248d \
  
  
  
  
  
  SOURCES += main.cpp\
  
          mainwindow.cpp
  
  
  
  HEADERS  += mainwindow.h
  
  
  
  FORMS    += mainwindow.ui

  and the MainWindow Class :

  #include "mainwindow.h"
  
  #include "ui_mainwindow.h"
  
  #include <qfiledialog>
  
  #include <iostream>
  
  #include 
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  #include <opencv></opencv>cv.h>
  
  
  
  
  
  MainWindow::MainWindow(QWidget *parent) :
  
  QMainWindow(parent),
  
  ui(new Ui::MainWindow)
  
  {
  
      ui->setupUi(this);
  
      ui->videoStatusLabel->setText("Kein Video geladen.");
  
  
  
      // SIGNALS &amp; SLOTS
  
  
  
      QObject::connect(ui->chooseVideoButton,SIGNAL(clicked()),
  
                   this,SLOT(chooseVideo()));
  
      QObject::connect(ui->startButton,SIGNAL(clicked()),
  
                   this,SLOT(startProcess()));
  
  
  
  }
  
  
  
  void MainWindow::chooseVideo(){
  
  
  
      QString fileName = QFileDialog::getOpenFileName(this,
  
           tr("Open Video"), "/home", tr("Video Files (*.avi *.mp4 *.mpeg *.mpg)"));
  
      qDebug() &lt;&lt; "Path:" &lt;&lt; fileName;
  
      ui->videoStatusLabel->setText(fileName);
  
  }
  
  
  
  void MainWindow::startProcess(){
  
      QString videoPath = ui->videoStatusLabel->text();
  
      QFileInfo video(videoPath);
  
      if(video.exists()){
  
          const std::string path = videoPath.toUtf8().constData();
  
          cv::VideoCapture capture(path);
  
          cv::Mat frame;
  
  
  
          if(!capture.isOpened()){
  
              qDebug() &lt;&lt; "Error, video not loaded";
  
          }
  
  
  
          cv::namedWindow("window",1);
  
          while(true)
  
          {
  
              bool success = capture.read(frame);
  
              if(success == false){
  
                  break;
  
              }
  
              cv::imshow("window",frame);
  
              cv::waitKey(20);
  
          }
  
          cv::waitKey(0);
  
      }
  
      else{
  
          qDebug() &lt;&lt; "Error, File doesn&#39;t exist";
  
      }
  
  }
  
  </iostream></qfiledialog>

  The paths are correct, I tried many different video formats but he never loads the videos. I’m running Qt on a Windows 8 machine and i have “K-Lite Codec Pack 10.2.0 Basic” and ffmpeg installed. The videos are playing properly with my video players. I also tried to copy the .dll to the working directory, searched for opencv dll's in the system32 directory and rebuild OpenCV with mingw on this computer. I know that many people have the same problems, but none of their suggestions solved it. Does anyone know how to solve this problem ?

  Thank you very much !

  Nadine

  ----UPDATE---- I still can't open video files, so I programmed the application on a Windows7 64-Bit system. It worked fine, but when I try to open the application on a Windows8 computer it still can't open the file. It doesn't matter which codecs are installed, because it generally runs on every Windows7 computer and fails on every Windows8 computer.. The same for older OpenCV-Versions. Is there a general problem with OpenCV and Windows8 ?

• RTSP/RTMP Video Streaming Client iOS [closed]

  28 mai 2015, par nathansizemore

  I’m in need of a open source solution/library to stream RTSP/RTMP to an iOS Application. I need to build an app that connects to a media server, and opens the provided video stream. I believe there has to be libraries out there, but I have yet to find one that is open source, compiles, actually works, and runs on iOS 5+, iPhone 4+. I do not have a preference, RTMP or RTSP will suffice. Preferably the one with the least amount of work. I have RTSP working on the Android side, but nothing for iOS yet.

  This is what I already know from research today -

  RTSP

  • Seems possible using Live555/FFMPEG
  • MooncatVenture Group - Old FFMPEG, not compatible with ARMv7s (No updates/blogs/commits in over a year)
  • DFURTSPPlayer - This is a working example.

  RTMP

  • Seems possible using Live555/FFMPEG
  • A few libraries are out there for data messaging, but that is all
  • MidnightCoders Project - Does not seem video support is build yet, as Audio is not.

  I’ve never messed with anything video related before, so encoding, frame rate, key frame, chunks, etc... is pretty foreign to me. Right now, it seems building a static binary from Live555/FFMPEG is the only solution to my problem. If so, can anyone give me a simple quickstart guide or links to a blog/example someone has out there ? I’m not looking for anything crazy, just a simple

  1. Download This - LINK
  2. Compile it like this - LINK
  3. Place it into X Folder in Xcode
  4. Create X Object
  5. Read Stream API here - LINK

  If not, anyone want to point me to a working open source library ?

  Oh yeah, this happens to be my first iPhone app and first time in Objective-C. Awesome first project, yeah ?