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• Things I Have Learned About Emscripten

  1er septembre 2015, par Multimedia Mike — Cirrus Retro

  3 years ago, I released my Game Music Appreciation project, a website with a ludicrously uninspired title which allowed users a relatively frictionless method to experience a range of specialized music files related to old video games. However, the site required use of a special Chrome plugin. Ever since that initial release, my #1 most requested feature has been for a pure JavaScript version of the music player.

  “Impossible !” I exclaimed. “There’s no way JS could ever run fast enough to run these CPU emulators and audio synthesizers in real time, and allow for the visualization that I demand !” Well, I’m pleased to report that I have proved me wrong. I recently quietly launched a new site with what I hope is a catchier title, meant to evoke a cloud-based retro-music-as-a-service product : Cirrus Retro. Right now, it’s basically the same as the old site, but without the wonky Chrome-specific technology.

  Along the way, I’ve learned a few things about using Emscripten that I thought might be useful to share with other people who wish to embark on a similar journey. This is geared more towards someone who has a stronger low-level background (such as C/C++) vs. high-level (like JavaScript).

  General Goals
  Do you want to cross-compile an entire desktop application, one that relies on an extensive GUI toolkit ? That might be difficult (though I believe there is a path for porting qt code directly with Emscripten). Your better wager might be to abstract out the core logic and processes of the program and then create a new web UI to access them.

  Do you want to compile a game that basically just paints stuff to a 2D canvas ? You’re in luck ! Emscripten has a porting path for SDL. Make a version of your C/C++ software that targets SDL (generally not a tall order) and then compile that with Emscripten.

  Do you just want to cross-compile some functionality that lives in a library ? That’s what I’ve done with the Cirrus Retro project. For this, plan to compile the library into a JS file that exports some public functions that other, higher-level, native JS (i.e., JS written by a human and not a computer) will invoke.

  Memory Levels
  When porting C/C++ software to JavaScript using Emscripten, you have to think on 2 different levels. Or perhaps you need to force JavaScript into a low level C lens, especially if you want to write native JS code that will interact with Emscripten-compiled code. This often means somehow allocating chunks of memory via JS and passing them to the Emscripten-compiled functions. And you wouldn’t believe the type of gymnastics you need to execute to get native JS and Emscripten-compiled JS to cooperate.
  

  “Emscripten : Pointers and Pointers” is the best (and, really, ONLY) explanation I could find for understanding the basic mechanics of this process, at least when I started this journey. However, there’s a mistake in the explanation that left me confused for a little while, and I’m at a loss to contact the author (doesn’t anyone post a simple email address anymore ?).

  Per the best of my understanding, Emscripten allocates a large JS array and calls that the memory space that the compiled C/C++ code is allowed to operate in. A pointer in C/C++ code will just be an index into that mighty array. Really, that’s not too far off from how a low-level program process is supposed to view memory– as a flat array.

  Eventually, I just learned to cargo-cult my way through the memory allocation process. Here’s the JS code for allocating an Emscripten-compatible byte buffer, taken from my test harness (more on that later) :

  var musicBuffer = fs.readFileSync(testSpec[’filename’]) ;
  var musicBufferBytes = new Uint8Array(musicBuffer) ;
  var bytesMalloc = player._malloc(musicBufferBytes.length) ;
  var bytes = new Uint8Array(player.HEAPU8.buffer, bytesMalloc, musicBufferBytes.length) ;
  bytes.set(new Uint8Array(musicBufferBytes.buffer)) ;
  

  So, read the array of bytes from some input source, create a Uint8Array from the bytes, use the Emscripten _malloc() function to allocate enough bytes from the Emscripten memory array for the input bytes, then create a new array… then copy the bytes…

  You know what ? It’s late and I can’t remember how it works exactly, but it does. It has been a few months since I touched that code (been fighting with front-end website tech since then). You write that memory allocation code enough times and it begins to make sense, and then you hope you don’t have to write it too many more times.

  Multithreading
  You can’t port multithreaded code to JS via Emscripten. JavaScript has no notion of threads ! If you don’t understand the computer science behind this limitation, a more thorough explanation is beyond the scope of this post. But trust me, I’ve thought about it a lot. In fact, the official Emscripten literature states that you should be able to port most any C/C++ code as long as 1) none of the code is proprietary (i.e., all the raw source is available) ; and 2) there are no threads.

  Yes, I read about the experimental pthreads support added to Emscripten recently. Don’t get too excited ; that won’t be ready and widespread for a long time to come as it relies on a new browser API. In the meantime, figure out how to make your multithreaded C/C++ code run in a single thread if you want it to run in a browser.

  Printing Facility
  Eventually, getting software to work boils down to debugging, and the most primitive tool in many a programmer’s toolbox is the humble print statement. A print statement allows you to inspect a piece of a program’s state at key junctures. Eventually, when you try to cross-compile C/C++ code to JS using Emscripten, something is not going to work correctly in the generated JS “object code” and you need to understand what. You’ll be pleading for a method of just inspecting one variable deep in the original C/C++ code.

  I came up with this simple printf-workalike called emprintf() :

  #ifndef EMPRINTF_H
  #define EMPRINTF_H
  #include <stdio .h>
  
  #include <stdarg .h>
  
  #include <emscripten .h>
  #define MAX_MSG_LEN 1000
  /* NOTE : Don’t pass format strings that contain single quote (’) or newline
  
  * characters. */
  
  static void emprintf(const char *format, ...)
  
  
  
      char msg[MAX_MSG_LEN] ;
  
      char consoleMsg[MAX_MSG_LEN + 16] ;
  
      va_list args ;
  
      /* create the string */
  
      va_start(args, format) ;
  
      vsnprintf(msg, MAX_MSG_LEN, format, args) ;
  
      va_end(args) ;
      /* wrap the string in a console.log(’’) statement */
  
      snprintf(consoleMsg, MAX_MSG_LEN + 16, "console.log(’%s’)", msg) ;
      /* send the final string to the JavaScript console */
  
      emscripten_run_script(consoleMsg) ;
  
  
  #endif  /* EMPRINTF_H */
  

  Put it in a file called “emprint.h”. Include it into any C/C++ file where you need debugging visibility, use emprintf() as a replacement for printf() and the output will magically show up on the browser’s JavaScript debug console. Heed the comments and don’t put any single quotes or newlines in strings, and keep it under 1000 characters. I didn’t say it was perfect, but it has helped me a lot in my Emscripten adventures.

  Optimization Levels
  Remember to turn on optimization when compiling. I have empirically found that optimizing for size (-Os) leads to the best performance all around, in addition to having the smallest size. Just be sure to specify some optimization level. If you don’t, the default is -O0 which offers horrible performance when running in JS.

  Static Compression For HTTP Delivery
  JavaScript code compresses pretty efficiently, even after it has been optimized for size using -Os. I routinely see compression ratios between 3.5:1 and 5:1 using gzip.

  Web servers in this day and age are supposed to be smart enough to detect when a requesting web browser can accept gzip-compressed data and do the compression on the fly. They’re even supposed to be smart enough to cache compressed output so the same content is not recompressed for each request. I would have to set up a series of tests to establish whether either of the foregoing assertions are correct and I can’t be bothered. Instead, I took it into my own hands. The trick is to pre-compress the JS files and then instruct the webserver to serve these files with a ‘Content-Type’ of ‘application/javascript’ and a ‘Content-Encoding’ of ‘gzip’.

  1. Compress your large Emscripten-build JS files with ‘gzip’ : ‘gzip compiled-code.js’
  2. Rename them from extension .js.gz to .jsgz
  3. Tell the webserver to deliver .jsgz files with the correct Content-Type and Content-Encoding headers

  To do that last step with Apache, specify these lines :

  AddType application/javascript jsgz
  AddEncoding gzip jsgz
  

  They belong in either a directory’s .htaccess file or in the sitewide configuration (/etc/apache2/mods-available/mime.conf works on my setup).

  Build System and Build Time Optimization
  Oh goodie, build systems ! I had a very specific manner in which I wanted to build my JS modules using Emscripten. Can I possibly coerce any of the many popular build systems to do this ? It has been a few months since I worked on this problem specifically but I seem to recall that the build systems I tried to used would freak out at the prospect of compiling stuff to a final binary target of .js.

  I had high hopes for Bazel, which Google released while I was developing Cirrus Retro. Surely, this is software that has been battle-tested in the harshest conditions of one of the most prominent software-developing companies in the world, needing to take into account the most bizarre corner cases and still build efficiently and correctly every time. And I have little doubt that it fulfills the order. Similarly, I’m confident that Google also has a team of no fewer than 100 or so people dedicated to developing and supporting the project within the organization. When you only have, at best, 1-2 hours per night to work on projects like this, you prefer not to fight with such cutting edge technology and after losing 2 or 3 nights trying to make a go of Bazel, I eventually put it aside.

  I also tried to use Autotools. It failed horribly for me, mostly for my own carelessness and lack of early-project source control.

  After that, it was strictly vanilla makefiles with no real dependency management. But you know what helps in these cases ? ccache ! Or at least, it would if it didn’t fail with Emscripten.

  Quick tip : ccache has trouble with LLVM unless you set the CCACHE_CPP2 environment variable (e.g. : “export CCACHE_CPP2=1”). I don’t remember the specifics, but it magically fixes things. Then, the lazy build process becomes “make clean && make”.

  Testing
  If you have never used Node.js, testing Emscripten-compiled JS code might be a good opportunity to start. I was able to use Node.js to great effect for testing the individually-compiled music player modules, wiring up a series of invocations using Python for a broader test suite (wouldn’t want to go too deep down the JS rabbit hole, after all).

  Be advised that Node.js doesn’t enjoy the same kind of JIT optimizations that the browser engines leverage. Thus, in the case of time critical code like, say, an audio synthesis library, the code might not run in real time. But as long as it produces the correct bitwise waveform, that’s good enough for continuous integration.

  Also, if you have largely been a low-level programmer for your whole career and are generally unfamiliar with the world of single-threaded, event-driven, callback-oriented programming, you might be in for a bit of a shock. When I wanted to learn how to read the contents of a file in Node.js, this is the first tutorial I found on the matter. I thought the code presented was a parody of bad coding style :

  var fs = require("fs") ;
  var fileName = "foo.txt" ;
  fs.exists(fileName, function(exists) 
  
    if (exists) 
  
      fs.stat(fileName, function(error, stats) 
  
        fs.open(fileName, "r", function(error, fd) 
  
          var buffer = new Buffer(stats.size) ;
  
          fs.read(fd, buffer, 0, buffer.length, null, function(error, bytesRead, buffer) 
  
            var data = buffer.toString("utf8", 0, buffer.length) ;
  
            console.log(data) ;
  
            fs.close(fd) ;
  
          ) ;
  
        ) ;
  
      ) ;
  
    ) ;
  

  Apparently, this kind of thing doesn’t raise an eyebrow in the JS world.

  Now, I understand and respect the JS programming model. But this was seriously frustrating when I first encountered it because a simple script like the one I was trying to write just has an ordered list of tasks to complete. When it asks for bytes from a file, it really has nothing better to do than to wait for the answer.

  Thankfully, it turns out that Node’s fs module includes synchronous versions of the various file access functions. So it’s all good.

  Conclusion
  I’m sure I missed or underexplained some things. But if other brave souls are interested in dipping their toes in the waters of Emscripten, I hope these tips will come in handy.

  The post Things I Have Learned About Emscripten first appeared on Breaking Eggs And Making Omelettes.

• Encoding images into a movie file

  5 avril 2014, par RuAware

  I am trying to save jpgs into a movie, I have tried jcodec and alothough my s3 plays it fine other devices do not. including vlc and windows media

  I have just spent most of the day playing with MediaCodec, although the SDK is so high, it will help people with jelly bean and above. But I can not work out how to get the Files to the encoder and then write the file.

  Ideally I wont to support down to SDK 9/8

  Has anyone got any code they can share, either to get MediaCodec to work or another option. If you say ffmpeg, I'd love to but my jin knowledge is non existent and I will need a very good guide.

  Code for MediaCodec so far

  public class EncodeAndMux extends AsyncTask {
  
      private static int bitRate = 2000000;
  
      private static int MAX_INPUT = 100000;
  
      private static String mimeType = "video/avc";
  
  
  
      private int frameRate = 15;     
  
      private int colorFormat;
  
      private int stride = 1;
  
      private int sliceHeight = 2;        
  
  
  
      private MediaCodec encoder = null;
  
      private MediaFormat inputFormat;
  
      private MediaCodecInfo codecInfo = null;
  
      private MediaMuxer muxer;
  
      private boolean mMuxerStarted = false;
  
      private int mTrackIndex = 0;  
  
      private long presentationTime = 0;
  
      private Paint bmpPaint;
  
  
  
      private static int WAITTIME = 10000;
  
      private static String TAG = "ENCODE";
  
  
  
      private ArrayList<string> mFilePaths;
  
      private String mPath;
  
  
  
      private EncodeListener mListener;
  
      private int width = 320;
  
      private int height = 240;
  
      private double mSpeed = 1;
  
  
  
      public EncodeAndMux(ArrayList<string> filePaths, String savePath) {
  
          mFilePaths = filePaths;
  
          mPath = savePath;   
  
  
  
          // Create paint to draw BMP
  
          bmpPaint = new Paint();
  
          bmpPaint.setAntiAlias(true);
  
          bmpPaint.setFilterBitmap(true);
  
          bmpPaint.setDither(true);
  
      }
  
  
  
      public void setListner(EncodeListener listener) {
  
          mListener = listener;
  
      }
  
  
  
      // set the speed, how many frames a second
  
      public void setSpead(int speed) {
  
          mSpeed = speed;
  
      }
  
  
  
      public double getSpeed() {
  
          return mSpeed;
  
      }
  
  
  
      private long computePresentationTime(int frameIndex) {
  
          final long ONE_SECOND = 1000000;
  
          return (long) (frameIndex * (ONE_SECOND / mSpeed));
  
      }
  
  
  
      public interface EncodeListener {
  
          public void finished();
  
          public void errored();
  
      }
  
  
  
      @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
  
      @Override
  
      protected Boolean doInBackground(Integer... params) {
  
  
  
          try {
  
              muxer = new MediaMuxer(mPath, OutputFormat.MUXER_OUTPUT_MPEG_4);
  
          } catch (Exception e){ 
  
              e.printStackTrace();
  
          }
  
  
  
          // Find a code that supports the mime type
  
          int numCodecs = MediaCodecList.getCodecCount();
  
          for (int i = 0; i &lt; numCodecs &amp;&amp; codecInfo == null; i++) {
  
              MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
  
              if (!info.isEncoder()) {
  
                  continue;
  
              }
  
              String[] types = info.getSupportedTypes();
  
              boolean found = false;
  
  
  
              for (int j = 0; j &lt; types.length &amp;&amp; !found; j++) {
  
                  if (types[j].equals(mimeType))
  
                      found = true;
  
              }
  
  
  
              if (!found)
  
                  continue;
  
              codecInfo = info;
  
          }
  
  
  
  
  
           for (int i = 0; i &lt; MediaCodecList.getCodecCount(); i++) {
  
                   MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
  
                   if (!info.isEncoder()) {
  
                       continue;
  
                   }
  
  
  
                   String[] types = info.getSupportedTypes();
  
                   for (int j = 0; j &lt; types.length; ++j) {
  
                       if (types[j] != mimeType) 
  
                           continue;
  
                       MediaCodecInfo.CodecCapabilities caps = info.getCapabilitiesForType(types[j]);
  
                       for (int k = 0; k &lt; caps.profileLevels.length; k++) {
  
                           if (caps.profileLevels[k].profile == MediaCodecInfo.CodecProfileLevel.AVCProfileHigh &amp;&amp; caps.profileLevels[k].level == MediaCodecInfo.CodecProfileLevel.AVCLevel4) {
  
                               codecInfo = info;
  
                           }
  
                       }
  
                   }
  
           }
  
  
  
          Log.d(TAG, "Found " + codecInfo.getName() + " supporting " + mimeType);
  
  
  
          MediaCodecInfo.CodecCapabilities capabilities = codecInfo.getCapabilitiesForType(mimeType);
  
          for (int i = 0; i &lt; capabilities.colorFormats.length &amp;&amp; colorFormat == 0; i++) {
  
              int format = capabilities.colorFormats[i];
  
              switch (format) {
  
                  case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
  
                  case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedPlanar:
  
                  case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
  
                  case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedSemiPlanar:
  
                  case MediaCodecInfo.CodecCapabilities.COLOR_TI_FormatYUV420PackedSemiPlanar:
  
                  colorFormat = format;
  
                  break;
  
              }
  
          }
  
          Log.d(TAG, "Using color format " + colorFormat);
  
  
  
          // Determine width, height and slice sizes
  
          if (codecInfo.getName().equals("OMX.TI.DUCATI1.VIDEO.H264E")) {
  
              // This codec doesn&#39;t support a width not a multiple of 16,
  
              // so round down.
  
              width &amp;= ~15;
  
          }
  
  
  
          stride = width;
  
          sliceHeight = height;
  
  
  
          if (codecInfo.getName().startsWith("OMX.Nvidia.")) {
  
              stride = (stride + 15) / 16 * 16;
  
              sliceHeight = (sliceHeight + 15) / 16 * 16;
  
          }
  
  
  
          inputFormat = MediaFormat.createVideoFormat(mimeType, width, height);
  
          inputFormat.setInteger(MediaFormat.KEY_BIT_RATE, bitRate);
  
          inputFormat.setInteger(MediaFormat.KEY_FRAME_RATE, frameRate);
  
          inputFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, colorFormat);
  
          inputFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 5);
  
  //          inputFormat.setInteger("stride", stride);
  
  //          inputFormat.setInteger("slice-height", sliceHeight);
  
          inputFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, MAX_INPUT);
  
  
  
          encoder = MediaCodec.createByCodecName(codecInfo.getName());
  
          encoder.configure(inputFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
  
          encoder.start();
  
  
  
          ByteBuffer[] inputBuffers = encoder.getInputBuffers();
  
          ByteBuffer[] outputBuffers = encoder.getOutputBuffers();
  
  
  
          int inputBufferIndex= -1, outputBufferIndex= -1;
  
          BufferInfo info = new BufferInfo();
  
          for (int i = 0; i &lt; mFilePaths.size(); i++) {
  
  
  
              // use decode sample to calculate inSample size and then resize
  
              Bitmap bitmapIn = Images.decodeSampledBitmapFromPath(mFilePaths.get(i), width, height);   
  
  
  
              // Create blank bitmap 
  
              Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);                   
  
  
  
              // Center scaled image
  
              Canvas canvas = new Canvas(bitmap);                 
  
              canvas.drawBitmap(bitmapIn,(bitmap.getWidth()/2)-(bitmapIn.getWidth()/2),(bitmap.getHeight()/2)-(bitmapIn.getHeight()/2), bmpPaint);
  
  
  
              Log.d(TAG, "Bitmap width: " + bitmapIn.getWidth() + " height: " + bitmapIn.getHeight() + " WIDTH: " + width + " HEIGHT: " + height);
  
              byte[] dat = getNV12(width, height, bitmap);
  
              bitmap.recycle();
  
  
  
              // Exception occurred on this below line in Emulator, LINE No. 182//**
  
              inputBufferIndex = encoder.dequeueInputBuffer(WAITTIME);
  
              Log.i("DAT", "Size= "+dat.length);
  
  
  
              if(inputBufferIndex >= 0){
  
                  int samplesiz= dat.length;
  
                  inputBuffers[inputBufferIndex].put(dat);
  
                  presentationTime = computePresentationTime(i);
  
                  if (i == mFilePaths.size()) {
  
                      encoder.queueInputBuffer(inputBufferIndex, 0, samplesiz, presentationTime, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
  
                      Log.i(TAG, "Last Frame");
  
                  } else { 
  
                      encoder.queueInputBuffer(inputBufferIndex, 0, samplesiz, presentationTime, 0);
  
                  }
  
  
  
                  while(true) {
  
                     outputBufferIndex = encoder.dequeueOutputBuffer(info, WAITTIME);
  
                     Log.i("BATA", "outputBufferIndex="+outputBufferIndex);
  
                     if (outputBufferIndex >= 0) {
  
                         ByteBuffer encodedData = outputBuffers[outputBufferIndex];
  
                         if (encodedData == null) {
  
                             throw new RuntimeException("encoderOutputBuffer " + outputBufferIndex +
  
                                     " was null");
  
                         }
  
  
  
                         if ((info.flags &amp; MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
  
                             // The codec config data was pulled out and fed to the muxer when we got
  
                             // the INFO_OUTPUT_FORMAT_CHANGED status.  Ignore it.
  
                             Log.d(TAG, "ignoring BUFFER_FLAG_CODEC_CONFIG");
  
                             info.size = 0;
  
                         }
  
  
  
                         if (info.size != 0) {
  
                             if (!mMuxerStarted) {
  
                                 throw new RuntimeException("muxer hasn&#39;t started");
  
                             }
  
  
  
                             // adjust the ByteBuffer values to match BufferInfo (not needed?)
  
                             encodedData.position(info.offset);
  
                             encodedData.limit(info.offset + info.size);
  
  
  
                             muxer.writeSampleData(mTrackIndex, encodedData, info);
  
                             Log.d(TAG, "sent " + info.size + " bytes to muxer");
  
                         }
  
  
  
                         encoder.releaseOutputBuffer(outputBufferIndex, false);
  
  
  
                         inputBuffers[inputBufferIndex].clear();
  
                         outputBuffers[outputBufferIndex].clear();
  
  
  
                         if ((info.flags &amp; MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
  
                             break;      // out of while
  
                         }
  
  
  
                     } else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
  
                         // Subsequent data will conform to new format.
  
                         MediaFormat opmediaformat = encoder.getOutputFormat();
  
                         if (!mMuxerStarted) {
  
                             mTrackIndex = muxer.addTrack(opmediaformat);
  
                             muxer.start();
  
                             mMuxerStarted = true;
  
                         }
  
                         Log.i(TAG, "op_buf_format_changed: " + opmediaformat);
  
                     } else if(outputBufferIndex == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
  
                         outputBuffers = encoder.getOutputBuffers();
  
                         Log.d(TAG, "Output Buffer changed " + outputBuffers);
  
                     } else if(outputBufferIndex == MediaCodec.INFO_TRY_AGAIN_LATER) {
  
                         // No Data, break out
  
                         break;
  
                     } else {
  
                         // Unexpected State, ignore it
  
                         Log.d(TAG, "Unexpected State " + outputBufferIndex);
  
                     }
  
                  }
  
  
  
              }     
  
          }
  
  
  
          if (encoder != null) {
  
              encoder.flush();
  
              encoder.stop();
  
              encoder.release();
  
              encoder = null;
  
          }
  
  
  
          if (muxer != null) {
  
              muxer.stop();
  
              muxer.release();
  
              muxer = null;
  
          }
  
  
  
          return true;
  
  
  
      };
  
  
  
      @Override
  
      protected void onPostExecute(Boolean result) {
  
          if (result) {
  
              if (mListener != null)
  
                  mListener.finished();
  
          } else {
  
              if (mListener != null)
  
                  mListener.errored();
  
          }
  
          super.onPostExecute(result);
  
      }
  
  
  
  
  
  
  
      byte [] getNV12(int inputWidth, int inputHeight, Bitmap scaled) {
  
          int [] argb = new int[inputWidth * inputHeight];
  
          scaled.getPixels(argb, 0, inputWidth, 0, 0, inputWidth, inputHeight);
  
          byte [] yuv = new byte[inputWidth*inputHeight*3/2];
  
          encodeYUV420SP(yuv, argb, inputWidth, inputHeight);
  
          scaled.recycle();
  
          return yuv;
  
      }
  
  
  
  
  
      void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width, int height) {
  
          final int frameSize = width * height;
  
          int yIndex = 0;
  
          int uvIndex = frameSize;
  
          int a, R, G, B, Y, U, V;
  
          int index = 0;
  
          for (int j = 0; j &lt; height; j++) {
  
              for (int i = 0; i &lt; width; i++) {
  
  
  
                  a = (argb[index] &amp; 0xff000000) >> 24; // a is not used obviously
  
                  R = (argb[index] &amp; 0xff0000) >> 16;
  
                  G = (argb[index] &amp; 0xff00) >> 8;
  
                  B = (argb[index] &amp; 0xff) >> 0;
  
  
  
                  // well known RGB to YVU algorithm
  
                  Y = ( (  66 * R + 129 * G +  25 * B + 128) >> 8) +  16;
  
                  V = ( ( -38 * R -  74 * G + 112 * B + 128) >> 8) + 128;
  
                  U = ( ( 112 * R -  94 * G -  18 * B + 128) >> 8) + 128;
  
  
  
                  yuv420sp[yIndex++] = (byte) ((Y &lt; 0) ? 0 : ((Y > 255) ? 255 : Y));
  
                  if (j % 2 == 0 &amp;&amp; index % 2 == 0) { 
  
                      yuv420sp[uvIndex++] = (byte)((V&lt;0) ? 0 : ((V > 255) ? 255 : V));
  
                      yuv420sp[uvIndex++] = (byte)((U&lt;0) ? 0 : ((U > 255) ? 255 : U));
  
                  }
  
  
  
                  index ++;
  
              }
  
          }
  
      }
  
  }
  
  </string></string>

  This has now been tested on 4 of my devices and works fine, is there are way to

  1/ Calculate the MAX_INPUT (to high and on the N7 II it crashes, I Don't want that happening once released)
  2/ Offer an api 16 solution ?
  3/ Do I need stride and stride height ?

  Thanks

• Problems with Streaming a Multicast RTSP Stream with Live555

  16 juin 2014, par ALM865

  I am having trouble setting up a Multicast RTSP session using Live555. The examples included with Live555 are mostly irrelevant as they deal with reading in files and my code differs because it reads in encoded frames generated from a FFMPEG thread within my own program (no pipes, no saving to disk, it is genuinely passing pointers to memory that contain the encoded frames for Live555 to stream).

  My Live555 project that uses a custom Server Media Subsession so that I can receive data from an FFMPEG thread within my program (instead of Live555’s default reading from a file, yuk !). This is a requirement of my program as it reads in a GigEVision stream in one thread, sends the decoded raw RGB packets to the FFMPEG thread, which then in turn sends the encoded frames off to Live555 for RTSP streaming.

  For the life of me I can’t work out how to send the RTSP stream as multicast instead of unicast !

  Just a note, my program works perfectly at the moment streaming Unicast, so there is nothing wrong with my Live555 implementation (before you go crazy picking out irrelevant errors !). I just need to know how to modify my existing code to stream Multicast instead of Unicast.

  My program is way too big to upload and share so I’m just going to share the important bits :

  Live_AnalysingServerMediaSubsession.h

  #ifndef _ANALYSING_SERVER_MEDIA_SUBSESSION_HH
  
  #define _ANALYSING_SERVER_MEDIA_SUBSESSION_HH
  
  
  
  #include 
  
  #include "Live_AnalyserInput.h"
  
  
  
  class AnalysingServerMediaSubsession: public OnDemandServerMediaSubsession {
  
  
  
  public:
  
    static AnalysingServerMediaSubsession*
  
    createNew(UsageEnvironment& env, AnalyserInput& analyserInput, unsigned estimatedBitrate,
  
          Boolean iFramesOnly = False,
  
              double vshPeriod = 5.0
  
              /* how often (in seconds) to inject a Video_Sequence_Header,
  
                 if one doesn't already appear in the stream */);
  
  
  
  protected: // we're a virtual base class
  
    AnalysingServerMediaSubsession(UsageEnvironment& env, AnalyserInput& AnalyserInput, unsigned estimatedBitrate, Boolean iFramesOnly, double vshPeriod);
  
    virtual ~AnalysingServerMediaSubsession();
  
  
  
  protected:
  
    AnalyserInput& fAnalyserInput;
  
    unsigned fEstimatedKbps;
  
  
  
  private:
  
    Boolean fIFramesOnly;
  
    double fVSHPeriod;
  
  
  
    // redefined virtual functions
  
    virtual FramedSource* createNewStreamSource(unsigned clientSessionId, unsigned& estBitrate);
  
    virtual RTPSink* createNewRTPSink(Groupsock* rtpGroupsock, unsigned char rtpPayloadTypeIfDynamic, FramedSource* inputSource);
  
  
  
  };
  
  
  
  #endif

  And "Live_AnalysingServerMediaSubsession.cpp"

  #include "Live_AnalysingServerMediaSubsession.h"
  
  #include 
  
  #include 
  
  #include 
  
  
  
  AnalysingServerMediaSubsession* AnalysingServerMediaSubsession::createNew(UsageEnvironment& env, AnalyserInput& wisInput, unsigned estimatedBitrate,
  
      Boolean iFramesOnly,
  
      double vshPeriod) {
  
          return new AnalysingServerMediaSubsession(env, wisInput, estimatedBitrate,
  
              iFramesOnly, vshPeriod);
  
  }
  
  
  
  AnalysingServerMediaSubsession
  
      ::AnalysingServerMediaSubsession(UsageEnvironment& env, AnalyserInput& analyserInput,   unsigned estimatedBitrate, Boolean iFramesOnly, double vshPeriod) 
  
      : OnDemandServerMediaSubsession(env, True /*reuse the first source*/),
  
  
  
      fAnalyserInput(analyserInput), fIFramesOnly(iFramesOnly), fVSHPeriod(vshPeriod) {
  
          fEstimatedKbps = (estimatedBitrate + 500)/1000;
  
  
  
  }
  
  
  
  AnalysingServerMediaSubsession
  
      ::~AnalysingServerMediaSubsession() {
  
  }
  
  
  
  FramedSource* AnalysingServerMediaSubsession ::createNewStreamSource(unsigned /*clientSessionId*/, unsigned& estBitrate) {
  
      estBitrate = fEstimatedKbps;
  
  
  
      // Create a framer for the Video Elementary Stream:
  
      //LOG_MSG("Create Net Stream Source [%d]", estBitrate);
  
  
  
      return MPEG1or2VideoStreamDiscreteFramer::createNew(envir(), fAnalyserInput.videoSource());
  
  }
  
  
  
  RTPSink* AnalysingServerMediaSubsession ::createNewRTPSink(Groupsock* rtpGroupsock, unsigned char /*rtpPayloadTypeIfDynamic*/, FramedSource* /*inputSource*/) {
  
      setVideoRTPSinkBufferSize();
  
      /*
  
      struct in_addr destinationAddress;
  
      destinationAddress.s_addr = inet_addr("239.255.12.42");
  
  
  
      rtpGroupsock->addDestination(destinationAddress,8888);
  
      rtpGroupsock->multicastSendOnly();
  
      */
  
      return MPEG1or2VideoRTPSink::createNew(envir(), rtpGroupsock);
  
  }

  Live_AnalyserSouce.h

  #ifndef _ANALYSER_SOURCE_HH
  
  #define _ANALYSER_SOURCE_HH
  
  
  
  #ifndef _FRAMED_SOURCE_HH
  
  #include "FramedSource.hh"
  
  #endif
  
  
  
  class FFMPEG;
  
  
  
  // The following class can be used to define specific encoder parameters
  
  class AnalyserParameters {
  
  public:
  
    FFMPEG * Encoding_Source;
  
  };
  
  
  
  class AnalyserSource: public FramedSource {
  
  public:
  
    static AnalyserSource* createNew(UsageEnvironment& env, FFMPEG * E_Source);
  
    static unsigned GetRefCount();
  
  
  
  
  
  public:
  
    static EventTriggerId eventTriggerId;
  
  
  
  protected:
  
    AnalyserSource(UsageEnvironment& env, FFMPEG *  E_Source);
  
    // called only by createNew(), or by subclass constructors
  
    virtual ~AnalyserSource();
  
  
  
  private:
  
    // redefined virtual functions:
  
    virtual void doGetNextFrame();
  
  
  
  private:
  
    static void deliverFrame0(void* clientData);
  
    void deliverFrame();
  
  
  
  
  
  private:
  
    static unsigned referenceCount; // used to count how many instances of this class currently exist
  
    FFMPEG * Encoding_Source;
  
  
  
    unsigned int Last_Sent_Frame_ID;
  
  };
  
  
  
  #endif

  Live_AnalyserSource.cpp

  #include "Live_AnalyserSource.h"
  
  #include  // for "gettimeofday()"
  
  #include "FFMPEGClass.h"
  
  
  
  AnalyserSource* AnalyserSource::createNew(UsageEnvironment& env, FFMPEG * E_Source) {
  
    return new AnalyserSource(env, E_Source);
  
  }
  
  
  
  
  
  EventTriggerId AnalyserSource::eventTriggerId = 0;
  
  
  
  unsigned AnalyserSource::referenceCount = 0;
  
  
  
  AnalyserSource::AnalyserSource(UsageEnvironment& env, FFMPEG * E_Source) : FramedSource(env), Encoding_Source(E_Source) {
  
    if (referenceCount == 0) {
  
      // Any global initialization of the device would be done here:
  
  
  
    }
  
    ++referenceCount;
  
  
  
    // Any instance-specific initialization of the device would be done here:
  
    Last_Sent_Frame_ID = 0;
  
  
  
    /* register us with the Encoding thread so we'll get notices when new frame data turns up.. */
  
    Encoding_Source->RegisterRTSP_Source(&(env.taskScheduler()), this);
  
  
  
    // We arrange here for our "deliverFrame" member function to be called
  
    // whenever the next frame of data becomes available from the device.
  
    //
  
    // If the device can be accessed as a readable socket, then one easy way to do this is using a call to
  
    //     envir().taskScheduler().turnOnBackgroundReadHandling( ... )
  
    // (See examples of this call in the "liveMedia" directory.)
  
    //
  
    // If, however, the device *cannot* be accessed as a readable socket, then instead we can implement is using 'event triggers':
  
    // Create an 'event trigger' for this device (if it hasn't already been done):
  
    if (eventTriggerId == 0) {
  
      eventTriggerId = envir().taskScheduler().createEventTrigger(deliverFrame0);
  
    }
  
  }
  
  
  
  AnalyserSource::~AnalyserSource() {
  
    // Any instance-specific 'destruction' (i.e., resetting) of the device would be done here:
  
  
  
    /* de-register this source from the Encoding thread, since we no longer need notices.. */
  
    Encoding_Source->Un_RegisterRTSP_Source(this);
  
  
  
    --referenceCount;
  
    if (referenceCount == 0) {
  
      // Any global 'destruction' (i.e., resetting) of the device would be done here:
  
  
  
      // Reclaim our 'event trigger'
  
      envir().taskScheduler().deleteEventTrigger(eventTriggerId);
  
      eventTriggerId = 0;
  
    }
  
  
  
  }
  
  
  
  unsigned AnalyserSource::GetRefCount() {
  
    return referenceCount;
  
  }
  
  
  
  void AnalyserSource::doGetNextFrame() {
  
    // This function is called (by our 'downstream' object) when it asks for new data.
  
    //LOG_MSG("Do Next Frame..");
  
    // Note: If, for some reason, the source device stops being readable (e.g., it gets closed), then you do the following:
  
    //if (0 /* the source stops being readable */ /*%%% TO BE WRITTEN %%%*/) {
  
    unsigned int FrameID = Encoding_Source->GetFrameID();
  
    if (FrameID == 0){
  
      //LOG_MSG("No Data. Close");
  
      handleClosure(this);
  
      return;
  
    }
  
  
  
  
  
  
  
    // If a new frame of data is immediately available to be delivered, then do this now:
  
    if (Last_Sent_Frame_ID != FrameID){
  
      deliverFrame();
  
      //DEBUG_MSG("Frame ID: %d",FrameID);
  
    }
  
  
  
    // No new data is immediately available to be delivered.  We don't do anything more here.
  
    // Instead, our event trigger must be called (e.g., from a separate thread) when new data becomes available.
  
  }
  
  
  
  void AnalyserSource::deliverFrame0(void* clientData) {
  
    ((AnalyserSource*)clientData)->deliverFrame();
  
  }
  
  
  
  void AnalyserSource::deliverFrame() {
  
  
  
    if (!isCurrentlyAwaitingData()) return; // we're not ready for the data yet
  
  
  
  
  
    static u_int8_t* newFrameDataStart;
  
    static unsigned newFrameSize = 0;
  
  
  
    /* get the data frame from the Encoding thread.. */
  
    if (Encoding_Source->GetFrame(&newFrameDataStart, &newFrameSize, &Last_Sent_Frame_ID)){
  
      if (newFrameDataStart!=NULL) {
  
          /* This should never happen, but check anyway.. */
  
          if (newFrameSize > fMaxSize) {
  
            fFrameSize = fMaxSize;
  
            fNumTruncatedBytes = newFrameSize - fMaxSize;
  
          } else {
  
            fFrameSize = newFrameSize;
  
          }
  
          gettimeofday(&fPresentationTime, NULL); // If you have a more accurate time - e.g., from an encoder - then use that instead.
  
          // If the device is *not* a 'live source' (e.g., it comes instead from a file or buffer), then set "fDurationInMicroseconds" here.
  
          /* move the data to be sent off.. */
  
          memmove(fTo, newFrameDataStart, fFrameSize);
  
  
  
          /* release the Mutex we had on the Frame's buffer.. */
  
          Encoding_Source->ReleaseFrame();
  
      }
  
      else {
  
          //AM Added, something bad happened
  
          //ALTRACE("LIVE555: FRAME NULL\n");
  
          fFrameSize=0;
  
          fTo=NULL;
  
          handleClosure(this);
  
      }
  
    }
  
    else {
  
      //LOG_MSG("Closing Connection due to Frame Error..");
  
      handleClosure(this);
  
    }
  
  
  
  
  
    // After delivering the data, inform the reader that it is now available:
  
    FramedSource::afterGetting(this);
  
  }

  Live_AnalyserInput.cpp

  #include "Live_AnalyserInput.h"
  
  #include "Live_AnalyserSource.h"
  
  
  
  
  
  ////////// WISInput implementation //////////
  
  
  
  AnalyserInput* AnalyserInput::createNew(UsageEnvironment& env, FFMPEG *Encoder) {
  
    if (!fHaveInitialized) {
  
      //if (!initialize(env)) return NULL;
  
      fHaveInitialized = True;
  
    }
  
  
  
    return new AnalyserInput(env, Encoder);
  
  }
  
  
  
  
  
  FramedSource* AnalyserInput::videoSource() {
  
    if (fOurVideoSource == NULL || AnalyserSource::GetRefCount() == 0) {
  
      fOurVideoSource = AnalyserSource::createNew(envir(), m_Encoder);
  
    }
  
    return fOurVideoSource;
  
  }
  
  
  
  
  
  AnalyserInput::AnalyserInput(UsageEnvironment& env, FFMPEG *Encoder): Medium(env), m_Encoder(Encoder) {
  
  }
  
  
  
  AnalyserInput::~AnalyserInput() {
  
    /* When we get destroyed, make sure our source is also destroyed.. */
  
    if (fOurVideoSource != NULL && AnalyserSource::GetRefCount() != 0) {
  
      AnalyserSource::handleClosure(fOurVideoSource);
  
    }
  
  }
  
  
  
  
  
  
  
  
  
  Boolean AnalyserInput::fHaveInitialized = False;
  
  int AnalyserInput::fOurVideoFileNo = -1;
  
  FramedSource* AnalyserInput::fOurVideoSource = NULL;

  Live_AnalyserInput.h

  #ifndef _ANALYSER_INPUT_HH
  
  #define _ANALYSER_INPUT_HH
  
  
  
  #include 
  
  #include "FFMPEGClass.h"
  
  
  
  
  
  class AnalyserInput: public Medium {
  
  public:
  
    static AnalyserInput* createNew(UsageEnvironment& env, FFMPEG *Encoder);
  
  
  
    FramedSource* videoSource();
  
  
  
  private:
  
    AnalyserInput(UsageEnvironment& env, FFMPEG *Encoder); // called only by createNew()
  
    virtual ~AnalyserInput();
  
  
  
  private:
  
    friend class WISVideoOpenFileSource;
  
    static Boolean fHaveInitialized;
  
    static int fOurVideoFileNo;
  
    static FramedSource* fOurVideoSource;
  
    FFMPEG *m_Encoder;
  
  };
  
  
  
  // Functions to set the optimal buffer size for RTP sink objects.
  
  // These should be called before each RTPSink is created.
  
  #define VIDEO_MAX_FRAME_SIZE 300000
  
  inline void setVideoRTPSinkBufferSize() { OutPacketBuffer::maxSize = VIDEO_MAX_FRAME_SIZE; }
  
  
  
  #endif

  And finally the relevant code from my Live555 worker thread that starts the whole process :

      Stop_RTSP_Loop=0;
  
      //  MediaSession     *ms;
  
      TaskScheduler    *scheduler;
  
      UsageEnvironment *env ;
  
      //  RTSPClient       *rtsp;
  
      //  MediaSubsession  *Video_Sub;
  
  
  
      char RTSP_Address[1024];
  
      RTSP_Address[0]=0x00;
  
  
  
      if (m_Encoder == NULL){
  
          //DEBUG_MSG("No Video Encoder registered for the RTSP Encoder");
  
          return 0;
  
      }
  
  
  
      scheduler = BasicTaskScheduler::createNew();
  
      env = BasicUsageEnvironment::createNew(*scheduler);
  
  
  
      UserAuthenticationDatabase* authDB = NULL;
  
  #ifdef ACCESS_CONTROL
  
      // To implement client access control to the RTSP server, do the following:
  
  
  
      if (m_Enable_Pass){
  
          authDB = new UserAuthenticationDatabase;
  
          authDB->addUserRecord(UserN, PassW);
  
      }
  
      ////////// authDB = new UserAuthenticationDatabase;
  
      ////////// authDB->addUserRecord((char*)"Admin", (char*)"Admin"); // replace these with real strings
  
      // Repeat the above with each <username>, <password> that you wish to allow
  
      // access to the server.
  
  #endif
  
  
  
      // Create the RTSP server:
  
      RTSPServer* rtspServer = RTSPServer::createNew(*env, 554, authDB);
  
      ServerMediaSession* sms;
  
  
  
      AnalyserInput* inputDevice;
  
  
  
  
  
      if (rtspServer == NULL) {
  
          TRACE("LIVE555: Failed to create RTSP server: %s\n", env->getResultMsg());
  
          return 0;
  
      }
  
      else {
  
          char const* descriptionString = "Session streamed by \"IMC Server\"";
  
  
  
  
  
  
  
          // Initialize the WIS input device:
  
          inputDevice = AnalyserInput::createNew(*env, m_Encoder);
  
          if (inputDevice == NULL) {
  
              TRACE("Live555: Failed to create WIS input device\n");
  
              return 0;
  
          }
  
          else {
  
              // A MPEG-1 or 2 video elementary stream:
  
              /* Increase the buffer size so we can handle the high res stream.. */
  
              OutPacketBuffer::maxSize = 300000;
  
              // NOTE: This *must* be a Video Elementary Stream; not a Program Stream
  
              sms = ServerMediaSession::createNew(*env, RTSP_Address, RTSP_Address, descriptionString);
  
  
  
              //sms->addSubsession(MPEG1or2VideoFileServerMediaSubsession::createNew(*env, inputFileName, reuseFirstSource, iFramesOnly));
  
  
  
              sms->addSubsession(AnalysingServerMediaSubsession::createNew(*env, *inputDevice, m_Encoder->Get_Bitrate()));
  
              //sms->addSubsession(WISMPEG1or2VideoServerMediaSubsession::createNew(sms->envir(), inputDevice, videoBitrate));
  
  
  
              rtspServer->addServerMediaSession(sms);
  
  
  
              //announceStream(rtspServer, sms, streamName, inputFileName);
  
              //LOG_MSG("Play this stream using the URL %s", rtspServer->rtspURL(sms));
  
  
  
          }
  
      }
  
  
  
      Stop_RTSP_Loop=0;
  
  
  
      for (;;)
  
      {
  
          /* The actual work is all carried out inside the LIVE555 Task scheduler */
  
          env->taskScheduler().doEventLoop(&amp;Stop_RTSP_Loop); // does not return
  
  
  
          if (mStop) {
  
              break;
  
          }
  
      }
  
  
  
      Medium::close(rtspServer); // will also reclaim "sms" and its "ServerMediaSubsession"s
  
      Medium::close(inputDevice);
  
  </password></username>