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• a problem with ffmpeg using pulse mode to open audio device blocking [closed]

  21 juin 2024, par ZhangKun

  on linux x86 system, command line terminal,
music on,
"ffmpeg -f pulse -i xxxx(audio dev name,is a loudspeaker) /tmp/xxxx.wav" run perfect ,
"aplay -i /tmp/xxxx.wav" can play Captured speaker sound,

  


  but,
in cpp code,

  


  {
   ...
   AVInputFormat * fmt = av_find_input_format("pluse");
   if(!fmt)
      return -1;
   
   AVFormatContext *ctx = avformat_alloc_context();
   if(!ctx)
     return -1;

   int ret = avformat_open_input(&ctx,"xxxx dev name",fmt,NULL);  //block.......

   ...
}


  


  why ternimal not,code blocking,Does anyone know ?

  


• FFmpeg player backporting to Android 2.1 - one more problem

  22 avril 2024, par tretdm

  I looked for a lot of information about how to build and use FFmpeg in early versions of Android, looked at the source codes of players from 2011-2014 and was able to easily build FFmpeg 4.0.4 and 3.1.4 on the NDKv5 platform. I have highlighted the main things for this purpose :

  


  

  • <android></android>bitmap.h> and <android></android>native_window.h> before Android 2.2 (API Level 8) such a thing did not exist

  


  • this requires some effort to implement buffer management for A/V streams, since in practice, when playing video, the application silently crashed after a few seconds due to overflow (below code example in C++ and Java)

  


  • FFmpeg - imho, the only way to support a sufficient number of codecs that are not officially included in Android 2.1 and above

  


  


  void decodeVideoFromPacket(JNIEnv *env, jobject instance,
                           jclass mplayer_class, AVPacket avpkt, 
                           int total_frames, int length) {
    AVFrame     *pFrame = NULL
    AVFrame     *pFrameRGB = NULL;
    pFrame = avcodec_alloc_frame();
    pFrameRGB = avcodec_alloc_frame();
    int frame_size = avpicture_get_size(PIX_FMT_RGB32, gVideoCodecCtx->width, gVideoCodecCtx->height);
    unsigned char* buffer = (unsigned char*)av_malloc((size_t)frame_size * 3);
    if (!buffer) {
        av_free(pFrame);
        av_free(pFrameRGB);
        return;
    }
    jbyteArray buffer2;
    jmethodID renderVideoFrames = env->GetMethodID(mplayer_class, "renderVideoFrames", "([BI)V");
    int frameDecoded;
    avpicture_fill((AVPicture*) pFrame,
                   buffer,
                   gVideoCodecCtx->pix_fmt,
                   gVideoCodecCtx->width,
                   gVideoCodecCtx->height
                  );

    if (avpkt.stream_index == gVideoStreamIndex) { // If video stream found
        int size = avpkt.size;
        total_frames++;
        struct SwsContext *img_convert_ctx = NULL;
        avcodec_decode_video2(gVideoCodecCtx, pFrame, &frameDecoded, &avpkt);
        if (!frameDecoded || pFrame == NULL) {
            return;
        }

        try {
            PixelFormat pxf;
            // RGB565 by default for Android Canvas in pre-Gingerbread devices.
            if(android::get_android_api_version(env) >= ANDROID_API_CODENAME_GINGERBREAD) {
                pxf = PIX_FMT_BGR32;
            } else {
                pxf = PIX_FMT_RGB565;
            }

            int rgbBytes = avpicture_get_size(pxf, gVideoCodecCtx->width,
                                            gVideoCodecCtx->height);

            // Converting YUV to RGB frame & RGB frame to char* buffer 
            
            buffer = convertYuv2Rgb(pxf, pFrame, rgbBytes); // result of av_image_copy_to_buffer()

            if(buffer == NULL) {
                return;
            }

            buffer2 = env->NewByteArray((jsize) rgbBytes);
            env->SetByteArrayRegion(buffer2, 0, (jsize) rgbBytes,
                                    (jbyte *) buffer);
            env->CallVoidMethod(instance, renderVideoFrames, buffer2, rgbBytes);
            env->DeleteLocalRef(buffer2);
            free(buffer);
        } catch (...) {
            if (debug_mode) {
                LOGE(10, "[ERROR] Render video frames failed");
                return;
            }
        }
    }
}


  


  private void renderVideoFrames(final byte[] buffer, final int length) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                Canvas c;
                VideoTrack track = null;
                for (int tracks_index = 0; tracks_index < tracks.size(); tracks_index++) {
                    if (tracks.get(tracks_index) instanceof VideoTrack) {
                        track = (VideoTrack) tracks.get(tracks_index);
                    }
                }
                if (track != null) {
                    int frame_width = track.frame_size[0];
                    int frame_height = track.frame_size[1];
                    if (frame_width > 0 && frame_height > 0) {
                        try {
                            // RGB_565  == 65K colours (16 bit)
                            // RGB_8888 == 16.7M colours (24 bit w/ alpha ch.)
                            int bpp = Build.VERSION.SDK_INT > 9 ? 16 : 24;
                            Bitmap.Config bmp_config =
                                    bpp == 24 ? Bitmap.Config.RGB_565 : Bitmap.Config.ARGB_8888;
                            Paint paint = new Paint();
                            if(buffer != null && holder != null) {
                                holder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);
                                if((c = holder.lockCanvas()) == null) {
                                    Log.d(MPLAY_TAG, "Lock canvas failed");
                                    return;
                                }
                                ByteBuffer bbuf =
                                        ByteBuffer.allocateDirect(minVideoBufferSize);
                                bbuf.rewind();
                                for(int i = 0; i < buffer.length; i++) {
                                    bbuf.put(i, buffer[i]);
                                }
                                bbuf.rewind();

                                // The approximate location where the application crashed.
                                Bitmap bmp = Bitmap.createBitmap(frame_width, frame_height, bmp_config);
                                bmp.copyPixelsFromBuffer(bbuf);
                                
                                float aspect_ratio = (float) frame_width / (float) frame_height;
                                int scaled_width = (int)(aspect_ratio * (c.getHeight()));
                                c.drawBitmap(bmp,
                                        null,
                                        new RectF(
                                                ((c.getWidth() - scaled_width) / 2), 0,
                                                ((c.getWidth() - scaled_width) / 2) + scaled_width,
                                                c.getHeight()),
                                        null);
                                holder.unlockCanvasAndPost(c);
                                bmp.recycle();
                                bbuf.clear();
                            } else {
                                Log.d(MPLAY_TAG, "Video frame buffer is null");
                            }
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        } catch (OutOfMemoryError oom) {
                            oom.printStackTrace();
                            stop();
                        }
                    }
                }
            }
        }).start();
    }


  


  Exception (tested in Android 4.1.2 emulator) :

  


  E/dalvikvm-heap: Out of memory on a 1228812-byte allocation
I/dalvikvm: "Thread-495" prio=5 tid=21 RUNNABLE
   ................................................
     at android.graphics.Bitmap.nativeCreate(Native Method)
     at android.graphics.Bitmap.createBitmap(Bitmap.java:640)
     at android.graphics.Bitmap.createBitmap(Bitmap.java:620)
     at [app_package_name].MediaPlayer$5.run(MediaPlayer.java:406)
     at java.lang.Thread.run(Thread.java:856)


  


  For clarification : I first compiled FFmpeg 0.11.x on a virtual machine with Ubuntu 12.04 LTS from my written build script, looked for player examples suitable for Android below 2.2 (there is little information about them, unfortunately) and opened the file on the player and after showing the first frames it crashed into a stack or buffer overflow, on I put off developing the player for some time.

  


  Is there anything ready-made that, as a rule, fits into one C++ file and takes into account all the nuances of backporting ? Thanks in advance.

  


• Problem with xampp, some other program you use ? [closed]

  4 avril 2024, par user13449797

  I have been using xampp for several years, but recently I have become more and more bothered by using this program.

  


  sometimes there is a problem with starting MYSQL services. Sometimes solution with helps
text
I don't understand why this problem hasn't been solved yet and what exactly is the problem that sometimes it stops working on its own.

  


  Maybe you have any better alternatives to Windows 11 ?