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• How to minimize latency in ffmpeg stream Java ?

  13 juillet 2022, par Taavi Sõerd

  I need to stream ffmpeg video feed in android studio and need minimal latency. Code below has achieved that when playing on galaxy s21 ultra but when I play it on galaxy tab then it's like in slow motion. When i set buffer size to 0 I get minimal latency but can't actually even see the video as it's all corrupted (all gray and colored noise).

  


  public class Decode implements Runnable {
public Activity activity;
AVFrame pFrameRGB;
SwsContext sws_ctx;
ByteBuffer bitmapBuffer;
Bitmap bmp;
byte[] array;
int imageViewWidth = 0;
int imageViewHeight = 0;
boolean imageChanged = true;
int v_stream_idx = -1;
int klv_stream_idx = -1;

boolean imageDrawMutex = false;

boolean imageIsSet = false;
ImageView imageView =  MainActivity.getmInstanceActivity().findViewById(R.id.imageView);

String mFilename = "udp://@" + MainActivity.connectionIP;;
UasDatalinkLocalSet mLatestDls;

public Decode(Activity _activity) {
    this.activity = _activity;
}

public void create_decoder(AVCodecContext codec_ctx) {
    imageChanged = true;

    // Determine required buffer size and allocate buffer
    int numBytes =av_image_get_buffer_size(AV_PIX_FMT_RGBA, codec_ctx.width(),
            codec_ctx.height(), 1);
    BytePointer buffer = new BytePointer(av_malloc(numBytes));

    bmp = Bitmap.createBitmap(codec_ctx.width(), codec_ctx.height(), Bitmap.Config.ARGB_8888);

    array = new byte[codec_ctx.width() * codec_ctx.height() * 4];
    bitmapBuffer = ByteBuffer.wrap(array);

    sws_ctx = sws_getContext(
            codec_ctx.width(),
            codec_ctx.height(),
            codec_ctx.pix_fmt(),
            codec_ctx.width(),
            codec_ctx.height(),
            AV_PIX_FMT_RGBA,
            SWS_POINT,
            null,
            null,
            (DoublePointer) null
    );

    if (sws_ctx == null) {
        Log.d("app", "Can not use sws");
        throw new IllegalStateException();
    }

    av_image_fill_arrays(pFrameRGB.data(), pFrameRGB.linesize(),
            buffer, AV_PIX_FMT_RGBA, codec_ctx.width(), codec_ctx.height(), 1);
}

@Override
public void run() {
    Log.d("app", "Start decoder");

    int ret = -1, i = 0;
    String vf_path = mFilename;

    AVFormatContext fmt_ctx = new AVFormatContext(null);
    AVPacket pkt = new AVPacket();


    AVDictionary multicastDict = new AVDictionary();

    av_dict_set(multicastDict, "rtsp_transport", "udp_multicast", 0);

    av_dict_set(multicastDict, "localaddr", getIPAddress(true), 0);
    av_dict_set(multicastDict, "reuse", "1", 0);

    av_dict_set(multicastDict, "buffer_size", "0.115M", 0);

    ret = avformat_open_input(fmt_ctx, vf_path, null, multicastDict);
    if (ret < 0) {
        Log.d("app", String.format("Open video file %s failed \n", vf_path));
        byte[] error_message = new byte[1024];
        int elen = av_strerror(ret, error_message, 1024);
        String s = new String(error_message, 0, 20);
        Log.d("app", String.format("Return: %d", ret));
        Log.d("app", String.format("Message: %s", s));
        throw new IllegalStateException();
    }
    
    if (avformat_find_stream_info(fmt_ctx, (PointerPointer) null) < 0) {
        //System.exit(-1);
        Log.d("app", "Stream info not found");
    }


    avformat.av_dump_format(fmt_ctx, 0, mFilename, 0);

    int nstreams = fmt_ctx.nb_streams();

    for (i = 0; i < fmt_ctx.nb_streams(); i++) {
        if (fmt_ctx.streams(i).codecpar().codec_type() == AVMEDIA_TYPE_VIDEO) {
            v_stream_idx = i;
        }
        if (fmt_ctx.streams(i).codecpar().codec_type() == AVMEDIA_TYPE_DATA) {
            klv_stream_idx = i;
        }
    }
    if (v_stream_idx == -1) {
        Log.d("app", "Cannot find video stream");
        throw new IllegalStateException();
    } else {
        Log.d("app", String.format("Video stream %d with resolution %dx%d\n", v_stream_idx,
                fmt_ctx.streams(v_stream_idx).codecpar().width(),
                fmt_ctx.streams(v_stream_idx).codecpar().height()));
    }

    AVCodecContext codec_ctx = avcodec_alloc_context3(null);
    avcodec_parameters_to_context(codec_ctx, fmt_ctx.streams(v_stream_idx).codecpar());


    AVCodec codec = avcodec_find_decoder(codec_ctx.codec_id());


    AVDictionary avDictionary = new AVDictionary();

    av_dict_set(avDictionary, "fflags", "nobuffer", 0);


    if (codec == null) {
        Log.d("app", "Unsupported codec for video file");
        throw new IllegalStateException();
    }
    ret = avcodec_open2(codec_ctx, codec, avDictionary);
    if (ret < 0) {
        Log.d("app", "Can not open codec");
        throw new IllegalStateException();
    }

    AVFrame frm = av_frame_alloc();

    // Allocate an AVFrame structure
    pFrameRGB = av_frame_alloc();
    if (pFrameRGB == null) {
        //System.exit(-1);
        Log.d("app", "unable to init pframergb");
    }

    create_decoder(codec_ctx);

    int width = codec_ctx.width();
    int height = codec_ctx.height();

    double fps = 15;
    

    while (true) {
        try {
            Thread.sleep(1);
        } catch (Exception e) {

        }

        try {
            if (av_read_frame(fmt_ctx, pkt) >= 0) {
                if (pkt.stream_index() == v_stream_idx) {
                    avcodec_send_packet(codec_ctx, pkt);

                    if (codec_ctx.width() != width || codec_ctx.height() != height) {
                        create_decoder(codec_ctx);
                        width = codec_ctx.width();
                        height = codec_ctx.height();
                    }
                }

                if (pkt.stream_index() == klv_stream_idx) {

                    byte[] klvDataBuffer = new byte[pkt.size()];

                    for (int j = 0; j < pkt.size(); j++) {
                        klvDataBuffer[j] = pkt.data().get(j);
                    }

                    try {
                        KLV k = new KLV(klvDataBuffer, KLV.KeyLength.SixteenBytes, KLV.LengthEncoding.BER);
                        byte[] main_payload = k.getValue();

                        // decode the Uas Datalink Local Set from main_payload binary blob.
                        mLatestDls = new UasDatalinkLocalSet(main_payload);

                        if (mLatestDls != null) {

                            MainActivity.getmInstanceActivity().runOnUiThread(new Runnable() {
                                @RequiresApi(api = Build.VERSION_CODES.Q)
                                @Override
                                public void run() {
                                    MainActivity.getmInstanceActivity().updateKlv(mLatestDls);
                                }
                            });
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    
                }

                int wasFrameDecoded = 0;
                while (wasFrameDecoded >= 0) {
                    wasFrameDecoded = avcodec_receive_frame(codec_ctx, frm);

                    if (wasFrameDecoded >= 0) {
                        // get clip fps
                        fps = 15; //av_q2d(fmt_ctx.streams(v_stream_idx).r_frame_rate());

                        sws_scale(
                                sws_ctx,
                                frm.data(),
                                frm.linesize(),
                                0,
                                codec_ctx.height(),
                                pFrameRGB.data(),
                                pFrameRGB.linesize()
                        );

                        if(!imageDrawMutex) {
                            MainActivity.getmInstanceActivity().runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    if (imageIsSet) {
                                        imageDrawMutex = true;
                                        pFrameRGB.data(0).position(0).get(array);
                                        bitmapBuffer.rewind();
                                        bmp.copyPixelsFromBuffer(bitmapBuffer);

                                        if (imageChanged) {
                                            (imageView).setImageBitmap(bmp);
                                            imageChanged = false;
                                        }

                                        (imageView).invalidate();
                                        imageDrawMutex = false;
                                    } else {
                                        (imageView).setImageBitmap(bmp);
                                        imageIsSet = true;
                                    }
                                }
                            });
                        }
                    }
                }
                av_packet_unref(pkt);

            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        if (false) {
            Log.d("threads", "false");

            av_frame_free(frm);

            avcodec_close(codec_ctx);
            avcodec_free_context(codec_ctx);

            avformat_close_input(fmt_ctx);
        }
    }
}


  


  This code is running in Android Studio with Java. I'm quite new on this topic so not really sure even where to start.
What could be the cause of that ?

  


• Concatenate chunk containg headers to another chunk in h264

  18 novembre 2014, par Ortixx

  I’m trying to extract thumbnails from a torrent stream by downloading the first couple of chunks to get the headers, another set of chunks from the middle and then concat them to have a single video file.

  For this I’m using nodejs but I’m having trouble with the concatenation part. Obviously the headers include the length of the video so if I simply concat another chunk to the end of the headers chunk, it won’t work.

  In other words, I have 2 chunks of a video file : The first one contains the headers and some material and the other one is fully composed of a video stream. I want to combine the two to form a single video file
  So my question is how can I make this work properly if at all ?

• Is there a built-in audio preprocessing within Android OS ?

  29 août 2022, par Larry lu

  I am running a dev team to build an Android application the major feature is to record a user's voice and merge it into a long movie. It's a dub film application.

  


  One struggle thing to my dev team is whether the Android OS pre-processes the recorded audio file. because we want the very original audio data from the built-in Microphone.
If there is a built-in pre-processing inside of Android OS that keeps updating some data of the recorded audio file, we want to know what is changed. We can't find any official post from Android speaking about it but would like to confirm from a professional.

  


  Many thanks