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• FFMPEG - local video to UDP streaming to OpenCV - video quality degraded

  6 juin 2021, par user3925023

  my goal is to re-stream local video content / desktop screencasting, to an UDP flow that I need to process on a Python script.

  



  Here is the FFMPEG script that I'm using :

  



  ffmpeg -re -i C:\Users\test\Downloads\out.ts -strict -2 -c:v copy -an -preset slower -tune stillimage -b 11200k -f rawvideo udp://127.0.0.1:5000


  



  And here is the simple Python script supposed to read the stream flow :

  



  import cv2

cap = cv2.VideoCapture('udp://127.0.0.1:5000',cv2.CAP_FFMPEG)
if not cap.isOpened():
    print('VideoCapture not opened')
    exit(-1)
width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)  # float
height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)  # float
print(str(width))
print(str(height))
while True:
    ret, frame = cap.read()
    imgray = frame[int(round((height/100)*70,0)):int(round((width/100)*42,0)), int(round((height/100)*74,0)):int(round((width/100)*54,0))]
    if not ret:
        print('frame empty')
        break
    cv2.imshow('image', imgray)
    if cv2.waitKey(1)&0XFF == ord('q'):
        break
cap.release()


  



  I'm able to visualize portion of the stream video as expect, but I'm facing lot of issue in video quality degradation, specially video artifact probably due missing packet processing :

  



  

  



  Also these are error log I'm geting from script :

  



  [h264 @ 0000026eb272f280] error while decoding MB 105 66, bytestream -21
[h264 @ 0000026eb2fcb740] error while decoding MB 100 53, bytestream -11
[h264 @ 0000026eb272f280] error while decoding MB 32 22, bytestream -11
[h264 @ 0000026ead9ee300] error while decoding MB 60 20, bytestream -25
[h264 @ 0000026eb27f00c0] error while decoding MB 9 62, bytestream -5
[h264 @ 0000026ead9ee780] error while decoding MB 85 44, bytestream -5
[h264 @ 0000026eb27f0800] error while decoding MB 64 25, bytestream -15
[h264 @ 0000026eb272f280] error while decoding MB 112 23, bytestream -17
[h264 @ 0000026eb2735200] error while decoding MB 30 21, bytestream -7


  



  Actually I don't care about video fluidity,I can also reduce the FPS, important thing is the video quality. Not sure if I'm doing wrong on the scripting python part or if I'm using wrong FFMPEG command.

  



  Many Thanks

  


• swresample : Add AVFrame based API

  11 août 2014, par Michael Niedermayer

  swresample : Add AVFrame based API
  Based on commit fb1ddcdc8f51b9d261ae8e9c26b91e81f7b6bf45 by Luca Barbato <lu_zero@gentoo.org>
  
  Adapted for libswresample by Michael Niedermayer
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] doc/APIchanges
  • [DH] libswresample/Makefile
  • [DH] libswresample/swresample.h
  • [DH] libswresample/swresample_frame.c
  • [DH] libswresample/version.h

• Encoding audio_common messages to OPUS

  14 juin 2023, par djangbahevans

  ---

  


  I am trying to stream microphone and camera data to Amazon KVS WebRTC. I'm able to make video work using this package (adapted for noetic) however I am struggling to make audio work. I'm using the audio_capture package to get mp3 frames. I'm trying to convert this to OPUS frames before streaming to KVS, but I'm unsure how to do this. I wrote this bit of code based on the small resources I can find on using ffmpeg, but it's not working. avcodec_fill_audio_frame is returning -22.

  


  #include "opus_encoder.h"

OPUSEncoder::OPUSEncoder() {
  av_register_all();
  codecContext == nullptr;
}

OPUSEncoder::~OPUSEncoder() {
  if (codecContext != nullptr) {
    avcodec_free_context(&codecContext);
  }
}

int OPUSEncoder::Initialize(int Fs, int channels) {
  AVCodec *codec = avcodec_find_encoder(AV_CODEC_ID_OPUS);
  if (!codec) {
    printf("Codec not found\n");
    return -1;
  }

  codecContext = avcodec_alloc_context3(codec);
  if (!codecContext) {
    printf("Could not allocate audio codec context\n");
    return -1;
  }

  codecContext->sample_fmt = AV_SAMPLE_FMT_S16;
  codecContext->bit_rate = 128000;
  codecContext->sample_rate = Fs;
  codecContext->channel_layout = av_get_default_channel_layout(channels);
  codecContext->channels = channels;

  if (avcodec_open2(codecContext, codec, nullptr) < 0) {
    printf("Could not open codec\n");
    return -1;
  }

  return 0;
}

int OPUSEncoder::Encode(const uint8_t *audio_data, int frameSize,
                        uint8_t *out) {
  AVPacket pkt;
  av_init_packet(&pkt);
  pkt.data = nullptr;
  pkt.size = 0;

  AVFrame *frame = av_frame_alloc();
  frame->nb_samples = frameSize;
  frame->format = codecContext->sample_fmt;
  frame->channel_layout = codecContext->channel_layout;

  int ret = avcodec_fill_audio_frame(frame, codecContext->channels,
                                     codecContext->sample_fmt, audio_data,
                                     frameSize * 2, 0);
  if (ret < 0) {
    printf("Error filling audio frame: %d\n", ret);
    return -1;
  }

  ret = avcodec_send_frame(codecContext, frame);
  if (ret < 0) {
    printf("Error sending the frame to the encoder\n");
    return -1;
  }

  while (ret >= 0) {
    ret = avcodec_receive_packet(codecContext, &pkt);
    if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
      return 0;
    } else if (ret < 0) {
      printf("Error encoding audio frame\n");
      return -1;
    }

    memcpy(out, pkt.data, pkt.size);
    out += pkt.size;
    av_packet_unref(&pkt);
  }

  av_frame_free(&frame);

  return 0;
}