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• Can I test funcion of nvidia decoder (nvdec/cuvid) on generated ffmpeg video?

  31 January 2021, by Milan Čížek

  goal: In my script I try to check if nvdec on my graphics card is available/functional.
I don't have any source video (H.264 / H.265) to use as input at this time intentionally, so I want to generate it.
It is also not necessary to use an encoder, because I do not need the output file.
I'm testing the exit code of command ffmpeg ($?).
I use nvidia-smi for check dec/enc load.

  


  My attempt:

  


  ffmpeg -y -hwaccel cuda -hwaccel_output_format cuda -c:v h264_cuvid -f lavfi -i testsrc="duration=5:size=1920x1080:rate=25" -c:v copy test.ts


  


  output of my commands:

  


  Input #0, lavfi, from 'testsrc=duration=5:size=1920x1080:rate=25':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h264, rgb24, 1920x1080 [SAR 1:1 DAR 16:9], 25 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> wrapped_avframe (native))
Press [q] to stop, [?] for help
No information about the input framerate is available. Falling back to a default value of 25fps for output stream #0:0. Use the -r option if you want a different framerate.
Output #0, null, to 'pipe:':
  Metadata:
    encoder         : Lavf58.65.101
    Stream #0:0: Video: wrapped_avframe, rgb24, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn
    Metadata:
      encoder         : Lavc58.119.100 wrapped_avframe
frame=    0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)


  


  I triead add -t 5 before test.ts but nothing changed.
Output ts file has zero size.

  


  If I debug the command, I expect to add it to the end "-f null - 2>/dev/null". Output file is only for debug purposes.

  


  Thank you.

  


• first few seconds of m3u8 clip isn't working, which is generated from another m3u8 file by node js

  13 January 2021, by Alan

  index.js

  


  
const ffmpegPath = require('@ffmpeg-installer/ffmpeg').path;
const ffmpeg = require('fluent-ffmpeg');
const process = require('process');


const args = process.argv.slice(2);
if (args.length !== 4) {
    console.error('Incorrect number of arguments');
    process.exit(1);
  }
const startTime = args[0];
const timeDuration = args[1];
const inputFile = args[2];
const outputFile=args[3];

ffmpeg.setFfmpegPath(ffmpegPath);

ffmpeg(inputFile)
  .setStartTime(startTime)
  .setDuration(timeDuration)
  .output(outputFile)
  .outputOptions('-hls_list_size 0')
  .on('end', function(err) {
    if(!err) { console.log('conversion Done') }
  })
  .on('error', function(err){
    console.log('error: ', err)
  }).run();



  


  


  Here is my code which I'm using to create a clip m3u8 formatted file from another m3u8 file. I'm using this command on the terminal to generate it.
Here is the command

  


  node index.js 5 40 ../path/input.m3u8 ../path/output.m3u8

  


  so here 5 is the starting time and 40 is the duration in seconds.
The issue is the first ts file it's generating (for example output_test0.ts) isn't working as it should. It's getting generated in kb format while the others in MB format. So when I play the new m3u8 file, the first 3-5 seconds clip is a static pic but other than that everything works fine.
Here is a link to the m3u8 file. https://mp4.to/downloads/0cb552cd749c4cf4b

  


  


  


  

  


  


  


  As you can see the first output_test0.ts file isn't like others. Other output ts files are in MB while the first one only in kb and this case been happening with the first file only. Any command input I'm missing? need help.

  


  


• My webcam works fine, while using cv2.Videocapture() but while trying to read from hard drive it shows error cap.isOpened() returns false, why?

  27 September 2017, by Hu Yang

  import cv2
  video_capture = cv2.VideoCapture("rtsp://admin:Trust1986_@10.58.94.47:554/h264/ch1/main/av_stream")
  video_capture.isOpened()

  False

  Other information below here, and ffmpeg I had installed.

    Video I/O:
  
      DC1394 1.x:                  NO
  
      DC1394 2.x:                  NO
  
      FFMPEG:                      NO
  
        avcodec:                   NO
  
        avformat:                  NO
  
        avutil:                    NO
  
        swscale:                   NO
  
        avresample:                NO
  
      GStreamer:                   NO
  
      OpenNI:                      NO
  
      OpenNI PrimeSensor Modules:  NO
  
      OpenNI2:                     NO
  
      PvAPI:                       NO
  
      GigEVisionSDK:               NO
  
      Aravis SDK:                  NO
  
      UniCap:                      NO
  
      UniCap ucil:                 NO
  
      V4L/V4L2:                    NO/NO
  
      XIMEA:                       NO
  
      Xine:                        NO
  
      Intel Media SDK:             NO
  
      gPhoto2:                     NO
  
  
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# ffmpeg -version
  
  ffmpeg version 3.3.4 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  configuration: 
  
  libavutil      55. 58.100 / 55. 58.100
  
  libavcodec     57. 89.100 / 57. 89.100
  
  libavformat    57. 71.100 / 57. 71.100
  
  libavdevice    57.  6.100 / 57.  6.100
  
  libavfilter     6. 82.100 /  6. 82.100
  
  libswscale      4.  6.100 /  4.  6.100
  
  libswresample   2.  7.100 /  2.  7.100
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# 
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# python3.6m -V
  
  Python 3.6.2
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# pkg-config --modversion opencv  
  
  3.3.0

  what shall I do next step? Thanks.