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• error while compiling simple c++ file with libavformat library

  21 février 2023, par Abdo Daood

  i create simple c++ file called test.cpp

  


  #include <iostream>&#xA;#include &#xA;using namespace std;&#xA;&#xA;int main() &#xA;{&#xA;    cout &lt;&lt; "Hello, World!";&#xA;    return 0;&#xA;}&#xA;&#xA;</iostream>

  


  and using g++ in terminal to compile test.cpp file with the command :

  


  


  g++ test.cpp -o test

  


  


  i get this error =>

  


  test.cpp:2:10: fatal error: libavformat\avformat.h: No such file or directory
    2 | #include 
      |          ^~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.


  


  Notes :
libavformat\avformat.h path is : /usr/include/x86_64-linux-gnu/libavformat/avformat.h

  


  and using ffmpeg version is :

  


  $ ffmpeg -version

  


  ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers
built with gcc 11 (Ubuntu 11.2.0-19ubuntu1)
configuration : —prefix=/usr —extra-version=0ubuntu0.22.04.1 —toolchain=hardened —libdir=/usr/lib/x86_64-linux-gnu —incdir=/usr/include/x86_64-linux-gnu —arch=amd64 —enable-gpl —disable-stripping —enable-gnutls —enable-ladspa —enable-libaom —enable-libass —enable-libbluray —enable-libbs2b —enable-libcaca —enable-libcdio —enable-libcodec2 —enable-libdav1d —enable-libflite —enable-libfontconfig —enable-libfreetype —enable-libfribidi —enable-libgme —enable-libgsm —enable-libjack —enable-libmp3lame —enable-libmysofa —enable-libopenjpeg —enable-libopenmpt —enable-libopus —enable-libpulse —enable-librabbitmq —enable-librubberband —enable-libshine —enable-libsnappy —enable-libsoxr —enable-libspeex —enable-libsrt —enable-libssh —enable-libtheora —enable-libtwolame —enable-libvidstab —enable-libvorbis —enable-libvpx —enable-libwebp —enable-libx265 —enable-libxml2 —enable-libxvid —enable-libzimg —enable-libzmq —enable-libzvbi —enable-lv2 —enable-omx —enable-openal —enable-opencl —enable-opengl —enable-sdl2 —enable-pocketsphinx —enable-librsvg —enable-libmfx —enable-libdc1394 —enable-libdrm —enable-libiec61883 —enable-chromaprint —enable-frei0r —enable-libx264 —enable-shared
libavutil 56. 70.100 / 56. 70.100
libavcodec 58.134.100 / 58.134.100
libavformat 58. 76.100 / 58. 76.100
libavdevice 58. 13.100 / 58. 13.100
libavfilter 7.110.100 / 7.110.100
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100

  


  using this command :

  


  g++ `pkg-config --cflags libavformat` test.cpp  `pkg-config --libs libavformat` -o test



  


• FFmpeg hevc_nvenc encoder B Frame problem

  16 mai 2023, par ramondq

  I'm using the latest FFmpeg windows Build (2022-12-02 12:44) from BtbN.
I'm trying to encode a video into HEVC codec using hevc_nvenc encoder. But it says [hevc_nvenc @ 00000263983f4280] B frames as references are not supported. Cause my GPU GTX1060 (GP106) doesn't support hardware accelerate encode HEVC of B frames.
command line

  


  I tried to disable the B frames by adding the parameter -bf 0, but it doesn't work.
Then I tried to use the latest build from gyan.dev and it is the same. But when I tried to use an older build (2021-02-28 12:32) of BtbN, it doesn't have the problem.
Is there a workaround to bypass this B frame problem ? Cause I don't want to switch to an older build. Thanks.

  


• Why does OpenCV read video faster than FFMPEG ?

  17 septembre 2022, par tadejsv

  I noticed that OpenCV reads video frames almost 2x faster than FFMPEG.

  


  Why is that ? I thought all OpenCV does is call FFMPEG under the hood, possibly adding its own overhead.

  


  Here's the code I use to obtain these results

  


  import cv2
import time
import numpy as np

cap = cv2.VideoCapture("BigBuckBunny.mp4", apiPreference=cv2.CAP_FFMPEG)
frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))

start = time.perf_counter()
while True:
    ret, frame = cap.read()
    if ret is False:
        break
    assert frame.shape == (720, 1280, 3)
    assert frame.dtype == np.uint8
end = time.perf_counter()

print(f"{frames/(end-start):.1f} frames per second")
# Output: 692.3 frames per second

cap.release()


  


  For FFMPEG (using the python-ffmpeg library :

  


  import ffmpeg
import numpy as np
import time

vid_info = ffmpeg.probe("BigBuckBunny.mp4")['streams'][1]
frames = int(vid_info['nb_frames'])

process1 = (
    ffmpeg
    .input("BigBuckBunny.mp4")
    .output('pipe:', format='rawvideo', pix_fmt='bgr24')
)
print(process1.compile())
# Output: ['ffmpeg', '-i', 'BigBuckBunny.mp4', '-f', 'rawvideo', '-pix_fmt', 'bgr24', 'pipe:']


process1 = process1.run_async(pipe_stdout=True)

start = time.perf_counter()
while True:
    in_bytes = process1.stdout.read(1280 * 720 * 3)
    if not in_bytes:
        break
    frame = np.frombuffer(in_bytes, np.uint8).reshape([720, 1280, 3])
end = time.perf_counter()
print(f"{frames/(end-start):.1f} frames per second")
# Output: 373.6 frames per second
process1.wait()


  


  Here's information about the video ( 10 minutes length)

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'BigBuckBunny.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isomavc1mp42
    creation_time   : 2010-01-10T08:29:06.000000Z
  Duration: 00:09:56.47, start: 0.000000, bitrate: 2119 kb/s
  Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      creation_time   : 2010-01-10T08:29:06.000000Z
      handler_name    : (C) 2007 Google Inc. v08.13.2007.
      vendor_id       : [0][0][0][0]
  Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1991 kb/s, 24 fps, 24 tbr, 24k tbn, 48 tbc (default)
    Metadata:
      creation_time   : 2010-01-10T08:29:06.000000Z
      handler_name    : (C) 2007 Google Inc. v08.13.2007.
      vendor_id       : [0][0][0][0]


  


  And FFMPEG and OpenCV versions :

  


  ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers


  


  opencv-python-headless        4.6.0.66