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• Rolling screen capture with ffmpeg on windows

  11 décembre 2020, par gap210

  I have the following code to capture a video stream from my webcam. I use ffmpeg to write to named windows pipe, then read it with python and display with opencv. The thing is that the opencv stream is 'rolling' as shown here https://www.youtube.com/watch?v=H78TRo3DZIo

  


  If I capture the output to a video instead of a pipe, with the command :

  


  ffmpeg -f dshow -video_size 1920x1080 -framerate 60 -i video="USB Video" -c:v copy out.avi

  


  everything looks fine. What should I change to achieve the desired effect ? (non-rolling stream)

  


  My code below :

  


  import cv2
import time
import subprocess
import numpy as np

w, h = 800, 600

# Get frame generator
gen = ffmpegGrab()

# Get start time
start = time.time()

# Read video frames from ffmpeg in loop
nFrames = 0
cmd = 'C:/Users/......./Downloads/ffmpeg-4.3.1-2020-11-19-full_build/bin/ffmpeg.exe -f dshow -framerate 60 -video_size 800x600 -i video="USB Video" -pix_fmt bgr24 -vcodec rawvideo -f image2pipe -'

proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True, bufsize=10**9)
while True:
    # Read next frame from ffmpeg

    frame = proc.stdout.read(w * h * 3)
    frame = np.frombuffer(frame, dtype=np.uint8).reshape((h, w, 3))
    cv2.imshow('screenshot', frame)

    if cv2.waitKey(1) == ord("q"):
        break

    fps = nFrames / (time.time() - start)
    print(f'FPS: {fps}')

cv2.destroyAllWindows()


  


• ffmpeg can not open video file while PotPlayer and VLCPlayer can

  13 décembre 2020, par popova-ksiusha912

  Win10

  


  Video file(21.83MB) :https://www.mediafire.com/file/7b7w8ssio32qo2p/sample.flv/file

  


  Pot Player and VLC Player can open this file without any problem.

  


  But ffmpeg,ffplay,ffprobe can not open it.

  


  Is there any way to make ffmpeg recognize this video file ?

  


  C:\external>ffmpeg -v 9 -loglevel 99 -i sample.flv
ffmpeg version n4.3.1-26-gca55240b8c Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 9.3-win32 (GCC) 20200320
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-version3 --disable-debug --disable-w32threads --enable-pthreads --enable-iconv --enable-zlib --enable-libxml2 --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-opencl --enable-libvmaf --disable-vulkan --enable-libvorbis --enable-amf --enable-libaom --disable-avisynth --enable-libdav1d --disable-libdavs2 --enable-ffnvcodec --enable-cuda-llvm --disable-libglslang --enable-libass --enable-libbluray --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvpx --enable-libwebp --enable-libmfx --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librav1e --disable-librubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libtwolame --disable-libvidstab --disable-libx264 --disable-libx265 --disable-libxavs2 --disable-libxvid --enable-libzimg --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-libs=-lgomp
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
Splitting the commandline.
Reading option '-v' ... matched as option 'v' (set logging level) with argument '9'.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument '99'.
Reading option '-i' ... matched as input url with argument 'sample.flv'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option v (set logging level) with argument 9.
Successfully parsed a group of options.
Parsing a group of options: input url sample.flv.
Successfully parsed a group of options.
Opening an input file: sample.flv.
[NULL @ 000001e044da4580] Opening 'sample.flv' for reading
[file @ 000001e044da4e80] Setting default whitelist 'file,crypto,data'
Probing flv score:100 size:2048
Probing mp3 score:1 size:2048
[flv @ 000001e044da4580] Format flv probed with size=2048 and score=100
[flv @ 000001e044da4580] Before avformat_find_stream_info() pos: 13 bytes read:32768 seeks:0 nb_streams:0
[flv @ 000001e044da4580] type:18, size:626, last:-1, dts:0 pos:21
[flv @ 000001e044da4580] type:8, size:4, last:-1, dts:0 pos:662
[flv @ 000001e044da4580] 1 AF 0
[flv @ 000001e044da4580] type:8, size:287, last:-1, dts:0 pos:681
[flv @ 000001e044da4580] 1 AF 0
[flv @ 000001e044da4580] type:9, size:13245, last:-1, dts:0 pos:983
[flv @ 000001e044da4580] 0 27 0
[NULL @ 000001e044e4bd80] missing picture in access unit with size 13240
[extract_extradata @ 000001e044e50600] No start code is found.
[flv @ 000001e044da4580] After avformat_find_stream_info() pos: 14235 bytes read:65845 seeks:3 frames:1
sample.flv: could not find codec parameters
Input #0, flv, from 'sample.flv':
Metadata:
d_cate : 1
d_client : 10001
dy_app_version : 6.3.6.1
dy_device_model : HONOR YAL-AL50 YAL-AL50
dy_level : Level51
dy_live_start_time: Sat Nov 28 22:05:50 GMT+08:00 2020
dy_location : null
dy_network : 4G 4
dy_os_version : 29
dy_profile : High
dy_pusher_version: 1.3.3
dy_timezone : Asia/Shanghai?
hasWatermark : 1
encoder : Lavf56.40.101
cdn_ip : 61.156.196.105
Duration: 00:01:14.46, start: 0.000000, bitrate: N/A
Stream #0:0, 1, 1/1000: Audio: aac, 44100 Hz, stereo, 98 kb/s
Stream #0:1, 0, 1/1000: Video: h264, 1 reference frame, none, 2048 kb/s, 1k tbn
Successfully opened the file.
At least one output file must be specified
[AVIOContext @ 000001e044dadd40] Statistics: 65845 bytes read, 3 seeks
C:\external>


  


• png is invalid argument when using ffmpeg

  20 octobre 2020, par Ace_Li

  I am running into invalid argument when I try to convert +5 photos into an mp4 file.
This worked on my mac but it doesnt work on windows 10. Can someone help :) Thanks in advance

  


  here is the command i entered.

  


  ffmpeg -r 1/5 -pattern_type glob -i '*.png' -c:v libx264 output.mp4

  


  C:\Users/userz\Desktop\photos>ffmpeg -r 1/5 -pattern_type glob -i '*.png' -c:v libx264 output.mp4
ffmpeg version N-99502-g0d156eb58a Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3-win32 (GCC) 20200320
  configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --enable-iconv --enable-zlib --enable-libxml2 --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-libvmaf --disable-vulkan --enable-libvorbis --enable-amf --enable-libaom --enable-avisynth --enable-libdav1d --enable-ffnvcodec --enable-cuda-llvm --disable-libglslang --enable-libass --enable-libbluray --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvpx --enable-libwebp --enable-libmfx --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librav1e --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libvidstab --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzimg --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-libs=-lgomp
  libavutil      56. 60.100 / 56. 60.100
  libavcodec     58.111.100 / 58.111.100
  libavformat    58. 62.100 / 58. 62.100
  libavdevice    58. 11.102 / 58. 11.102
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
'*.png': Invalid argument