Recherche avancée

Sur d’autres sites (6984)

• How to start an FFmpeg process, create a pipe and write data from the parent process ?

  3 mai 2021, par xlxs

  My code is based on https://stackoverflow.com/a/32279430/5941827.

  


  I run FFmpeg with the following params :

  


  std::stringstream sstm;
sstm << "ffmpeg -loglevel error -y -f rawvideo -vcodec rawvideo -s " << std::to_string(width) << "x" << std::to_string(height) //
        << " -pix_fmt rgb24 -framerate " << std::to_string(fps) << " -i - -c:v libx264 -preset " << getPreset(encodeSpeed) << //
        " -crf " << std::to_string(crf) << " -shortest " << path;


  


  (the variables are initialized in a class constructor correctly)

  


  Then I open the pipe with pPipe = popen(sstm.str().c_str(), "w").The problem is after I fwrite to it and calling fclose, based on the contents I write sometimes less or more bytes reach FFmpeg, and I get

  


  [rawvideo @ 000000000010c3df] Invalid buffer size, packet size 196606 < expected frame_size 196608
Error while decoding stream #0:0: Invalid argument


  


  The saved output video usually has one frame more or less than the expected.
I have checked the array I'm sending trough the pipe with fwrite and it's size is correct.
It appears that based on the data I send some bytes don't get there, or more bytes than I send go through the pipe.

  


  I have also tried two different FFmpeg versions, but with the same error message.

  


• How to merge two ffmpeg queries to one pipe ?

  19 mai 2021, par Aleksey Timoshchenko

  I have a sequence (100 images) (image ex : https://drive.google.com/file/d/1V8HwOuIo9PBX3ix0eKFQFGimskU_H0mN/view?usp=sharing) of Bayer images, what I need to do is

  


  

  1. debayer them

  


  2. compress the result in the .h264 file

  


  


  So, there are two queries that I use

  


  for debayer

  


  ffmpeg -y -i D:\Buffer\Bayer\Time%7d_img.bmp -vf format=gray -f rawvideo pipe: -hide_banner | ffmpeg -y -f rawvideo -pixel_format bayer_rggb8 -video_size 4104x3006 -i pipe: -frames 100 D:\Buffer\res\result%7d.png -hide_banner


  


  and for compression

  


  ffmpeg -framerate 30 -i D:\Buffer\res\result%7d.png -c:v hevc_nvenc -qp 0 D:\Buffer\res264\test5.h264 -hide_banner


  


  I need to merge these two queries into one, I tried to do it like this

  


  ffmpeg -y -i D:\Buffer\Bayer\Time%7d_img.bmp -vf format=gray -f rawvideo pipe: -hide_banner | ffmpeg -y -f rawvideo -pixel_format bayer_rggb8 -video_size 4104x3006 pipe: -hide_banner | ffmpeg -c:v hevc_nvenc -qp 0 -i pipe D:\Buffer\res264\test5.h264 -hide_banner


  


  but I get an error here

  


  Input #0, image2, from 'D:\Buffer\Bayer\Time%7d_img.bmp':
Output #0, rawvideo, to 'pipe:':  Duration:
00:00:40.0Output file #0 does not contain any stream0
, start: 0.000000, bitrate: N/AUnknown decoder 'hevc_nvenc'

    Stream #0:0: Video: bmp, pal8, 2464x2056, 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (bmp (native) -> rawvideo (native))
Press [q] to stop, [?] for help
Output #0, rawvideo, to 'pipe:':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #0:0: Video: rawvideo (Y800 / 0x30303859), gray, 2464x2056, q=2-31, 1013196 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc58.54.100 rawvideo
av_interleaved_write_frame(): Invalid argument
Error writing trailer of pipe:: Invalid argument
frame=    1 fps=0.0 q=-0.0 Lsize=    4947kB time=00:00:00.04 bitrate=1013196.8kbits/s speed=   2x
video:4947kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
Conversion failed!


  


  What am I doing wrong here ?

  


• How to pipe attachment to variable

  1er juin 2021, par ioundesin

  I would like to pipe an attachement from inside a *.mka to a variable instead of to a file.

  


  Saving the attachment to a *.txt file looks like this (and works) :

  


  import io
import subprocess
import sys, os
import soundfile as sf

full_path = os.path.realpath(__file__)
path, filex = os.path.split(full_path)

fname = 'my_own_soundfile.mka'
fullpath = path + '\\' + fname
pathffmpeg = 'C:/FFmpeg/bin/ffmpeg.exe'

command = [pathffmpeg, "-dump_attachment:t:0",
           "C:\folder\\attachment.txt",
           "-i", fullpath] # This one works

proc = subprocess.run(command, stdout=subprocess.PIPE)


  


  This command is my attempt at piping the attachment, however this does not work :

  


  command = [pathffmpeg, "-dump_attachment:t:0",
           "-f", "PIPE:0",
           "-i", fullpath]


  


  What can I do to make this work ?