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• How to pipe ffmpeg output to ImageMagick's convert tool ?

  30 décembre 2020, par Donny V.

  After a lot of searching I have come up with this to pipe a frame from ffmpeg to imagemagick's convert tool.

  


  ffmpeg -y -ss 00:02:01 -i ...\pano.mp4 -frames:v 1 -f png - | convert -sharpen 0x1 ...\pano_00_02_01.png


  


  I keep getting this error message.

  


  [NULL @ 000002e6cd1e00c0] Requested output format 'png' is not a suitable output format
pipe:: Invalid argument


  


  I have checked for png support using ffmpeg -format and its listed as png_pipe.

  


  I'm using ffmpeg version 4.3.1-2020-11-19-full_build
https://www.gyan.dev/ffmpeg/builds/

  


• Force CMD to update pipe to clipboard

  2 janvier 2021, par Dominic Mason

  I'm running ffmpeg to find scenechanges successfully, but was hoping to ouput ffmpeg's STDERR to another program, starting by testing it by piping to the clipboard. Capturing STDERR alone 2 | makes ffmpeg think it should output using format 2 through a pipe, but I found I could successfully capture STDOUT & STDERR together :

  


  ffmpeg -i "inputfile.mkv" -filter_complex "select='gte(scene,0.4)',metadata=print:file=FrameDifferences.txt" -f null - 2>&1 | clip


  


  Problem is, when I pipe to the clipboard, I only get an update once the program has finished running. As one of my reasons for piping STDERR was to get progress updates on the encoding, this was rather sad. Is there a simple way to force CMD to periodically update the pipe ? Or is this a limitation to using the clipboard such that I'll have to begin testing by preparing another program to receive the pipe ?

  


• FFMPEG raises exception only when writing to pipe

  13 janvier 2021, par user14893379

  I am currently writing a small application in Python that gets audio from a Youtube Link and converts this into wave data for visualization. I am using Pafy to get the appropriate URL, ffmpeg-python for the conversion, and matplotlib for visualization.

  


  Currently, I am trying to skip the step of downloading the file to a local directory and instead want to write it directly into ffmpeg's pipe, so I can process it directly.

  


  The function is the following :

  


  import pafy
import os
import ffmpeg
import numpy as np
import matplotlib.pyplot as plt
import wave

def getaudio(url, filename='temp.wav'):
    if os.path.exists(filename):
        os.remove(filename)
    source = pafy.new(url).getbestaudio(preftype='m4a').url
    try:
        out, _ = (
            ffmpeg.input(source)
            .output(filename, format='wav')
            .run(capture_stdout=True, capture_stderr=True)
        )
    except ffmpeg._run.Error as e:
        print(e.stderr.decode('utf-8'))
        raise e
    w = wave.open('temp.wav', 'r').readframes(-1)
    audio = np.frombuffer(w, dtype=np.int16)
    return audio


url = 'https://www.youtube.com/watch?v=bhZs3ALdL7Y'
audio = getaudio(url)
plt.plot(audio)
plt.show()



  


  This works in general - however this does two things : It returns the audio so it can be opened with the wave package, and it also saves it as 'temp.wav' to the current directory, which I would like to skip by replacing the 'temp.wav' output with 'pipe :' :

  


      try:
        out, _ = (
            ffmpeg.input(source)
            .output('pipe:', format='wav')
            .run(capture_stdout=True, capture_stderr=True)
        )
    except ffmpeg._run.Error as e:
        print(e.stderr.decode('utf-8'))
        raise e


  


  This raises an exception with the following output for stderr :

  


  ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers&#xA;  built with gcc 9.2.1 (GCC) 20200122&#xA;  configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid &#xA;--enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt&#xA;  libavutil      56. 31.100 / 56. 31.100&#xA;  libavcodec     58. 54.100 / 58. 54.100&#xA;  libavformat    58. 29.100 / 58. 29.100&#xA;  libavdevice    58.  8.100 / 58.  8.100&#xA;  libavfilter     7. 57.100 /  7. 57.100&#xA;  libswscale      5.  5.100 /  5.  5.100&#xA;  libswresample   3.  5.100 /  3.  5.100&#xA;  libpostproc    55.  5.100 / 55.  5.100&#xA;Input #0, mov,mp4,m4a,3gp,3g2,mj2, from &#x27;https://r4---sn-h0jelne7.googlevideo.com/videoplayback?expire=1610319670&amp;ei=1jL7X_uZIoeC6dsP9Z6nsA8&amp;ip=2a02%3A810d%3Aabbf%3Abeed%3A98a1%3Ae204%3A805c%3Aa5b1&amp;id=o-AGmTIS4LdQhQz5h7nplFZ0h5iWHR3KxieH44x8mIvXab&amp;itag=140&amp;source=youtube&amp;requiressl=yes&amp;mh=dj&amp;mm=31%2C26&amp;mn=sn-h0jelne7%2Csn-4g5e6nzz&amp;ms=au%2Conr&amp;mv=m&amp;mvi=4&amp;pl=33&amp;initcwndbps=1885000&amp;vprv=1&amp;mime=audio%2Fmp4&amp;ns=qyAm3FG5c0DyOAH11rcQFxYF&amp;gir=yes&amp;clen=55649&amp;dur=3.459&amp;lmt=1508976590967371&amp;mt=1610297792&amp;fvip=4&amp;keepalive=yes&amp;c=WEB&amp;n=YvU_SOWuTrPG1W&amp;sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cns%2Cgir%2Cclen%2Cdur%2Clmt&amp;sig=AOq0QJ8wRAIgLR-oEO3oWoBfBGslerzo-jO57JhY-xbfKxQJ1GcnpscCIAhuoixcr1X_uDGiUuJ5IbPD2zynF-R8Qp5BjQqSWUaF&amp;lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&amp;lsig=AG3C_xAwRgIhAO9pxuDZZeOd6pESsk4tjlpzDJeCnSqPv4G1-zJKoDI1AiEAjjwkSBZeeEivgAU_DRdnI-GokWQ3P-6gKhdGHe9Za7o%3D&amp;ratebypass=yes&#x27;:&#xA;  Metadata:&#xA;    major_brand     : dash&#xA;    minor_version   : 0&#xA;    compatible_brands: iso6mp41&#xA;    creation_time   : 2017-10-26T00:09:50.000000Z&#xA;  Duration: 00:00:03.46, start: 0.000000, bitrate: 128 kb/s&#xA;    Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)&#xA;    Metadata:&#xA;      creation_time   : 2017-10-26T00:09:50.000000Z&#xA;      handler_name    : SoundHandler&#xA;Stream mapping:&#xA;  Stream #0:0 -> #0:0 (aac (native) -> pcm_s16le (native))&#xA;Press [q] to stop, [?] for help&#xA;Output #0, wav, to &#x27;pipe:&#x27;:&#xA;  Metadata:&#xA;    major_brand     : dash&#xA;    minor_version   : 0&#xA;    compatible_brands: iso6mp41&#xA;    ISFT            : Lavf58.29.100&#xA;    Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s (default)&#xA;    Metadata:&#xA;      creation_time   : 2017-10-26T00:09:50.000000Z&#xA;      handler_name    : SoundHandler&#xA;      encoder         : Lavc58.54.100 pcm_s16le&#xA;size=     596kB time=00:00:03.45 bitrate=1411.4kbits/s speed= 316x&#xA;video:0kB audio:596kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.012781%&#xA;&#xA;Traceback (most recent call last):&#xA;  File "e:/Coding Projects/YTStream/Test2.py", line 27, in <module>&#xA;    audio = getaudio(url)&#xA;  File "e:/Coding Projects/YTStream/Test2.py", line 20, in getaudio&#xA;    raise e&#xA;  File "e:/Coding Projects/YTStream/Test2.py", line 16, in getaudio&#xA;    .run(capture_stdout=True, capture_stderr=True)&#xA;  File "C:\Users\xxx\anaconda3\lib\site-packages\ffmpeg\_run.py", line 325, in run&#xA;    raise Error(&#x27;ffmpeg&#x27;, out, err)&#xA;ffmpeg._run.Error: ffmpeg error (see stderr output for detail)&#xA;</module>

  


  I am confused how to deal with this exception as there is no obvious error message here (at least to me). It simply stops, as opposed to when I give an obvious error (such as an invalid format that is not supported by ffmpeg -formats).
Help would be much appreciated !