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• AV1 extract keyframes

  18 avril 2021, par Steven Penny

  Using this file [1], I can run this command with no problem :

  


  ffmpeg -i crushed-between-two-portals.mp4 %d.jpg


  


  but if I run either of these commands [2] :

  


  ffmpeg -i crushed-between-two-portals.mp4 -vf "select='eq(pict_type,I)'" %d.jpg
ffmpeg -i crushed-between-two-portals.mp4 -vf "select='eq(pict_type,PICT_TYPE_I)'" %d.jpg


  


  I get this result :

  


  Output file is empty, nothing was encoded (check -ss / -t / -frames parameters
if used)


  


  I think it is because of the video stream :

  


  Stream #0:0(und): Video: av1 (Main) (av01 / 0x31307661), yuv420p(tv, bt709),
1280x720 [SAR 1:1 DAR 16:9], 19 kb/s, 59.94 fps, 59.94 tbr, 60k tbn, 60k tbc
(default)


  


  I have used this command before with other codecs. How can I extract keyframes
or similar from AV1 codec ?

  


  

  1. https://f002.backblazeb2.com/file/ql8mlh/crushed-between-two-portals.mp4

  


  2. Create a thumbnail image every X seconds of the video

  


  


• ffmpeg - HDR to SDR - Unable to find a suitable output format for 'format=gbrpf32le'

  17 avril 2020, par Saxon Rix

  I'm on windows 10 using ffmpeg 4.0.2. I found the script for HDR to SDR [here][1], but when I run the script from the bottom of the page :

  



  ffmpeg.exe -i input.mkv -vf zscale=t=linear:npl=100,format=gbrpf32le,
zscale=p=bt709,tonemap=tonemap=hable:desat=0,zscale=t=bt709:m=bt709:r=tv,
format=yuv420p -c:v libx265 -crf 18 -preset slower output.mkv


  



  I get this error :

  



  [NULL @ 0000014588707480] Unable to find a suitable output format for 
'format=gbrpf32le'
format=gbrpf32le: Invalid argument


  



  When I run the first script from the page :

  



  ffmpeg.exe -i input.mkv -vf select=gte(n\,360) -vframes 1 output.png


  



  I get this error :

  



  At line:1 char:41
+ ffmpeg.exe -i Hook.mkv -vf select=gte(n\,360) -vframes 1 output.png
+                                         ~
Missing argument in parameter list.
+ CategoryInfo          : ParserError: (:) [], 
ParentContainsErrorRecordException
+ FullyQualifiedErrorId : MissingArgument
[1]: https://stevens.li/guides/video/converting-hdr-to-sdr-with-ffmpeg/


  



  I'm pretty new to ffmpeg, could someone please explain what is going on ?

  



  Many thanks !

  


• ffmpeg fails to connect a second camera when run using python thread

  1er juin 2023, par LemonJumps

  I'm starting ffmpeg dshow -> rawvideo over pipe in python thread, see code below

  


      def run(self):
        proc = subprocess.Popen(
            [FFMPEG_DIR + "ffmpeg", "-hide_banner", "-f", "dshow", 
                "-video_size", str(self.resolution[0]) + "x" + str(self.resolution[1]), # select resolution
                "-framerate", str(self.framerate), # select framerate
                "-i", "video=" + self.device, # select device
                "-f", "rawvideo", "-pix_fmt", "bgr24", "pipe:"], # output to pipe
            stdout = subprocess.PIPE)
        
        buf = b''
        
        while True:
            outs = proc.stdout.read(self.resolution[0] * self.resolution[1] *3)
            buf += outs
            
            if len(buf) >= (self.resolution[0] * self.resolution[1] *3):
                with self.lock:
                    self.frame = buf[0:self.resolution[0] * self.resolution[1] *3] 
                    self.cnt += 1
                    
                buf = b''
                
            if self.endEvent.isSet():
                proc.kill()
                return


  


  I am using alternative name as camera name, both cameras are the same model.
both devices name and alternative name :

  


  ('ACR010 USB Webcam', '@device_pnp_\\\\?\\usb#vid_0c45&pid_636a&mi_00#8&83c432e&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\\global')

  


  ('ACR010 USB Webcam', '@device_pnp_\\\\?\\usb#vid_0c45&pid_636a&mi_00#8&34de11d9&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\\global')

  


  when I run this code for each camera individually it works flawlessly.
But when I run this for both cameras at the same time, the code results this error :


  


  The "Could not run graph" sounds like ffmpeg can't open multiple devices, or isn't allowed by windows, or maybe there's a token that gets reused because it's all within a single process ?

  


  What could be really causing this error and how can I mitigate it ?