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• How do I encode a video stream to multiple output formats in parallel with ffmpeg ?

  21 juillet 2022, par rgov

  I would like to use one FFmpeg process to receive video input and then pass that video to multiple separate encoder processes in order to efficiently make use of all available CPU cores.

  


  The FFmpeg wiki article on Creating multiple outputs has this note from @rogerdpack :

  


  


  Outputting and re encoding multiple times in the same FFmpeg process will typically slow down to the "slowest encoder" in your list. Some encoders (like libx264) perform their encoding "threaded and in the background" so they will effectively allow for parallel encodings, however audio encoding may be serial and become the bottleneck, etc. It seems that if you do have any encodings that are serial, it will be treated as "real serial" by FFmpeg and thus your FFmpeg may not use all available cores. One work around to this is to use multiple ffmpeg instances running in parallel, or possible piping from one ffmpeg to another to "do the second encoding" etc. Or if you can avoid the limiting encoder (ex : using a different faster one [ex : raw format] or just doing a raw stream copy) that might help.

  


  


  The article has an example of using a tee pseudo-muxer, but it uses "a single instance of FFmpeg. The example of piping from one instance of FFmpeg to another only allows one encoder process.

  


  A 10-year-old version of the same article mentions using the tee process but it was subsequently deleted :

  


  


  Another option is to output from FFmpeg to "-" then to pipe that to a "tee" command, which can send it to multiple other processes, for instance 2 different other ffmpeg processes for encoding (this may save time, as if you do different encodings, and do the encoding in 2 different simultaneous processes, it might do encoding more in parallel than elsewise). Un benchmarked, however.

  


  


  Along the same lines : Some of the example commands use the mpegts to encapsulate frames before passing them between processes. Is there any constraint that this applies to the codecs or types of metadata that can be sent to downstream processes ?

  


• How to decode and display real-time H264 stream using ffmpeg in Python ?

  25 mars 2022, par yiiiiiiiran

  I would like to port the live stream to ffmpeg and display it in real time using Python.

  


  Anyone knows how to port the stream to PIPE ? And in the mean time to display it after decoding ?

  


  I managed to get real-time stream from my Raspberry Pi3 to Windows PC, using RS232 connection with Baud Rate 2M.

  


  The format of the stream is in H264. The data package I get for each frame is in .
In order for the program to know when does each package ends, I've add

  


  bytes([0xcc,0xdd,0xee,0xff])


  


  to the end of package. So that my serial port will read for a package until it sees those bytes.

  


  Lets assume the stream WIDTH, HEIGHT, NUM_FRAMES, FPS = 320, 240, 90, 30

  


  I have the command for decode the h264 stream :

  


  cmd = ["C:/XXXXXX/ffmpeg.exe",
    "-probesize", "32",
    "-flags", "low_delay",
    "-f", "h264",
    "-i", "pipe:",
    "-f", "rawvideo", "-pix_fmt", "rgb24", "-s", "384x216",
    "pipe:"]

decode_process = sp.Popen(cmd, stdin=sp.PIPE, stdout=sp.PIPE)


  


  The stream package I got is

  


  while datetime.now() &lt; end_time:&#xA;    pkg = ser.read_until(expected=bytes([0xcc,0xdd,0xee,0xff])) #output <class>&#xA;    frame_len = len(pkg)-4&#xA;    frame_inBytes = pkg[0:frame_len]&#xA;    decode_process.stdin.write(frame_inBytes)&#xA;</class>

  


  I want to write the real time stream to PIPE however it shows error :

  


  [h264 @ 0000017322a3e980] missing picture in access unit with size 48
[h264 @ 0000017322a3e980] no frame!
[h264 @ 0000017322a2d240] Stream #0: not enough frames to estimate rate; consider increasing probesize
[h264 @ 0000017322a2d240] Could not find codec parameters for stream 0 (Video: h264, none): unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (32) options        
Input #0, h264, from 'pipe:':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: h264, none, 25 tbr, 1200k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
[h264 @ 0000017322a3f180] no frame!
Error while decoding stream #0:0: Invalid data found when processing input
Cannot determine format of input stream 0:0 after EOF
Error marking filters as finished
Conversion failed!


  


• How to capture movie with Gphoto2 + ffmpeg and redirect serve to html embed

  1er avril 2021, par Doglas Antonio Dembogurski Fei

  Iam trying to capture video from Panasonic DC-GH5 camera to serve this and access from browser withoud ffserver because ffserver is deprecated

  


  Iam using Ubuntu 20.04

  


  #gphoto2 -v


gphoto2         2.5.23         gcc, popt(m), exif, cdk, aa, jpeg, readline
libgphoto2      2.5.25         standard camlibs (SKIPPING lumix), gcc, ltdl, EXIF
libgphoto2_port 0.12.0         iolibs: disk ptpip serial usb1 usbdiskdirect usbscsi, gcc, ltdl, EXIF, USB, serial without locking


  


  Iam try this code

  


  ffmpeg -f video4linux2 -s 640x480 -r 30 -i /dev/video0 -thread_queue_size 512 -ac 1 -f alsa -i pulse -f webm -listen 1 -seekable 0 -multiple_requests 1 http://localhost:8090


  


  and embed

  


  <video src="http://localhost:8090"></video>&#xA;

  


  in index.php but don`t appear anything.
If anyone knows a way to make a server for a specific port I would appreciate it
Thank you.