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• Revision 15679: traiter les src ...

  11 May 2010, by cedric@… — Log

  traiter les src de progid:DXImageTransform.Microsoft.AlphaImageLoader(src=...) lors du passage en url absolue dans les css

• Streaming images to ffmpeg out of order

  6 November 2022, by Jason C

  I have an algorithm that generates a video frame by frame, which I am refactoring to stream the images to ffmpeg rather than save them all to disk first.

  


  The algorithm currently generates and saves a bunch of QImages then executes ffmpeg (with QProcess). The new version will generate QImages then stream them out to ffmpeg's stdin via QProcess. I can do all that just fine.

  


  The issue is, I'm not actually generating the images serially, I'm generating them on a thread pool, maybe 12-16 at a time (just using QtConcurrent). I'd like to keep this parallelism for performance reasons, since the operation (even excluding image encoding and file I/O) does take a long time.

  


  So my question is, does ffmpeg have something like image2pipe but that can take the images slightly out of order (let's assume there's some sane maximum offset, +/- 20 or so)?

  


  If not, my solution will be to divide the image set into small batches, then for each batch, run it on the pool, reorder it, and stream them in the correct order; sacrificing some fraction of performance depending on the batch size. I'd rather not do that just because the code right now is dirt simple, and simple is good. So I'm wondering if there's a way to get ffmpeg to accept the images out of order.

  


  They're at a fixed frame rate, if that is useful (maybe there's some way to set PTS's or something, then I just find a codec + container that can store out-of-order frames).

  


• ffmpeg crashed if run as subprocess from nicegui

  23 March 2023, by user1113159

  I need to trigger a long ffmpeg process by nicegui button.
I have created a code :

  


  from concurrent.futures import ProcessPoolExecutor
import shlex, subprocess
import argparse
import asyncio
from nicegui import ui, app

def run_cmd():
  cmd = "ffmpeg -y -i data/video.mp4 -acodec libmp3lame -ab 128000 data/video.mp3"
  subprocess.call(shlex.split(cmd))

pool = ProcessPoolExecutor()
async def async_run():
  loop = asyncio.get_running_loop()
  await loop.run_in_executor(pool, run_cmd)

args = argparse.ArgumentParser()
args.add_argument("--webui", action="store_true")
args = args.parse_args()

if args.webui:
  ui.button('Translate', on_click=async_run)
  app.on_shutdown(pool.shutdown)
  ui.run()
else:
  run_cmd()


  


  ffmpeg works well if run just from python.
But when I run it from nicegui (python3 ./main.py --webui)
ffmpeg failed or crashed:

  


  ...
Error while decoding stream #0:1: Invalid argument
[aac @ 0x555e54100440] Sample rate index in program config element does not match the sample rate index configured by the container.
[aac @ 0x555e54100440] Inconsistent channel configuration.
[aac @ 0x555e54100440] get_buffer() failed
...
ac @ 0x555e54100440] Error decoding AAC frame header.
Error while decoding stream #0:1: Error number -50531338 occurred
[aac @ 0x555e54100440] channel element 2.8 is not allocated
Error while decoding stream #0:1: Invalid data found when processing input
[aac @ 0x555e54100440] Pulse data corrupt or invalid.
Error while decoding stream #0:1: Invalid data found when processing input
ffmpeg: psymodel.c:576: calc_energy: Assertion `el >= 0' failed.
...


  


  What am I doing wrong?
Or maybe there is a more straightforward pattern to start long-term background process with nicegui?