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• How to set normal speed of playback after capturing and transcoding stream video by `ffmpeg_streaming` in Python project ?

  30 avril 2020, par Harley Club

  Using ffmpeg_streaming module in Python project with Flask, I try to set up video streaming from online camera into local file. My purpose is receiving input stream that comes as HLS-compatible data. To implement this property, I've inserted some code accessible by this link :

  



  import ffmpeg_streaming
from ffmpeg_streaming import Formats, Bitrate, Representation, Size

from flask import render_template, Flask, send_from_directory, abort, json, Response  

import sys

app = Flask(__name__)

video = ffmpeg_streaming.input('http://wmccpinetop.axiscam.net/mjpg/video.mjpg')

_480p = Representation(Size(854, 480), Bitrate(750 * 1024, 192 * 1024))
hls_stream = video.hls(Formats.h264(), hls_list_size = 10, hls_time = 5)
hls_stream.representations(_480p)
hls_stream.output('/var/media/hls_outputs.m3u8')


  



  It works as expected, i.e. video stream gets written into local file, then I can see what camera shot somewhere far from there...But an only problem arises here which I can't manage : once playback starts, the video is being displayed utterly fast. Nearly 2 minutes period covered by camera (I can see how long real time was over due to camera-embedded timer option) has duration of 5 seconds when playing back. So, how do I want to enable video speed just as it fits into real-world timing ? My OS is Ubuntu 18.04 LTS and I open file with preinstalled Videos app to watch content.

  


• aacdec : do not mutate input packet metadata

  8 mars 2017, par wm4

  aacdec : do not mutate input packet metadata
  Apparently the demuxer outputs the wrong padding for HE-AAC (based on
  
  the raw sample rate, or so). aacdec contains a hack to adjust the muxer
  
  padding accordingly before it’s used to trim the decoder output. This
  
  modified the packet side data, which in combination with the old
  
  decoding API would change the packet the user passed to the decoder.
  
  This is clearly not allowed, and it breaks running some gapless fate
  
  tests with "-fflags +keepside" applied (without keepside, the packet
  
  metadata is typically newly allocated, essentially making a copy and not
  
  modifying the user’s input packet).
  This should probably be fixed in the demuxer (and consequently also the
  
  muxer), but for now only fix the immediate problem.
  Regression since 946ed78f5f8 (2012).
  

  • [DH] libavcodec/aacdec_template.c
  • [DH] libavcodec/internal.h
  • [DH] libavcodec/utils.c

• Why can I not change the number of frames (nframes) in a gganimate animation ? SOLVED

  26 décembre 2022, par Gekin

  I have produced an animation per gganimate and rendered it per ffmpeg. It works just fine, but only, if I do not change the number of frames. If I do set the number of frames, I get this error message :

  


  nframes and fps adjusted to match transition
Error parsing framerate 8,4.                           
Error: Rendering with ffmpeg failed


  


  I produced the gganim MonthlyAveragePrecipitationMap the following way :

  


  options(scipen = 999, OutDec  =  ",")

MonthlyAveragePrecipitationMap = ggplot(MonthlyAverageExtremePrecipitation) + 
  geom_path(data = map_data("world","Germany"),
            aes(x = long, y = lat, group = group)) +
  coord_fixed(xlim = c(6,15),
              ylim = c(47,55)) + 
  geom_point(aes(x=lon, y=lat, 
                 colour = ShareOfExtremePrecipitationEvents,
                 group = MonthOfYear),
             size = 3) + 
  scale_color_gradient(low="blue", high="yellow") + 
  xlab("Longitude (degree)") +
  ylab("Latitude (degree)") + 
  theme_bw() +
  transition_manual(frames = MonthOfYear) + 
  labs(title = '{unique(MonthlyAverageExtremePrecipitation$MonthOfYear)[as.integer(frame)]}', 
       color = paste0("Share of Extreme Precipitation Events \namong all Precipitation Events")) 


  


  I call the animation the following way :

  


  animate(MonthlyAveragePrecipitationMap,
        nframes = 300,
        renderer =
          ffmpeg_renderer(
            format = "auto",
            ffmpeg = NULL,
            options = list(pix_fmt = "yuv420p")))



  


  I used this exact code just a few days ago and it worked fine.

  


  Has someone had similar experiences ?
Thanks in advance.

  


  EDIT : Problem solved.

  


  

  • Problem : Changing the decimal seperator from . to , per options(dec=",")

  


  • Solution : Changing the decimal seperator locally within the axis scaling per function.