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• Why SIGSEGV appears when trying to decode audio using libavcodec.57 and libopus-1.2 alpha2-1 ?

  10 août 2021, par Greg Joy

  I'm decoding audio using FFMPEG libavcodec's function avcodec_decode_audio4(). Everything works perfect on Windows and Ubuntu 18.04, but I receive segmentation fault when trying to run the same app on Debian 9. I've debugged my code with gdb, and it showed this result :

  


  Thread 24 "SDLAudioDev2" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff7fea700 (LWP 1657)]
0x00007fffecdd6eff in ?? () from /usr/lib/x86_64-linux-gnu/libopus.so.0
(gdb) bt
#0  0x00007fffecdd6eff in ?? ()
   from /usr/lib/x86_64-linux-gnu/libopus.so.0
#1  0x00007fffecde0b18 in ?? ()
   from /usr/lib/x86_64-linux-gnu/libopus.so.0
#2  0x00007fffece04ac1 in ?? ()
   from /usr/lib/x86_64-linux-gnu/libopus.so.0
#3  0x00007fffece05b5b in ?? ()
   from /usr/lib/x86_64-linux-gnu/libopus.so.0
#4  0x00007fffece0e87e in ?? ()
   from /usr/lib/x86_64-linux-gnu/libopus.so.0
#5  0x00007fffece0eba7 in opus_multistream_decode ()
   from /usr/lib/x86_64-linux-gnu/libopus.so.0
#6  0x00007ffff4f8a235 in ?? ()
   from /usr/lib/x86_64-linux-gnu/libavcodec.so.57
#7  0x00007ffff51893fd in avcodec_decode_audio4 ()
   from /usr/lib/x86_64-linux-gnu/libavcodec.so.57
#8  0x00007ffff5189e78 in ?? ()
   from /usr/lib/x86_64-linux-gnu/libavcodec.so.57
#9  0x00007ffff518f098 in avcodec_send_packet ()


  


  Seems that data race appears somewhere. I've tried to remove avcodec_decode_audio4() and use avcodec_send_packet() and avcodec_receive_frame() functions, however in libavcodec.57 of FFMPEG ver.3.2.10 function avcodec_send_packet() invokes avcodec_decode_audio4() and the problem occurs again.

  


  Could someone help me with what do I need to change to make it all be compatible with Debian 9 packages' versions, please ?

  


  On Windows I have libavcodec.58, on Ubuntu 18.04 libavcodec.57 ver.3.4.8

  


  On Debian 9 I have libavcodec.57 ver.3.2.15

  


• Ffmpeg is installed, but I get the exception : You do not have ffmpeg installed on your machine

  13 janvier 2023, par Tin Kommen

  I've searched for hours for a solution, but I haven't found one yet. Maybe someone here knows what is going wrong.

  


  I'm trying to make a Bar Chart Race in Python. Although I have downloaded and installed Ffmpeg,
I keep on getting multiple errors :

  


      MovieWriter ffmpeg unavailable; using Pillow instead.
    Traceback (most recent call last):
      File "/Users/___/PycharmProjects/data_visualization/venv/lib/python3.6/site-        packages/matplotlib/animation.py", line 251, in saving
        yield self
      File "/Users/___/PycharmProjects/data_visualization/venv/lib/python3.6/site-        packages/matplotlib/animation.py", line 1161, in save
        writer.grab_frame(**savefig_kwargs)
      File "/Users/____/PycharmProjects/data_visualization/venv/lib/python3.6/site-        packages/matplotlib/animation.py", line 549, in grab_frame
        renderer = self.fig.canvas.get_renderer()
    AttributeError: 'FigureCanvasBase' object has no attribute 'get_renderer'

    During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
      File "/Users/___/PycharmProjects/data_visualization/venv/lib/python3.6/site-        packages/bar_chart_race/_make_chart.py", line 435, in make_animation
        ret_val = anim.save(self.filename, fps=self.fps, writer=self.writer)
      File "/Users/___/PycharmProjects/data_visualization/venv/lib/python3.6/site-        packages/matplotlib/animation.py", line 1161, in save
        writer.grab_frame(**savefig_kwargs)
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/contextlib.py", line         100, in __exit__
        self.gen.throw(type, value, traceback)
      File "/Users/___/PycharmProjects/data_visualization/venv/lib/python3.6/site-                        packages/matplotlib/animation.py", line 253, in saving
        self.finish()
              File "/Users/____/PycharmProjects/data_visualization/venv/lib/python3.6/site-        packages/matplotlib/animation.py", line 554, in finish
        self._frames[0].save(
            IndexError: list index out of range

    During handling of the above exception, another exception occurred:

    Exception: You do not have ffmpeg installed on your machine. Download
    ffmpeg from here: https://www.ffmpeg.org/download.html.
    Matplotlib's original error message below:
    list index out of range


  


  I've tried installing ffmpeg with conda, pip and homebrew. When I check the version, i get the following :

  


      ffmpeg version 4.2.3 Copyright (c) 2000-2020 the FFmpeg developers
      built with clang version 9.0.1
      configuration: --prefix=/Users/___/opt/miniconda3 --cc=x86_64-apple-darwin13.4.0-clang --disable-doc --disable-openssl --enable-avresample --enable-gnutls --enable-gpl --enable-hardcoded-tables --enable-libfreetype --enable-libopenh264 --enable-libx264 --enable-pic --enable-pthreads --enable-shared --enable-static --enable-version3 --enable-zlib --enable-libmp3lame
      libavutil      56. 31.100 / 56. 31.100
      libavcodec     58. 54.100 / 58. 54.100
      libavformat    58. 29.100 / 58. 29.100
      libavdevice    58.  8.100 / 58.  8.100
      libavfilter     7. 57.100 /  7. 57.100
      libavresample   4.  0.  0 /  4.  0.  0
      libswscale      5.  5.100 /  5.  5.100
      libswresample   3.  5.100 /  3.  5.100
      libpostproc    55.  5.100 / 55.  5.100


  


  Here is the code :

  


      import numpy as np
    import pandas as pd
    import bar_chart_race as bcr
    import os



    df = pd.read_csv('/Users/____/Documents/data/dummy_data.csv', delimiter=';', encoding="utf-8-sig")
    bcr.bar_chart_race(
        df=df,
        filename='test_win2.mov',
        orientation='h',
        sort='desc',
        n_bars=8,
        fixed_order=False,
        fixed_max=False,
        steps_per_period=50,
        interpolate_period=False,
        label_bars=True,
        bar_size=.95,
        period_label={'x': .99, 'y': .25, 'ha': 'right', 'va': 'center'},
        period_summary_func=lambda v, r: {'x': .99, 'y': .18,
                                  's': f'Totaal: {v.nlargest(8).sum():,.0f}',
                                  'ha': 'right', 'size': 8, 'family': 'Courier New'},
        perpendicular_bar_func='median',
        figsize=(3.5, 3),
        period_length=100,
        dpi=300,
        cmap='dark12',
        title='Title?',
        title_size='',
        bar_label_size=4,
        tick_label_size=4,
        shared_fontdict={'family': 'Helvetica', 'color': '.1'},
        scale='linear',
        writer=None,
        fig=None,
        bar_kwargs={'alpha': .3},
        filter_column_colors=False)


  


• FFMPEG Aligning Timestamps in m3u8 Stream

  16 septembre 2021, par maxwellray

  I'm receiving an m3u8 stream with the following structure

  


  #EXTM3U
#EXT-X-VERSION:3
#EXT-X-ALLOW-CACHE:YES
#EXT-X-MEDIA-SEQUENCE:1193
#EXT-X-PROGRAM-DATE-TIME:2021-09-15T22:57:30+00:00
#EXT-X-TARGETDURATION:11
#EXTINF:10.054589,
20210915220000/20210915225710.ts
#EXTINF:10.008855,
20210915220000/20210915225720.ts


  


  Every 10 seconds, the playlist is updated with a new media file path and the oldest media path is removed. Each media file path contains a clip that is approximately 10 seconds long (i.e., over a very long time, the average length of each clip should be 10 seconds). Each media path is timestamped, rounded to 10 seconds.

  


  I run a system where I record continuous 32-minute clips of this stream using ffmpeg, and I need to know the exact timestamp where I start to record and where I stop. I'm encountering a sort of race condition where ffmpeg will start recording at the beginning of the oldest clip in the playlist instead of when it actually gets kicked off. The problem is illustrated below

  


  Clip 1: |==========|
Clip 2:            |==========|
FFMPEG:    |==================| <= ffmpeg is kicked off at t=3
OUTPUT: |=====================| <= but video would actually start at t=0


  


  I'm wondering if there's a way to ensure that the clips I record actually start when ffmpeg is kicked off, not from the start of the earliest clip in the stream.

  


  Thanks !