Recherche avancée

Sur d’autres sites (5001)

• How to grab specific segments of M3U8 via ffmpeg ?

  30 juillet 2020, par Lysander Cox

  I recently asked baout how I could download segments of an online m3u8 file, and someone pointed out that this could be accomplished via ffmpeg :

  


  ffmpeg -i [LINK] -codec copy [OUTPUT FILE] #downloads only audio segments;
ffmpeg -i [LINK] -bsf:a aac_adtstoasc -vcodec copy -c copy -crf 50 [OUTPUT] #downloads audio and video segments


  


  For those who aren't familiar, m3u8 is formatted kinda of like a "playlist", with an m3u8 file pointing to a bunch of smaller "segments" which are pieced together to form the whole of the video. As a result, it's completely possible to halt the above commands partway through their execution and still produce a watchable video (i.e. one that will be interpreted correctly by video editors).

  


  I'm wondering if there's a built-in method with ffmpeg that allows me to grab segments N-M of a given m3u8. If there are methods outside of ffmpeg, feel free to mention them as well. Thanks for the help.

  


• ffmpeg video stream to app c# [on hold]

  3 septembre 2014, par Alexey Medvedev

  I am trying to make a video mixer for online broadcasts. To do this, I use ffmpeg and C #. I had a problem with the transfer of the video stream from ffmpeg to my program. I would like to receive a stream of ffmpeg using network protocols (e.g. TCP, UDP or others) or capturing if from ffplay window, but I don`t how I can do it. Can you give me some ideas ?

  For example, I have command for ffmpeg : "ffmpeg -i video1.mp4 -f mpegts udp:127.0.0.1:5000" or same command with other output formats or network protocols. How i can read video stream from the port and convert it to Bitmap ?
  I need to send video stream from my program from computer A to my program to computer B. I write program on C#. I dont know how I can compress video which I must send between my computers and I decided to use Ffmpeg. Now, I can streaming video from my program in computer A to ffmpeg and compress it with parameters which I need.
  On second computer I can read this steam using ffmpeg or ffplay, but I don`t know how I can get this stream into my program.
  1) How can I get this stream in my program ? Which libraries can you recommend me ?
  2) Do you know any libraries which can compress video, instead of using ffmpeg ?

• Generate waveforms for audio files with large amount of channels

  3 mai 2021, par motio

  I want to generate .png files displaying the waveforms of interleaved audio .wav files using the FFmpeg libraries. http://ffmpeg.org/documentation.html

  


  If the interleaved audio file contains maximum 8 channels, I manage to successfully achieve this using the following command line :

  


  ffmpeg -i 8_channels_input.wav -y -filter_complex "showwavespic=s=1920x1200:split_channels=1" -frames:v 1 8_channels_waveform_output.png


  


  However, if the interleaved audio file contains more than 8 channels, FFmpeg gives the following :

  


  


  Input #0, wav, from '30_channels_input.wav' : Duration : 00:00:02.08,
bitrate : 31752 kb/s Stream #0:0 : Audio : pcm_s24le ([1][0][0][0] /
0x0001), 44100 Hz, 30 channels, s32 (24 bit), 31752 kb/s Stream
mapping : Stream #0:0 (pcm_s24le) -> showwavespic showwavespic ->
Stream #0:0 (png) Press [q] to stop, [?] for help [auto_resampler_0 @
0x7faf5d60a3c0] Cannot select channel layout for the link between
filters auto_resampler_0 and Parsed_showwavespic_0. [auto_resampler_0
@ 0x7faf5d60a3c0] Unknown channel layouts not supported, try
specifying a channel layout using 'aformat=channel_layouts=something'.
Error reinitializing filters ! Failed to inject frame into filter
network : Invalid argument Error while processing the decoded data for
stream #0:0 Conversion failed !

  


  


  Here is the related documentation (c.f. bottom of the page) :
https://trac.ffmpeg.org/wiki/AudioChannelManipulation

  


  My problem is :
I need to generate the visual waveforms of audio files containing up to 30 channels.
All my attempts were unsuccessful so far (I am trying to define custom channel layouts and I am not sure if I am on the right track here).

  


  To simplify, I need to complete/modify the following command to make it work :

  


  ffmpeg -i 30_channels_input.wav -y -filter_complex "showwavespic=s=1920x1200:split_channels=1" -frames:v 1 30_channels_waveform_output.png 


  


  [EDIT] Remarks :

  


  I manage to generate the waveforms of a 10 channels input by combining existing layouts :

  


  ffmpeg -i 10_channels_input.wav -y -filter_complex "aformat=channel_layouts=7.1+downmix, showwavespic=s=1920x1200:split_channels=1" -frames:v 1 10_channels_waveform_output.png


  


  However, if you attempt to do it for a 30 channels input by combining 5x 6.0 layouts :

  


  ffmpeg -i 30_channels_input.wav -y -filter_complex "aformat=channel_layouts=6.0+6.0+6.0+6.0+6.0, showwavespic=s=1920x1200:split_channels=1" -frames:v 1 30_channels_waveform_output.png


  


  FFmpeg gives the following :

  


  


  [auto_resampler_0 @ 0x7ffd7002a480] [SWR @ 0x7ffd7013a000] Rematrix is
needed between 30 channels and 6.0 but there is not enough information
to do it [auto_resampler_0 @ 0x7ffd7002a480] Failed to configure
output pad on auto_resampler_0 Error reinitializing filters ! Failed to
inject frame into filter network : Invalid argument Error while
processing the decoded data for stream #0:0

  


  


  My assumption is that I need to create a custom layout using 30 unique channel IDs (c.f. https://trac.ffmpeg.org/wiki/AudioChannelManipulation bottom of the page) instead of combining existing layouts.

  


  It seems that only 25 channel IDs are available though. Creating a custom layout with 30 channels is maybe not possible at all...

  


  [EDIT 2] Remarks :

  


  I finally found the documentation I was looking for. But it still seems that generating the waveforms of 30 channels would be difficult.

  


  Here is how to create custom layouts :
https://ffmpeg.org/ffmpeg-utils.html

  


  


  A custom channel layout can be specified as a sequence of terms,
separated by ’+’ or ’|’. Each term can be :

  


  the name of a standard channel layout (e.g. ‘mono’, ‘stereo’, ‘4.0’,
‘quad’, ‘5.0’, etc.) the name of a single channel (e.g. ‘FL’, ‘FR’,
‘FC’, ‘LFE’, etc.) a number of channels, in decimal, followed by ’c’,
yielding the default channel layout for that number of channels (see
the function av_get_default_channel_layout). Note that not all channel
counts have a default layout. a number of channels, in decimal,
followed by ’C’, yielding an unknown channel layout with the specified
number of channels. Note that not all channel layout specification
strings support unknown channel layouts. a channel layout mask, in
hexadecimal starting with "0x" (see the AV_CH_* macros in
libavutil/channel_layout.h. Before libavutil version 53 the trailing
character "c" to specify a number of channels was optional, but now it
is required, while a channel layout mask can also be specified as a
decimal number (if and only if not followed by "c" or "C").

  


  See also the function av_get_channel_layout defined in
libavutil/channel_layout.h.

  


  


  e.g.

  


  Therefore, for 11 channels input :

  


  ffmpeg -i 11_channels_input.wav -y -filter_complex "aformat=channel_layouts=FL+FR+FC+BL+BR+BC+SL+SR+WL+WR+TBL, showwavespic=s=1920x1200:split_channels=1" -frames:v 1 11_waveform_output.png


  


  —> worked for me

  


  while :

  


  ffmpeg -i 11_channels_input.wav -y -filter_complex "aformat=channel_layouts=11c, showwavespic=s=1920x1200:split_channels=1" -frames:v 1 11_waveform_output.png


  


  —> does not work

  


  But :

  


  ffmpeg -i 24_channels_input.wav -y -filter_complex "aformat=channel_layouts=24c, showwavespic=s=1920x1200:split_channels=1" -frames:v 1 24_waveform_output.png


  


  —> does work

  


  and finally, what I am still trying to achieve :

  


  ffmpeg -i 30_channels_input.wav -y -filter_complex "aformat=channel_layouts=30c, showwavespic=s=1920x1200:split_channels=1" -frames:v 1 30_waveform_output.png


  


  —> does not work

  


  p.s.

  


  

  • I execute these commands in sub shells via Ruby scripts (puts %x...)

  


  • My system : macOS 10.15.6 | zsh | FFmpeg 4.4 | Ruby 2.6.3