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• Stream voice from Android's micro to RTMP server using FFMPEG

  5 avril 2020, par user2258282

  I'm trying to mix audios from Android's microphone and a mp3 file in storage and stream to a RTMP server using FFMPEG

  



  Now, I could stream a single mp3 file to RTMP server by the below command

  



  ffmpeg -i  -acodec libmp3lame -ab 128k -ac 2 -ar 44100 -f flv rtmp://


  



  And, I could stream audio from Mac's microphone to RTMP server by the below command

  



  ffmpeg -f avfoundation -i ":0" -f flv rtmp://


  



  But now I haven't found command to mix audios from Android's microphone and a mp3 file in storage and stream to a RTMP server using FFMPEG. Can you help me ?

  



  Thank you so much.

  


• ffmpeg randomly stops recording rtmp stream

  14 novembre 2022, par M9A

  I am trying to record a rtmp stream using ffmpeg. On the whole it records the stream fine but every so often it stops recording the stream and when I then go to record it again, it will only record around a second or 2 before it stops again. This usually goes on for like 10-15mins. In this time if I want to record the stream, I would have to manually record 1-2 seconds each time. This sounds like it is a server issue - perhaps there is a mechanism that cuts off the stream every few seconds.

  


  In the case where the stream cuts off, is there a way to keep trying and recording all of these 1-2 second segments rather than me doing it manually ? Doing it manually creates gaps in the recording due to the time taken to connect and record the stream. I even tried running the command in a loop but even with that there are gaps in the video.

  


  The code I am using to record the stream is as follows :

  


  ffmpeg -i "rtmp://example.com/stream?id=12345" -vcodec copy -acoded copy "output.mp4"


  


  When it is recording fine and cuts off the first time, there is no error given. It's like the stream came to an end so it stops recording. The subsequent times where I can only record 1-2 seconds are the same - there is no error

  


  As there are no error messages such as timeout or connection errors, I cannot even run flags on the command to retry recording.

  


• Using an actual audio recording to filter out noise from a video

  9 mars 2021, par user2751530

  I use my laptop (Ubuntu 18.04 LTS derivative on a Dell XPS13) for recording videos (these are just narrated presentations) using OBS. After a presentation is done (.flv format), I process it using ffmpeg using filters that try to reduce background noise, reduce the size of the video, change encoding to .mp4, insert a watermark, etc. Over several months, this system has worked well.

  


  However, my laptop is now beginning to show its age (it is 4 years old). That means that the fan becomes loud - loud enough to notice in a recording, not loud enough to notice when you are working. So, even after filtering for low frequency in ffmpeg, there are clicking and other type of sounds that are left in the video. I am a scientist, though not an audio/video expert. So, I was thinking - is it possible for me to simply record the noise coming out of my machine when I am not presenting, and then use that recording to filter out the noise that my machine makes during the presentation ?

  


  Blanket approaches like filtering out certain ranges of the audio spectrum, etc. are unlikely to work, as the power spectrum of the noise likely has many peaks, and these are likely to extend into human voice range as well (I can hear them). Further, this is a moving target - the laptop is aging and in any case, the amount and type of noise it makes depends on the load and how long it has been on. Algorithm :

  


  

  1. Record actual computer noise (with the added bonus of background noise) while I am not recording. Ideally, just before starting to record the presentation. This could take the form of a 1-2 minute audio sample.

  


  2. Record the presentation on OBS.

  


  3. Use 1 as a filter to get rid of noise in 2. I imagine it would involve doing a Fourier analysis of 1, and then removing those peaks from the spectrum of 2 at each time epoch.

  


  


  I have looked into sox, which is what people somewhat flippantly point you to without giving any details. I do not know how to separate out audio channels from a video and then interleave them back together (not an expert on the software here). Other than RTFM, is there any helpful advice anyone could offer ? I have searched, but have not been able to find a HOWTO. I expect that that is probably the fault of my search since I refuse to believe that this is a new idea - it is a standard method used in many fields to get rid of noise, including astronomy.