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• Cannot get JACK Audio/Netjack working over LAN

  23 juin 2020, par James

  I'm trying to stream low latency audio between 2 raspberry pis. Both gstreamer and ffmpeg induce 2+ second delays for me.

  



  I've played around with Jack Audio and locally on a single pi it seems promising. I can route mic input to a speaker locally and it is almost instantaneous.

  



  However, I have been having trouble getting it to route between devices using Netjack.

  



  # ON SERVER
jackd -P70 -p16 -t2000 -dalsa -dhw:1 -p128 -n3 -r44100 -s 

# ON CLIENT
jackd -v -R -P70 -dnetone -i1 -o1 -I0 -O0  -r44100 -p128 -n3

# ON SERVER
jack_netsource -H < ip address of client >
jack_lsp # list availible connection ports

>system:capture_1
>system:playback_1
>system:playback_2
>netjack:capture_1
>netjack:capture_2
>netjack:capture_3
>netjack:playback_1
>netjack:playback_2
>netjack:playback_3

jack_connect system:capture_1 system:playback_1 # this works
jack_connect system:capture_1 netjack:playback_1 # this doesn't work :(


  



  Most of the launch options I pulled from here http://wiki.linuxaudio.org/wiki/raspberrypi#using_jack. I'll be honest I don't really know what they do.

  



  The client jackd output shows messages like

  



  Jack: data not valid
Jack: data not valid
Jack: JackSocketServerChannel::Execute : fPollTable i = 1 fd = 6
Jack: JackRequest::Notification
Jack: JackEngine::ClientNotify: no callback for notification = 3
Jack: JackEngine::ClientNotify: no callback for notification = 3
netxruns... duration: 139ms
Jack: JackSocketServerChannel::Execute : fPollTable i = 1 fd = 6
Jack: JackRequest::Notification
Jack: JackEngine::ClientNotify: no callback for notification = 3
Jack: JackEngine::ClientNotify: no callback for notification = 3


  



  And the server jack_netsource output looks like

  



  current latency 114
current latency 20
current latency 27
current latency 29
current latency 48
current latency 23
current latency 33
current latency 28
current latency 41
current latency 84
current latency 44


  



  and the server jackd output looks like

  



  JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackEngine::XRun: client = netjack was not finished, state = Triggered
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackEngine::XRun: client = netjack was not finished, state = Triggered
JackEngine::XRun: client = netjack was not finished, state = Triggered


  



  I believe the -dnetone flag indicates to use Netjack2. Netjack 1, which I've tried with the -dnet flag results in a single Not Connected message from jack_netsource and :

  



  Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: JackSocketServerChannel::Execute : fPollTable i = 1 fd = 6


  



  from the client jackd.

  


• avformat/mvdec : Fix integer overflow with billions of channels

  23 juin 2020, par Michael Niedermayer

  avformat/mvdec : Fix integer overflow with billions of channels
  Fixes : signed integer overflow : 1394614304 * 2 cannot be represented in type 'int'
  
  Fixes : 23491/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5697377020411904
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mvdec.c

• How to download a part of mp3 from server ?

  20 août 2020, par Sharukh Mohammed

  Use Case

  


  My use case is roughly equal to, adding a 15-second mp3 file to a 1 min video. All transcoding merging part will be done by FFmpeg-android so that's not the concern right now.

  


  The flow is as follows

  


  

  • User can select any 15 seconds (ExoPlayer-streaming) of an mp3 (considering 192Kbps/44.1KHz of 3mins = up to 7MB)

  


  • Then download ONLY the 15 second part and add it to the video's audio stream. (using FFmpeg)

  


  • Use the obtained output

  


  


  Tried solutions

  


  


  • Extracting fragment of audio from a url

    


    RANGE_REQUEST - I have replicated the exact same algorithm/formula in Kotlin using the exact sample file provided. But the output is not accurate (± 1.5 secs * c) where c is proportional to startTime

    


  


  • How to crop a mp3 from x to x+n using ffmpeg ?

    


    FFMPEG_SS - This works flawlessly with remote URLs as input, but there are two downsides,

    


    

    1. as startTime increases, the size of downloaded bytes are closer to the actual size of the mp3.

    


    2. ffmpeg-android does not support network requests module (at least the way we complied)

    


    


  


  


  So above two solutions have not been fruitful and currently, I am downloading the whole file and trimming it locally, which is definitely a bad UX.
I wonder how Instagram's music addition to story feature works because that's close to what I wanted to implement.