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• SOX got nothing from SoundFlower

  12 septembre 2016, par xiaose

  For some reason on some comps SoundFlower does not catch audio.
  I.e. there are SoundFlower but when I switch input\output to the SoundFlower I cannot get any sound. I have got only not empty file without any sound.

  Okay, how I try to get the sound...

  Just FYI :

  $ system_profiler SPSoftwareDataType

  Software:
  
  
  
      System Software Overview:
  
  
  
        System Version: OS X 10.10.5 (14F1912)
  
        Kernel Version: Darwin 14.5.0
  
        Boot Volume: Macintosh HD
  
        Boot Mode: Normal
  
        Computer Name: Craig Computer
  
        User Name: Craig (craigm)
  
        Secure Virtual Memory: Enabled
  
        Time since boot: 1 day22:12

  Gonna check is AVFoundation works :

  $ ./ffmpeg -h demuxer=avfoundation

  Demuxer avfoundation [AVFoundation input device]:
  
  AVFoundation input device AVOptions:
  
    -list_devices      <int>        .D...... list available devices (from 0 to 1) (default false)
  
       true                         .D...... 
  
       false                        .D...... 
  
    -video_device_index <int>        .D...... select video device by index for devices with same name (starts at 0) (from -1 to INT_MAX) (default -1)
  
    -audio_device_index <int>        .D...... select audio device by index for devices with same name (starts at 0) (from -1 to INT_MAX) (default -1)
  
    -pixel_format          .D...... set pixel format (default yuv420p)
  
    -framerate          .D...... set frame rate (default "ntsc")
  
    -video_size         .D...... set video size
  
    -capture_cursor    <int>        .D...... capture the screen cursor (from 0 to 1) (default 0)
  
    -capture_mouse_clicks <int>        .D...... capture the screen mouse clicks (from 0 to 1) (default 0)
  
  </int></int></int></int></int>

  Gonna get list of AVFoundation audio devices :

  $ ./ffmpeg -f avfoundation -list_devices true -i ’’

  ffmpeg version 3.1.1-tessus Copyright (c) 2000-2016 the FFmpeg developers
  
    built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
  
    configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --as=yasm --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzmq --enable-version3 --disable-ffplay --disable-indev=qtkit --disable-indev=x11grab_xcb
  
    libavutil      55. 28.100 / 55. 28.100
  
    libavcodec     57. 48.101 / 57. 48.101
  
    libavformat    57. 41.100 / 57. 41.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 47.100 /  6. 47.100
  
    libswscale      4.  1.100 /  4.  1.100
  
    libswresample   2.  1.100 /  2.  1.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [AVFoundation input device @ 0x7fda40421000] AVFoundation video devices:
  
  [AVFoundation input device @ 0x7fda40421000] [0] Built-in iSight
  
  [AVFoundation input device @ 0x7fda40421000] [1] Capture screen 0
  
  [AVFoundation input device @ 0x7fda40421000] AVFoundation audio devices:
  
  [AVFoundation input device @ 0x7fda40421000] [0] Soundflower (64ch)
  
  [AVFoundation input device @ 0x7fda40421000] [1] Built-in Microphone
  
  [AVFoundation input device @ 0x7fda40421000] [2] Soundflower (2ch)
  
  [AVFoundation input device @ 0x7fda40421000] [3] Built-in Input
  
  : Input/output error

  Okay, we have SoundFlower in devices :

  [AVFoundation input device @ 0x7fda40421000] [2] Soundflower (2ch)

  Then I run AppleScript which gonna switch to the "SoundFlower (2ch)" :

  enableSF("input")

  enableSF("output")

  Where enableSF(stdname) is :

  on enableSF(stdname)    
  
      tell application "System Preferences"   
  
          -- activate 
  
          tell anchor stdname of pane "com.apple.preference.sound" to reveal  
  
          tell application "System Events"    
  
              tell application process "System Preferences"   
  
                  tell tab group 1 of window 1    
  
                      delay 2 
  
                      set rowslist to selected of row of table 1 of scroll area 1 
  
                      set counter to 0    
  
                      repeat with id in rowslist  
  
                          set counter to counter + 1  
  
                          set rowName to (value of text field 1 of row counter of table 1 of scroll area 1)   
  
  
  
                          set output to stdname & " " & rowName   
  
                          set scrpt to "echo \"" & output & "\" >> ~/Desktop/ds.log"  
  
                          do shell script scrpt   
  
  
  
                          if (rowName is equal to "Soundflower (2ch)") then   
  
                              set selected of row counter of table 1 of scroll area 1 to true 
  
  
  
                              set output to "
  
                              !!! FOUND SF for " & stdname & " " & rowName    
  
                              set scrpt to "echo \"" & output & "\" >> ~/Desktop/ds.log"  
  
                              log output  
  
                              do shell script scrpt
  
                              exit repeat 
  
                          end if  
  
                      end repeat  
  
                  end tell    
  
              end tell    
  
          end tell    
  
      end tell    
  
  end enableSF    

  In result I have got this :

  input Internal Microphone
  
  input Line In
  
  input Digi CoreAudio Device
  
  input Soundflower (2ch)
  
  
  
          !!! FOUND SF for input Soundflower (2ch)
  
  
  
  output Headphones
  
  output Digi CoreAudio Device
  
  output Soundflower (2ch)
  
  
  
          !!! FOUND SF for output Soundflower (2ch)

  It means that we switch to the SoundFlower. Actually the same can be done by hands, but the script is more reliable as for me.

  Okay, next we can try to save some audio via SOX :

  $ /Applications/sox-14.3.2/sox -d /Desktop/out.wav

  Input File     : 'default' (coreaudio)
  
  Channels       : 2
  
  Sample Rate    : 44100
  
  Precision      : 32-bit
  
  Sample Encoding: 32-bit Signed Integer PCM
  
  
  
  
  
  In:0.00% 00:00:00.00 [00:00:00.00] Out:0     [      |      ]        Clip:0    
  
  ...
  
  ...
  
  ... 
  
  In:0.00% 00:00:02.51 [00:00:00.00] Out:106k  [      |      ]        Clip:0    
  
  ...
  
  ...
  
  ...
  
  In:0.00% 00:00:11.80 [00:00:00.00] Out:516k  [      |      ]        Clip:0    /Applications/sox-14.3.2/sox WARN coreaudio: coreaudio: unhandled buffer overrun.  Data discarded.
  
  ...
  
  ...
  
  ...    
  
  In:0.00% 00:00:12.35 [00:00:00.00] Out:545k  [      |      ]        Clip:0    /Applications/sox-14.3.2/sox WARN coreaudio: coreaudio: unhandled buffer overrun.  Data discarded.
  
  ...
  
  ...
  
  ...
  
  In:0.00% 00:00:13.28 [00:00:00.00] Out:582k  [      |      ]        Clip:0    
  
  Aborted.

  And, as you can see, the SOX gives me an empty file. Rather, it gives the data, but there is no sound.

  This happens on all OS from 10.10 to 10.11.6. Normal output should be this type :

  In:0.00% 00:00:00.28 [00:00:00.00] Out:8.19k [======|======]        Clip:0      
  
  ...
  
  ...
  
  ...
  
  In:0.00% 00:00:04.37 [00:00:00.00] Out:188k  [ -====|===== ] Hd:1.1 Clip:0 
  
  ...
  
  ...
  
  ...     
  
  In:0.00% 00:00:08.82 [00:00:00.00] Out:385k  [======|=====-] Hd:1.1 Clip:0      
  
  In:0.00% 00:00:09.01 [00:00:00.00] Out:393k  [-=====|=====-] Hd:1.1 Clip:0      
  
  In:0.00% 00:00:09.20 [00:00:00.00] Out:401k  [======|======] Hd:1.1 Clip:0 

• Best approach to real time http streaming to HTML5 video client

  28 juin 2017, par deandob

  I’m really stuck trying to understand the best way to stream real time output of ffmpeg to a HTML5 client using node.js, as there are a number of variables at play and I don’t have a lot of experience in this space, having spent many hours trying different combinations.

  My use case is :

  1) IP video camera RTSP H.264 stream is picked up by FFMPEG and remuxed into a mp4 container using the following FFMPEG settings in node, output to STDOUT. This is only run on the initial client connection, so that partial content requests don’t try to spawn FFMPEG again.

  liveFFMPEG = child_process.spawn("ffmpeg", [
  
                  "-i", "rtsp://admin:12345@192.168.1.234:554" , "-vcodec", "copy", "-f",
  
                  "mp4", "-reset_timestamps", "1", "-movflags", "frag_keyframe+empty_moov", 
  
                  "-"   // output to stdout
  
                  ],  {detached: false});

  2) I use the node http server to capture the STDOUT and stream that back to the client upon a client request. When the client first connects I spawn the above FFMPEG command line then pipe the STDOUT stream to the HTTP response.

  liveFFMPEG.stdout.pipe(resp);

  I have also used the stream event to write the FFMPEG data to the HTTP response but makes no difference

  xliveFFMPEG.stdout.on("data",function(data) {
  
          resp.write(data);
  
  }

  I use the following HTTP header (which is also used and working when streaming pre-recorded files)

  var total = 999999999         // fake a large file
  
  var partialstart = 0
  
  var partialend = total - 1
  
  
  
  if (range !== undefined) {
  
      var parts = range.replace(/bytes=/, "").split("-"); 
  
      var partialstart = parts[0]; 
  
      var partialend = parts[1];
  
  } 
  
  
  
  var start = parseInt(partialstart, 10); 
  
  var end = partialend ? parseInt(partialend, 10) : total;   // fake a large file if no range reques 
  
  
  
  var chunksize = (end-start)+1; 
  
  
  
  resp.writeHead(206, {
  
                    'Transfer-Encoding': 'chunked'
  
                   , 'Content-Type': 'video/mp4'
  
                   , 'Content-Length': chunksize // large size to fake a file
  
                   , 'Accept-Ranges': 'bytes ' + start + "-" + end + "/" + total
  
  });

  3) The client has to use HTML5 video tags.

  I have no problems with streaming playback (using fs.createReadStream with 206 HTTP partial content) to the HTML5 client a video file previously recorded with the above FFMPEG command line (but saved to a file instead of STDOUT), so I know the FFMPEG stream is correct, and I can even correctly see the video live streaming in VLC when connecting to the HTTP node server.

  However trying to stream live from FFMPEG via node HTTP seems to be a lot harder as the client will display one frame then stop. I suspect the problem is that I am not setting up the HTTP connection to be compatible with the HTML5 video client. I have tried a variety of things like using HTTP 206 (partial content) and 200 responses, putting the data into a buffer then streaming with no luck, so I need to go back to first principles to ensure I’m setting this up the right way.

  Here is my understanding of how this should work, please correct me if I’m wrong :

  1) FFMPEG should be setup to fragment the output and use an empty moov (FFMPEG frag_keyframe and empty_moov mov flags). This means the client does not use the moov atom which is typically at the end of the file which isn’t relevant when streaming (no end of file), but means no seeking possible which is fine for my use case.

  2) Even though I use MP4 fragments and empty MOOV, I still have to use HTTP partial content, as the HTML5 player will wait until the entire stream is downloaded before playing, which with a live stream never ends so is unworkable.

  3) I don’t understand why piping the STDOUT stream to the HTTP response doesn’t work when streaming live yet if I save to a file I can stream this file easily to HTML5 clients using similar code. Maybe it’s a timing issue as it takes a second for the FFMPEG spawn to start, connect to the IP camera and send chunks to node, and the node data events are irregular as well. However the bytestream should be exactly the same as saving to a file, and HTTP should be able to cater for delays.

  4) When checking the network log from the HTTP client when streaming a MP4 file created by FFMPEG from the camera, I see there are 3 client requests : A general GET request for the video, which the HTTP server returns about 40Kb, then a partial content request with a byte range for the last 10K of the file, then a final request for the bits in the middle not loaded. Maybe the HTML5 client once it receives the first response is asking for the last part of the file to load the MP4 MOOV atom ? If this is the case it won’t work for streaming as there is no MOOV file and no end of the file.

  5) When checking the network log when trying to stream live, I get an aborted initial request with only about 200 bytes received, then a re-request again aborted with 200 bytes and a third request which is only 2K long. I don’t understand why the HTML5 client would abort the request as the bytestream is exactly the same as I can successfully use when streaming from a recorded file. It also seems node isn’t sending the rest of the FFMPEG stream to the client, yet I can see the FFMPEG data in the .on event routine so it is getting to the FFMPEG node HTTP server.

  6) Although I think piping the STDOUT stream to the HTTP response buffer should work, do I have to build an intermediate buffer and stream that will allow the HTTP partial content client requests to properly work like it does when it (successfully) reads a file ? I think this is the main reason for my problems however I’m not exactly sure in Node how to best set that up. And I don’t know how to handle a client request for the data at the end of the file as there is no end of file.

  7) Am I on the wrong track with trying to handle 206 partial content requests, and should this work with normal 200 HTTP responses ? HTTP 200 responses works fine for VLC so I suspect the HTML5 video client will only work with partial content requests ?

  As I’m still learning this stuff its difficult to work through the various layers of this problem (FFMPEG, node, streaming, HTTP, HTML5 video) so any pointers will be greatly appreciated. I have spent hours researching on this site and the net, and I have not come across anyone who has been able to do real time streaming in node but I can’t be the first, and I think this should be able to work (somehow !).

• Best approach to real time http streaming to HTML5 video client

  12 octobre 2016, par deandob

  I’m really stuck trying to understand the best way to stream real time output of ffmpeg to a HTML5 client using node.js, as there are a number of variables at play and I don’t have a lot of experience in this space, having spent many hours trying different combinations.

  My use case is :

  1) IP video camera RTSP H.264 stream is picked up by FFMPEG and remuxed into a mp4 container using the following FFMPEG settings in node, output to STDOUT. This is only run on the initial client connection, so that partial content requests don’t try to spawn FFMPEG again.

  liveFFMPEG = child_process.spawn("ffmpeg", [
  
                  "-i", "rtsp://admin:12345@192.168.1.234:554" , "-vcodec", "copy", "-f",
  
                  "mp4", "-reset_timestamps", "1", "-movflags", "frag_keyframe+empty_moov", 
  
                  "-"   // output to stdout
  
                  ],  {detached: false});

  2) I use the node http server to capture the STDOUT and stream that back to the client upon a client request. When the client first connects I spawn the above FFMPEG command line then pipe the STDOUT stream to the HTTP response.

  liveFFMPEG.stdout.pipe(resp);

  I have also used the stream event to write the FFMPEG data to the HTTP response but makes no difference

  xliveFFMPEG.stdout.on("data",function(data) {
  
          resp.write(data);
  
  }

  I use the following HTTP header (which is also used and working when streaming pre-recorded files)

  var total = 999999999         // fake a large file
  
  var partialstart = 0
  
  var partialend = total - 1
  
  
  
  if (range !== undefined) {
  
      var parts = range.replace(/bytes=/, "").split("-"); 
  
      var partialstart = parts[0]; 
  
      var partialend = parts[1];
  
  } 
  
  
  
  var start = parseInt(partialstart, 10); 
  
  var end = partialend ? parseInt(partialend, 10) : total;   // fake a large file if no range reques 
  
  
  
  var chunksize = (end-start)+1; 
  
  
  
  resp.writeHead(206, {
  
                    'Transfer-Encoding': 'chunked'
  
                   , 'Content-Type': 'video/mp4'
  
                   , 'Content-Length': chunksize // large size to fake a file
  
                   , 'Accept-Ranges': 'bytes ' + start + "-" + end + "/" + total
  
  });

  3) The client has to use HTML5 video tags.

  I have no problems with streaming playback (using fs.createReadStream with 206 HTTP partial content) to the HTML5 client a video file previously recorded with the above FFMPEG command line (but saved to a file instead of STDOUT), so I know the FFMPEG stream is correct, and I can even correctly see the video live streaming in VLC when connecting to the HTTP node server.

  However trying to stream live from FFMPEG via node HTTP seems to be a lot harder as the client will display one frame then stop. I suspect the problem is that I am not setting up the HTTP connection to be compatible with the HTML5 video client. I have tried a variety of things like using HTTP 206 (partial content) and 200 responses, putting the data into a buffer then streaming with no luck, so I need to go back to first principles to ensure I’m setting this up the right way.

  Here is my understanding of how this should work, please correct me if I’m wrong :

  1) FFMPEG should be setup to fragment the output and use an empty moov (FFMPEG frag_keyframe and empty_moov mov flags). This means the client does not use the moov atom which is typically at the end of the file which isn’t relevant when streaming (no end of file), but means no seeking possible which is fine for my use case.

  2) Even though I use MP4 fragments and empty MOOV, I still have to use HTTP partial content, as the HTML5 player will wait until the entire stream is downloaded before playing, which with a live stream never ends so is unworkable.

  3) I don’t understand why piping the STDOUT stream to the HTTP response doesn’t work when streaming live yet if I save to a file I can stream this file easily to HTML5 clients using similar code. Maybe it’s a timing issue as it takes a second for the FFMPEG spawn to start, connect to the IP camera and send chunks to node, and the node data events are irregular as well. However the bytestream should be exactly the same as saving to a file, and HTTP should be able to cater for delays.

  4) When checking the network log from the HTTP client when streaming a MP4 file created by FFMPEG from the camera, I see there are 3 client requests : A general GET request for the video, which the HTTP server returns about 40Kb, then a partial content request with a byte range for the last 10K of the file, then a final request for the bits in the middle not loaded. Maybe the HTML5 client once it receives the first response is asking for the last part of the file to load the MP4 MOOV atom ? If this is the case it won’t work for streaming as there is no MOOV file and no end of the file.

  5) When checking the network log when trying to stream live, I get an aborted initial request with only about 200 bytes received, then a re-request again aborted with 200 bytes and a third request which is only 2K long. I don’t understand why the HTML5 client would abort the request as the bytestream is exactly the same as I can successfully use when streaming from a recorded file. It also seems node isn’t sending the rest of the FFMPEG stream to the client, yet I can see the FFMPEG data in the .on event routine so it is getting to the FFMPEG node HTTP server.

  6) Although I think piping the STDOUT stream to the HTTP response buffer should work, do I have to build an intermediate buffer and stream that will allow the HTTP partial content client requests to properly work like it does when it (successfully) reads a file ? I think this is the main reason for my problems however I’m not exactly sure in Node how to best set that up. And I don’t know how to handle a client request for the data at the end of the file as there is no end of file.

  7) Am I on the wrong track with trying to handle 206 partial content requests, and should this work with normal 200 HTTP responses ? HTTP 200 responses works fine for VLC so I suspect the HTML5 video client will only work with partial content requests ?

  As I’m still learning this stuff its difficult to work through the various layers of this problem (FFMPEG, node, streaming, HTTP, HTML5 video) so any pointers will be greatly appreciated. I have spent hours researching on this site and the net, and I have not come across anyone who has been able to do real time streaming in node but I can’t be the first, and I think this should be able to work (somehow !).