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• MacOS - how to choose audio device from terminal

  9 octobre 2024, par jon_two

  I've been working on a Python program to create audio and also play back existing sound files. I can spawn multiple processes and have them all play to the laptop speakers, but I was wondering if it was possible to send each signal to a separate sound device. This is so I can apply effects to some processes but not all together.

  


  I'm using a MacBook and python simpleaudio, which calls AudioToolbox to connect to the output device. I've also got ffmpeg installed, so could use ffplay if that is easier. The pydub library uses this - it exports the current wave to a temp file then uses subprocess and ffplay to play it back.

  


  I can get a list of devices, but am not sure how to use this list to choose a device.

  


  % ffplay -devices
Devices:
 D. = Demuxing supported
 .E = Muxing supported
 --
  E audiotoolbox    AudioToolbox output device
 D  avfoundation    AVFoundation input device
 D  lavfi           Libavfilter virtual input device
  E sdl,sdl2        SDL2 output device
 D  x11grab         X11 screen capture, using XCB


  


  I did see a post that suggested using ffmpeg to list devices, again I can't figure out how to use this list.

  


  % ffmpeg -f lavfi -i sine=r=44100 -f audiotoolbox -list_devices true -
Input #0, lavfi, from 'sine=r=44100':
  Duration: N/A, start: 0.000000, bitrate: 705 kb/s
  Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
[AudioToolbox @ 0x135e3f230] CoreAudio devices:
[AudioToolbox @ 0x135e3f230] [0]               Background Music, (null)
[AudioToolbox @ 0x135e3f230] [1]   Background Music (UI Sounds), BGMDevice_UISounds
[AudioToolbox @ 0x135e3f230] [2]         MacBook Air Microphone, BuiltInMicrophoneDevice
[AudioToolbox @ 0x135e3f230] [3]           MacBook Air Speakers, BuiltInSpeakerDevice
[AudioToolbox @ 0x135e3f230] [4]               Aggregate Device, ~:AMS2_Aggregate:0
Output #0, audiotoolbox, to 'pipe:':
  Metadata:
    encoder         : Lavf59.27.100
  Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
    Metadata:
      encoder         : Lavc59.37.100 pcm_s16le
size=N/A time=00:00:05.06 bitrate=N/A speed=0.984x    
video:0kB audio:436kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Exiting normally, received signal 2.


  


  This does at least give me a recognisable list of devices. If I add more Aggregate Devices, can I play back different files to each device ?

  


• FFMPEG Command working ok from terminal but not when launched as a process

  16 juin 2023, par Pit Digger

  I am launching an FFMPEG process from C++ , the command is workign fine from command line, but gives error when laucnhed from code. What could cause this ?

  


  [AVFilterGraph @ 0x3cfadc0] Error parsing filterchain '"[0:v]split=3[v1][v2][v3] ;[v1]copy[v1out] ;[v2]scale=w=1280:h=720[v2out] ;[v3]scale=w=640:h=360[v3out]"'

  


  AVFilterGraph @ 0x3cfadc0] Trailing garbage after a filter : split=3[v1][v2][v3] ;[v1]copy[v1out] ;[v2]scale=w=1280:h=720[v2out] ;[v3]scale=w=640:h=360[v3out]"

  


  Command :

  


  ffmpeg -re -i input.mp4 -c copy -filter_complex "[0:v]split=3[v1][v2][v3] ;[v1]copy[v1out] ;[v2]scale=w=1280:h=720[v2out] ;[v3]scale=w=640:h=360[v3out]" -map [v1out] -c:v:0 libx264 -x264-params "nal-hrd=cbr:force-cfr=1" -b:v:0 1M -maxrate:v:0 2M -minrate:v:0 2M -bufsize:v:0 2M -preset fast -g 48 -sc_threshold 0 -keyint_min 48 -map [v2out] -c:v:1 libx264 -x264-params 'nal-hrd=cbr:force-cfr=1' -b:v:1 1M -maxrate:v:1 1M -minrate:v:1 1M -bufsize:v:1 1M -preset fast -g 48 -sc_threshold 0 -keyint_min 48 -map [v3out] -c:v:2 libx264 -x264-params 'nal-hrd=cbr:force-cfr=1' -b:v:2 500K -maxrate:v:2 500K -minrate:v:2 500K -bufsize:v:2 500K -preset fast -g 48 -sc_threshold 0 -keyint_min 48 -map a:0 -c:a:0 aac -b:a:0 96k -ac 2 -map a:0 -c:a:1 aac -b:a:1 96k -ac 2 -map a:0 -c:a:2 aac -b:a:2 48k -ac 2 -avoid_negative_ts 1 -f hls -hls_time 6 -hls_list_size 15 -hls_flags independent_segments -hls_segment_type mpegts -hls_segment_filename /output/stream_%v_data%02d.ts -master_pl_name index.m3u8 -var_stream_map 'v:0,a:0 v:1,a:1 v:2,a:2' /output/stream_%v.m3u8

  


• Oddly-named file "not found" when trying to move/copy via MacOS Terminal [closed]

  15 juin 2024, par Ben C

  This is a head scratcher.

  


  I need to move these three oddly-named files from an external 2.5" SSD to my desktop. The file names were intended to have variables replaced by date info, however, clearly it didn't work. So I'm left with these filenames that MacOS seems to want to interpret rather than treat as a string. I wish it was as easy as tossing in single quotes or escaping chars, but so far, that hasn't worked.

  


  Files: Test01-$(internal:date_y)-$(internal:date_m)-$(internal:date_d)-.mp4 Test01-$(internal:date_y)-$(internal:date_m)-$(internal:date_d)-0001.mp4 Test01-$(internal:date_y)-$(internal:date_m)-$(internal:date_d)-0002.mp4

  


  I'm on MacOS. In the Finder, the files are not visible. But they are not hidden files.

  


  In Terminal, however, when I navigate to "/Volumes/TestDrive", then run a quick "ls", I can see all three files no problem. Including permissions, size, owners, full filename, etc.

  


  However, when I attempt to move the files to my desktop, and rename in the process (even if I don't rename), Terminal tells me that "No such file or folder can be found" or something very close to that.

  


  I've tried using mv and cp commands to put the filename in single quotes so the filename is read literally. Yet, I'm still given feedback that the file cannot be transferred because it cannot be found or doesn't exist.

  


  mv 'Test01-$(internal:date_y)-$(internal:date_m)-$(internal:date_d)-.mp4' ~/Desktop/Test01-01.mp4' 'cp 'Test01-$(internal:date_y)-$(internal:date_m)-$(internal:date_d)-.mp4' ~/Desktop/Test01-01.mp4

  


  When I try to escape special characters instead of quotes, I am also told the file doesn't exist. But clearly it does when I list out the contents of the drive. And there's only 3x .mp4 files, two hiddne files .fseventsd and some spotlight file.

  


  mv Test01-\$\(internal\:date_y\)-\$\(internal\:date_m\)-\$\(internal\:date_d\)-.mp4 ~/Desktop/Test01-01.mp4

  


  I've tried copying by inode. No luck. I've tried pulling the videos into ffmpeg (CLI based media mgmt tool) to see if I can get some info on the files, and same thing, ffmpeg (or ffprobe) both will tell me the file doesn't exist...even though I can list the files and see that it does.

  


  I hope I'm missing something obvious, but but it seems all the obvious approaches are not yet working for me.

  


  So my question is, what do I need to do to make these files "exist" so that I can rename them and back them up ? Happy to go down any rabbit hole.

  


  Thanks in advance !