Hello,
I'm using the following batch file (Windows 7) for a live ultrasound
conversion.
set "SR=44100" :: Sample rate
set "F=14000" :: Subtracted frequency
set "VOL=10" :: Volume factor
set /a "N=4096*%F%/%SR%" :: N = 4096 * F / SR
c:\ffmpeg\ffmpeg -f dshow -sample_rate %SR% -sample_size 16 -channels 2
-i audio="Microphone (SoundMAX Integrated" -af
volume=%VOL%,afftfilt='real=if(lt(b+%N%,nb),real(b+%N%,ch),0)':'imag=if(lt(b+%N%,nb),imag(b+%N%,ch),0)'
-f nut - | c:\ffmpeg\ffplay -
FFmpeg gets the audio input from the computer's microphone input and
passes the converted output to FFplay.
This works fine for hearing bats, but it has about 1-2 seconds delay
between input and output.
Are there any options for minimizing the delay?
The console output is copied below.
Thanks,
Michael
C:\Users\mkoch\Desktop\Ultrasound Live>c:\ffmpeg\ffmpeg -f dshow
-sample_rate 44
100 -sample_size 16 -channels 2 -i audio="Microphone (SoundMAX
Integrated" -af v
olume=10,afftfilt='real=if(lt(b+1300,nb),real(b+1300,ch),0)':'imag=if(lt(b+1300,
nb),imag(b+1300,ch),0)' -f nut - | c:\ffmpeg\ffplay -
ffmpeg version N-92857-g3e461f9d4c Copyright (c) 2000-2018 the FFmpeg
developers
built with gcc 8.2.1 (GCC) 20181201
configuration: --enable-gpl --enable-version3 --enable-sdl2
--enable-fontconfi
g --enable-gnutls --enable-iconv --enable-libass --enable-libbluray
--enable-lib
freetype --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amr
wb --enable-libopenjpeg --enable-libopus --enable-libshine
--enable-libsnappy --
enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx
--enable-l
ibwavpack --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxml2 --
enable-libzimg --enable-lzma --enable-zlib --enable-gmp
--enable-libvidstab --en
able-libvorbis --enable-libvo-amrwbenc --enable-libmysofa
--enable-libspeex --en
able-libxvid --enable-libaom --enable-libmfx --enable-amf
--enable-ffnvcodec --e
nable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec
--enable-dxva2 --enab
le-avisynth --enable-libopenmpt
libavutil 56. 25.100 / 56. 25.100
libavcodec 58. 42.104 / 58. 42.104
libavformat 58. 25.100 / 58. 25.100
ffplay version N-92857-g3e461f9d4c libavdevice 58. 6.101 / 58.
6.101 Copyr
ight (c) 2003-2018 the FFmpeg developers
libavfilter 7. 46.101 / 7. 46.101 built with gcc 8.2.1 (GCC)
20181201
configuration: --enable-gpl --enable-version3 --enable-sdl2
--enable-fontconfi
g --enable-gnutls --enable-iconv --enable-libass --enable-libbluray
--enable-lib
freetype --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amr
wb --enable-libopenjpeg --enable-libopus --enable-libshine
--enable-libsnappy --
enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx
--enable-l
ibwavpack --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxml2 --
enable-libzimg --enable-lzma --enable-zlib --enable-gmp
--enable-libvidstab --en
able-libvorbis --enable-libvo-amrwbenc --enable-libmysofa
--enable-libspeex --en
able-libxvid --enable-libaom --enable-libmfx --enable-amf
--enable-ffnvcodec --e
nable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec
--enable-dxva2 --enab
le-avisynth --enable-libopenmpt
libswscale 5. 4.100 / 5. 4.100
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
libavutil 56. 25.100 / 56. 25.100
libavcodec 58. 42.104 / 58. 42.104
libavformat 58. 25.100 / 58. 25.100
libavdevice 58. 6.101 / 58. 6.101
libavfilter 7. 46.101 / 7. 46.101
libswscale 5. 4.100 / 5. 4.100
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
Guessed Channel Layout for Input Stream #0.0 : stereo 0B f=0/0
Input #0, dshow, from 'audio=Microphone (SoundMAX Integrated':
Duration: N/A, start: 1701.243000, bitrate: 1411 kb/s
Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
Output #0, nut, to 'pipe:': aq= 0KB vq= 0KB sq= 0B f=0/0
Metadata:
encoder : Lavf58.25.100
Stream #0:0: Audio: vorbis (libvorbis) (oV[0][0] / 0x566F), 44100
Hz, stereo
, fltp
Metadata:
encoder : Lavc58.42.104 libvorbis
Input #0, nut, from 'pipe:':
Metadata:
encoder : Lavf58.25.100
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Audio: vorbis (oV[0][0] / 0x566F), 44100 Hz, stereo, fltp
Metadata:
encoder : Lavc58.42.104 libvorbis
16.27 M-A: 0.000 fd= 0 aq= 3KB vq= 0KB sq= 0B f=0/0
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