Hello, When I perform this command to generate what I expect should be a sine wave sweeping from 262 hZ to the next octave higher over a duration of 10 seconds, using this command:
ffmpeg -f lavfi -i aevalsrc=sin(262*2^^(t/10)*2*PI*t):d=10 test.ogg
I get the following output:
ffmpeg version N-82759-g1f5630a Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib
--enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv
--enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca
--enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc
--enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg
--enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy
--enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame
--enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx
--enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma
--enable-decklink --enable-zlib
libavutil 55. 41.101 / 55. 41.101
libavcodec 57. 66.109 / 57. 66.109
libavformat 57. 58.101 / 57. 58.101
libavdevice 57. 2.100 / 57. 2.100
libavfilter 6. 68.100 / 6. 68.100
libswscale 4. 3.101 / 4. 3.101
libswresample 2. 4.100 / 2. 4.100
libpostproc 54. 2.100 / 54. 2.100
Input #0, lavfi, from 'aevalsrc=sin(262*2^(t/10)*2*PI*t):d=10':
Duration: N/A, start: 0.000000, bitrate: 2822 kb/s
Stream #0:0: Audio: pcm_f64le, 44100 Hz, mono, dbl, 2822 kb/s
Output #0, ogg, to 'test.ogg':
Metadata:
encoder : Lavf57.58.101
Stream #0:0: Audio: vorbis (libvorbis), 44100 Hz, mono, fltp
Metadata:
encoder : Lavc57.66.109 libvorbis
Stream mapping:
Stream #0:0 -> #0:0 (pcm_f64le (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
size= 21kB time=00:00:09.99 bitrate= 17.1kbits/s speed=47.7x
video:0kB audio:17kB subtitle:0kB other streams:0kB global headers:3kB muxing
overhead: 23.471869%
resulting in the attached Ogg file. The resulting frequency sweep ends up
almost an
octave higher than I expected. What am I doing wrong? How can I fix this?
Thanks,
Adam
test.ogg
Description: audio/ogg
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