In the first example I have two identical 1kHz sine sources. The first
source is delayed by 0.5ms (which means 180° phase shift), and then both
channels are mixed. This works as expected, the result is silence.
ffmpeg -f lavfi -i sine=f=1000:d=5 -f lavfi -i sine=f=1000:d=5
-filter_complex "adelay=0.5,amix" -y test1.mp3
In the second example the only difference is that the other channel is
delayed. The result should be the same. But it doesn't work, the result
isn't silence. Why doesn't it work?
ffmpeg -f lavfi -i sine=f=1000:d=5 -f lavfi -i sine=f=1000:d=5
-filter_complex "adelay=0|0.5,amix" -y test2.mp3
Uncut console outputs for both examples are below.
Thanks,
Michael
c:/ffmpeg/ffmpeg -f lavfi -i sine=f=1000:d=
5 -f lavfi -i sine=f=1000:d=5 -filter_complex "adelay=0.5,amix" -y test1.mp3
ffmpeg version N-91565-g1940c27c82 Copyright (c) 2000-2018 the FFmpeg
developers
built with gcc 7.3.1 (GCC) 20180722
configuration: --enable-gpl --enable-version3 --enable-sdl2
--enable-bzlib --e
nable-fontconfig --enable-gnutls --enable-iconv --enable-libass
--enable-libblur
ay --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb
--enable-
libopencore-amrwb --enable-libopenjpeg --enable-libopus
--enable-libshine --enab
le-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame
--enable-li
bvpx --enable-libwavpack --enable-libwebp --enable-libx264
--enable-libx265 --en
able-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp
--enable-
libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa
--enabl
e-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf
--enabl
e-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc
--enable-nvdec --enab
le-dxva2 --enable-avisynth
libavutil 56. 18.102 / 56. 18.102
libavcodec 58. 22.100 / 58. 22.100
libavformat 58. 17.101 / 58. 17.101
libavdevice 58. 4.101 / 58. 4.101
libavfilter 7. 26.100 / 7. 26.100
libswscale 5. 2.100 / 5. 2.100
libswresample 3. 2.100 / 3. 2.100
libpostproc 55. 2.100 / 55. 2.100
Input #0, lavfi, from 'sine=f=1000:d=5':
Duration: N/A, start: 0.000000, bitrate: 705 kb/s
Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
Input #1, lavfi, from 'sine=f=1000:d=5':
Duration: N/A, start: 0.000000, bitrate: 705 kb/s
Stream #1:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
Stream mapping:
Stream #0:0 (pcm_s16le) -> adelay
Stream #1:0 (pcm_s16le) -> amix:input1
amix -> Stream #0:0 (libmp3lame)
Press [q] to stop, [?] for help
Output #0, mp3, to 'test1.mp3':
Metadata:
TSSE : Lavf58.17.101
Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, fltp (default)
Metadata:
encoder : Lavc58.22.100 libmp3lame
[Parsed_sine_0 @ 0000000000512840] EOF timestamp not reliable
[Parsed_sine_0 @ 0000000000514c00] EOF timestamp not reliable
size= 40kB time=00:00:05.01 bitrate= 64.7kbits/s speed=32.2x
video:0kB audio:39kB subtitle:0kB other streams:0kB global headers:0kB
muxing ov
erhead: 0.562815%
c:/ffmpeg/ffmpeg -f lavfi -i sine=f=1000:d=
5 -f lavfi -i sine=f=1000:d=5 -filter_complex "adelay=0|0.5,amix" -y
test2.mp3
ffmpeg version N-91565-g1940c27c82 Copyright (c) 2000-2018 the FFmpeg
developers
built with gcc 7.3.1 (GCC) 20180722
configuration: --enable-gpl --enable-version3 --enable-sdl2
--enable-bzlib --e
nable-fontconfig --enable-gnutls --enable-iconv --enable-libass
--enable-libblur
ay --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb
--enable-
libopencore-amrwb --enable-libopenjpeg --enable-libopus
--enable-libshine --enab
le-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame
--enable-li
bvpx --enable-libwavpack --enable-libwebp --enable-libx264
--enable-libx265 --en
able-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp
--enable-
libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa
--enabl
e-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf
--enabl
e-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc
--enable-nvdec --enab
le-dxva2 --enable-avisynth
libavutil 56. 18.102 / 56. 18.102
libavcodec 58. 22.100 / 58. 22.100
libavformat 58. 17.101 / 58. 17.101
libavdevice 58. 4.101 / 58. 4.101
libavfilter 7. 26.100 / 7. 26.100
libswscale 5. 2.100 / 5. 2.100
libswresample 3. 2.100 / 3. 2.100
libpostproc 55. 2.100 / 55. 2.100
Input #0, lavfi, from 'sine=f=1000:d=5':
Duration: N/A, start: 0.000000, bitrate: 705 kb/s
Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
Input #1, lavfi, from 'sine=f=1000:d=5':
Duration: N/A, start: 0.000000, bitrate: 705 kb/s
Stream #1:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
Stream mapping:
Stream #0:0 (pcm_s16le) -> adelay
Stream #1:0 (pcm_s16le) -> amix:input1
amix -> Stream #0:0 (libmp3lame)
Press [q] to stop, [?] for help
Output #0, mp3, to 'test2.mp3':
Metadata:
TSSE : Lavf58.17.101
Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, fltp (default)
Metadata:
encoder : Lavc58.22.100 libmp3lame
[Parsed_sine_0 @ 00000000003f4c80] EOF timestamp not reliable
[Parsed_sine_0 @ 00000000003f2880] EOF timestamp not reliable
size= 40kB time=00:00:05.01 bitrate= 64.7kbits/s speed=45.9x
video:0kB audio:39kB subtitle:0kB other streams:0kB global headers:0kB
muxing ov
erhead: 0.562815%
_______________________________________________
ffmpeg-user mailing list
ffmpeg-user@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-user
To unsubscribe, visit link above, or email
ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
