Hello ffmpeg-user and devs,
FFmpeg binary used:
ffmpeg version N-102342-g5541cff-Reino Copyright (c) 2000-2021 the FFmpeg
developers
built with gcc 10.3.0 (GCC)
configuration: --arch=x86 --target-os=mingw32
--prefix=/cygdrive/[...]/cross_compilers/mingw-w64-i686/i686-w64-mingw32
--cross-prefix=/cygdrive/[...]/cross_compilers/mingw-w64-i686/bin/i686-w64-mingw32-
--extra-cflags='-march=pentium3 -mtune=athlon-xp -O2 -mfpmath=sse -msse'
--pkg-config=pkg-config --pkg-config-flags=--static --extra-version=Reino
--enable-gpl --enable-gray --enable-version3 --disable-debug --disable-doc
--disable-htmlpages --disable-manpages --disable-mediafoundation
--disable-podpages --disable-txtpages --disable-w32threads --enable-avisynth
--enable-frei0r --enable-filter=frei0r --enable-gmp --enable-libaom
--enable-libass --enable-libfdk-aac --enable-libflite --enable-libfontconfig
--enable-libfreetype --enable-libfribidi --enable-libgme --enable-libmp3lame
--enable-libopenmpt --enable-libopus --enable-libsoxr --enable-libtwolame
--enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp
--enable-libx264 --enable-libx265 --enable-libxml2
--enable-libxvid --enable-libzimg --enable-mbedtls
libavutil 57. 0.100 / 57. 0.100
libavcodec 59. 0.100 / 59. 0.100
libavformat 59. 0.100 / 59. 0.100
libavdevice 59. 0.100 / 59. 0.100
libavfilter 8. 0.101 / 8. 0.101
libswscale 6. 0.100 / 6. 0.100
libswresample 4. 0.100 / 4. 0.100
libpostproc 56. 0.100 / 56. 0.100
Input file:
ffmpeg -v 40 -i "D:\input.wav" -f null NUL
[...]
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'D:\input.wav':
Duration: 00:00:25.50, bitrate: 1411 kb/s
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16,
1411 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
[graph_0_in_0_0 @ 0510f980] tb:1/44100 samplefmt:s16 samplerate:44100
chlayout:0x3
[...]
FFmpeg sets "-channel_layout stereo" in the background, hence "[graph_0_in_0_0
@ 0510f980] ... chlayout:-0x3-".
FFplay for some reason doesn't guess the channel layout:
ffplay -v 40 -nodisp -autoexit "D:\input.wav"
[...]
Input #0, wav, from 'D:\input.wav':
Duration: 00:00:25.50, bitrate: 1411 kb/s
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 2 channels,
s16, 1411 kb/s
[ffplay_abuffer @ 05b1e0c0] tb:1/44100 samplefmt:s16 samplerate:44100
chlayout:-(null)-
[...]
It plays the wav-file nontheless. Problems start to occur however when
audiofilters are applied, like when changing the tempo and pitch for instance.
No problem for FFmpeg:
ffmpeg -v 40 [-channel_layout stereo] -i "D:\input.wav" -af "asetrate=22050" -f
null NUL
[...]
[graph_0_in_0_0 @ 05117c80] tb:1/44100 samplefmt:s16 samplerate:44100
chlayout:0x3
Output #0, null, to 'NUL':
Metadata:
encoder : Lavf59.0.100
Stream #0:0: Audio: pcm_s16le, 22050 Hz, stereo, s16, 705 kb/s
[...]
But FFplay returns:
ffplay -v 40 -nodisp -autoexit -af "asetrate=22050" "D:\input.wav"
[...]
[ffplay_abuffer @ 05ad1200] tb:1/44100 samplefmt:s16 samplerate:44100
chlayout:(null)
[Parsed_asetrate_0 @ 05b43300] auto-inserting filter 'auto_resampler_0' between
the filter 'ffplay_abuffer' and the filter 'Parsed_asetrate_0'
[auto_resampler_0 @ 05a2d040] Cannot select channel layout for the link between
filters auto_resampler_0 and Parsed_asetrate_0.
[auto_resampler_0 @ 05a2d040] Unknown channel layouts not supported, try
specifying a channel layout using 'aformat=channel_layouts=something'.
It appears that "-channel_layout" isn't a valid option for FFplay, so would...
ffplay -v 40 -nodisp -autoexit -af "aformat=cl=stereo,asetrate=22050"
"D:\input.wav"
...be the only way to set the channel layout (to satisfy asetrate at least)?
Isn't there a "-channel_layout" like option for FFplay to properly set the
channel layout? But more importantly, why doesn't FFplay try to guess the
channel layout of wav-files like FFmpeg does?
---
Small side question:
-af "loudnorm,aformat=cl=stereo,aresample=44100"
-af "loudnorm,aresample=44100:ocl=stereo"
Is there a difference between the two, or is the end result the same
quality-wise?
--
Reino
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