Hi Remy,
To record zmovie.avi I used webcam.exe /a/n and the following line:
ffmpeg -async 1 -framerate 25 -itsoffset 2.0 -i \PIPE\Webcam\Video -i \PIPE\Webcam\Audio -c:v copy -c:a copy -map 0:0 -map 1:0 zmovie.avi
And it works very well. The following line produces compressed output (10 times reduction in filesize):
ffmpeg -async 1 -framerate 25 -itsoffset 2.0 -i \PIPE\Webcam\Video -i \PIPE\Webcam\Audio -map 0:0 -map 1:0 zmovie.avi
And works very well too. But I do prefer the uncompressed movie.
There is no delay in the recorded audio and it stays in sync.
Best regards,
Wim.
Oh well done,
I have missplaced parameters...
Your command line as given:
It will not work with ffmpeg 4.0.2 and up (many options or parameters changed between versions.
(I have to check ffmpeg version to use correct ffmpeg version/parameters under AVxCAT)
ffmpeg -async 1 -framerate 25 -itsoffset 2.0 -i \PIPE\Webcam\Video -i \PIPE
\Webcam\Audio -c:v copy -c:a copy -map 0:0 -map 1:0 zmovie.avi
ffmpeg version 4.0.2 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 5.5.0 (GCC)
configuration: --enable-gpl --disable-doc --cpu=i686 --enable-fontconfig --ena
ble-libfreetype --enable-libxvid --enable-libvpx --enable-libx264 --enable-libmp
3lame --enable-libopus --enable-libtheora --prefix='h:/tmp/ffmpeg' --disable-sta
tic --enable-shared --extra-libs=-lcx --extra-ldflags=-Zhigh-mem --extra-cflags=
'-isysroot k:/usr/include'
libavutil 56. 14.100 / 56. 14.100
libavcodec 58. 18.100 / 58. 18.100
libavformat 58. 12.100 / 58. 12.100
libavdevice 58. 3.100 / 58. 3.100
libavfilter 7. 16.100 / 7. 16.100
libswscale 5. 1.100 / 5. 1.100
libswresample 3. 1.100 / 3. 1.100
libpostproc 55. 1.100 / 55. 1.100
Option framerate not found.
Without framerate, it works but it is played very fast (not real framerate) due to auto set to 25 which is too fast (accelerated video/audio)
But, from yous suggestion I did a new test changing parameters as needed and it work now well here with c270 using :
ffmpeg -async 1 -framerate 15 -itsoffset 2.0 -f mjpeg -i \PIPE\Webcam\Video
-i \PIPE\Webcam\Audio -c:v copy -c:a copy -map 0:0 -map 1:0 zmovie.avi
note: mapping is not needed here because each input file only has one stream (video or audio), it is automatically mapped by ffmpeg.
copy will copy frames as is without changes (this produces a big file)
I have to set framerate to 15 to get normal speed and add -f mjpeg to use -framerate option.
The best command line with a resulting small video size:
ffmpeg -async 1 -framerate 15 -itsoffset 2.0 -f mjpeg -i \PIPE\Webcam\Video -i \PIPE\Webcam\Audio -q:v 3 -b:a 192k zmovie.avi
To remove the thread_queue_size message, I add one more parameter:
ffmpeg -async 1 -framerate 15 -itsoffset 2.0 -f mjpeg -i \PIPE\Webcam\Video -thread_queue_size 96 -i \PIPE\Webcam\Audio -q:v 3 -b:a 192k zmovie.avi
video quality set to a good value and audio set to CBR (converted into mp3) with a good 192K bitrate.
Thanks

Regards
Rémy
logfile from a test using an experimental ffmpeg build (not available yet by its author):
Update: after adding -framerate 25 to the input stream just after -f mjpeg, It works too using the -framerate 25 setting after -async, having a correct 25 fps output.
ffmpeg -async 1 -framerate 25 -itsoffset 2.0 -f mjpeg -framerate 25 -i \PIPE\Webcam\Video -i \PIPE\Webcam\Audio -q:v 3 -b:a 192k zmovie.avi
(adding the -thread_queue_size may introduce some out of sync