我要说的是，在相机启动后的前 2/3 分钟内，音频/视频似乎是同步的。也就是说，视频没有延迟。然后我听到相机快门关闭时发出“咔”的一声，然后开始延迟。
sudo modprobe v4l2loopback && gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video2
看来关键部分是speed=1x...如果速度够快> 1，我们就会玩得很开心...然而，溪流开放的时间越长，速度似乎就越慢。
ffmpeg version N-49161-g50e194e6e1-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
libavutil 56. 30.100 / 56. 30.100
libavcodec 58. 53.101 / 58. 53.101
libavformat 58. 28.101 / 58. 28.101
libavdevice 58. 7.100 / 58. 7.100
libavfilter 7. 55.100 / 7. 55.100
libswscale 5. 4.101 / 5. 4.101
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
Capturing preview frames as movie to 'stdout'. Press Ctrl-C to abort.
[mjpeg @ 0x57bc940] Format mjpeg detected only with low score of 25, misdetection possible!
Input #0, mjpeg, from 'pipe:':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: mjpeg (Baseline), yuvj422p(pc, bt470bg/unknown/unknown), 640x426, 25 tbr, 1200k tbn, 25 tbc
Stream mapping:
Stream #0:0 -> #0:0 (mjpeg (native) -> rawvideo (native))
[swscaler @ 0x57e9040] deprecated pixel format used, make sure you did set range correctly
Output #0, video4linux2,v4l2, to '/dev/video2':
Metadata:
encoder : Lavf58.28.101
Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 640x426, q=2-31, 81792 kb/s, 25 fps, 25 tbn, 25 tbc
Metadata:
encoder : Lavc58.53.101 rawvideo
^CCtrl-C pressed ... Exiting.ze=N/A time=00:01:18.04 bitrate=N/A speed=0.973x
我不确定如何解决，或者是否可以解决？