speed not displayed when encoding 2 pass with no audio

[xamarin]

Summary of the bug:
How to reproduce:
Running ffmpeg version 2022-04-11-git-d6d46a2c50-full_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.

[xamarin]

Running the 2pass command setting some audio output, does display progress at the bottom:

% ffmpeg -i input.mp4 -c:a libopus -b:a 96k -c:v libvpx-vp9 -b:v 1000k -r 25 -pass 1 -f null NUL && ffmpeg -i input.mp4 -c:a libopus -b:a 96k -c:v libvpx-vp9 -b:v 1000k -r 25 -pass 2 video.webm
...
frame=  797 fps=112 q=0.0 Lsize=N/A time=00:00:16.70 bitrate=N/A speed=2.34x

[xamarin]

However disabling audio for output, there is no progress indication on time or speed, only on frame:

% ffmpeg -i input.mp4 -an -c:v libvpx-vp9 -b:v 1000k -r 25 -pass 1 -f null NUL && ffmpeg -i input.mp4 -an -c:v libvpx-vp9 -b:v 1000k -r 25 -pass 2 video.webm
...
frame= 1199 fps=132 q=0.0 size=N/A time=00:00:00.00 bitrate=N/A speed=   0x

[xamarin]

Only happens on first pass, on second one it works fine.

[xamarin]

Sample log:

% ffmpeg -i input.mp4 -an -c:v libvpx-vp9 -b:v 1000k -r 25 -pass 1 -f null NUL && ffmpeg -i input.mp4 -an -c:v libvpx-vp9 -b:v 1000k -r 25 -pass 2 video.webm
...
ffmpeg version 2022-04-11-git-d6d46a2c50-full_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 11.2.0 (Rev7, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      57. 24.101 / 57. 24.101
  libavcodec     59. 26.100 / 59. 26.100
  libavformat    59. 21.100 / 59. 21.100
  libavdevice    59.  6.100 / 59.  6.100
  libavfilter     8. 30.100 /  8. 30.100
  libswscale      6.  6.100 /  6.  6.100
  libswresample   4.  6.100 /  4.  6.100
  libpostproc    56.  5.100 / 56.  5.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000296520b6100] Skipping unhandled metadata com.android.video.temporal_layers_count of type 67
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2022-04-11T16:54:26.000000Z
    com.android.version: 12
    com.android.capture.fps: 60.000000
  Duration: 03:00:13.63, start: 0.000000, bitrate: 3813 kb/s
  Stream #0:0[0x1](eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 2280x1080, 3675 kb/s, 48.33 fps, 90k tbr, 90k tbn (default)
    Metadata:
      creation_time   : 2022-04-11T16:54:26.000000Z
      handler_name    : VideoHandle
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2022-04-11T16:54:26.000000Z
      handler_name    : SoundHandle
      vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> vp9 (libvpx-vp9))
Press [q] to stop, [?] for help
[libvpx-vp9 @ 000002965216b740] v1.11.0-141-g6e1b7c6c1
Output #0, null, to 'NUL':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    com.android.capture.fps: 60.000000
    com.android.version: 12
    encoder         : Lavf59.21.100
  Stream #0:0(eng): Video: vp9, yuv420p(tv, bt709, progressive), 2280x1080, q=2-31, 1000 kb/s, 25 fps, 25 tbn (default)
    Metadata:
      creation_time   : 2022-04-11T16:54:26.000000Z
      handler_name    : VideoHandle
      vendor_id       : [0][0][0][0]
      encoder         : Lavc59.26.100 libvpx-vp9
    Side data:
      cpb: bitrate max/min/avg: 0/0/1000000 buffer size: 0 vbv_delay: N/A
frame=  368 fps= 32 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded
Exiting normally, received signal 2.