[Android 13] V4L2 Sink is empty.

[Antonino294]

• [Y] I have read the FAQ.
• [Y] I have searched in existing issues.

Environment

• OS: [Debian 11]
• scrcpy version: [2.0]
• installation method: [manual build]
• device model: Samsung A51
• Android version: [13]

Describe the bug

Using the --v42l-sink argument results in an empty, unplayable stream, as showcased by ffplay's output:

scrcpy -m 800 --v4l2-sink=/dev/video3 -N

scrcpy 2.0 <https://github.com/Genymobile/scrcpy>
INFO: Video orientation is locked for v4l2 sink. See --lock-video-orientation.
INFO: No display and no recording: audio disabled
/usr/local/share/scrcpy/scrcpy-server: 1 file pushed. 1.5 MB/s (52867 bytes in 0.033s)
[server] INFO: Device: samsung SM-A515F (Android 13)
INFO: v4l2 sink started to device: /dev/video3

ffplay -i /dev/video3

ffplay version 4.3.5-0+deb11u1 Copyright (c) 2003-2022 the FFmpeg developers
  built with gcc 10 (Debian 10.2.1-6)

...

nan    :  0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0

The ffmpeg version is the one from Debian's repositories. Using v4l2 without scrcpy works as expected:

ffmpeg -i Video.mp4 -f v4l2 /dev/video3

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Video.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf58.29.100
  Duration: 00:00:51.13, start: 0.000000, bitrate: 889 kb/s
    Stream #0:0(und): Video: av1 (Main) (av01 / 0x31307661), yuv420p(tv, bt709), 952x720, 753 kb/s, 60.02 fps, 60 tbr, 15360 tbn, 15360 tbc (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
[libdav1d @ 0x5599ff9be4c0] libdav1d 0.7.1
Stream mapping:
  Stream #0:0 -> #0:0 (av1 (libdav1d) -> rawvideo (native))
Press [q] to stop, [?] for help
Output #0, video4linux2,v4l2, to '/dev/video3':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf58.45.100
    Stream #0:0(und): Video: rawvideo (I420 / 0x30323449), yuv420p, 952x720 [SAR 1:1 DAR 119:90], q=2-31, 493516 kb/s, 60 fps, 60 tbn, 60 tbc (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
      encoder         : Lavc58.91.100 rawvideo
frame=  253 fps=0.0 q=-0.0 Lsize=N/A time=00:00:04.21 bitrate=N/A speed= 4.9x

ffplay -i /dev/video3

ffplay version 4.3.5-0+deb11u1 Copyright (c) 2003-2022 the FFmpeg developers
  built with gcc 10 (Debian 10.2.1-6)
  configuration: --prefix=/usr --extra-version=0+deb11u1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, video4linux2,v4l2, from '/dev/video3':B sq=    0B f=0/0
  Duration: N/A, start: 3849.855156, bitrate: 246758 kb/s
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 952x720, 246758 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc

...

It's also worth noting that using the H265 codec with any encoder results in an immediate V4L2 error (results above were done with H264):

scrcpy --video-codec=h265 -m 800 --v4l2-sink=/dev/video3 -N

scrcpy 2.0 <https://github.com/Genymobile/scrcpy>
INFO: Video orientation is locked for v4l2 sink. See --lock-video-orientation.
INFO: No display and no recording: audio disabled
/usr/local/share/scrcpy/scrcpy-server: 1 file pushed. 1.4 MB/s (52867 bytes in 0.036s)
[server] INFO: Device: samsung SM-A515F (Android 13)
INFO: v4l2 sink started to device: /dev/video3
ERROR: [FFmpeg] Unknown V4L2 pixel format equivalent for yuv420p
ERROR: Failed to write header to /dev/video3
WARN: Could not send packet to v4l2 sink
ERROR: Could not send frame to v4l2 sink
^C

It might be more appropriate to open a separate issue for this, as I haven't tested this thoroughly.

[rom1v]

Thank you very much for your report. Fixed by cbca79b on master (just git pull)