Encode fails if source video file is located on a NAS and display_progress=yes

[radar-duker]

mpv version and platform

Windows 11

mpv v0.37.0-1-g2a57a6ee Copyright © 2000-2023 mpv/MPlayer/mplayer2 projects
built on Nov 22 2023 00:29:32
libplacebo version: v6.338.0-58-g2385b36-dirty
FFmpeg version: N-112812-gc961ac4b0
FFmpeg library versions:
libavutil 58.32.100
libavcodec 60.34.100
libavformat 60.17.100
libswscale 7.6.100
libavfilter 9.13.100
libswresample 4.13.100

Description

If I try to encode a clip from a video file that is located on a NAS, and I set display_progress=yes, then the encode will fail. If the same video file is located on my local SSD, then the encode will succeed. If the file is located on the NAS, but I set display_progress=no, then the encode will succeed.

Related portions of the log files are below. Is it possible that the subprocess needs "//" at the beginning of the video path to denote a network drive?

Log file

Log file on NAS demonstrating encode fail:

[ 24.861][d][cplayer] Run command: script-message, flags=64, args=[args="webm-encode-started"]
[ 24.865][i][webm] Encoding to C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm
[ 24.867][v][webm] Command line: mpv \NAS\anime\SM\Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].mkv --start=0:00:00.000 --end=0:00:05.130 --loop-file=no --no-pause --ovc=libvpx-vp9 --oac=libopus --sid=1 --vid=1 --aid=2 --sub-ass-override=yes --sub-ass-vsfilter-aspect-compat=yes --sub-auto=exact --sub-pos=100.000000 --sub-delay=0.000000 --video-rotate=0 --deinterlace=no --vf-add=lavfi-scale=-2:480 --vf-add=lavfi-eq=contrast=1:saturation=1:brightness=0 --ovcopts-add=threads=4 --ovcopts-add=b=6237k --ovcopts-add=crf=0 --o=C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm
[ 24.872][v][webm] run_subprocess_popen: running "mpv "\NAS\anime\SM\Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].mkv" "--start=0:00:00.000" "--end=0:00:05.130" --loop-file=no --no-pause --ovc=libvpx-vp9 --oac=libopus --sid=1 --vid=1 --aid=2 --sub-ass-override=yes --sub-ass-vsfilter-aspect-compat=yes --sub-auto=exact "--sub-pos=100.000000" "--sub-delay=0.000000" --video-rotate=0 --deinterlace=no --vf-add=lavfi-scale=-2:480 --vf-add=lavfi-eq=contrast=1:saturation=1:brightness=0 --ovcopts-add=threads=4 --ovcopts-add=b=6237k --ovcopts-add=crf=0 "--o=C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm" "--term-status-msg=Encode time-pos: ${=time-pos}\n"" 2>&1
[ 24.942][d][cplayer] Run command: script-binding, flags=73, args=[name="webm/e"]
[ 25.106][d][cplayer] Run command: script-message, flags=64, args=[args="webm-encode-finished", args="fail"]

Log file on local SSD demonstrating successful encode start:

[ 4.459][d][cplayer] Run command: script-message, flags=64, args=[args="webm-encode-started"]
[ 4.459][i][webm] Encoding to C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm
[ 4.459][v][webm] Command line: mpv F:\anime\SM\Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].mkv --start=0:00:00.000 --end=0:00:05.130 --loop-file=no --no-pause --ovc=libvpx-vp9 --oac=libopus --vid=1 --aid=2 --sub-file=F:\anime\SM\Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].ass --sub-ass-override=yes --sub-ass-vsfilter-aspect-compat=yes --sub-auto=exact --sub-pos=100.000000 --sub-delay=0.000000 --video-rotate=0 --deinterlace=no --vf-add=lavfi-scale=-2:480 --vf-add=lavfi-eq=contrast=1:saturation=1:brightness=0 --ovcopts-add=threads=4 --ovcopts-add=b=6237k --ovcopts-add=crf=0 --o=C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm
[ 4.460][v][webm] run_subprocess_popen: running "mpv "F:\anime\SM\Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].mkv" "--start=0:00:00.000" "--end=0:00:05.130" --loop-file=no --no-pause --ovc=libvpx-vp9 --oac=libopus --vid=1 --aid=2 "--sub-file=F:\anime\SM\Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].ass" --sub-ass-override=yes --sub-ass-vsfilter-aspect-compat=yes --sub-auto=exact "--sub-pos=100.000000" "--sub-delay=0.000000" --video-rotate=0 --deinterlace=no --vf-add=lavfi-scale=-2:480 --vf-add=lavfi-eq=contrast=1:saturation=1:brightness=0 --ovcopts-add=threads=4 --ovcopts-add=b=6237k --ovcopts-add=crf=0 "--o=C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm" "--term-status-msg=Encode time-pos: ${=time-pos}\n"" 2>&1
[ 4.553][d][cplayer] Run command: script-binding, flags=73, args=[name="webm/e"]
[ 4.748][v][webm] " (+) Video --vid=1 () (mpeg2video 720x576 23.976fps)"
[ 4.748][v][webm] " Audio --aid=1 --alang=ita () (ac3 2ch 48000Hz)"
[ 4.748][v][webm] " (+) Audio --aid=2 --alang=jpn (ac3 2ch 48000Hz)"
[ 4.748][v][webm] " Subs --sid=1 --slang=ita (*) (f) (dvd_subtitle)"
[ 4.748][v][webm] " Subs --sid=2 --slang=ita (dvd_subtitle)"
[ 4.748][v][webm] " (+) Subs --sid=3 'Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux].ass' (ass) (external)"
[ 4.772][v][webm] "VO: [lavc] 600x480 => 639x480 yuv420p"
[ 4.772][v][webm] "[vo/lavc] Opening encoder: libvpx VP9 [libvpx-vp9]"
[ 4.780][v][webm] "[ao/lavc] Opening encoder: libopus Opus [libopus]"
[ 4.783][v][webm] "[ffmpeg] libopus: No bit rate set. Defaulting to 96000 bps."
[ 4.783][v][webm] "[encode] Opening output file: C:\Users\Radar Duker/Pictures/mpv/Sailor Moon 047 [576p][Ita-Jap+Subs-Ita][Jap-Angle][R2ITA-Remux]-[00.00.000-00.05.130]-4mb-audio.webm"
[ 4.783][v][webm] "[encode] Opening muxer: WebM [webm]"
[ 4.783][v][webm] "AO: [lavc] 48000Hz stereo 2ch float"
[ 4.789][v][webm] "Encode time-pos: 0.000000"
[ 4.793][v][webm] ""
[ 4.793][v][webm] "Encode time-pos: 0.042000"
[ 4.794][v][webm] ""