An exception occurs when the multi-threaded version executes video-to-image conversion.

[tqq1994516]

Describe the bug
When I execute exec('-i', 'aa.mp4', '-y', '-r', '5', '-f', 'image2', 'frame_%04d.png'), it works normally with the core version, but gets stuck when using mt-core.

To Reproduce

ffmpeg.exec('-i', 'aa.mp4', '-y', '-r', '5', '-f', 'image2', 'frame_%04d.png')

Expected behavior
Outputs normally just like the single-threaded version

type stderr message ffmpeg version 5.1.4 Copyright (c) 2000-2023 the FFmpeg developers
game_tools.js:782 type stderr message   built with emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.40 (5c27e79dd0a9c4e27ef2326841698cdd4f6b5784)
game_tools.js:782 type stderr message   configuration: --target-os=none --arch=x86_32 --enable-cross-compile --disable-asm --disable-stripping --disable-programs --disable-doc --disable-debug --disable-runtime-cpudetect --disable-autodetect --nm=emnm --ar=emar --ranlib=emranlib --cc=emcc --cxx=em++ --objcc=emcc --dep-cc=emcc --extra-cflags='-I/opt/include -O3 -msimd128' --extra-cxxflags='-I/opt/include -O3 -msimd128' --disable-pthreads --disable-w32threads --disable-os2threads --enable-gpl --enable-libx264 --enable-libx265 --enable-libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libopus --enable-zlib --enable-libwebp --enable-libfreetype --enable-libfribidi --enable-libass --enable-libzimg
   libavutil      57. 28.100 / 57. 28.100
   libavcodec     59. 37.100 / 59. 37.100
   libavformat    59. 27.100 / 59. 27.100
   libavdevice    59.  7.100 / 59.  7.100
   libavfilter     8. 44.100 /  8. 44.100
   libswscale      6.  7.100 /  6.  7.100
   libswresample   4.  7.100 /  4.  7.100
   libpostproc    56.  6.100 / 56.  6.100
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0xdee970] Unknown cover type: 0x1.
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'aa.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     LvMetaInfo      : {"data":{"os":"web","product":"dreamina","exportType":"generation","videoId":"0"},"trace_info":{"originItemId":"7556831327778131226"}}
     UserComment     : {"aigc_label_type":0,"source_info":"dreamina"}
     comment         : vid:v02870g10004d3fk4cnog65qngdcfsc0
     encoder         : Lavf58.76.100
   Duration: 00:00:05.02, start: 0.000000, bitrate: 6974 kb/s
   Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 960x960 [SAR 1:1 DAR 1:1], 6968 kb/s, 24.12 fps, 60 tbr, 15360 tbn (default)
     Metadata:
       handler_name    : VideoHandler
       vendor_id       : [0][0][0][0]
 Stream mapping:
   Stream #0:0 -> #0:0 (h264 (native) -> png (native))
 [swscaler @ 0x1200350] No accelerated colorspace conversion found from yuv420p to rgb24.
 Output #0, image2, to 'frame_%04d.png':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     LvMetaInfo      : {"data":{"os":"web","product":"dreamina","exportType":"generation","videoId":"0"},"trace_info":{"originItemId":"7556831327778131226"}}
     UserComment     : {"aigc_label_type":0,"source_info":"dreamina"}
     comment         : vid:v02870g10004d3fk4cnog65qngdcfsc0
     encoder         : Lavf59.27.100
   Stream #0:0(und): Video: png, rgb24(pc, gbr/unknown/unknown, progressive), 960x960 [SAR 1:1 DAR 1:1], q=2-31, 200 kb/s, 5 fps, 5 tbn (default)
     Metadata:
       handler_name    : VideoHandler
       vendor_id       : [0][0][0][0]
       encoder         : Lavc59.37.100 png
 frame=    1 fps=0.0 q=-0.0 size=N/A time=00:00:00.20 bitrate=N/A speed=3.88x    
 frame=    4 fps=0.0 q=-0.0 size=N/A time=00:00:00.80 bitrate=N/A dup=0 drop=6 speed=1.24x    
 frame=    7 fps=5.7 q=-0.0 size=N/A time=00:00:01.40 bitrate=N/A dup=0 drop=17 speed=1.13x    
 frame=    9 fps=4.8 q=-0.0 size=N/A time=00:00:01.80 bitrate=N/A dup=0 drop=25 speed=0.956x    
 frame=   11 fps=4.4 q=-0.0 size=N/A time=00:00:02.20 bitrate=N/A dup=0 drop=33 speed=0.886x    
 frame=   13 fps=4.2 q=-0.0 size=N/A time=00:00:02.60 bitrate=N/A dup=0 drop=40 speed=0.843x    
 frame=   14 fps=3.9 q=-0.0 size=N/A time=00:00:02.80 bitrate=N/A dup=0 drop=47 speed=0.775x    
 frame=   16 fps=3.8 q=-0.0 size=N/A time=00:00:03.20 bitrate=N/A dup=0 drop=52 speed=0.762x    
 frame=   18 fps=3.8 q=-0.0 size=N/A time=00:00:03.60 bitrate=N/A dup=0 drop=59 speed=0.753x    
 frame=   20 fps=3.7 q=-0.0 size=N/A time=00:00:04.00 bitrate=N/A dup=0 drop=67 speed=0.742x    
 frame=   22 fps=3.7 q=-0.0 size=N/A time=00:00:04.40 bitrate=N/A dup=0 drop=74 speed=0.742x    
 frame=   25 fps=3.9 q=-0.0 size=N/A time=00:00:05.00 bitrate=N/A dup=0 drop=86 speed=0.776x    
 frame=   27 fps=3.9 q=-0.0 Lsize=N/A time=00:00:05.40 bitrate=N/A dup=0 drop=94 speed=0.781x    
 video:13941kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
 Aborted()

Screenshots

Desktop (please complete the following information):

• OS: [window11]
• Browser [chrome]
• Version [141.0.7390.76]

Additional context
When executing the multi-threaded version, the log output gets stuck at

Stream mapping:
   Stream #0:0 -> #0:0 (h264 (native) -> png (native))

And in the browser's network, a request for ffmpeg-core.worker.js is found to be in a pending state all the time.

[zkmio]

specify threads limit in exec args:
'-threads', ${THREADS}``

[tqq1994516]

specify threads limit in exec args: '-threads', ${THREADS}``

Thank you, this solved my problem.