Removing greenscreen to create transparent video RuntimeError: memory access out of bounds

[jonleinena]

Describe the bug
When trying to remove the greenscreen background of a video to output a transparent bg video (using libvpx-vp9 and colorkey) throws a Memory acces out of bounds error.

To Reproduce

`

            await ffmpeg.writeFile('input.mp4', await fetchFile(processedVideoUrl));
            await ffmpeg.exec([
                '-i',
                'input.mp4',
                '-vf',
                'colorkey=#00DD01:similarity=0.3:blend=0.1',
                '-c',
                'copy',
                '-c:v',
                'libvpx-vp9',
                'output.webm'
            ]);


            const outputData = (await ffmpeg.readFile('output.webm')) as any;

           
            const webmBlob = new Blob([outputData.buffer], { type: 'video/webm' });
            const webmUrl = URL.createObjectURL(webmBlob);

`

Expected behavior
To remove the greenscreen background of the input video and output a transparent bg webm format video (works in console).

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Using in nextjs with typescript. Full execution log:

ffmpeg version 5.1.4 Copyright (c) 2000-2023 the FFmpeg developers
ffmpeg version 5.1.4 Copyright (c) 2000-2023 the FFmpeg developers
built with emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.40 (5c27e79dd0a9c4e27ef2326841698cdd4f6b5784)
built with emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.40 (5c27e79dd0a9c4e27ef2326841698cdd4f6b5784)
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
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
libavutil 57. 28.100 / 57. 28.100
libavcodec 59. 37.100 / 59. 37.100
libavcodec 59. 37.100 / 59. 37.100
libavformat 59. 27.100 / 59. 27.100
libavformat 59. 27.100 / 59. 27.100
libavdevice 59. 7.100 / 59. 7.100
libavdevice 59. 7.100 / 59. 7.100
libavfilter 8. 44.100 / 8. 44.100
libavfilter 8. 44.100 / 8. 44.100
libswscale 6. 7.100 / 6. 7.100
libswscale 6. 7.100 / 6. 7.100
libswresample 4. 7.100 / 4. 7.100
libswresample 4. 7.100 / 4. 7.100
libpostproc 56. 6.100 / 56. 6.100
libpostproc 56. 6.100 / 56. 6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
Metadata:
Metadata:
major_brand : isom
major_brand : isom
minor_version : 512
minor_version : 512
compatible_brands: isomiso2avc1mp41
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.76.100
encoder : Lavf58.76.100
Duration: 00:00:16.10, start: 0.000000, bitrate: 3444 kb/s
Duration: 00:00:16.10, start: 0.000000, bitrate: 3444 kb/s
Stream #0:00x1: Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 480x848 [SAR 1:1 DAR 30:53], 3442 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
Stream #0:00x1: Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 480x848 [SAR 1:1 DAR 30:53], 3442 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
Metadata:
Metadata:
handler_name : VideoHandler
handler_name : VideoHandler
vendor_id : [0][0][0][0]
vendor_id : [0][0][0][0]
Multiple -c, -codec, -acodec, -vcodec, -scodec or -dcodec options specified for stream 0, only the last option '-c:v libvpx-vp9' will be used.
Multiple -c, -codec, -acodec, -vcodec, -scodec or -dcodec options specified for stream 0, only the last option '-c:v libvpx-vp9' will be used.
Stream mapping:
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> vp9 (libvpx-vp9))
Stream #0:0 -> #0:0 (h264 (native) -> vp9 (libvpx-vp9))
[swscaler @ 0x118d7f0] No accelerated colorspace conversion found from yuv420p to argb.
[swscaler @ 0x118d7f0] No accelerated colorspace conversion found from yuv420p to argb.
[libvpx-vp9 @ 0xdf1ae0] v1.13.1
[libvpx-vp9 @ 0xdf1ae0] v1.13.1
[libvpx-vp9 @ 0xdf1ae0] Neither bitrate nor constrained quality specified, using default CRF of 32
[libvpx-vp9 @ 0xdf1ae0] Neither bitrate nor constrained quality specified, using default CRF of 32
Output #0, webm, to 'output.webm':
Output #0, webm, to 'output.webm':
Metadata:
Metadata:
major_brand : isom
major_brand : isom
minor_version : 512
minor_version : 512
compatible_brands: isomiso2avc1mp41
compatible_brands: isomiso2avc1mp41
encoder : Lavf59.27.100
encoder : Lavf59.27.100
Stream #0:0(und): Video: vp9, yuva420p(tv, progressive), 480x848 [SAR 1:1 DAR 30:53], q=2-31, 30 fps, 1k tbn (default)
Stream #0:0(und): Video: vp9, yuva420p(tv, progressive), 480x848 [SAR 1:1 DAR 30:53], q=2-31, 30 fps, 1k tbn (default)
Metadata:
Metadata:
handler_name : VideoHandler
handler_name : VideoHandler
vendor_id : [0][0][0][0]
vendor_id : [0][0][0][0]
encoder : Lavc59.37.100 libvpx-vp9
encoder : Lavc59.37.100 libvpx-vp9
Side data:
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame= 1 fps=0.0 q=0.0 size= 1kB time=00:00:00.00 bitrate=N/A speed= 0x
frame= 1 fps=0.0 q=0.0 size= 1kB time=00:00:00.00 bitrate=N/A speed= 0x