[FFmpeg-user] how to set the color background when i use overlay_qsv

[zhaofg at bstar.com.cn]

hello:
    I want to splice four or more video into one video，i want to set the background to a fixed size and the color is black, so i must scale the image then overlay. 
    
    My environment is ubuntu and I used command is:

    ffmpeg -i h1.mp4 -i h2.mp4 -i h3.mp4 -i h4.mp4 -filter_complex "color=c=black:s=1920x1080[bg];[0:v]scale=iw/2:-1[img0];[1:v]scale=iw/2:-1[img1];[2:v] scale=iw/2:-1[img2];[3:v]scale=iw/2:-1[img3];[bg][img0]overlay=shortest=1[out0];[out0][img1]overlay=shortest=1:x=w[out1];[out1][img2]overlay=shortest=1:y=h[out2];[out2][img3]overlay=shortest=1:x=w:y=h" -y out.mp4

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the comman is correct,but when i change it to qsv. It's not working correctly:

    ./ffmpeg -hwaccel qsv -c:v h264_qsv -i h1.mp4 -hwaccel qsv -c:v h264_qsv -i h2.mp4 -hwaccel qsv -c:v h264_qsv -i h3.mp4 -hwaccel qsv -c:v h264_qsv -i h4.mp4 -filter_complex "color=black:r=30:size=1920x1080:sar=1/1, hwupload=extra_hw_frames=64,format=qsv[bg];[0:v]scale_qsv=iw/2:ih/2[img0];[1:v]scale_qsv=iw/2:ih/2[img1];[2:v] scale_qsv=iw/2:ih/2[img2];[3:v]scale_qsv=iw/2:ih/2[img3];[bg][img0]overlay_qsv=shortest=1[out0];[out0][img1]overlay_qsv=shortest=1:x=w[out1];[out1][img2]overlay_qsv=shortest=1:y=h[out2];[out2][img3]overlay_qsv=shortest=1:x=w:y=h" -y out.mp4

 output:
[hwupload @ 0x5593003e07c0] A hardware device reference is required to upload frames to.
[Parsed_hwupload_1 @ 0x5593003e0680] Query format failed for 'Parsed_hwupload_1': Invalid argument
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #3:0
Conversion failed!
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./ffmpeg -init_hw_device qsv=hw -filter_hw_device hw -hwaccel qsv -c:v h264_qsv -i h1.mp4 -hwaccel qsv -c:v h264_qsv -i h2.mp4 -hwaccel qsv -c:v h264_qsv -i h3.mp4 -hwaccel qsv -c:v h264_qsv -i h4.mp4 -filter_complex "color=black:r=30:size=1920x1080:sar=1/1, hwupload=extra_hw_frames=64,format=qsv[bg];[0:v]scale_qsv=iw/2:ih/2[img0];[1:v]scale_qsv=iw/2:ih/2[img1];[2:v] scale_qsv=iw/2:ih/2[img2];[3:v]scale_qsv=iw/2:ih/2[img3];[bg][img0]overlay_qsv=shortest=1[out0];[out0][img1]overlay_qsv=shortest=1:x=w[out1];[out1][img2]overlay_qsv=shortest=1:y=h[out2];[out2][img3]overlay_qsv=shortest=1:x=w:y=h" -y out.mp4


output:
[Parsed_overlay_qsv_7 @ 0x563881a99180] Inputs with different underlying QSV devices are forbidden.
[Parsed_overlay_qsv_7 @ 0x563881a99180] Failed to configure output pad on Parsed_overlay_qsv_7
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #3:0
Conversion failed!
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I want to know How can I modify my command to run correctly. Thank you.