[problem] [swscaler] Slice parameters 0, 720 are invalid

[nowgood]

platform:
maxOS version 10.13.4 (17E202)
opencv_version 3.4.1

I come cross error "Slice parameters 0, 720 are invalid" when I run this file. the reason is following code which set camera frame size don't work.

 cam.set(cv::CAP_PROP_FRAME_WIDTH, width);
 cam.set(cv::CAP_PROP_FRAME_HEIGHT, height);

you can debug code to find camera property CAP_PROP_FRAME_WIDTH and CAP_PROP_FRAME_HEIGHT, in my case, both of them are 1280, not 800 or 600.

the solution is to add cv::resize(image, image, cv::Size(width, height)); to stream_video function

do
  {
    cam >> image;
    cv::resize(image, image, cv::Size(width, height));
    const int stride[] = {static_cast<int>(image.step[0])};
    sws_scale(swsctx, &image.data, stride, 0, image.rows, frame->data, frame->linesize);
    frame->pts += av_rescale_q(1, out_codec_ctx->time_base, out_stream->time_base);

    write_frame(out_codec_ctx, ofmt_ctx, frame);
  } while (!end_of_stream);

[berli]

same problem
open VID_20160502_162358.mp4 success!
ret=0
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid
[swscaler @ 0x1582d00] Slice parameters 0, 720 are invalid