# VOXL-MAVCAM-MANAGER crashes on MAV_CMD_VIDEO_START_CAPTURE mavlink command when trying to record video Source: https://forum.modalai.com/topic/3666/voxl-mavcam-manager-crashes-on-mav_cmd_video_start_capture-mavlink-command-when-trying-to-record-video Category: VOXL SDK and Software (https://forum.modalai.com/category/47/voxl-sdk-and-software) Posted: 2024-07-23 17:29:24 UTC by AndriiHlyvko Replies: 2 · Views: 1205 ## AndriiHlyvko · 2024-07-23 17:29:24 UTC Hi, I am trying to use the voxl-mavcam-manager to record videos on voxl by sending mavlink MAV_CMD_VIDEO_START_CAPTURE to it. I already successfully had sent MAV_CMD_IMAGE_START_CAPTURE commands and was able to capture snapshots. However, when I send the MAV_CMD_VIDEO_START_CAPTURE it crashes the voxl-mavcam-manager with a segfault. Has anyone experienced this before? Here is the debug output from voxl-mavcam-manager: ``` Connected to video pipe hires_large_encoded ERROR channel 0 helper tried to read into NULL buffer ERROR channel 0 helper tried to read into NULL buffer ERROR channel 0 helper tried to read into NULL buffer starting new video: /data/video/video_2024-05-14_19:33:14.h265 ERROR validating mavlink_message_t data received through pipe: read partial packet read 85 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: 3 of 3 packets failed last magic number received was 128, expected MAVLINK_STX=253 ERROR validating mavlink_message_t data received through pipe: read partial packet read 1896 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 1734 bytes, but it should be a multiple of 44 ERROR: invalid metadata, magic number=-805240319, expected 1448040524 most likely client fell behind and pipe overflowed ERROR validating mavlink_message_t data received through pipe: read partial packet read 1682 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 1494 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet ........ read 832 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 731 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 705 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 682 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 656 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 681 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 650 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 687 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 675 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 642 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 889 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 813 bytes, but it should be a multiple of 44 lMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsg array is nullMsgERROR validating mavlink_message_t data received through pipe: read partial packet read 781 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 774 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 769 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 805 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 740 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 679 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 615 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 634 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 667 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 561 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 635 bytes, but it should be a multiple of 44 ERROR validating mavlink_message_t data received through pipe: read partial packet read 4570 bytes, but it should be a multiple of 44 ERROR: invalid metadata, magic number=-1912241965, expected 1448040524 most likely client fell behind and pipe overflowed ERROR validating mavlink_message_t data received through pipe: read partial packet read 192 bytes, but it should be a multiple of 44 Segmentation fault: Fault thread: voxl-mavcam-man(tid: 2626) Fault address: 0x4fd00000399 Address not mapped. Segmentation fault ``` ## Reply by Eric Katzfey (ModalAI staff) · 2024-07-24 15:40:26 UTC @AndriiHlyvko What drone are you using? What SDK version are you using? ## Reply by AndriiHlyvko · 2024-07-24 17:03:28 UTC (in reply to Eric Katzfey) @Eric-Katzfey I figured out the problem. I changed the mavlink pipe to mavlink_onboard keeping the channel number as 1. Setting the channel number as 2 seems to fix the problem. I haven't looked into the implementation of modal-pipe architecture but I thought that the channel number is just used by the client of the pipe (kind of like an open file descriptor number?). Basically it looks like having the channel number as 1 breaks the mavlink pipe somehow.