Playback of recorded bag causes segfault

Technical Support & Q&A
1

Overview

I am using SDK 1.8.3 for Linux to try and playback a recorded .bag file, using the Example/cpp/Sample-Playback/Playback.cpp demo. The bag was recorded from a Femto W if that matters, and has both depth + color images in it.

The playback works initially and displays both color and depth side-by-side in a GUI window. However, after several hundred frames, the playback abruptly stops with a segfault.

This is unfortunate because the frames I care about are somewhat later in this recording…

What I’ve Tried

  • The backtrace seems to point to SDK/lib/libOrbbecSDK.so.1.8 RvlCompression::mdecompressBuffer()
  • SDK 1.7 gives similar results.
  • The Python SDK also crashes similarly.

Questions

  1. Is this a known issue?
  2. Are there any recommendations for further debugging?
  3. Is there any way I could “jump past” the problematic frame(s) using existing APIs? I’m curious if playback would work if I jumped to frame ~1000 for instance.
2

Could you please using the Sample Recorder to record then Sample Playback to play? The bag file recorded by other application is not compatible with Orbbec SDK.

3

Hi Nathan, that is how the .bag file was recorded. I used recorder.py from the Python SDK

4

I was able to use Python bagpy to determine some details of the .bag file:

bagpy_output
bagpy_output924×285 40.3 KB

From this, I was able to parse the /cam0/color_raw messages and convert to cv2 format for display. So basically working around the segfault issue in the Orbbec SDK by not using it.

I have not been successful decoding /cam0/depth_raw using a similar flow. I suspect depth has a custom encoding, but haven’t been able to determine the format.

5

There is source code with record.py and playback.py. The samples work on my side. Do your problems come with play side?

6

Yes, the issue is on the playback end. I have recorded a handful of .bag files that work fine, but these specific files are larger (3GB) and throw an error partway into playback. As mentioned above, I tried both the C and Python SDKs for playback, and saw the same segfault issue using either approach.

7

If it’s possible to provide details on the format of the /cam0/depth_raw topic in the bag file, I believe I could proceed with implementing my own decoder.