Decode as USB-PTP not available

asked 2025-12-12 08:17:55 +0000

I have a camera I'm working with over USB with MTP/PTP. Yesterday when I used a remote control application on my computer it was correctly interpreting the packets as USB-PTP and showing a lot of helpful information. Today, it is not recognizing them and there is no way I've found to "force" it. I've tried disabling everything in protocols except USB-PTP, the Decode As menu in the software, as well as starting Wireshark from the command line with wireshark --only-protocols usb-ptp.

I have a saved dump from yesterday that worked and one from today that is not working if it's helpful.

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Sample capture attached to: 8431: New Dissector Patch - USB PTP / MTP

epan/dissectors/packet-usb-ptp.c:

    dissector_add_uint("usb.bulk", IF_CLASS_IMAGE, usb_ptp_dissector_handle);

From packet-usb.h: #define IF_CLASS_IMAGE 0x06

Do you have packets that match usb.bInterfaceClass == 0x06 in the second capture?

Chuckc ( 2025-12-12 14:45:51 +0000 )edit

From @kevinschaich via Discord, since he is unable to comment himself for some as-yet unknown reason:

"No, in the second (failed) capture, they are being detected as [bInterfaceClass: Unknown (0xffff)] (which is incorrect, it is a still imaging device). They show as [bInterfaceClass: Imaging (0x06)] in the capture file that worked yesterday."

cmaynard ( 2025-12-12 16:35:58 +0000 )edit

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answered 2025-12-12 19:03:27 +0000

Chuckc
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Issue opened: 20908: Allow decode as USB-PTP over USB

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answered 2025-12-12 11:23:07 +0000

grahamb

flag of United Kingdom of Great Britain and Northern Ireland

23850 ●4 ●992 ●227 https://www.wireshark.org

Try using a new "default" profile, select it using the profile options at the bottom right.

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From @kevinschaich via Discord, since he is unable to comment himself for some as-yet unknown reason:

"I managed to create a new profile for USB-PTP. However when I go to Edit -> Configuration Profiles..., the only thing I'm seeing that might be relevant is "Auto Switch Filter", which seems like it would be relevant if I was able to get "Decode As..." to work, but I couldn't find the right setting there."

cmaynard ( 2025-12-12 16:37:12 +0000 )edit

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