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Most USB cameras send JPEG frames because USB 2.0 isn't nearly enough to support raw frames: 60 frames/second * 19201080 pixels/frame 4 bytes/pixel = ~475MiB

Most USB cameras send JPEG frames because USB 2.0 isn't nearly enough to support raw frames: 60 frames/second * 1920*1080 pixels/frame * 4 bytes/pixel = ~475MiB/s, while maximum USB 2.0 bandwidth is ~60MiB/s. You also don't want to store raw frames on the cloud storage, your bill would skyrocket. Those are some of the reasons for using JPEG. If you're using dockerized services (which are a must for NVidia-based CV, since their CV libraries are a dependency hell), you must use some kind of networking solution to communicate. RabbitMQ might be considered overkill, but it does the job and is robust. It's not nice to talk that way about others' work, especially when your comment insults, but doesn't provide any insight whatsoever.

deleted 4y ago
[deleted]
ltbarcly3 4y ago
Yea you're right of course, I was being glib. Glad it worked out in the end for you. For the record I don't think RabbitMQ was overkill, I think it's just way too much overhead to work for something like sending frames of video (which I think is the moral of your story). Anyway I'm guessing this was for a school project and you won't have to live with it so it's moot.
- bheadmaster 4y ago
  It was actually a production system we built on my first job. It wasn't just sending frames from A to B, it did have a few moving parts. It eventually got stable and stopped changing, so in a way, I don't have to live with it. But it's up and running and does its job.
lmm 4y ago
> If you're using dockerized services (which are a must for NVidia-based CV, since their CV libraries are a dependency hell), you must use some kind of networking solution to communicate. Eithen the two processes can share memory, in which case they don't need to communicate via network, much less RabbitMQ, or they can't, in which case the hack wouldn't have worked at all.
- bheadmaster 4y ago
  Good point. I suppose what I meant to say is you need to communicate between processes somehow. Shared memory is fast, but it's hard to communicate with it exclusively - message-based protocols are better suited for that, and most of them are implemented over TCP.
  - lmm 4y ago
    A lot of standard protocols can run over a unix domain socket, if you're not at the level of implementing a shared memory communication protocol but want to cut some overhead for more or less free.

Most USB cameras send JPEG frames because USB 2.0 isn't nearly enough to support raw frames: 60 frames/second * 1920*1080 pixels/frame * 4 bytes/pixel = ~475MiB

deleted 4y ago

[deleted]

ltbarcly3 4y ago

Yea you're right of course, I was being glib. Glad it worked out in the end for you. For the record I don't think RabbitMQ was overkill, I think it's just way too much overhead to work for something like sending frames of video (which I think is the moral of your story). Anyway I'm guessing this was for a school project and you won't have to live with it so it's moot.

bheadmaster 4y ago
It was actually a production system we built on my first job. It wasn't just sending frames from A to B, it did have a few moving parts. It eventually got stable and stopped changing, so in a way, I don't have to live with it. But it's up and running and does its job.

lmm 4y ago

> If you're using dockerized services (which are a must for NVidia-based CV, since their CV libraries are a dependency hell), you must use some kind of networking solution to communicate. Eithen the two processes can share memory, in which case they don't need to communicate via network, much less RabbitMQ, or they can't, in which case the hack wouldn't have worked at all.

bheadmaster 4y ago
Good point. I suppose what I meant to say is you need to communicate between processes somehow. Shared memory is fast, but it's hard to communicate with it exclusively - message-based protocols are better suited for that, and most of them are implemented over TCP.
- lmm 4y ago
  A lot of standard protocols can run over a unix domain socket, if you're not at the level of implementing a shared memory communication protocol but want to cut some overhead for more or less free.