I am trying to use a software-defined radio receiver to get data from a wireless thermometer. The program that controls the radio sends a stream of JSON strings separated by newline characters to its standard output. (All of this is running on a Pi with Raspbian.) If I start the program with the exe…

The solution may be a function node that buffers and concatenates payloads till it sees a CR then sends the message on.

@wb666greene , you may still be able to use the split node with "Handle as a stream of messages" option to assemble complete images. I believe that the jpeg/mpeg format has delimiters that mark the beginning and end of frames, but I don't have a copies of the standards handy. Might be worth a look.

Do we have a 100% offline test case flow using ffmpeg we can experiment with?

Morning guys, I confirm that (on my Windows 10 labtop) I can reproduce now the issue, by changing the option to 'spawn' as @wb666greene advised. Then I indeed get 16K chunked output, instead of one complete image: [image] [{"id":"eb2c3372.d484b","type":"exec","z":"22de6542.a4c0fa","command":"cur…

so using join as above works fine with that example Note: I changed the command to not append the timestamp (not sure why you had that) - and to not show the progress meter ( -s ) So yes still need an example with ffmpeg and local source of video that I can play with. [{"id":"bc6c07d1.7f0128","ty…

[image] dceejay: so using join as above works fine with that example Hey Dave, Even if the join works, isn't that a bit inefficient? Because now Node-RED has to handle all the separate messages, which can become quite a lot of extra processing required. Or not ?

[image] BartButenaers: isn't that a bit inefficient? Trivial I think compared to the amount of work ffmpeg is doing decoding the rtsp stream.

[image] dceejay: The exec node just outputs "chunks" of data as given to it by the operating system. We don't have any control over it Of course Dave is always right, but like my wife always says: "Trust is good, but control is better...". So to gather some evidence, I have quickly debugged …

[image] dceejay: Do we have a 100% offline test case flow using ffmpeg we can experiment with? replace the ffmpeg (or curl command in Bart's example) with: ffmpeg -i /path/to/local/1080p.mp4 -f image2pipe pipe:1 The size of the output jpegs will depend on the bit rate of the videofile, bu…

[image] wb666greene: If Bart's RIP is correct, too bad, as this would have been an extremely slick way to convert rtsp streams Yes but only the idea (to adapt the Exec-node to generate a single chunk per image) is RIP. But if we can use the Join or Split nodes - as Dave and Michael suggest -…

I think there is a fundamental issue with trying to use join and split nodes on binary buffers as produced by ffmpeg piping frames to stdout. There is a set of "magic bytes" at the start of standardized compressed file formats, jpeg for example generally start with 0xFF 0xD8 0xFF but there is not…

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Exec and daemon nodes break up a data stream

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Colin 2 June 2019 09:43 41

Trivial I think compared to the amount of work ffmpeg is doing decoding the rtsp stream.

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Exec and daemon nodes break up a data stream

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