getting something out of buffer
gir:field to get stuff out of structs but getting 'data still doesn't work null in length
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@ -8,6 +8,7 @@
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(in-package :capturing-frames)
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(gir:require-namespace "GLib")
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(defvar *gstreamer* (gir:require-namespace "Gst"))
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(defvar *gstapp* (gir:require-namespace "GstApp"))
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(defun cast-with-videobox (&optional stream-num)
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(gir:invoke (*gstreamer* 'init) '())
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@ -20,7 +21,8 @@
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(queue1 (gir:invoke (*gstreamer* "ElementFactory" 'make) "queue" "queue1"))
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(queue2 (gir:invoke (*gstreamer* "ElementFactory" 'make) "queue" "queue2"))
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(sink (gir:invoke (*gstreamer* "ElementFactory" 'make) "autovideosink" "sink"))
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(appsink (gir:invoke (*gstreamer* "ElementFactory" 'make) "appsink" "appsink")))
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(appsink (gir:invoke (*gstreamer* "ElementFactory" 'make) "appsink" "appsink"))
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)
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(when stream-num
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;; Set pipewiresrc properties, such as the path
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(setf (gir:property source 'path) (format nil "~A" stream-num)))
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@ -49,29 +51,49 @@
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(gir:invoke (pipeline 'set-state) (gir:nget *gstreamer* "State" :playing))
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;; Example: Move the video 10 pixels down and 20 pixels to the right
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pipeline))
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(values pipeline appsink)))
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(defun process-frame (sample)
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(format t ">>> got to process sample with ~A~%" sample)
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(let* ((buffer (gir:invoke (sample 'get-buffer)))
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(info (gir:invoke (buffer 'get-memory) 0))
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(map-info (gir:invoke (info 'map) (gir:nget *gstreamer* "MapFlags" :read)))
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(data (gir:property map-info 'data))
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(size (gir:property map-info 'size)))
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;; Process the frame data here
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(format t "Received frame of size ~A bytes~%" size)
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;; Example: Calculate average brightness
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(let ((sum 0))
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(dotimes (i size)
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(incf sum (aref data i)))
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(format t "Average brightness: ~A~%" (/ sum size)))
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(info (gir:invoke (sample 'get-info)))
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(caps (gir:invoke (sample 'get-caps)))
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(caps-struct (gir:invoke (caps 'get-structure) 0))
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(width (gir:invoke ((gir:invoke (caps-struct 'get-value) "width") 'get-int)))
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(height (gir:invoke ((gir:invoke (caps-struct 'get-value) "height") 'get-int))))
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(multiple-value-bind (found map-info) (gir:invoke (buffer 'map) (gir:nget *gstreamer* "MapFlags" :read))
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(format t ">>>> the buffer has offset ~A~%" (gir:field buffer 'offset))
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(format t ">>>> what's in struct? ~A~%" (gir:invoke (caps-struct 'to-string)))
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(format t ">>>> the fields are width ~A, height ~A~%" width height)
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(format t ">>>> and map result are ~A and ~A~%" found map-info)
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(when found
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(let ((data (gir:field map-info 'data))
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(size (gir:field map-info 'size)))
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(format t ">>>> and struct info? ~A~%" map-info)
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; (format t ">>>> and data has size ~A and buf ~A~%" size (or data "empty data"))
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)))
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;; Unmap the memory when done
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(gir:invoke (info 'unmap) map-info)))
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;; (gir:invoke (info 'unmap) map-info)
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))
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(defun start-processing (appsink)
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(gir:connect appsink "new-sample"
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(lambda (appsink)
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(format t ">> got printed object ~A~%" appsink)
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(format t ">> got printed class ~A~%" (gir:gir-class-of appsink))
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(format t ">> trying to get method on sink ~A~%" (gir:nget appsink 'pull-sample))
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(let ((sample (gir:invoke (appsink 'pull-sample))))
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(when sample
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(process-frame sample)
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(gir:invoke (sample 'unref))))
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(process-frame sample)))
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(gir:nget *gstreamer* "FlowReturn" :ok))))
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(defun try-run ()
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(multiple-value-bind (pipeline appsink) (cast-with-videobox)
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(format t "got appsink ~A" appsink)
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(start-processing appsink)
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(loop
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(sleep 1))))
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;(try-run)
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82
notes.org
82
notes.org
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@ -304,3 +304,85 @@ last time i got stuck on video displaying frozen when i tried to add appsink
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just re-checking my basic gstreamer pipeline and screencast start - thing works
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but i want to clean it up i guess, to allow for simpler retries?
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** so, for the appsnk there are signals
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https://gstreamer.freedesktop.org/documentation/app/appsink.html?gi-language=python#appsink::new-sample
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new-sample
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#+begin_src python
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def new_sample_callback (appsink, udata):
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#python callback for the 'new-sample' signal
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#+end_src
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Signal that a new sample is available.
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but how do i connect to a callback from common lisp and gobject introspection
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https://github.com/andy128k/cl-gobject-introspection
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does the gitlab repo has info on callbacks?
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can't seem to call method 'pull-sample'
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maybe article will help?
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https://gstreamer.freedesktop.org/documentation/application-development/advanced/pipeline-manipulation.html?gi-language=python#grabbing-data-with-appsink
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well, this looks like method on gst namespace? "gst_app_sink_pull_sample()"
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https://gstreamer.freedesktop.org/documentation/applib/gstappsink.html?gi-language=python#gst_app_sink_pull_sample
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there's article for python bindings
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https://lifestyletransfer.com/how-to-use-gstreamer-appsink-in-python/
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* [2024-08-22 Thu]
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** hey, i think this is progress
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i am able to call appsink 'pull-sample after all (for some reason, i don't know what i was doing differently)
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new error:
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>>> got to process sample with #<STRUCT-INSTANCE {10128D02F3}>
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but in the code for processing of the sample some type errors
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Backtrace:
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0: ((:METHOD GIR::THIS-OF (T)) T) [fast-method]
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1: (GIR:PROPERTY T DATA)
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2: (PROCESS-FRAME #<GIR::STRUCT-INSTANCE {100BCDAB73}>)
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3: ((LAMBDA (APPSINK) :IN START-PROCESSING) #<GIR::OBJECT-INSTANCE {100BBE02D3}>)
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ok, but when i have struct instance, how do i introspect it?
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** let's just go and read documentation for the type that's returned from pull-sample, sure
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also there's that python code, right?
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doc 1: get sample on appsink https://people.freedesktop.org/~tsaunier/documentation/gst-plugins-base-app-1.0/gstappsink.html?gi-language=c#gst_app_sink_pull_sample
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doc 2: GstSample class https://people.freedesktop.org/~tsaunier/documentation/gstreamer-1.0/gstsample.html?gi-language=c#GstSample
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so on GstSample everything is taken as results of funciton calls? let's try that
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well, maybe i don't need get-info on sample, it returns null, maybe i need it on buffer?
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doc 3: get-buffer on sample https://people.freedesktop.org/~tsaunier/documentation/gstreamer-1.0/gstsample.html?gi-language=python#gst_sample_get_buffer
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doc 4: buffer class info https://people.freedesktop.org/~tsaunier/documentation/gstreamer-1.0/gstbuffer.html?gi-language=python#gst_buffer_peek_memory
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** i'm recommended to look into GstBuffer.map
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https://people.freedesktop.org/~tsaunier/documentation/gstreamer-1.0/gstbuffer.html?gi-language=python#gst_buffer_map
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it returns some https://people.freedesktop.org/~tsaunier/documentation/gstreamer-1.0/gstmemory.html?gi-language=python#GstMapInfo
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** struggling, searching for answers
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https://github.com/andy128k/cl-gobject-introspection/issues/73#issuecomment-755316735
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Examples of inspection of a repository can be found in test files.
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https://github.com/andy128k/cl-gobject-introspection/blob/master/test/test1.lisp
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and i mean it's possible that referencing members of a structure is not implemented?
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so, huh
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using internal functions
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#+begin_src lisp
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(data (gir:fields-dict-of (gir:struct-class-of map-info)))
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#+end_src
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i see
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>>>> and data has size NIL and buf ((memory . #<FIELD-INFO {100FEB4083}>)
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(flags . #<FIELD-INFO {100FEB4153}>)
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(data . #<FIELD-INFO {100FEB4223}>)
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(size . #<FIELD-INFO {100FEB42F3}>)
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(maxsize . #<FIELD-INFO {100FEB43C3}>)
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(user_data . #<FIELD-INFO {100FEB4493}>)
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(_gst_reserved
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. #<FIELD-INFO {100FEB4563}>))
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; Evaluation aborted on T
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CAPTURING-FRAMES>
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so. there are data and size fields.
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