Capturing images

README.md

@@ -8,6 +8,7 @@ This series of docs provides a cheat sheet for Gstreamer on the command-line.
 * [Basics](basics.md)
 * [RTMP](rtmp.md)
 * [Mixing video](mixing.md)
+* [Capturing images](capturing_images.md)
 
 ## Sources and references
 

capturing_images.md

@@ -0,0 +1,29 @@
+# Capturing images (GStreamer command-line cheat sheet)
+
+### Capture an image as png
+
+```
+gst-launch-1.0 videotestsrc ! pngenc ! filesink location=foo.png
+```
+
+
+### Capture an image as jpeg
+
+```
+gst-launch-1.0 videotestsrc ! jpegenc ! filesink location=foo.jpg
+```
+
+### Capturing images every X seconds
+
+This example captures one frame every 3 seconds, and places it in files with the format `img00001.jpg`.
+It also displays the video (as the `tee` command sends the video to both `multifilesink` and `autovideosink`).
+To change the frequency, change the `framerate=1/3`.
+e.g. `framerate=2/1` would capture a frame twice a second.
+
+```
+gst-launch-1.0 videotestsrc ! \
+    videoscale ! videoconvert ! video/x-raw,width=640,height=480 ! \
+    queue ! decodebin ! tee name=t ! queue ! videoconvert ! videoscale ! \
+    videorate ! video/x-raw,width=640,height=480,framerate=1/3  ! \
+    jpegenc ! multifilesink location=img%05d.jpg t. ! queue ! autovideosink
+```

test_streams.md

@@ -1,12 +1,28 @@
 # Test streams (GStreamer command-line cheat sheet)
 
-Display a test pattern:
+### Display a test pattern
 
 ```
 gst-launch-1.0 videotestsrc ! videoconvert ! autovideosink
 ```
 
-Listen to a test audio (beep):
+This should display the test pattern in a window, that looks a 
+bit like this:
+
+![Test pattern window](images/test-pattern.png "Test pattern window")
+
+There are multiple test patterns available, such as
+
+| `videotestsrc pattern=snow`  | !(images/test_snow.png) |
+| `videotestsrc pattern=red` (and blue and green) | !(images/test_red.png) |
+| `videotestsrc pattern=red` (and blue and green) | !(images/test_red.png) |
+| `videotestsrc pattern=pinwheel` | !(images/test_pinwheel.png) |
+| `videotestsrc pattern=smpte100` (color test bars) | !(images/test_smpte100.png) |
+| `videotestsrc pattern=colors` | !(images/test_colors.png) |
+
+For the full list of patterns, see https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-plugins/html/gst-plugins-base-plugins-videotestsrc.html
+
+### Listen to a test audio (beep)
 
 ```
 gst-launch-1.0 audiotestsrc ! audioconvert ! autoaudiosink