[gst-devel] allowed caps and v4l2src

[marc doz]

Hi
I would like do some test with gstreamer and my webcam Philips 1330 NC and i
have a understanding problem with "capabilities for filtering " and "allowed
caps" :

1) with a videotestsrc element, I can do that :
videotestsrc ! video/x-raw-rgb ! ffmpegcolorspace ! ximagesink
videotestsrc ! video/x-raw-yuv ! ffmpegcolorspace ! ximagesink

2) with a v4l2src element, I can do that :
v4l2src ! video/x-raw-rgb ! ffmpegcolorspace ! ximagesink
3) but i can't do that :
v4l2src ! video/x-raw-rgb ! ffmpegcolorspace ! ximagesink
Setting pipeline to PAUSED ...
ERROR: Pipeline doesn't want to pause.
ERROR: from element /pipeline0/v4l2src0: Could not negotiate format
Additional debug info:
gstbasesrc.c(2387): gst_base_src_start (): /pipeline0/v4l2src0:
Check your filtered caps, if any
Setting pipeline to NULL ...
FREEING pipeline ...

4) So I have built a tiny program that i use to print allowed caps of the
pad between v4l2src and ffmpegcolorspace
./main v4l2src src ffmpegcolorspace sink

GStreamer 0.10.18
  video/x-raw-rgb
                bpp: 24
              depth: 24
           red_mask: 16711680
         green_mask: 65280
          blue_mask: 255
         endianness: 4321
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-rgb
                bpp: 24
              depth: 24
           red_mask: 255
         green_mask: 65280
          blue_mask: 16711680
         endianness: 4321
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: YV12
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: YUY2
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-rgb
                bpp: 32
              depth: 32
           red_mask: 255
         green_mask: 65280
          blue_mask: 16711680
         endianness: 4321
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
         alpha_mask: -16777216
  video/x-raw-yuv
             format: I420
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: Y42B
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-rgb
                bpp: 32
              depth: 32
           red_mask: -16777216
         green_mask: 16711680
          blue_mask: 65280
         endianness: 4321
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
         alpha_mask: 255
  video/x-raw-rgb
                bpp: 16
              depth: 16
           red_mask: 63488
         green_mask: 2016
          blue_mask: 31
         endianness: 1234
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-rgb
                bpp: 16
              depth: 15
           red_mask: 31744
         green_mask: 992
          blue_mask: 31
         endianness: 1234
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-rgb
                bpp: 8
              depth: 8
           red_mask: 224
         green_mask: 28
          blue_mask: 3
         endianness: 1234
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: YVU9
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: YUV9
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: Y41B
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]
  video/x-raw-yuv
             format: UYVY
              width: [ 1, 32768 ]
             height: [ 1, 32768 ]
          framerate: [ 0/1, 100/1 ]

my pad can use x-raw-rgb (and I would like use video/x-raw-rgb, bpp: 8) but
i can't use rgb format ... with gst-launch
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