Not able to use downstream (kmssink) bufferpool in omx decoder component

[Devarsh Thakkar]

Hi,

I am using below pipeline :

gst-launch-1.0 ! filesrc <input_file> ! h264parse ! omxh264dec ! kmssink

After inserting some debug messages (after gst_is_kms_memory() in kmssink code) i got to know that omxh264dec doesn't use downstream i.e kmssink bufferpool,

however when I use below pipeline, kmssink bufferpool is used  :
gst-launch-1.0 videotestsrc ! 'video/x-raw, format=(string)NV12, width=176, height=144, framerate=30/1' ! kmssink

QUESTIONS :
Any ideas on what changes need to be done in gst-omx so that it uses kmssink buffer pool?
Any examples of omxh264dec using downstream bufferpool would also be helpful.

I think if downstream element is able to provide a buffer pool and omx component uses it than it should increase the performance of overall pipeline, isn't omxvideodec code designed such a way to handle this or am I missing something?

Kindly let me know if there is anything wrong with my understanding as I am a gstreamer newbie.
Thanks in advance.

Best Regards,
Devarsh

[Victor Jaquez]

On 01/15/17 at 05:06am, Devarsh Thakkar wrote:

> Hi,
>
> I am using below pipeline :
>
> /gst-launch-1.0 ! filesrc <input_file> ! h264parse ! omxh264dec ! kmssink/
>
> After inserting some debug messages (after gst_is_kms_memory() in kmssink
> code) i got to know that omxh264dec doesn't use downstream i.e kmssink
> bufferpool,
>
> however when I use below pipeline, kmssink bufferpool is used  :
> /gst-launch-1.0 videotestsrc ! 'video/x-raw, format=(string)NV12, width=176,
> height=144, framerate=30/1' ! kmssink/
>
> QUESTIONS :
> Any ideas on what changes need to be done in gst-omx so that it uses kmssink
> buffer pool?
> Any examples of omxh264dec using downstream bufferpool would also be
> helpful.

I guess, if I recall correctly, that will depend on you hardware/platform: if
the decoding subsystem can use an external memory area (in the case of
kmssink, a DRM's dumb buffer). Normally it is not the case, and the media
subsystem needs a special memory area, hence a memcopy is unavoidable.

The special case, if you see the gst-omx code, is the EGL, the video decoder
will export a EGL if downstream supports GstGLMemory (EGL).

You could add another special case: DMABuf. If your platform can export
DMABUf, you could use GstDMABufAllocator, and kmssink can import DMABufs.

vmjl

>
> I think if downstream element is able to provide a buffer pool and omx
> component uses it than it should increase the performance of overall
> pipeline, isn't omxvideodec code designed such a way to handle this or am I
> missing something?
>
> Kindly let me know if there is anything wrong with my understanding as I am
> a gstreamer newbie.
> Thanks in advance.
>
> Best Regards,
> Devarsh
>
>
>
> --
> View this message in context: http://gstreamer-devel.966125.n4.nabble.com/Not-able-to-use-downstream-kmssink-bufferpool-in-omx-decoder-component-tp4681455.html
> Sent from the GStreamer-devel mailing list archive at Nabble.com.
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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[Nicolas Dufresne-5]

Le dimanche 15 janvier 2017 à 05:06 -0800, Devarsh Thakkar a écrit :
> Hi,
>
> I am using below pipeline :
>
> /gst-launch-1.0 ! filesrc <input_file> ! h264parse ! omxh264dec ! kmssink/
>
> After inserting some debug messages (after gst_is_kms_memory() in kmssink
> code) i got to know that omxh264dec doesn't use downstream i.e kmssink
> bufferpool, 

That is exact. This was never implemented as no-one had access to an
OMX component that supported doing so. A component that supports that
would implement UseBuffer method on the output port. If your component
supports it, and the color format and strides are compatible, then it
would be a great opportunity to enhance gst-omx.

>
> however when I use below pipeline, kmssink bufferpool is used  :
> /gst-launch-1.0 videotestsrc ! 'video/x-raw, format=(string)NV12, width=176,
> height=144, framerate=30/1' ! kmssink/
>
> QUESTIONS :
> Any ideas on what changes need to be done in gst-omx so that it uses kmssink
> buffer pool?
> Any examples of omxh264dec using downstream bufferpool would also be
> helpful.
>
> I think if downstream element is able to provide a buffer pool and omx
> component uses it than it should increase the performance of overall
> pipeline, isn't omxvideodec code designed such a way to handle this or am I
> missing something?
>
> Kindly let me know if there is anything wrong with my understanding as I am
> a gstreamer newbie.
> Thanks in advance.
>
> Best Regards,
> Devarsh
>
>
>
> --
> View this message in context: http://gstreamer-devel.966125.n4.nabble.com/Not-able-to-use-downstream-kmssink-bufferpool-in-omx-decoder-component-tp4681455.html
> Sent from the GStreamer-devel mailing list archive at Nabble.com.
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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