v4l2 element stay in READY state

Thu Feb 12 11:34:27 PST 2015

It sounds like it is time to crank up logging on the decodebin and v4l2sink
elements to see what is(n't) happening.

Something like:
export GST_DEBUG=decodebin:5,v4l2sink:5

This should generate enough messages to understand what is failing.

On Thu, Feb 12, 2015 at 5:05 AM, Russell <danrenjian at gmail.com> wrote:

> By the way, target v4l2 device is created by v4l2loopback
> <https://github.com/umlaeute/v4l2loopback>
> Besides, I have output the caps of all pads (static or dynamic) of these
> elements whenever one of them change states. They seem to be fixed at the
> end. That is, (dynamic) src pad of rtspsrc and sink pad of decodebin have
> same fixed caps, and (dynamic) src pad of decodebin and sink pad of
> v4l2sink have same fixed caps. Does that mean the caps negotiation is
> completed?
>
> Thanks,
> Russell
>
> On Thu, Feb 12, 2015 at 5:58 PM, Russell <danrenjian at gmail.com> wrote:
>
>> fakesink works, too.
>> rtspsrc, decodebin and fakesink (as well as the pipeline itself) are all
>> in PLAYING state at the end.
>>
>> Thanks,
>> Russell
>>
>> On Thu, Feb 12, 2015 at 5:46 PM, Russell <danrenjian at gmail.com> wrote:
>>
>>> Hi,
>>>
>>> autovideosink in code works ok, will give fakesink a try.
>>>
>>> Thanks,
>>> Russell
>>>
>>> On Thu, Feb 12, 2015 at 5:03 PM, Sérgio Agostinho <
>>> sergio.r.agostinho at gmail.com> wrote:
>>>
>>>> Just for completion, do you have the same issue if you replace v4l2sink
>>>> for fakesink and then for an autovideosink *in your code*. Trying to
>>>> understand if this is something specific about the way you're connecting
>>>> v4l2sink or just live sinks in general.
>>>>
>>>> Cheers
>>>> Sérgio
>>>>
>>>> 2015-02-12 7:44 GMT+01:00 Russell <danrenjian at gmail.com>:
>>>>
>>>>> Hi,
>>>>>
>>>>> Here is how I add and link decodebin and v4l2sink into pipeline:
>>>>>
>>>>>    1. When a new src pad is created for rtspsrc
>>>>>       1. add decodebin to pipeline
>>>>>       2. set decodebin to PLAYING async
>>>>>       3. link src pad of rtspsrc to sink pad of decodebin
>>>>>    2. When a new src pad is created for decodebin
>>>>>       1. add v4l2sink to pipeline
>>>>>       2. set v4l2sink to PLAYING async
>>>>>       3. link src pad of decodebin to sink pad of v4l2sink
>>>>>
>>>>> Eventually, rtspsrc will be PLAYING, decodebin be PAUSED, and v4l2sink
>>>>> be READY.
>>>>>
>>>>> But if I detect state change for decodebin, so what when it move to
>>>>> PAUSED, I set its state to PLAYING asyc again, then eventually decodebin
>>>>> would be in PLAYING state.
>>>>> v4l2sink would always be READY state even if I set its state several
>>>>> times like decodebin.
>>>>>
>>>>> And, If I only did 1 and no 2 as decribed above (that is, without
>>>>> adding and linking for v4l2sink), then both rtspsrc and decodebin would be
>>>>> in PLAYING state.
>>>>>
>>>>>
>>>>> Is there anything else I can try??
>>>>>
>>>>> Thanks,
>>>>> Russell
>>>>>
>>>>>
>>>>> On Thu, Feb 12, 2015 at 9:06 AM, Russell <danrenjian at gmail.com> wrote:
>>>>>
>>>>>> Hi, Wonchul
>>>>>>
>>>>>> How can I confirm whether v4l2sink receives any buffer, are there any
>>>>>> logs that I can inspect?
>>>>>>
>>>>>> Thanks,
>>>>>> Russell
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wed, Feb 11, 2015 at 10:06 PM, Wonchul Lee <chul0812 at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I guess that v4l2sink didn't receive any buffer.
>>>>>>> Sink element what inherited from basesink will change to PAUSED
>>>>>>> states
>>>>>>> after receiving a buffer for preroll.
>>>>>>>
>>>>>>>
>>>>>>> http://cgit.freedesktop.org/gstreamer/gstreamer/tree/docs/design/part-states.txt#n41
>>>>>>>
>>>>>>>
>>>>>>> 2015-02-11 18:23 GMT+09:00 Sérgio Agostinho <
>>>>>>> sergio.r.agostinho at gmail.com>:
>>>>>>> > Hi Russel,
>>>>>>> >
>>>>>>> > If you do
>>>>>>> >
>>>>>>> > gst-launch-1.0 videotestsrc ! v4l2sink
>>>>>>> >
>>>>>>> > do you see video on your v4l2device? Also, if you do
>>>>>>> >
>>>>>>> > gst-launch-1.0 rtspsrc location=rtspaddress ! decodebin !
>>>>>>> autovideosink
>>>>>>> >
>>>>>>> > Do you see your rtsp video stream playing on a window?
>>>>>>> >
>>>>>>> > Cheers
>>>>>>> >
>>>>>>> >
>>>>>>> > 2015-02-11 7:50 GMT+01:00 Russell <danrenjian at gmail.com>:
>>>>>>> >>
>>>>>>> >> Hi,
>>>>>>> >>
>>>>>>> >> I was trying this pipeline to feed rtsp stream into a v4l2 virtual
>>>>>>> >> loopback device:
>>>>>>> >> gst-launch-1.0 rtspsrc location=rtspaddress ! decodebin ! v4l2sink
>>>>>>> >>
>>>>>>> >> Terminal gave this output and stops, and there are no video in
>>>>>>> the v4l2
>>>>>>> >> device:
>>>>>>> >> Progress: (request) Sending PLAY request
>>>>>>> >> Progress: (request) Sending PLAY request
>>>>>>> >> Progress: (request) Sent PLAY request
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> So I am implementing the pipeline in c to see what happened.
>>>>>>> decodebin and
>>>>>>> >> v4l2sink are added and linked on on pad-added event. Eventually I
>>>>>>> found the
>>>>>>> >> v4l2sink element stay in READY state while the other two are
>>>>>>> PLAYING. I have
>>>>>>> >> set v4l2sink to PLAYING asynchronously but the state does not
>>>>>>> change.
>>>>>>> >>
>>>>>>> >> What is the matter here? and where I can find any detailed reason
>>>>>>> why
>>>>>>> >> v4l2sink cannot go to PLAYING state?
>>>>>>> >>
>>>>>>> >> Thanks in advance.
>>>>>>> >>
>>>>>>> >> Sincerely,
>>>>>>> >> Russell
>>>>>>> >>
>>>>>>> >> _______________________________________________
>>>>>>> >> gstreamer-devel mailing list
>>>>>>> >> gstreamer-devel at lists.freedesktop.org
>>>>>>> >> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>>>> >>
>>>>>>> >
>>>>>>> >
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>>>>>>
>>>>>
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