[uvch264src in 1.1.1.1] "Got data flow before segment event" warnings until crash

Robert Krakora rob.krakora at messagenetsystems.com
Fri Jul 26 06:47:15 PDT 2013


Actually, you can probably get away with this...

      if (max_buffers == 0 || num_buffers < max_buffers) {
        /* if we are asked to provide more buffers than we have allocated,
start
         * copying buffers when we only have 2 buffers left in the pool */
        copy_threshold = num_buffers + 1;
      } else {
        /* we are certain that we have enough buffers so we don't need to
         * copy */
        copy_threshold = num_buffers + 1;
      }



On Fri, Jul 26, 2013 at 9:45 AM, Robert Krakora <
rob.krakora at messagenetsystems.com> wrote:

> You want the copy threshold to ALWAYS be bigger then the number of buffers
> queued so that the copy ALWAYS happens... :-)  To do this, make
> "copy_threshold" bigger than "max_buffers"...
>
>
>  if (pool->num_queued < pool->copy_threshold) {
>
>
> On Fri, Jul 26, 2013 at 9:26 AM, Robert Krakora <
> rob.krakora at messagenetsystems.com> wrote:
>
>> Basically, you want to set up v4l2src so that it ALWAYS copies it's
>> buffer pool buffers to freshly allocated buffers...this was it's default
>> behaviour in 0.10.
>>
>>
>> On Fri, Jul 26, 2013 at 9:24 AM, Robert Krakora <
>> rob.krakora at messagenetsystems.com> wrote:
>>
>>> If the only thing that I do is set the copy threshold to 100 I can run
>>> until the memory leak that I mentioned before invokes the OS to kill
>>> gst-launch...I don't see the error reported...
>>>
>>>
>>> On Fri, Jul 26, 2013 at 9:03 AM, Peter Rennert <p.rennert at cs.ucl.ac.uk>wrote:
>>>
>>>>  Hmm that is not the solution. It still fails after some minutes,
>>>> reporting the same error as before. I am trying to find the right way to
>>>> manipulate the buffer numbers now.
>>>>
>>>>
>>>>
>>>> On 07/26/2013 01:13 PM, Peter Rennert wrote:
>>>>
>>>> Rob,
>>>>
>>>> Well spotted!
>>>>
>>>> It works for me. I am monitoring the memory only with htop at the
>>>> moment, but it seems to be stable. I think the memory leak stems from the
>>>> fact that max_buffers is set to 0, so it will always make the buffer bigger
>>>> and bigger. I think that is generally a bad idea. This might affect also
>>>> plain v4l2src applications.
>>>>
>>>> Try this patch to get rid of the memory leak:
>>>>
>>>> diff --git a/sys/v4l2/gstv4l2bufferpool.c
>>>> b/sys/v4l2/gstv4l2bufferpool.c
>>>>
>>>> index 1e74fc7..282ac2b
>>>> 100644
>>>>
>>>> --- a/sys/v4l2/gstv4l2bufferpool.c
>>>> +++ b/sys/v4l2/gstv4l2bufferpool.c
>>>> @@ -411,7 +411,7 @@ gst_v4l2_buffer_pool_set_config (GstBufferPool *
>>>> bpool, GstStructure * config)
>>>>        if (max_buffers == 0 || num_buffers < max_buffers) {
>>>>          /* if we are asked to provide more buffers than we have
>>>> allocated, start
>>>>           * copying buffers when we only have 2 buffers left in the
>>>> pool */
>>>> -        copy_threshold = 2;
>>>> +        copy_threshold = 15;// 2;
>>>>        } else {
>>>>          /* we are certain that we have enough buffers so we don't need
>>>> to
>>>>           * copy */
>>>> diff --git a/sys/v4l2/gstv4l2src.c b/sys/v4l2/gstv4l2src.c
>>>> index 107ea21..0c5d91a 100644
>>>> --- a/sys/v4l2/gstv4l2src.c
>>>> +++ b/sys/v4l2/gstv4l2src.c
>>>> @@ -529,7 +529,8 @@ gst_v4l2src_decide_allocation (GstBaseSrc * bsrc,
>>>> GstQuery * query)
>>>>      update = TRUE;
>>>>    } else {
>>>>      pool = NULL;
>>>> -    min = max = 0;
>>>> +    min = 0;
>>>> +    max = 100;
>>>>      size = 0;
>>>>      update = FALSE;
>>>>    }
>>>>
>>>>
>>>> On 07/25/2013 09:52 PM, Robert Krakora wrote:
>>>>
>>>>  Hi Peter,
>>>>
>>>> I also wanted to note that when you apply the aforementioned "hack" to
>>>> emulate the default operation of v4l2src in version 0.10
>>>> ("always-copy=true") with the pipeline below, your system will run out of
>>>> memory due to a memory leak.  It will then kill off the gst-launch process
>>>> instantiated to run your pipeline.  However, your pipeline will run for
>>>> quite a bit (a lot longer than the previous 36 seconds noted by Yusuf a
>>>> couple of months ago).
>>>>
>>>> gst-launch-1.0 uvch264src device=/dev/video0 name=src auto-start=true
>>>> src.vfsrc ! queue ! fakesink src.vidsrc ! queue ! video/x-h264 ! fakesink
>>>>
>>>>  Best Regards,
>>>>
>>>> Rob Krakora
>>>>
>>>>
>>>>
>>>> On Thu, Jul 25, 2013 at 4:27 PM, Robert Krakora <
>>>> rob.krakora at messagenetsystems.com> wrote:
>>>>
>>>>>  Hi Peter,
>>>>>
>>>>>  I forgot to mention that the file that needs modification is named
>>>>> gstv4l2bufferpool.c and is under sys/v4l2 under plugins-good.
>>>>>
>>>>>
>>>>>       if (max_buffers == 0 || num_buffers < max_buffers) {
>>>>>         /* if we are asked to provide more buffers than we have
>>>>> allocated, start
>>>>>          * copying buffers when we only have 2 buffers left in the
>>>>> pool */
>>>>>         copy_threshold = 100; //2;
>>>>>       } else {
>>>>>         /* we are certain that we have enough buffers so we don't need
>>>>> to
>>>>>          * copy */
>>>>>         copy_threshold = 0;
>>>>>       }
>>>>>
>>>>>
>>>>> On Thu, Jul 25, 2013 at 4:21 PM, Robert Krakora <
>>>>> rob.krakora at messagenetsystems.com> wrote:
>>>>>
>>>>>>  Hi Peter,
>>>>>>
>>>>>>  In version 0.10 v4l2src used to have a property to force buffers
>>>>>> from it's pool to always be copied prior to being pushed out.  This
>>>>>> property was called "always-copy" and defaulted to "true".  It seems that
>>>>>> this was removed in version 1.x.  If you go to version 1.x good plugins and
>>>>>> change "copy_threadhold" from 2 to 100 you effectively get the same
>>>>>> behaviour with 1.x in this regard (same as "always-copy=true" default in
>>>>>> 0.10 v4l2src) and there is no error after 30 some odd seconds that causes
>>>>>> the stream to abort.
>>>>>>
>>>>>>       if (max_buffers == 0 || num_buffers < max_buffers) {
>>>>>>         /* if we are asked to provide more buffers than we have
>>>>>> allocated, start
>>>>>>          * copying buffers when we only have 2 buffers left in the
>>>>>> pool */
>>>>>>         copy_threshold = 100; //2;
>>>>>>       } else {
>>>>>>         /* we are certain that we have enough buffers so we don't
>>>>>> need to
>>>>>>          * copy */
>>>>>>         copy_threshold = 0;
>>>>>>       }
>>>>>>
>>>>>>  Best Regards,
>>>>>>
>>>>>> Rob Krakora
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Jul 25, 2013 at 1:06 PM, Robert Krakora <
>>>>>> rob.krakora at messagenetsystems.com> wrote:
>>>>>>
>>>>>>>   Hi Peter,
>>>>>>>
>>>>>>>  I did some work yesterday on this and enabled logging on
>>>>>>> uvcvideo.ko and was able to correlate the buffer sizes reported by it and
>>>>>>> by the uvch264src plugin.  Below is the frame that failed...the
>>>>>>> size in the kernel module was the same as the size of the buffer once it
>>>>>>> got back up to the application to v4l2src and uvch264src.
>>>>>>>
>>>>>>> uvcvideo: Frame complete (EOF found).
>>>>>>> uvcvideo: EOF in empty payload.
>>>>>>> uvcvideo: uvc_v4l2_poll
>>>>>>> uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF)
>>>>>>> uvcvideo: HD Pro Webcam C920: PTS 1029592232 y 2948.098587 SOF
>>>>>>> 2948.098587 (x1 2149480048 x2 2179588048 y1 193593344 y2 199426048
>>>>>>> SOF offset 39)
>>>>>>> uvcvideo: HD Pro Webcam C920: SOF 2948.098587 y 927116325 ts
>>>>>>> 589.071670 buf ts 589.232519 (x1 197984256/205/906 x2 204537856/49/995 y1
>>>>>>> 1000000000 y2 1099975668)
>>>>>>> uvcvideo: uvc_dequeue_buffer - buf->bytesused = 220410
>>>>>>> uvcvideo: uvc_v4l2_ioctl(VIDIOC_QBUF)
>>>>>>>
>>>>>>>  Best Regards,
>>>>>>>
>>>>>>>  Rob
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Jul 25, 2013 at 12:22 PM, Peter Rennert <
>>>>>>> p.rennert at cs.ucl.ac.uk> wrote:
>>>>>>>
>>>>>>>> A bit of an update today.
>>>>>>>>
>>>>>>>> To figure out what is going on normally and what is different in
>>>>>>>> the diseased frame I printed out the debug line [line 508] that was already
>>>>>>>> in the code, augmented with the total size of the buffer. The original line
>>>>>>>> was:
>>>>>>>>
>>>>>>>> GST_DEBUG_OBJECT (self,
>>>>>>>>           "Found APP4 marker (%d). JPG: %d-%d - APP4: %d - %d",
>>>>>>>> segment_size,
>>>>>>>>           last_offset, i, i, i + 2 + segment_size);
>>>>>>>>
>>>>>>>> I print for each time in the loop (before the sanity test that will
>>>>>>>> fail finally):
>>>>>>>>
>>>>>>>> printf("Found APP4 marker (%d). JPG: %d-%d - APP4: %d - %d - size:
>>>>>>>> %d\n", segment_size,
>>>>>>>>           last_offset, i, i, i + 2 + segment_size, (int)size);
>>>>>>>>
>>>>>>>> What I get for a normal frame is about this. The total buffer size
>>>>>>>> changes and also the size of the first APP4 chunk, however, I always seem
>>>>>>>> to get 4 blocks for each frame. The segment size of the first marker
>>>>>>>> differs between the individual frames, while the 2nd, 3rd and 4th markers
>>>>>>>> are the same size all the time as far as I can tell:
>>>>>>>>
>>>>>>>> Found APP4 marker (13010). JPG: 0-8 - APP4: 8 - 13020 - size: 166660
>>>>>>>>
>>>>>>>> Found APP4 marker (65533). JPG: 13020-13020 - APP4: 13020 - 78555 -
>>>>>>>> size: 166660
>>>>>>>>
>>>>>>>> Found APP4 marker (65533). JPG: 78555-78555 - APP4: 78555 - 144090
>>>>>>>> - size: 166660
>>>>>>>>
>>>>>>>> Found APP4 marker (22566). JPG: 144090-144090 - APP4: 144090 -
>>>>>>>> 166658 - size: 166660
>>>>>>>>
>>>>>>>>
>>>>>>>> The frame that causes the failure of the system has the following
>>>>>>>> output:
>>>>>>>>
>>>>>>>> Found APP4 marker (12084). JPG: 0-8 - APP4: 8 - 12094 - size: 165485
>>>>>>>>
>>>>>>>> Found APP4 marker (65533). JPG: 12094-12094 - APP4: 12094 - 77629 -
>>>>>>>> size: 165485
>>>>>>>>
>>>>>>>> Found APP4 marker (65533). JPG: 77629-77629 - APP4: 77629 - 143164
>>>>>>>> - size: 165485
>>>>>>>>
>>>>>>>> Found APP4 marker (22566). JPG: 143164-143164 - APP4: 143164 -
>>>>>>>> 165732 - size: 165485
>>>>>>>>
>>>>>>>>
>>>>>>>> As you can see it seems as the last segment reaches out of the
>>>>>>>> total size of the buffer. As the last segment seems to be always of a
>>>>>>>> length 22566, I think for some reason (that does not happen in gstreamer
>>>>>>>> 0.10) a piece of the h264 stream is missing in this particular buffer.
>>>>>>>>
>>>>>>>> The number of bytes getting lost is not the same for different
>>>>>>>> trials, neither is the cut-off. For my second trial I got:
>>>>>>>>
>>>>>>>> Found APP4 marker (22566). JPG: 144796-144796 - APP4: 144796 -
>>>>>>>> 167364 - size: 165815
>>>>>>>>
>>>>>>>> So where are these bytes? And why are they missing so regularly?
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> gstreamer-devel mailing list
>>>>>>>> gstreamer-devel at lists.freedesktop.org
>>>>>>>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>  --
>>>>>>> Rob Krakora
>>>>>>> MessageNet Systems
>>>>>>> 101 East Carmel Dr. Suite 105
>>>>>>> Carmel, IN 46032
>>>>>>> (317)566-1677 Ext 212
>>>>>>> (317)663-0808 Fax
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Rob Krakora
>>>>>> MessageNet Systems
>>>>>> 101 East Carmel Dr. Suite 105
>>>>>> Carmel, IN 46032
>>>>>> (317)566-1677 Ext 212
>>>>>> (317)663-0808 Fax
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Rob Krakora
>>>>> MessageNet Systems
>>>>> 101 East Carmel Dr. Suite 105
>>>>> Carmel, IN 46032
>>>>> (317)566-1677 Ext 212
>>>>> (317)663-0808 Fax
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Rob Krakora
>>>> MessageNet Systems
>>>> 101 East Carmel Dr. Suite 105
>>>> Carmel, IN 46032
>>>> (317)566-1677 Ext 212
>>>> (317)663-0808 Fax
>>>>
>>>>
>>>> _______________________________________________
>>>> gstreamer-devel mailing listgstreamer-devel at lists.freedesktop.orghttp://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> gstreamer-devel mailing listgstreamer-devel at lists.freedesktop.orghttp://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> gstreamer-devel mailing list
>>>> gstreamer-devel at lists.freedesktop.org
>>>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>
>>>>
>>>
>>>
>>> --
>>> Rob Krakora
>>> MessageNet Systems
>>> 101 East Carmel Dr. Suite 105
>>> Carmel, IN 46032
>>> (317)566-1677 Ext 212
>>> (317)663-0808 Fax
>>>
>>
>>
>>
>> --
>> Rob Krakora
>> MessageNet Systems
>> 101 East Carmel Dr. Suite 105
>> Carmel, IN 46032
>> (317)566-1677 Ext 212
>> (317)663-0808 Fax
>>
>
>
>
> --
> Rob Krakora
> MessageNet Systems
> 101 East Carmel Dr. Suite 105
> Carmel, IN 46032
> (317)566-1677 Ext 212
> (317)663-0808 Fax
>



-- 
Rob Krakora
MessageNet Systems
101 East Carmel Dr. Suite 105
Carmel, IN 46032
(317)566-1677 Ext 212
(317)663-0808 Fax
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