gst_buffer_get getting stale data

[HtGst]

Hi

On gstreamer 1.4.5, running on CentOs 7.2, having problem with reading meta data attached to buffers. The following scenario is the where the problem is observed:

State 1:

Meta data is conditionally attached to outgoing buffers, i.e., only if there is valid meta, it would get attached, e.g.:

…

if(userdata){

                    gst_buffer_add_userdata_meta (frame->output_buffer,& userdata_meta);

…

Intended recipient of meta properly ignores  gst_buffer_get  call:

…

GstUserdataMeta *userdata_meta=gst_buffer_get_userdata_meta (input_frame->input_buffer);

      if(userdata_meta && userdata_meta->userdatameta){

          // This is not executed

      }

 

State 2:

Meta attachment condition becomes true, proper meta data are attached

Recipient properly extracts meta:

GstUserdataMeta *userdata_meta=gst_buffer_get_userdata_meta (input_frame->input_buffer);

      if(userdata_meta && userdata_meta->userdatameta){

          // This is  executed

      }

State 3:

Meta data attachment condition becomes false, no meta is attached

Recipient still extracts meta!

 

It is noted that due to buffering, it is expected that there would be a lag from the time that meta attachment condition become false to the time that recipient is expected to ignor gst_buffer_get calls. Here is what I am getting:

 

On State 2, the recipient sees: GST_INFO_OBJECT(xx,"%p %p\n”, userdata_meta, userdata_meta->userdatameta);

…

0:00:52.027950698 27204      0x16e6f20 INFO       xx           xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde757e20 0x7f8c0826ab90

0:00:52.047961117 27204      0x16e6f20 INFO       xx          xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde864ae0 0x7f8c082683f0

0:00:52.068356845 27204      0x16e6f20 INFO       xx            xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bdf2e8120 0x7f8c082685b0

0:00:52.087984535 27204      0x16e6f20 INFO       xx             xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bdf2eeea0 0x7f8c08268db0

0:00:52.107973286 27204      0x16e6f20 INFO       xx           xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde76d1e0 0x7f8c080b2620

…

(Note that meta field address changes per call, as the meta server is allocating new memory for each meta data)

 

On State 3,  the recipient sees: GST_INFO_OBJECT(xx,"%p %p\n”, userdata_meta, userdata_meta->userdatameta);

…

0:00:53.528208158 27204      0x16e6f20 INFO                  xx xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde8abe20 0x7f8c0bf11a40

0:00:53.547948573 27204      0x16e6f20 INFO                  xx xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde845ae0 0x7f8c0bf11a40

0:00:53.567948574 27204      0x16e6f20 INFO                  xx xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde74f1e0 0x7f8c0bf11a40

0:00:53.587983423 27204      0x16e6f20 INFO                  xx xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde785ae0 0x7f8c0bf11a40

0:00:53.607985743 27204      0x16e6f20 INFO                  xx xx.cpp:1547:gst_xx_encode_frame:<xx> 0x7f8bde7681e0 0x7f8c0bf11a40

…

Note that recipient keeps reading the same stale memory location.

 

Any thoughts?

Cheers,

 

 

 

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