[gst-devel] Segmentation fault while using GST_BUFFER macros

irfanshaikh irfanshaikh at tataelxsi.co.in
Thu Nov 6 16:32:23 CET 2008


Hi Sudarshan,

I was not able to do changes as you suggested to me. Instead i tried the
following. Since i just needed a flag or something which my next plug-in
element should recognize i used following.

  for(m=0; m<pkt->payload_count; m++)
  {
          if(pkt->payloads[m].key_frame == 1)
          {
              g_print("Inside IF\n");
              GST_BUFFER_OFFSET(outputbuf) = 1;
/*Segmentation fault*/
              GST_BUFFER_FLAG_SET (outputbuf, GST_BUFFER_FLAG_DELTA_UNIT);
/*Segmentation fault*/
              GST_BUFFER_DURATION(outputbuf)=(GstClockTime)1;
/*Segmentation fault*/
              /*
              At RTP ASF payloader check using...
              GST_BUFFER_FLAG_IS_SET(buf, GST_BUFFER_FLAG_DELTA_UNIT);
              */
              g_print("In Packet Payload %d consists of KEY FRAME\n", m);
          }
    }

I am not able to use any of the macros, if i use them i get a segmentation
fault. How shall i avoid Segmentation fault.


Regards,
Irfan

  -----Original Message-----
  From: sudarshan bisht [mailto:bisht.sudarshan at gmail.com]
  Sent: Thursday, November 06, 2008 2:14 PM
  To: Discussion of the development of GStreamer
  Subject: Re: [gst-devel] Size of output buffer


  Hi Irfan  ,
           Yes this can be done in better way . Use  gst_caps_new_simple ()
to set the flag for key frame . You can see how asfdemux sends extradata to
decoder .( see gstasfdemux.c file ) ,
       Once you do this , you can receive the same data in decoder or next
element . So in order to receive this information next element has to
register funtion using gst_pad_set_setcaps_function( )  ( just check some
decode's code which gets frame height and width from demuxer in this
manner )  .



  On Thu, Nov 6, 2008 at 11:23 AM, Irfan Shaikh
<irfanshaikh at tataelxsi.co.in> wrote:


    Hi sudarshan,

         I have completed the asfparser plug-in code now itz working fine as
per requirrement :-)

    I am only facing a small problem. I want to convey to next Plug-in
element. Whether ASF data packet i m sending to next element consists of Key
frame or no ?


    For conveying this information i have thought of using following field
of GstBuffer.
      guint64 offset;
    I would either SET it or RESET it while pushing the data
gst_pad_push(asfparse->srcpad, outputbuf)


    Is there any other convinent{feasible} way of conveying the above
information to next plug-in element {Is there some macro or Some flag that i
can use using GstBuffer before pushing outputbuf}
    So as to convey to next element whether the outputbuf {consisting ASF
data packet} has a KEY frame or no ??


    Regards,
    Irfan


    -----Original Message-----
    From: sudarshan bisht [mailto:bisht.sudarshan at gmail.com]

    Sent: Thu 11/6/2008 10:55 AM
    To: Discussion of the development of GStreamer
    Subject: Re: [gst-devel] Size of output buffer

    Hi Irfan ,

            U r right data is pushed on src pad .

    On Tue, Oct 21, 2008 at 6:58 PM, Irfan Shaikh
    <irfanshaikh at tataelxsi.co.in>wrote:

    >
    > Thanks a lot Sudarshan....
    >
    > The sample code which you have send is really helping me a lot.
    >
    > If i am not wrong, I think-------- gst_pad_push(sinkpad, my_buffer)
should
    > be like------ gst_pad_push(asfparse->srcpad, my_buffer).
    >
    > Am i corrrect ?
    >
    > Thanks a lot for your help and support,
    > Regards,
    > Irfan
    >
    >
    >
    > -----Original Message-----

    > From: sudarshan bisht
[mailto:bisht.sudarshan at gmail.com<bisht.sudarshan at gmail.com>
    > ]
    > Sent: Tue 10/21/2008 6:44 PM
    > To: Discussion of the development of GStreamer
    > Subject: Re: [gst-devel] Size of output buffer
    >
    >  Hi Irfan ,
    >
    >           I think here no need to use circular buffer , because the
buffer
    > which u receive in ur plugin , u have to unref that after properly
copying
    > required buffer from that . And the buffer which ul allocate in your
    > plugin
    > will be sent u next element thus will be unref by the next element .
    >
    >   I am writing a piece of code , may give u some hint  :-
    >
    >  asf_parser_plugin_chain(GstPad pad, GstBuffer *buffer)
    >  {
    >
    >       gint packet_size=0;
    >       GstBuffer *my_buffer=NULL;
    >
    >       packet_size = parse_buffer(GST_BUFFER_DATA(buffer) ); // get
    > the packet size
    >
    >       my_buffer=gst_buffer_new_and_alloc ( packet_size );
    >
    >
    > memcpy(GST_BUFFER_DATA( my_buffer),  GST_BUFFER_DATA(buffer),
packet_size
    > ); // can use other APIs also provided by GstBuffer (
    >
    >
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstr
eamer-GstBuffer.html
    > )
    >
    >         gst_pad_push(sinkpad, my_buffer);
    >
    >         gst_buffer_unref(buffer) ; // check if u have copied all the
data
    >
    >         return GST_FLOW_OK ;
    >       }
    >
    >
    >
    >
    >
    >
    >
    >
    >
    >
    > On Tue, Oct 21, 2008 at 5:13 PM, Irfan Shaikh
    > <irfanshaikh at tataelxsi.co.in>wrote:
    >
    > >  Hi sudarshan,
    > >
    > >           Thanks a lot for your reply. I am pretty clear now.
    > >
    > > Earlier i had decided some other appoach as follows:
    > >           SO now i think i should not use A circular buffer,
directly i
    > can
    > > use the existing Gstreamer buffer ritee ??
    > >
    > > Thanks for your reply.
    > >
    > >       Regarding my query :
    > >       1)I have written an ASF parser code which reads an ASF file
from a
    > > file location path.
    > >       2)It uses fseek and fread to read the data from file in a
temperory
    > > buffer
    > >       3)It uses the temporary buffer to parse the ASf headers
    > >       4)Lastly collect the ASF data packets after parsing the
headers
    > into
    > > another temperory bufffer (tempbuf).
    > >       5) When i make ASF parser as gstreamer plugin, i will use
    > > gst_pad_push (asfparse->srcpad, tempbuf);
    > >
    > > I am clear about the output interface when i make the ASF parser as
    > > gstreamer plug-in.
    > >
    > >       Actual scenario:
    > >
    > >       1) Input module to ASF parser plug-in is output from
"ffmux_asf"
    > > which will be in form of data buffers.
    > >       2) I will need some buffer to collect these data buffers
    > >       3) I thought of having a "Circular buffer" to take input from
    > > ffmux_asf.{Is it feasible to use a normal buffer like uint8_t
*Newbuf to
    > > collect
    > >          data buffers from ffmux_asf ?? {If YES. How much memory
should i
    > > allocate for NewBuf}}
    > >       4) Since my application is related to Live Streaming the
buffer
    > > NewBuf size can be huge.
    > >       5) Circular buffer would have been useful.Since i will free
the
    > > memory as soon as i read the Circular buffer.
    > >       6) I can use pointer operations similar to file operations
    > >
    > > In gstreamer i have GstBuffer *buf, If i use circular buffer how can
i
    > use
    > > the existing "buf".
    > >
    > > Regards,
    > > Irfan.
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > >
    > > -----Original Message-----
    >  > From: sudarshan bisht
[mailto:bisht.sudarshan at gmail.com<bisht.sudarshan at gmail.com>
    > <bisht.sudarshan at gmail.com>
    > > ]
    > > Sent: Tue 10/21/2008 4:53 PM
    > > To: Discussion of the development of GStreamer
    > > Subject: Re: [gst-devel] Size of output buffer
    > >
    > > HI Irfan ,
    > >               You are trying to write a ASF Parser plugin which will
be
    > > used
    > > after ffmux_asf in pipeline .
    > >  Now you want to parse data packets and send them to next element .
    > >
    > >    The buffer you get from ffmux_asf is already allocated so you
dont
    > need
    > > to allocated a separate buffer for that .
    > >    To know the size of input buffer in your ASF Parser plugin you
can use
    > > GST_BUFFER_SIZE(buffer) .
    > >      So now you have to parse data part of this buffer , because
data
    > part
    > > of the buffer have the actual data .
    > >      For your outgoing packets allocate one more GstBuffer and copy
the
    > > required number of bytes of data from received buffer to this buffer
and
    > > push this buffer to next element.
    > >
    > >  You can use adapter APIs also to make it simpler . Read GstBuffer
APIs
    > > thoroughly for good practice.
    > >
    > >
    > >
    > > On Tue, Oct 21, 2008 at 3:59 PM, Irfan Shaikh
    > > <irfanshaikh at tataelxsi.co.in>wrote:
    > >
    > > >
    > > >
    > > >
    > > >  -----Original Message-----
    > >  > From: sudarshan bisht
[mailto:bisht.sudarshan at gmail.com<bisht.sudarshan at gmail.com>
    > <bisht.sudarshan at gmail.com>
    > > <bisht.sudarshan at gmail.com>
    > > > ]
    > > > Sent: Tue 10/21/2008 2:25 PM
    > > > To: Discussion of the development of GStreamer
    > > > Subject: Re: [gst-devel] Size of output buffer
    > > >
    > > >  Hi
    > > >
    > > >  "gst_pad_push_event" function pushes only events ( EOS , new
segment
    > etc
    > > )
    > > > not buffer , in order to push buffer use "gst_pad_push"  api .
    > > >
    > > > On Tue, Oct 21, 2008 at 1:58 PM, Irfan Shaikh
    > > > <irfanshaikh at tataelxsi.co.in>wrote:
    > > >
    > > > >
    > > > > Hi Julien,
    > > > >
    > > > >      Thanks for your reply..
    > > > >
    > > > >      For ffmux_asf plug-in in gstffmpegmux.c.
    > > > >
    > > > >      Is "gst_pad_push_event" is the fuction which pushes the
buffer
    > > which
    > > > > has ASF data into sink pad of next elemnt ?
    > > > >      i.e. gst_pad_push_event (ffmpegmux->srcpad,
gst_event_new_eos
    > ());
    > > > > When i checked the sise of buffer its variable in size.
    > > > >
    > > > >
    > > > >       I need to allocate buffer for the next module to
"ffmux_asf".
    > > Which
    > > > > is an asf parse. i need to allocate buffer in asf parser plugin.
I
    > > wanted
    > > > to
    > > > > know what size of buffer should i allocate for ASF parser
plug-in to
    > > take
    > > > > i/p from ffmux_asf
    > > > >
    > > > > I checked the buffer size in ffmux_asf in
gst_ffmpegmux_collected
    > > > > (GstCollectPads * pads, gpointer user_data)
    > > > >
    > > > > But it shows variable part. Tell me whether i am right ??
    > > > >
    > > > > Size of buf:5757
    > > > > Size of buf:7134
    > > > > Size of buf:6927
    > > > > Size of buf:5670
    > > > > Size of buf:4989
    > > > > Size of buf:4004
    > > > > Size of buf:3615
    > > > > Size of buf:3188
    > > > > Size of buf:3022
    > > > > Size of buf:2703
    > > > >
    > > > > Thanks and regards,
    > > > > Irfan
    > > > >
    > > > >
    > > > >
    > > > > -----Original Message-----
    > > >  > From: Julien Puydt [mailto:jpuydt at free.fr <jpuydt at free.fr> <
    > jpuydt at free.fr> <
    > > jpuydt at free.fr> <
    > > > jpuydt at free.fr>]
    > > > > Sent: Mon 10/20/2008 3:29 PM
    > > > > To: Discussion of the development of GStreamer
    > > > > Subject: Re: [gst-devel] Size of output buffer
    > > > >
    > > > > irfanshaikh a écrit :
    > > > > >         How can i find size of output buffer in "ffmux_asf"
which
    > is
    > > > > pushed
    > > > > > to the sink pad of next element ?
    > > > >
    > > > > GST_BUFFER_SIZE (buffer) ?
    > > > >
    > > > > Snark on #gstreamer
    > > > >
    > > > >
    >
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    > > > Sudarshan Bisht
    > > >
    > > >
    > > > Hi sudarshan/Ved,
    > > >
    > > >       In gstffmpegmux.c {gst-ffmpeg-0.10.5/ext/ffmpeg} i do not
see any
    > > > "gst_pad_push" function.
    > > >
    > > > I understand we need a function something like "gst_pad_push
    > > > (asfmux->srcpad, buf)", so as to push the buffer to the sink pad
of
    > next
    > > > module.
    > > >
    > > > But i do not find any such api in gstffmpegmux.c.
    > > >
    > > > So i am unable to find the size of output buffer which is send to
the
    > > next
    > > > module.So i got confused with "gst_pad_push_event"
    > > >
    > > > Please can you help me regarding this issue.
    > > >
    > > > I need all this information to allocate buffer size for my module
"ASF
    > > > parser" which is built from scratch in C. rite know i am reading
from
    > > file.
    > > >
    > > > I need to do same processing in ASF parser when i use ffmux_asf as
    > input
    > > > module for ASF parser.
    > > >
    > > > Please help me regarding this.
    > > >
    > > >
    > > > Regards,
    > > > Irfan
    > > >
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    Regards,

    Sudarshan Bisht


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  Regards,

  Sudarshan Bisht

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