memory leak on custom meta data insert

[tom]

Hello Michael, (sorry for the re-send as I forgot to include the mail-list)

Thank you for picking up on that !  In my mind I was taking the input
buffer and turning it into an output buffer, but that obviously is the
wrong way to do it. I've changed it to:

static GstFlowReturn
gst_mtdata_meta_inject_prepare_output_buffer(GstBaseTransform *trans,
GstBuffer *input, GstBuffer **outbuf)
{
GstMtdataMetaInject *self = GST_MTDMETAINJECT(trans);
GstFlowReturn ret;
ret = GST_BASE_TRANSFORM_CLASS(gst_mtdata_meta_inject_parent_class)->
prepare_output_buffer(trans, input, outbuf);
if (ret != GST_FLOW_OK)
return ret;

*outbuf = gst_buffer_make_writable(*outbuf);
// Then you can add the meta to the output buffer.

// add extra meta data
if (*outbuf != NULL)
if (ret != GST_FLOW_OK)
return ret;

*outbuf = gst_buffer_make_writable(*outbuf);
if (*outbuf != NULL) .....

or should I completely skip the
ret = GST_BASE_TRANSFORM_CLASS(gst_mtdata_meta_inject_parent_class)->
prepare_output_buffer(trans, input, outbuf);
part ?

Kind regards,
Tom

On Tue, 8 Mar 2022 at 04:04, Michael Gruner <michael.gruner at ridgerun.com>
wrote:

> Hey Tom
>
> Is this line ok?
>
>   *outbuf = gst_buffer_make_writable(input);
>
> Shouldn’t it be:
>
>   *outbuf = gst_buffer_make_writable(*outbuf);
>
> The way it is right now you are leaking the outbuf creating when calling:
>
>
>  ret = GST_BASE_TRANSFORM_CLASS(gst_mtdata_meta_inject_parent_class)->prepare_output_buffer(trans, input, outbuf);
>
> Michael
>
> On 6 Mar 2022, at 21:11, tom via gstreamer-devel <
> gstreamer-devel at lists.freedesktop.org> wrote:
>
> Hello,
>
> I'm trying to write a simple plugin that only inserts data as meta data to
> the stream.
> My plugin is derived from GstBaseTransform
>
> typedef struct GstMtdataMetaInject
> {
> GstBaseTransform base_mtdataplugins;
>
> and i've created a simple meta data like: (see attached files)
>
> struct _MtdataMeta
> {
> GstMeta meta;
> gchar *jsonstring;
> };
>
>
> and to insert the meta data (on every frame for now)
>
>
> static GstFlowReturn
> gst_mtdata_meta_inject_prepare_output_buffer(GstBaseTransform *trans,
> GstBuffer *input, GstBuffer **outbuf)
> {
> GstMtdataMetaInject *self = GST_MTDMETAINJECT(trans);
> GstFlowReturn ret;
> ret = GST_BASE_TRANSFORM_CLASS(gst_mtdata_meta_inject_parent_class)->
> prepare_output_buffer(trans, input, outbuf);
> if (ret != GST_FLOW_OK)
> return ret;
> *outbuf = gst_buffer_make_writable(input);
> if (*outbuf != NULL)
> {
> // string hello = StringUtils::current_date_time_string();
> // string hello = "12345678901234";
> string hello = StringUtils::random_string(14);
>
> MtdataMeta *in = gst_buffer_add_mtdata_meta(*outbuf, (gchar *)hello.c_str
> ());
>
> GST_WARNING("Added metdata: %s", in->jsonstring);
> }
> return ret;
> }
> however i'm getting a quite fast memory leak that i can see in
> gst-launch-1.0 where it goes from 30% memory up to 60% in a matter of a
> minute.
> the funny think is that if i change the meta data string to be something
> constant like "12345678901234" with the same length, there is no memory
> leak and it stays on 28% forever.
>
> Do I need to go to the last element in the stream and 'free' the meta data
> so it doesn't add up ?
> Kind regards,
> Tom
>
> <mtdata_meta.h><mtdata_meta.cpp><gstmtdmetainject.h><gstmtdmetainject.cpp>
>
>
>

-- 
☕𝓉𝓈
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