Is it possible to set initial index of splitmuxsink? - gstreamer

Question

I have setup gstreamer with few pipes (with help of RidgRun GSTd & gst-interpipe).
First pipe realize snapshots with multifilesink with max-files and could setup starting index=start_index.
Second pipe realize record with splitmuxsink and max-files & max-size-time
GStreamer 1.10.4
gstd v.0.7.0
multifilesink name=snapshot_sink index=${start_index} max-files=20 location=pic_%04d.jpg
splitmuxsink name=rec_file_sink location=rec_%03d.mpg max-size-time=60000000000 send-keyframe-requests=true max-files=5 muxer=mpegtsmux
The problem is that if I restart gstreamer (respectively gstd) the indexes are reset.
If I start recording in second pipe index begins from 000.
I could setup starting index in multifilesink pipe I couldn't find same for splitmuxsink.
Any ideas ?

Answer 1

How about the start-index property
https://gstreamer.freedesktop.org/documentation/multifile/splitmuxsink.html?gi-language=c#splitmuxsink:start-index

Answer 2

I just ran into this issue myself and I am afraid there is no way to do that using command line parameters only.
However, for those who are not afraid of diving into the API and create a gstreamer application, it is achievable using the 'format-location' signal (see the splitmuxsink documentation).
In C/C++, you may define the signal handler as follows:
static gchar* cb_FormatLocation(GstElement* splitmux, guint fragment_id, const int* offset)
{
char* location;
g_object_get(splitmux, "location", &location, nullptr);
gchar* fileName = g_strdup_printf(location, fragment_id + *offset);
g_free(location);
return fileName;
}
and, in the pipeline definition, all you need to do is to compute an offset and pass it to g_signal_connect:
#include <filesystem>
...
GstElement* sink = gst_element_factory_make("splitmuxsink", "sink");
...
std::filesystem::path fileTemplate = "/path/to/folder/%04d.mp4";
int offset = 0;
while (std::filesystem::exists(g_strdup_printf(fileTemplate.c_str(), offset))) offset++;
g_object_set(sink, "location", fileTemplate.c_str(), nullptr);
g_signal_connect (sink, "format-location", G_CALLBACK(cb_FormatLocation), &offset);
Side note: make sure the offset variable is not destroyed before the application terminates.
It should be possible to achieve the same behaviour with the Python API.