Created attachment 312342 [details] [review]
Patch to free hidden groups at the time of switching

I am running below pipeline:

gst-launch-1.0 playbin uri=https://devimages.apple.com.edgekey.net/streaming/examples/bipbop_4x3/bipbop_4x3_variant.m3u8

I am using a h/w based video decoder.

At the time of switching pads, hlsdemux sends an EOS on older pad and unlinks it.
But my h/w based video decoder was not getting any information that it should close the underlying device apart from EOS.

Upon investigation, I came to gstdecodebin2.c

 
>>>>>>>> gst_decode_chain_start_free_hidden_groups_thread (chain);
        gst_decode_group_hide (chain->active_group);
        chain->old_groups =
            g_list_prepend (chain->old_groups, chain->active_group);
        GST_DEBUG_OBJECT (dbin, "Switching to next group %p",
            chain->next_groups->data);
        chain->active_group = chain->next_groups->data;
        chain->next_groups =
            g_list_delete_link (chain->next_groups, chain->next_groups);
        *switched = TRUE;
        chain->drained = FALSE;

In this code, it first starts a thread to free up old_group and then update the old_group itself (which should be in reverse order, that first update the old_group and then call a function to free it)

Due to this, old_group was freed only at the time of closing of pipeline itself.

This also leads to increase in memory footprint, as hlsdemux keeps selecting different bitrates according to network conditions.