player: make various commands for managing external tracks abortable

Until now, they could be aborted only by ending playback, and calling
mpv_abort_async_command didn't do anything.

This requires furthering the mess how playback abort is done. The main
reason why mp_cancel exists at all is to avoid that a "frozen" demuxer
(blocked on network I/O or whatever) cannot freeze the core. The core
should always get its way. Previously, there was a single mp_cancel
handle, that could be signaled, and all demuxers would unfreeze. With
external files, we might want to abort loading of a certain external
file, which automatically means they need a separate mp_cancel. So give
every demuxer its own mp_cancel, and "slave" it to whatever parent
mp_cancel handles aborting.

Since the mpv demuxer API conflates creating the demuxer and reading the
file headers, mp_cancel strictly need to be created before the demuxer
is created (or we couldn't abort loading). Although we give every
demuxer its own mp_cancel (as "enforced" by cancel_and_free_demuxer),
it's still rather messy to create/destroy it along with the demuxer.

1 files changed, 3 insertions, 0 deletions

diff --git a/input/cmd.h b/input/cmd.h
index 0f74424f87..a2cbaae510 100644
--- a/input/cmd.h
+++ b/input/cmd.h
@@ -58,6 +58,9 @@ struct mp_cmd_def {
     // asynchronous abort of the command, and explicitly uses mp_cmd_ctx.abort.
     // (Not setting it when it's not needed can save resources.)
     bool can_abort;
+    // If playback ends, and the command is still running, an abort is
+    // automatically triggered.
+    bool abort_on_playback_end;
 };
 
 enum mp_cmd_flags {