cache: make backbuffer size configurable

Allow setting an arbitrary amount, instead of the fixed 50%.

This is nto striclty backwards compatible. The defaults don't change,
but the --cache/--cache-default options now set the readahead portion.
So in practice, users who configured this until now will see the
double amount of cache being used, _plus_ the 75MB default backbuffer
will be in use.

2 files changed, 4 insertions, 1 deletions

diff --git a/options/options.c b/options/options.c
index db91d66149..4f6839eede 100644
--- a/options/options.c
+++ b/options/options.c
@@ -156,6 +156,7 @@ const m_option_t mp_opts[] = {
                       ({"no", 0})),
     OPT_INTRANGE("cache-initial", stream_cache.initial, 0, 0, 0x7fffffff),
     OPT_INTRANGE("cache-seek-min", stream_cache.seek_min, 0, 0, 0x7fffffff),
+    OPT_INTRANGE("cache-backbuffer", stream_cache.back_buffer, 0, 0, 0x7fffffff),
     OPT_STRING("cache-file", stream_cache.file, M_OPT_FILE),
     OPT_INTRANGE("cache-file-size", stream_cache.file_max, 0, 0, 0x7fffffff),
 
@@ -712,9 +713,10 @@ const struct MPOpts mp_default_opts = {
     .position_resume = 1,
     .stream_cache = {
         .size = -1,
-        .def_size = 150000,
+        .def_size = 75000,
         .initial = 0,
         .seek_min = 500,
+        .back_buffer = 75000,
         .file_max = 1024 * 1024,
     },
     .demuxer_thread = 1,
diff --git a/options/options.h b/options/options.h
index 5d8bd2ea09..3dcb783164 100644
--- a/options/options.h
+++ b/options/options.h
@@ -53,6 +53,7 @@ struct mp_cache_opts {
     int def_size;
     int initial;
     int seek_min;
+    int back_buffer;
     char *file;
     int file_max;
 };