shithub: libvpx

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Set the maximum decode threads to be 8.

This will fix the frame parallel decode hang on windows
due to not enough semaphores.

This will also make the frame parallel decode safer as
the number of frame buffers could only support maximum
8 threads.

Change-Id: Id9ef50692819dcbebbd74a0aabffbfb3f39a4309

--- a/vp9/common/vp9_thread.h

+++ b/vp9/common/vp9_thread.h

@@ -22,6 +22,10 @@

 extern "C" {

 #endif

+// Set maximum decode threads to be 8 due to the limit of frame buffers

+// and not enough semaphores in the emulation layer on windows.

+#define MAX_DECODE_THREADS 8

+

 #if CONFIG_MULTITHREAD

 #if defined(_WIN32)

@@ -103,8 +107,8 @@

 static INLINE int pthread_cond_init(pthread_cond_t *const condition,

                                     void* cond_attr) {

   (void)cond_attr;

-  condition->waiting_sem_ = CreateSemaphore(NULL, 0, 1, NULL);

-  condition->received_sem_ = CreateSemaphore(NULL, 0, 1, NULL);

+  condition->waiting_sem_ = CreateSemaphore(NULL, 0, MAX_DECODE_THREADS, NULL);

+  condition->received_sem_ = CreateSemaphore(NULL, 0, MAX_DECODE_THREADS, NULL);

   condition->signal_event_ = CreateEvent(NULL, FALSE, FALSE, NULL);

   if (condition->waiting_sem_ == NULL ||

       condition->received_sem_ == NULL ||

--- a/vp9/vp9_dx_iface.c

+++ b/vp9/vp9_dx_iface.c

@@ -363,6 +363,8 @@

   ctx->num_cache_frames = 0;

   ctx->num_frame_workers =

       (ctx->frame_parallel_decode == 1) ? ctx->cfg.threads: 1;

+  if (ctx->num_frame_workers > MAX_DECODE_THREADS)

+    ctx->num_frame_workers = MAX_DECODE_THREADS;

   ctx->available_threads = ctx->num_frame_workers;

   ctx->flushed = 0;