multithreaded/SMP motion estimation

multithreaded/SMP encoding for MPEG1/MPEG2/MPEG4/H263
all pthread specific code is in pthread.c
to try it, run configure --enable-pthreads and ffmpeg ... -threads <num>
the internal thread API is a simple AVCodecContext.execute() callback which executes a given function pointer with different arguments and returns after finishing all, that way no mutexes or other thread-mess is needed outside pthread.c

Originally committed as revision 2772 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 139 insertions, 0 deletions

diff --git a/libavcodec/pthread.c b/libavcodec/pthread.c
new file mode 100644
index 0000000000..6f98dc41f4
--- /dev/null
+++ b/libavcodec/pthread.c
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+#include <semaphore.h>
+#include <pthread.h>
+
+//#define DEBUG
+
+#include "avcodec.h"
+#include "common.h"
+
+
+typedef struct ThreadContext{
+    AVCodecContext *avctx;
+    pthread_t thread;
+    sem_t work_sem;
+    sem_t done_sem;
+    int (*func)(AVCodecContext *c, void *arg);
+    void *arg;
+    int ret;
+}ThreadContext;
+
+static void * thread_func(void *v){
+    ThreadContext *c= v;
+
+    for(;;){
+//printf("thread_func %X enter wait\n", (int)v); fflush(stdout);
+        sem_wait(&c->work_sem);
+//printf("thread_func %X after wait (func=%X)\n", (int)v, (int)c->func); fflush(stdout);
+        if(c->func)
+            c->ret= c->func(c->avctx, c->arg);
+        else
+            return NULL;
+//printf("thread_func %X signal complete\n", (int)v); fflush(stdout);
+        sem_post(&c->done_sem);
+    }
+    
+    return NULL;
+}
+
+/**
+ * free what has been allocated by avcodec_pthread_init().
+ * must be called after decoding has finished, especially dont call while avcodec_pthread_execute() is running
+ */
+void avcodec_pthread_free(AVCodecContext *s){
+    ThreadContext *c= s->thread_opaque;
+    int i;
+
+    for(i=0; i<s->thread_count; i++){
+        int val;
+        
+        sem_getvalue(&c[i].work_sem, &val); assert(val == 0);
+        sem_getvalue(&c[i].done_sem, &val); assert(val == 0);
+
+        c[i].func= NULL;
+        sem_post(&c[i].work_sem);
+        pthread_join(c[i].thread, NULL);
+        sem_destroy(&c[i].work_sem);
+        sem_destroy(&c[i].done_sem);
+    }
+
+    av_freep(&s->thread_opaque);
+}
+
+int avcodec_pthread_execute(AVCodecContext *s, int (*func)(AVCodecContext *c2, void *arg2),void **arg, int *ret, int count){
+    ThreadContext *c= s->thread_opaque;
+    int i, val;
+    
+    assert(s == c->avctx);
+    assert(count <= s->thread_count);
+    
+    /* note, we can be certain that this is not called with the same AVCodecContext by different threads at the same time */
+
+    for(i=0; i<count; i++){
+        sem_getvalue(&c[i].work_sem, &val); assert(val == 0);
+        sem_getvalue(&c[i].done_sem, &val); assert(val == 0);
+        
+        c[i].arg= arg[i];
+        c[i].func= func;
+        c[i].ret= 12345;
+        sem_post(&c[i].work_sem);
+    }
+    for(i=0; i<count; i++){
+        sem_wait(&c[i].done_sem);
+
+        sem_getvalue(&c[i].work_sem, &val); assert(val == 0);
+        sem_getvalue(&c[i].done_sem, &val); assert(val == 0);
+        
+        c[i].func= NULL;
+        if(ret) ret[i]= c[i].ret;
+    }
+    return 0;
+}
+
+int avcodec_pthread_init(AVCodecContext *s, int thread_count){
+    int i;
+    ThreadContext *c;
+
+    s->thread_count= thread_count;
+
+    assert(!s->thread_opaque);
+    c= av_mallocz(sizeof(ThreadContext)*thread_count);
+    s->thread_opaque= c;
+    
+    for(i=0; i<thread_count; i++){
+//printf("init semaphors %d\n", i); fflush(stdout);
+        c[i].avctx= s;
+        if(sem_init(&c[i].work_sem, 0, 0))
+            goto fail;
+        if(sem_init(&c[i].done_sem, 0, 0))
+            goto fail;
+//printf("create thread %d\n", i); fflush(stdout);
+        if(pthread_create(&c[i].thread, NULL, thread_func, &c[i]))
+            goto fail;
+    }
+//printf("init done\n"); fflush(stdout);
+    
+    s->execute= avcodec_pthread_execute;
+
+    return 0;
+fail:
+    avcodec_pthread_free(s);
+    return -1;
+}