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* Copyright (c) 2004 François Revol <revol@free.fr>
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* This file is part of FFmpeg.
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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typedef struct ThreadContext{
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AVCodecContext *avctx;
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int (*func)(AVCodecContext *c, void *arg);
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// it's odd Be never patented that :D
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static inline int lock_ben(struct benaphore *ben)
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if (atomic_add(&ben->atom, 1) > 0)
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return acquire_sem(ben->sem);
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static inline int unlock_ben(struct benaphore *ben)
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if (atomic_add(&ben->atom, -1) > 1)
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return release_sem(ben->sem);
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static struct benaphore av_thread_lib_ben;
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static int32 ff_thread_func(void *v){
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//printf("thread_func %X enter wait\n", (int)v); fflush(stdout);
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acquire_sem(c->work_sem);
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//printf("thread_func %X after wait (func=%X)\n", (int)v, (int)c->func); fflush(stdout);
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c->ret= c->func(c->avctx, c->arg);
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//printf("thread_func %X signal complete\n", (int)v); fflush(stdout);
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release_sem(c->done_sem);
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* Free what has been allocated by avcodec_thread_init().
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* Must be called after decoding has finished, especially do not call while avcodec_thread_execute() is running.
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void avcodec_thread_free(AVCodecContext *s){
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ThreadContext *c= s->thread_opaque;
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for(i=0; i<s->thread_count; i++){
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release_sem(c[i].work_sem);
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wait_for_thread(c[i].thread, &ret);
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if(c[i].work_sem > B_OK) delete_sem(c[i].work_sem);
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if(c[i].done_sem > B_OK) delete_sem(c[i].done_sem);
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av_freep(&s->thread_opaque);
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static int avcodec_thread_execute(AVCodecContext *s, int (*func)(AVCodecContext *c2, void *arg2),void *arg, int *ret, int count, int size){
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ThreadContext *c= s->thread_opaque;
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assert(s == c->avctx);
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assert(count <= s->thread_count);
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/* note, we can be certain that this is not called with the same AVCodecContext by different threads at the same time */
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for(i=0; i<count; i++){
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c[i].arg= (char*)arg + i*size;
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release_sem(c[i].work_sem);
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for(i=0; i<count; i++){
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acquire_sem(c[i].done_sem);
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if(ret) ret[i]= c[i].ret;
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int avcodec_thread_init(AVCodecContext *s, int thread_count){
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s->thread_count= thread_count;
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if (thread_count <= 1)
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assert(!s->thread_opaque);
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c= av_mallocz(sizeof(ThreadContext)*thread_count);
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for(i=0; i<thread_count; i++){
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//printf("init semaphors %d\n", i); fflush(stdout);
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if((c[i].work_sem = create_sem(0, "ff work sem")) < B_OK)
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if((c[i].done_sem = create_sem(0, "ff done sem")) < B_OK)
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//printf("create thread %d\n", i); fflush(stdout);
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c[i].thread = spawn_thread(ff_thread_func, "libavcodec thread", B_LOW_PRIORITY, &c[i] );
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if( c[i].thread < B_OK ) goto fail;
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resume_thread(c[i].thread );
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//printf("init done\n"); fflush(stdout);
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s->execute= avcodec_thread_execute;
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avcodec_thread_free(s);
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/* provide a mean to serialize calls to avcodec_*() for thread safety. */
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int avcodec_thread_lock_lib(void)
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return lock_ben(&av_thread_lib_ben);
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int avcodec_thread_unlock_lib(void)
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return unlock_ben(&av_thread_lib_ben);
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/* our versions of _init and _fini (which are called by those actually from crt.o) */
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void initialize_after(void)
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av_thread_lib_ben.atom = 0;
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av_thread_lib_ben.sem = create_sem(0, "libavcodec benaphore");
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void uninitialize_before(void)
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delete_sem(av_thread_lib_ben.sem);