lavfi: add a slice threading infrastructure

Mostly based on libavcodec's

Changelog

@@ -20,6 +20,7 @@ version 10:
 - avconv -deinterlace option removed, the yadif filter should be used instead
 - Apple Intermediate Codec decoder
 - Escape 130 video decoder
+- support for slice multithreading in libavfilter
 
 
 version 9:

cmdutils.c

@@ -1284,6 +1284,9 @@ static void show_help_filter(const char *name)
 
     printf("Filter %s [%s]:\n", f->name, f->description);
 
+    if (f->flags & AVFILTER_FLAG_SLICE_THREADS)
+        printf("    slice threading supported\n");
+
     printf("    Inputs:\n");
     count = avfilter_pad_count(f->inputs);
     for (i = 0; i < count; i++) {

doc/APIchanges

@@ -13,6 +13,13 @@ libavutil:     2012-10-22
 
 API changes, most recent first:
 
+2013-05-xx - xxxxxxx - lavfi 3.10.0 - avfilter.h
+  Add support for slice multithreading to lavfi. Filters supporting threading
+  are marked with AVFILTER_FLAG_SLICE_THREADS.
+  New fields AVFilterContext.thread_type, AVFilterGraph.thread_type and
+  AVFilterGraph.nb_threads (accessible directly or through AVOptions) may be
+  used to configure multithreading.
+
 2013-xx-xx - xxxxxxx - lavu 52.12.0 - cpu.h
   Add av_cpu_count() function for getting the number of logical CPUs.
 

libavfilter/Makefile

@@ -92,5 +92,7 @@ OBJS-$(CONFIG_TESTSRC_FILTER)                += vsrc_testsrc.o
 
 OBJS-$(CONFIG_NULLSINK_FILTER)               += vsink_nullsink.o
 
+OBJS-$(HAVE_THREADS)                         += pthread.o
+
 TOOLS     = graph2dot
 TESTPROGS = filtfmts

libavfilter/avfilter.c

@@ -352,14 +352,37 @@ static const AVClass *filter_child_class_next(const AVClass *prev)
     return NULL;
 }
 
+#define OFFSET(x) offsetof(AVFilterContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption options[] = {
+    { "thread_type", "Allowed thread types", OFFSET(thread_type), AV_OPT_TYPE_FLAGS,
+        { .i64 = AVFILTER_THREAD_SLICE }, 0, INT_MAX, FLAGS, "thread_type" },
+        { "slice", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AVFILTER_THREAD_SLICE }, .unit = "thread_type" },
+    { NULL },
+};
+
 static const AVClass avfilter_class = {
     .class_name = "AVFilter",
     .item_name  = filter_name,
     .version    = LIBAVUTIL_VERSION_INT,
     .child_next = filter_child_next,
     .child_class_next = filter_child_class_next,
+    .option           = options,
 };
 
+static int default_execute(AVFilterContext *ctx, action_func *func, void *arg,
+                           int *ret, int nb_jobs)
+{
+    int i;
+
+    for (i = 0; i < nb_jobs; i++) {
+        int r = func(ctx, arg, i, nb_jobs);
+        if (ret)
+            ret[i] = r;
+    }
+    return 0;
+}
+
 AVFilterContext *ff_filter_alloc(const AVFilter *filter, const char *inst_name)
 {
     AVFilterContext *ret;
@@ -380,11 +403,17 @@ AVFilterContext *ff_filter_alloc(const AVFilter *filter, const char *inst_name)
             goto err;
     }
 
+    av_opt_set_defaults(ret);
     if (filter->priv_class) {
         *(const AVClass**)ret->priv = filter->priv_class;
         av_opt_set_defaults(ret->priv);
     }
 
+    ret->internal = av_mallocz(sizeof(*ret->internal));
+    if (!ret->internal)
+        goto err;
+    ret->internal->execute = default_execute;
+
     ret->nb_inputs = avfilter_pad_count(filter->inputs);
     if (ret->nb_inputs ) {
         ret->input_pads   = av_malloc(sizeof(AVFilterPad) * ret->nb_inputs);
@@ -421,6 +450,7 @@ err:
     av_freep(&ret->output_pads);
     ret->nb_outputs = 0;
     av_freep(&ret->priv);
+    av_freep(&ret->internal);
     av_free(ret);
     return NULL;
 }
@@ -478,6 +508,7 @@ void avfilter_free(AVFilterContext *filter)
     av_freep(&filter->inputs);
     av_freep(&filter->outputs);
     av_freep(&filter->priv);
+    av_freep(&filter->internal);
     av_free(filter);
 }
 
@@ -525,6 +556,21 @@ int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options)
 {
     int ret = 0;
 
+    ret = av_opt_set_dict(ctx, options);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Error applying generic filter options.\n");
+        return ret;
+    }
+
+    if (ctx->filter->flags & AVFILTER_FLAG_SLICE_THREADS &&
+        ctx->thread_type & ctx->graph->thread_type & AVFILTER_THREAD_SLICE &&
+        ctx->graph->internal->thread_execute) {
+        ctx->thread_type       = AVFILTER_THREAD_SLICE;
+        ctx->internal->execute = ctx->graph->internal->thread_execute;
+    } else {
+        ctx->thread_type = 0;
+    }
+
     if (ctx->filter->priv_class) {
         ret = av_opt_set_dict(ctx->priv, options);
         if (ret < 0) {

libavfilter/avfilter.h

@@ -401,6 +401,11 @@ enum AVMediaType avfilter_pad_get_type(const AVFilterPad *pads, int pad_idx);
  * the options supplied to it.
  */
 #define AVFILTER_FLAG_DYNAMIC_OUTPUTS       (1 << 1)
+/**
+ * The filter supports multithreading by splitting frames into multiple parts
+ * and processing them concurrently.
+ */
+#define AVFILTER_FLAG_SLICE_THREADS         (1 << 2)
 
 /**
  * Filter definition. This defines the pads a filter contains, and all the
@@ -472,6 +477,13 @@ typedef struct AVFilter {
     struct AVFilter *next;
 } AVFilter;
 
+/**
+ * Process multiple parts of the frame concurrently.
+ */
+#define AVFILTER_THREAD_SLICE (1 << 0)
+
+typedef struct AVFilterInternal AVFilterInternal;
+
 /** An instance of a filter */
 struct AVFilterContext {
     const AVClass *av_class;              ///< needed for av_log()
@@ -497,6 +509,29 @@ struct AVFilterContext {
     void *priv;                     ///< private data for use by the filter
 
     struct AVFilterGraph *graph;    ///< filtergraph this filter belongs to
+
+    /**
+     * Type of multithreading being allowed/used. A combination of
+     * AVFILTER_THREAD_* flags.
+     *
+     * May be set by the caller before initializing the filter to forbid some
+     * or all kinds of multithreading for this filter. The default is allowing
+     * everything.
+     *
+     * When the filter is initialized, this field is combined using bit AND with
+     * AVFilterGraph.thread_type to get the final mask used for determining
+     * allowed threading types. I.e. a threading type needs to be set in both
+     * to be allowed.
+     *
+     * After the filter is initialzed, libavfilter sets this field to the
+     * threading type that is actually used (0 for no multithreading).
+     */
+    int thread_type;
+
+    /**
+     * An opaque struct for libavfilter internal use.
+     */
+    AVFilterInternal *internal;
 };
 
 /**
@@ -793,6 +828,8 @@ int avfilter_copy_buf_props(AVFrame *dst, const AVFilterBufferRef *src);
  */
 const AVClass *avfilter_get_class(void);
 
+typedef struct AVFilterGraphInternal AVFilterGraphInternal;
+
 typedef struct AVFilterGraph {
     const AVClass *av_class;
 #if FF_API_FOO_COUNT
@@ -809,6 +846,32 @@ typedef struct AVFilterGraph {
 #if FF_API_FOO_COUNT
     unsigned nb_filters;
 #endif
+
+    /**
+     * Type of multithreading allowed for filters in this graph. A combination
+     * of AVFILTER_THREAD_* flags.
+     *
+     * May be set by the caller at any point, the setting will apply to all
+     * filters initialized after that. The default is allowing everything.
+     *
+     * When a filter in this graph is initialized, this field is combined using
+     * bit AND with AVFilterContext.thread_type to get the final mask used for
+     * determining allowed threading types. I.e. a threading type needs to be
+     * set in both to be allowed.
+     */
+    int thread_type;
+
+    /**
+     * Maximum number of threads used by filters in this graph. May be set by
+     * the caller before adding any filters to the filtergraph. Zero (the
+     * default) means that the number of threads is determined automatically.
+     */
+    int nb_threads;
+
+    /**
+     * Opaque object for libavfilter internal use.
+     */
+    AVFilterGraphInternal *internal;
 } AVFilterGraph;
 
 /**

libavfilter/avfiltergraph.c

@@ -20,6 +20,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "config.h"
+
 #include <string.h>
 
 #include "libavutil/avassert.h"
@@ -27,22 +29,59 @@
 #include "libavutil/channel_layout.h"
 #include "libavutil/common.h"
 #include "libavutil/log.h"
+#include "libavutil/opt.h"
+
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
+#include "thread.h"
+
+#define OFFSET(x) offsetof(AVFilterGraph, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption filtergraph_options[] = {
+    { "thread_type", "Allowed thread types", OFFSET(thread_type), AV_OPT_TYPE_FLAGS,
+        { .i64 = AVFILTER_THREAD_SLICE }, 0, INT_MAX, FLAGS, "thread_type" },
+        { "slice", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AVFILTER_THREAD_SLICE }, .flags = FLAGS, .unit = "thread_type" },
+    { "threads",     "Maximum number of threads", OFFSET(nb_threads),
+        AV_OPT_TYPE_INT,   { .i64 = 0 }, 0, INT_MAX, FLAGS },
+    { NULL },
+};
 
 static const AVClass filtergraph_class = {
     .class_name = "AVFilterGraph",
     .item_name  = av_default_item_name,
     .version    = LIBAVUTIL_VERSION_INT,
+    .option     = filtergraph_options,
 };
 
+#if !HAVE_THREADS
+void ff_graph_thread_free(AVFilterGraph *graph)
+{
+}
+
+int ff_graph_thread_init(AVFilterGraph *graph)
+{
+    graph->thread_type = 0;
+    graph->nb_threads  = 1;
+    return 0;
+}
+#endif
+
 AVFilterGraph *avfilter_graph_alloc(void)
 {
     AVFilterGraph *ret = av_mallocz(sizeof(*ret));
     if (!ret)
         return NULL;
+
+    ret->internal = av_mallocz(sizeof(*ret->internal));
+    if (!ret->internal) {
+        av_freep(&ret);
+        return NULL;
+    }
+
     ret->av_class = &filtergraph_class;
+    av_opt_set_defaults(ret);
+
     return ret;
 }
 
@@ -67,9 +106,12 @@ void avfilter_graph_free(AVFilterGraph **graph)
     while ((*graph)->nb_filters)
         avfilter_free((*graph)->filters[0]);
 
+    ff_graph_thread_free(*graph);
+
     av_freep(&(*graph)->scale_sws_opts);
     av_freep(&(*graph)->resample_lavr_opts);
     av_freep(&(*graph)->filters);
+    av_freep(&(*graph)->internal);
     av_freep(graph);
 }
 
@@ -123,6 +165,14 @@ AVFilterContext *avfilter_graph_alloc_filter(AVFilterGraph *graph,
 {
     AVFilterContext **filters, *s;
 
+    if (graph->thread_type && !graph->internal->thread) {
+        int ret = ff_graph_thread_init(graph);
+        if (ret < 0) {
+            av_log(graph, AV_LOG_ERROR, "Error initializing threading.\n");
+            return NULL;
+        }
+    }
+
     s = ff_filter_alloc(filter, name);
     if (!s)
         return NULL;

libavfilter/internal.h

@@ -25,6 +25,7 @@
  */
 
 #include "avfilter.h"
+#include "thread.h"
 
 #if !FF_API_AVFILTERPAD_PUBLIC
 /**
@@ -117,6 +118,17 @@ struct AVFilterPad {
 };
 #endif
 
+struct AVFilterGraphInternal {
+    void *thread;
+    int (*thread_execute)(AVFilterContext *ctx, action_func *func, void *arg,
+                          int *ret, int nb_jobs);
+};
+
+struct AVFilterInternal {
+    int (*execute)(AVFilterContext *ctx, action_func *func, void *arg,
+                   int *ret, int nb_jobs);
+};
+
 /** default handler for freeing audio/video buffer when there are no references left */
 void ff_avfilter_default_free_buffer(AVFilterBuffer *buf);
 

libavfilter/pthread.c

+/*
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Libavfilter multithreading support
+ */
+
+#include "config.h"
+
+#include "libavutil/common.h"
+#include "libavutil/cpu.h"
+#include "libavutil/mem.h"
+
+#include "avfilter.h"
+#include "internal.h"
+#include "thread.h"
+
+#if HAVE_PTHREADS
+#include <pthread.h>
+#elif HAVE_W32THREADS
+#include "compat/w32pthreads.h"
+#endif
+
+typedef struct ThreadContext {
+    AVFilterGraph *graph;
+
+    int nb_threads;
+    pthread_t *workers;
+    action_func *func;
+
+    /* per-execute perameters */
+    AVFilterContext *ctx;
+    void *arg;
+    int   *rets;
+    int nb_rets;
+    int nb_jobs;
+
+    pthread_cond_t last_job_cond;
+    pthread_cond_t current_job_cond;
+    pthread_mutex_t current_job_lock;
+    int current_job;
+    int done;
+} ThreadContext;
+
+static void* attribute_align_arg worker(void *v)
+{
+    ThreadContext *c = v;
+    int our_job      = c->nb_jobs;
+    int nb_threads   = c->nb_threads;
+    int self_id;
+
+    pthread_mutex_lock(&c->current_job_lock);
+    self_id = c->current_job++;
+    for (;;) {
+        while (our_job >= c->nb_jobs) {
+            if (c->current_job == nb_threads + c->nb_jobs)
+                pthread_cond_signal(&c->last_job_cond);
+
+            pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
+            our_job = self_id;
+
+            if (c->done) {
+                pthread_mutex_unlock(&c->current_job_lock);
+                return NULL;
+            }
+        }
+        pthread_mutex_unlock(&c->current_job_lock);
+
+        c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
+
+        pthread_mutex_lock(&c->current_job_lock);
+        our_job = c->current_job++;
+    }
+}
+
+static void slice_thread_uninit(ThreadContext *c)
+{
+    int i;
+
+    pthread_mutex_lock(&c->current_job_lock);
+    c->done = 1;
+    pthread_cond_broadcast(&c->current_job_cond);
+    pthread_mutex_unlock(&c->current_job_lock);
+
+    for (i = 0; i < c->nb_threads; i++)
+         pthread_join(c->workers[i], NULL);
+
+    pthread_mutex_destroy(&c->current_job_lock);
+    pthread_cond_destroy(&c->current_job_cond);
+    pthread_cond_destroy(&c->last_job_cond);
+    av_freep(&c->workers);
+}
+
+static void slice_thread_park_workers(ThreadContext *c)
+{
+    pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
+    pthread_mutex_unlock(&c->current_job_lock);
+}
+
+static int thread_execute(AVFilterContext *ctx, action_func *func,
+                          void *arg, int *ret, int nb_jobs)
+{
+    ThreadContext *c = ctx->graph->internal->thread;
+    int dummy_ret;
+
+    if (nb_jobs <= 0)
+        return 0;
+
+    pthread_mutex_lock(&c->current_job_lock);
+
+    c->current_job = c->nb_threads;
+    c->nb_jobs     = nb_jobs;
+    c->ctx         = ctx;
+    c->arg         = arg;
+    c->func        = func;
+    if (ret) {
+        c->rets    = ret;
+        c->nb_rets = nb_jobs;
+    } else {
+        c->rets    = &dummy_ret;
+        c->nb_rets = 1;
+    }
+    pthread_cond_broadcast(&c->current_job_cond);
+
+    slice_thread_park_workers(c);
+
+    return 0;
+}
+
+static int thread_init(ThreadContext *c, int nb_threads)
+{
+    int i, ret;
+
+    if (!nb_threads) {
+        int nb_cpus = av_cpu_count();
+        av_log(c->graph, AV_LOG_DEBUG, "Detected %d logical cores.\n", nb_cpus);
+        // use number of cores + 1 as thread count if there is more than one
+        if (nb_cpus > 1)
+            nb_threads = nb_cpus + 1;
+        else
+            nb_threads = 1;
+    }
+
+    if (nb_threads <= 1)
+        return 1;
+
+    c->nb_threads = nb_threads;
+    c->workers = av_mallocz(sizeof(*c->workers) * nb_threads);
+    if (!c->workers)
+        return AVERROR(ENOMEM);
+
+    c->current_job = 0;
+    c->nb_jobs     = 0;
+    c->done        = 0;
+
+    pthread_cond_init(&c->current_job_cond, NULL);
+    pthread_cond_init(&c->last_job_cond,    NULL);
+
+    pthread_mutex_init(&c->current_job_lock, NULL);
+    pthread_mutex_lock(&c->current_job_lock);
+    for (i = 0; i < nb_threads; i++) {
+        ret = pthread_create(&c->workers[i], NULL, worker, c);
+        if (ret) {
+           pthread_mutex_unlock(&c->current_job_lock);
+           c->nb_threads = i;
+           slice_thread_uninit(c);
+           return AVERROR(ret);
+        }
+    }
+
+    slice_thread_park_workers(c);
+
+    return c->nb_threads;
+}
+
+int ff_graph_thread_init(AVFilterGraph *graph)
+{
+    int ret;
+
+#if HAVE_W32THREADS
+    w32thread_init();
+#endif
+
+    if (graph->nb_threads == 1) {
+        graph->thread_type = 0;
+        return 0;
+    }
+
+    graph->internal->thread = av_mallocz(sizeof(ThreadContext));
+    if (!graph->internal->thread)
+        return AVERROR(ENOMEM);
+
+    ret = thread_init(graph->internal->thread, graph->nb_threads);
+    if (ret <= 1) {
+        av_freep(&graph->internal->thread);
+        graph->thread_type = 0;
+        graph->nb_threads  = 1;
+        return (ret < 0) ? ret : 0;
+    }
+    graph->nb_threads = ret;
+
+    graph->internal->thread_execute = thread_execute;
+
+    return 0;
+}
+
+void ff_graph_thread_free(AVFilterGraph *graph)
+{
+    if (graph->internal->thread)
+        slice_thread_uninit(graph->internal->thread);
+    av_freep(&graph->internal->thread);
+}

libavfilter/thread.h

+/*
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFILTER_THREAD_H
+#define AVFILTER_THREAD_H
+
+#include "avfilter.h"
+
+typedef int (action_func)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
+
+int ff_graph_thread_init(AVFilterGraph *graph);
+
+void ff_graph_thread_free(AVFilterGraph *graph);
+
+#endif /* AVFILTER_THREAD_H */

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  9
+#define LIBAVFILTER_VERSION_MINOR  10
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \