fftools/ffmpeg: supply hw_device_ctx to filters before initializing them

This is more correct, but was not possible before the recently-added
filtergraph parsing API.

Also, only pass hw devices to filters that are flagged as capable of
using them.

Tested-by: Niklas Haas

fftools/ffmpeg.h

@@ -802,7 +802,12 @@ void hw_device_free_all(void);
 
 int hw_device_setup_for_decode(InputStream *ist);
 int hw_device_setup_for_encode(OutputStream *ost);
-int hw_device_setup_for_filter(FilterGraph *fg);
+/**
+ * Get a hardware device to be used with this filtergraph.
+ * The returned reference is owned by the callee, the caller
+ * must ref it explicitly for long-term use.
+ */
+AVBufferRef *hw_device_for_filter(void);
 
 int hwaccel_decode_init(AVCodecContext *avctx);
 

fftools/ffmpeg_filter.c

@@ -440,7 +440,8 @@ static int graph_opts_apply(AVFilterGraphSegment *seg)
 }
 
 static int graph_parse(AVFilterGraph *graph, const char *desc,
-                       AVFilterInOut **inputs, AVFilterInOut **outputs)
+                       AVFilterInOut **inputs, AVFilterInOut **outputs,
+                       AVBufferRef *hw_device)
 {
     AVFilterGraphSegment *seg;
     int ret;
@@ -456,6 +457,20 @@ static int graph_parse(AVFilterGraph *graph, const char *desc,
     if (ret < 0)
         goto fail;
 
+    if (hw_device) {
+        for (int i = 0; i < graph->nb_filters; i++) {
+            AVFilterContext *f = graph->filters[i];
+
+            if (!(f->filter->flags & AVFILTER_FLAG_HWDEVICE))
+                continue;
+            f->hw_device_ctx = av_buffer_ref(hw_device);
+            if (!f->hw_device_ctx) {
+                ret = AVERROR(ENOMEM);
+                goto fail;
+            }
+        }
+    }
+
     ret = graph_opts_apply(seg);
     if (ret < 0)
         goto fail;
@@ -480,7 +495,7 @@ int init_complex_filtergraph(FilterGraph *fg)
         return AVERROR(ENOMEM);
     graph->nb_threads = 1;
 
-    ret = graph_parse(graph, fg->graph_desc, &inputs, &outputs);
+    ret = graph_parse(graph, fg->graph_desc, &inputs, &outputs, NULL);
     if (ret < 0)
         goto fail;
 
@@ -1114,6 +1129,7 @@ static int graph_is_meta(AVFilterGraph *graph)
 
 int configure_filtergraph(FilterGraph *fg)
 {
+    AVBufferRef *hw_device;
     AVFilterInOut *inputs, *outputs, *cur;
     int ret, i, simple = filtergraph_is_simple(fg);
     const char *graph_desc = simple ? fg->outputs[0]->ost->avfilter :
@@ -1157,11 +1173,9 @@ int configure_filtergraph(FilterGraph *fg)
         fg->graph->nb_threads = filter_complex_nbthreads;
     }
 
-    if ((ret = graph_parse(fg->graph, graph_desc, &inputs, &outputs)) < 0)
-        goto fail;
+    hw_device = hw_device_for_filter();
 
-    ret = hw_device_setup_for_filter(fg);
-    if (ret < 0)
+    if ((ret = graph_parse(fg->graph, graph_desc, &inputs, &outputs, hw_device)) < 0)
         goto fail;
 
     if (simple && (!inputs || inputs->next || !outputs || outputs->next)) {

fftools/ffmpeg_hw.c

@@ -548,17 +548,14 @@ int hwaccel_decode_init(AVCodecContext *avctx)
     return 0;
 }
 
-int hw_device_setup_for_filter(FilterGraph *fg)
+AVBufferRef *hw_device_for_filter(void)
 {
-    HWDevice *dev;
-    int i;
-
     // Pick the last hardware device if the user doesn't pick the device for
     // filters explicitly with the filter_hw_device option.
     if (filter_hw_device)
-        dev = filter_hw_device;
+        return filter_hw_device->device_ref;
     else if (nb_hw_devices > 0) {
-        dev = hw_devices[nb_hw_devices - 1];
+        HWDevice *dev = hw_devices[nb_hw_devices - 1];
 
         if (nb_hw_devices > 1)
             av_log(NULL, AV_LOG_WARNING, "There are %d hardware devices. device "
@@ -567,17 +564,9 @@ int hw_device_setup_for_filter(FilterGraph *fg)
                    "%s is not usable for filters.\n",
                    nb_hw_devices, dev->name,
                    av_hwdevice_get_type_name(dev->type), dev->name);
-    } else
-        dev = NULL;
 
-    if (dev) {
-        for (i = 0; i < fg->graph->nb_filters; i++) {
-            fg->graph->filters[i]->hw_device_ctx =
-                av_buffer_ref(dev->device_ref);
-            if (!fg->graph->filters[i]->hw_device_ctx)
-                return AVERROR(ENOMEM);
-        }
+        return dev->device_ref;
     }
 
-    return 0;
+    return NULL;
 }