amd_media - decoder multi-gpu support (#706)

* add multiple device support for vaapi

* choose multiple devices only if it is available

* check for devices and allow only if it exists for using hwaccel

* minor change

Author: rrawther

amd_openvx_extensions/amd_media/decoder.cpp

@@ -122,14 +122,50 @@ class CLoomIoMediaDecoder {
 
 static enum AVPixelFormat hwPixelFormat;
 
-static int hw_decoder_init(AVCodecContext *ctx, const enum AVHWDeviceType type, AVBufferRef *hw_device_ctx)
+static inline bool exists (const char *name) {
+    if (FILE *file = fopen(name, "r")) {
+        fclose(file);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+static inline int num_hw_devices() {
+    char device[128] = "";
+    int num_hw_devices = 0;
+    for (int i=0; i<10000; i++){
+        snprintf(device, sizeof(device), "/dev/dri/renderD%d", 128 + i);
+        // check  if the device file exists in the system: todo:: is there any other way to enumerate the device?
+        if (exists(device))
+            num_hw_devices++;
+        else
+            break;
+    }
+    return num_hw_devices;
+}
+
+static int hw_decoder_init(AVCodecContext *ctx, const enum AVHWDeviceType type, AVBufferRef *hw_device_ctx, int hw_device_id)
 {
     int err = 0;
-
-    if ((err = av_hwdevice_ctx_create(&hw_device_ctx, type,
-                                      NULL, NULL, 0)) < 0) {
+    char device[128] = "";
+    char* pdevice = NULL;
+    int num_devices = 1; // default;
+    if (type == AV_HWDEVICE_TYPE_VAAPI)
+      num_devices = num_hw_devices();
+    if (hw_device_id >= 0 && hw_device_id < 10000) {
+        if (type == AV_HWDEVICE_TYPE_VAAPI) {
+          snprintf(device, sizeof(device), "/dev/dri/renderD%d", (128 + (hw_device_id % num_devices)));
+        }else {
+          snprintf(device, sizeof(device), "%d", hw_device_id);
+        }
+        pdevice = device;
+    }
+    const char* device_name = pdevice? pdevice : NULL;
+    if ((err = av_hwdevice_ctx_create(&hw_device_ctx, type, device_name, NULL, 0)) < 0) {
         return err;
     }
+    printf("VAAPI device created for device %s and stream %d\n", device_name, hw_device_id);
     ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 
     return err;
@@ -377,7 +413,7 @@ vx_status CLoomIoMediaDecoder::Initialize()
                 vxAddLogEntry((vx_reference)node, status, "ERROR: vaapi is not supported for this device\n");
                 return status;
             }
-            printf("Found vaapi device for %d\n", mediaIndex);
+            //printf("Found vaapi device for %d\n", mediaIndex);
         }
         int err = avformat_open_input(&formatContext, mediaFileName, inputFormat, nullptr);
         if (err) {
@@ -451,7 +487,7 @@ vx_status CLoomIoMediaDecoder::Initialize()
             return -1;
         if (useVaapi[mediaIndex]) {
             codecContext->get_format  = get_hw_format;
-            if (hw_decoder_init(codecContext, hw_type, hw_device_ctx) < 0) {
+            if (hw_decoder_init(codecContext, hw_type, hw_device_ctx, mediaIndex) < 0) {
                 vxAddLogEntry((vx_reference)node, VX_FAILURE, "ERROR: Failed to create specified HW device.\n");
                 return VX_FAILURE;
             }