libavfilter/dnn: add header into native model file

Signed-off-by: Guo, Yejun <yejun.guo@intel.com>
Signed-off-by: Pedro Arthur <bygrandao@gmail.com>

libavfilter/dnn/dnn_backend_native.c

@@ -64,6 +64,10 @@ static DNNReturnType set_input_output_native(void *model, DNNInputData *input, c
 DNNModel *ff_dnn_load_model_native(const char *model_filename)
 {
     DNNModel *model = NULL;
+    char header_expected[] = "FFMPEGDNNNATIVE";
+    char *buf;
+    size_t size;
+    int version, header_size, major_version_expected = 0;
     ConvolutionalNetwork *network = NULL;
     AVIOContext *model_file_context;
     int file_size, dnn_size, kernel_size, i;
@@ -84,6 +88,41 @@ DNNModel *ff_dnn_load_model_native(const char *model_filename)
     }
     file_size = avio_size(model_file_context);
 
+    /**
+     * check file header with string and version
+     */
+    size = sizeof(header_expected);
+    buf = av_malloc(size);
+    if (!buf) {
+        avio_closep(&model_file_context);
+        av_freep(&model);
+        return NULL;
+    }
+
+    // size - 1 to skip the ending '\0' which is not saved in file
+    avio_get_str(model_file_context, size - 1, buf, size);
+    dnn_size = size - 1;
+    if (strncmp(buf, header_expected, size) != 0) {
+        av_freep(&buf);
+        avio_closep(&model_file_context);
+        av_freep(&model);
+        return NULL;
+    }
+    av_freep(&buf);
+
+    version = (int32_t)avio_rl32(model_file_context);
+    dnn_size += 4;
+    if (version != major_version_expected) {
+        avio_closep(&model_file_context);
+        av_freep(&model);
+        return NULL;
+    }
+
+    // currently no need to check minor version
+    version = (int32_t)avio_rl32(model_file_context);
+    dnn_size += 4;
+    header_size = dnn_size;
+
     network = av_mallocz(sizeof(ConvolutionalNetwork));
     if (!network){
         avio_closep(&model_file_context);
@@ -95,8 +134,8 @@ DNNModel *ff_dnn_load_model_native(const char *model_filename)
     avio_seek(model_file_context, file_size - 8, SEEK_SET);
     network->layers_num = (int32_t)avio_rl32(model_file_context);
     network->operands_num = (int32_t)avio_rl32(model_file_context);
-    dnn_size = 8;
-    avio_seek(model_file_context, 0, SEEK_SET);
+    dnn_size += 8;
+    avio_seek(model_file_context, header_size, SEEK_SET);
 
     network->layers = av_mallocz(network->layers_num * sizeof(Layer));
     if (!network->layers){

tools/python/convert_from_tensorflow.py

@@ -20,6 +20,7 @@
 import tensorflow as tf
 import numpy as np
 import sys, struct
+import convert_header as header
 
 __all__ = ['convert_from_tensorflow']
 
@@ -229,6 +230,8 @@ class TFConverter:
 
     def dump_to_file(self):
         with open(self.outfile, 'wb') as f:
+            f.write(header.str.encode('utf-8'))
+            np.array([header.major, header.minor], dtype=np.uint32).tofile(f)
             self.dump_layers_to_file(f)
             self.dump_operands_to_file(f)
             np.array([self.layer_number, len(self.name_operand_dict)], dtype=np.uint32).tofile(f)

tools/python/convert_header.py

@@ -0,0 +1,26 @@
+# Copyright (c) 2019
+#
+# This file is part of FFmpeg.
+#
+# FFmpeg 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.
+#
+# FFmpeg 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 FFmpeg; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+# ==============================================================================
+
+str = 'FFMPEGDNNNATIVE'
+
+# increase major and reset minor when we have to re-convert the model file
+major = 0
+
+# increase minor when we don't have to re-convert the model file
+minor = 1