avformat/segafilm: Do not assume AV_CODEC_ID_NONE is 0

Suggested-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/segafilm.c

@@ -144,11 +144,11 @@ static int film_read_header(AVFormatContext *s)
         film->video_type = AV_CODEC_ID_NONE;
     }
 
-    if (!film->video_type && !film->audio_type)
+    if (film->video_type == AV_CODEC_ID_NONE && film->audio_type == AV_CODEC_ID_NONE)
         return AVERROR_INVALIDDATA;
 
     /* initialize the decoder streams */
-    if (film->video_type) {
+    if (film->video_type != AV_CODEC_ID_NONE) {
         st = avformat_new_stream(s, NULL);
         if (!st)
             return AVERROR(ENOMEM);
@@ -169,7 +169,7 @@ static int film_read_header(AVFormatContext *s)
         }
     }
 
-    if (film->audio_type) {
+    if (film->audio_type != AV_CODEC_ID_NONE) {
         st = avformat_new_stream(s, NULL);
         if (!st)
             return AVERROR(ENOMEM);
@@ -244,7 +244,7 @@ static int film_read_header(AVFormatContext *s)
             film->sample_table[i].pts = AV_RB32(&scratch[8]) & 0x7FFFFFFF;
             film->sample_table[i].keyframe = (scratch[8] & 0x80) ? 0 : AVINDEX_KEYFRAME;
             video_frame_counter++;
-            if (film->video_type)
+            if (film->video_type != AV_CODEC_ID_NONE)
                 av_add_index_entry(s->streams[film->video_stream_index],
                                    film->sample_table[i].sample_offset,
                                    film->sample_table[i].pts,
@@ -253,10 +253,10 @@ static int film_read_header(AVFormatContext *s)
         }
     }
 
-    if (film->audio_type)
+    if (film->audio_type != AV_CODEC_ID_NONE)
         s->streams[film->audio_stream_index]->duration = audio_frame_counter;
 
-    if (film->video_type)
+    if (film->video_type != AV_CODEC_ID_NONE)
         s->streams[film->video_stream_index]->duration = video_frame_counter;
 
     film->current_sample = 0;