fftools/ffmpeg: add a helper function to access output file size

Stop accessing muxer internals from outside of ffmpeg_mux.

fftools/ffmpeg.c

@@ -1516,8 +1516,7 @@ static void print_report(int is_last_report, int64_t timer_start, int64_t cur_ti
 {
     AVBPrint buf, buf_script;
     OutputStream *ost;
-    AVFormatContext *oc;
-    int64_t total_size;
+    int64_t total_size = of_filesize(output_files[0]);
     AVCodecContext *enc;
     int vid, i;
     double bitrate;
@@ -1546,13 +1545,6 @@ static void print_report(int is_last_report, int64_t timer_start, int64_t cur_ti
 
     t = (cur_time-timer_start) / 1000000.0;
 
-
-    oc = output_files[0]->ctx;
-
-    total_size = avio_size(oc->pb);
-    if (total_size <= 0) // FIXME improve avio_size() so it works with non seekable output too
-        total_size = avio_tell(oc->pb);
-
     vid = 0;
     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_AUTOMATIC);
     av_bprint_init(&buf_script, 0, AV_BPRINT_SIZE_AUTOMATIC);

fftools/ffmpeg.h

@@ -705,5 +705,6 @@ void of_close(OutputFile **pof);
 
 void of_write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost,
                      int unqueue);
+int64_t of_filesize(OutputFile *of);
 
 #endif /* FFTOOLS_FFMPEG_H */

fftools/ffmpeg_mux.c

@@ -333,3 +333,17 @@ int of_muxer_init(OutputFile *of)
 
     return 0;
 }
+
+int64_t of_filesize(OutputFile *of)
+{
+    AVIOContext *pb = of->ctx->pb;
+    int64_t ret = -1;
+
+    if (pb) {
+        ret = avio_size(pb);
+        if (ret <= 0) // FIXME improve avio_size() so it works with non seekable output too
+            ret = avio_tell(pb);
+    }
+
+    return ret;
+}