avformat/matroskaenc: Change signature of mkv_write_track()

Up until now, mkv_write_track() received the index of the stream whose
header data it is about to write as parameter; this index has until
recently been explicitly used to generate both TrackNumber and TrackUID.
But this is no longer so and as there is no reason why the function
for writing a single TrackEntry should even know the index of the
TrackEntry it is about to write, said index is replaced in the list of
function parameters by the corresponding AVStream and mkv_track.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/matroskaenc.c

@@ -1081,11 +1081,11 @@ static int mkv_write_stereo_mode(AVFormatContext *s, AVIOContext *pb,
 }
 
 static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
-                           int i, AVIOContext *pb, int default_stream_exists)
+                           AVStream *st, mkv_track *track, AVIOContext *pb,
+                           int default_stream_exists)
 {
-    AVStream *st = s->streams[i];
     AVCodecParameters *par = st->codecpar;
-    ebml_master subinfo, track;
+    ebml_master subinfo, track_master;
     int native_id = 0;
     int qt_id = 0;
     int bit_depth;
@@ -1108,9 +1108,9 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
             return ret;
     }
 
-    track = start_ebml_master(pb, MATROSKA_ID_TRACKENTRY, 0);
-    put_ebml_uint (pb, MATROSKA_ID_TRACKNUMBER, mkv->tracks[i].track_num);
-    put_ebml_uid  (pb, MATROSKA_ID_TRACKUID, mkv->tracks[i].uid);
+    track_master = start_ebml_master(pb, MATROSKA_ID_TRACKENTRY, 0);
+    put_ebml_uint(pb, MATROSKA_ID_TRACKNUMBER, track->track_num);
+    put_ebml_uid (pb, MATROSKA_ID_TRACKUID,    track->uid);
     put_ebml_uint (pb, MATROSKA_ID_TRACKFLAGLACING , 0);    // no lacing (yet)
 
     if ((tag = av_dict_get(st->metadata, "title", NULL, 0)))
@@ -1207,7 +1207,7 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
         else if (!native_id) {
             // if there is no mkv-specific codec ID, use VFW mode
             put_ebml_string(pb, MATROSKA_ID_CODECID, "V_MS/VFW/FOURCC");
-            mkv->tracks[i].write_dts = 1;
+            track->write_dts = 1;
             s->internal->avoid_negative_ts_use_pts = 0;
         }
 
@@ -1283,9 +1283,9 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
                 av_log(s, AV_LOG_ERROR, "Initial padding is invalid\n");
                 return AVERROR(EINVAL);
             }
-//            mkv->tracks[i].ts_offset = av_rescale_q(par->initial_padding,
-//                                                    (AVRational){ 1, par->sample_rate },
-//                                                    st->time_base);
+//            track->ts_offset = av_rescale_q(par->initial_padding,
+//                                            (AVRational){ 1, par->sample_rate },
+//                                            st->time_base);
 
             put_ebml_uint(pb, MATROSKA_ID_CODECDELAY, codecdelay);
         }
@@ -1301,7 +1301,7 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
         subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKAUDIO, 0);
         put_ebml_uint  (pb, MATROSKA_ID_AUDIOCHANNELS    , par->channels);
 
-        mkv->tracks[i].sample_rate_offset = avio_tell(pb);
+        track->sample_rate_offset = avio_tell(pb);
         put_ebml_float (pb, MATROSKA_ID_AUDIOSAMPLINGFREQ, sample_rate);
         if (output_sample_rate)
             put_ebml_float(pb, MATROSKA_ID_AUDIOOUTSAMPLINGFREQ, output_sample_rate);
@@ -1337,13 +1337,13 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
     }
 
     if (mkv->mode != MODE_WEBM || par->codec_id != AV_CODEC_ID_WEBVTT) {
-        mkv->tracks[i].codecpriv_offset = avio_tell(pb);
+        track->codecpriv_offset = avio_tell(pb);
         ret = mkv_write_codecprivate(s, pb, par, native_id, qt_id);
         if (ret < 0)
             return ret;
     }
 
-    end_ebml_master(pb, track);
+    end_ebml_master(pb, track_master);
 
     return 0;
 }
@@ -1365,7 +1365,9 @@ static int mkv_write_tracks(AVFormatContext *s)
         default_stream_exists |= st->disposition & AV_DISPOSITION_DEFAULT;
     }
     for (i = 0; i < s->nb_streams; i++) {
-        ret = mkv_write_track(s, mkv, i, mkv->tracks_bc, default_stream_exists);
+        AVStream *st = s->streams[i];
+        ret = mkv_write_track(s, mkv, st, &mkv->tracks[i],
+                              mkv->tracks_bc, default_stream_exists);
         if (ret < 0)
             return ret;
     }