Decode streams once and only when needed (#1218)

* split data into specialized structs

* move MPEG4-audio decoding into streamTrack

* restore video/audio synchronization in HLS muxer and RTMP server

* log decode errors

* move H264 decoding and re-encoding here from gortsplib

* add tests

* update gortsplib

internal/core/rtmp_source.go

@@ -170,12 +170,15 @@ func (s *rtmpSource) run(ctx context.Context) error {
 							return fmt.Errorf("unable to decode AVCC: %v", err)
 						}
 
-						res.stream.writeData(&data{
+						err = res.stream.writeData(&dataH264{
 							trackID:      videoTrackID,
 							ptsEqualsDTS: h264.IDRPresent(nalus),
 							pts:          tmsg.DTS + tmsg.PTSDelta,
-							h264NALUs:    nalus,
+							nalus:        nalus,
 						})
+						if err != nil {
+							s.Log(logger.Warn, "%v", err)
+						}
 					}
 
 				case *message.MsgAudio:
@@ -184,12 +187,14 @@ func (s *rtmpSource) run(ctx context.Context) error {
 							return fmt.Errorf("received an AAC packet, but track is not set up")
 						}
 
-						res.stream.writeData(&data{
-							trackID:      audioTrackID,
-							ptsEqualsDTS: true,
-							pts:          tmsg.DTS,
-							mpeg4AudioAU: tmsg.Payload,
+						err := res.stream.writeData(&dataMPEG4Audio{
+							trackID: audioTrackID,
+							pts:     tmsg.DTS,
+							aus:     [][]byte{tmsg.Payload},
 						})
+						if err != nil {
+							s.Log(logger.Warn, "%v", err)
+						}
 					}
 				}
 			}