record option in mediamtx.yml leads to chopped up video

[jkimsis]

Question

Hello,

I've turned on the recording option in mediamtx.yml. It correctly creates the directory for each path, but the video gets recorded in very small segments. Based on the filenames it seems that it starts recording, records for less then a second, throws an error and then starts recording again. The result is a bunch of small .mp4 or .ts files (I tried both) around 100Kb in size of very short duration. I tried concatinating them with ffmpeg and got a playable video, but it goes at 5x - 10x speed. It seems to me that I'm recording about one second for every five to ten seconds of stream.

I'm also watching the stream at the same time and it's going fine, latency less then a second and very little stuttering.

I'm using mediamtx v1.6.0 on a Debian 12 server. The only changes I've made are these:

record: yes
recordPath: /home/user/recordings/%path/%Y-%m-%d_%H-%M-%S-%f
recordFormat: mpegts #or fmp4
recordPartDuration: 100ms
recordSegmentDuration: 1h
recordDeleteAfter: 0s

The input is an rtsp stream from a drone.

Syslog output looks like this (mediamtx log is set at debug level):

2024-03-17T14:51:06.937818+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:06 INF [path live/1703] [record] recording 1 track (H264)
2024-03-17T14:51:07.920217+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:07 ERR [path live/1703] [record] DTS is not monotonically increasing, was 7m10.219s, now is 7m10.219s
2024-03-17T14:51:07.920634+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:07 DEB [path live/1703] [record] creating segment /home/user/recordings/live/1703/2024-03-17_14-51-07-915202.ts
2024-03-17T14:51:07.921012+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:07 DEB [path live/1703] [record] closing segment /home/user/recordings/live/1703/2024-03-17_14-51-07-915202.ts
2024-03-17T14:51:09.921751+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:09 INF [path live/1703] [record] recording 1 track (H264)
2024-03-17T14:51:09.938112+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:09 ERR [path live/1703] [record] DTS is not monotonically increasing, was 7m12.225s, now is 7m12.225s
2024-03-17T14:51:09.938183+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:09 DEB [path live/1703] [record] creating segment /home/user/recordings/live/1703/2024-03-17_14-51-09-932168.ts
2024-03-17T14:51:09.938603+02:00 rtsp mediamtx[10886]: 2024/03/17 14:51:09 DEB [path live/1703] [record] closing segment /home/user/recordings/live/1703/2024-03-17_14-51-09-932168.ts

Has anyone encountered this? If not, does anyone know what command is actually used to record when the record option is on? It seems to be ffmpeg, but I'm not sure.

[obecny]

Yes I have the same issue as well the recording is loosing packets and then mediamtx is restarting the recording. This is bad. The same rtsp stream and ffmpeg commands works perfectly fine though so something is wrong.

[jkimsis]

What do you mean by the same ffmpeg commands working fine?

[aler9]

I think this is a duplicate of #1002 - if you want to contribute to the solution, reply to #1002 and attach a sample video that allows to replicate the issue.