# Troubleshooting

## Logs

While Moonfire NVR is running, logs will be written to stderr.

   * When running `moonfire-nvr config`, you typically should redirect stderr
     to a text file to avoid poor interaction between the interactive stdout
     output and the logging.
   * When running through systemd, stderr will be redirected to the journal.
     Try `sudo journalctl --unit moonfire-nvr` to view the logs. You also
     likely want to set `MOONFIRE_FORMAT=google-systemd` to format logs as
     expected by systemd.

Logging options are controlled by environmental variables:

   * `MOONFIRE_LOG` controls the log level. Its format is similar to the
     `RUST_LOG` variable used by the
     [env-logger](http://rust-lang-nursery.github.io/log/env_logger/) crate.
     `MOONFIRE_LOG=info` is the default.
     `MOONFIRE_LOG=info,moonfire_nvr=debug` gives more detailed logging of the
     `moonfire_nvr` crate itself.
   * `MOONFIRE_FORMAT` selects the output format. The two options currently
     accepted are `google` (the default, like the Google
     [glog](https://github.com/google/glog) package) and `google-systemd` (a
     variation for better systemd compatibility).

## Problems

### `Error: pts not monotonically increasing; got 26615520 then 26539470`

If your streams cut out with an error message like this one, there are a
couple possibilities.

One is that your camera outputs [B
frames](https://en.wikipedia.org/wiki/Video_compression_picture_types#Bi-directional_predicted_.28B.29_frames.2Fslices_.28macroblocks.29).
If you believe this is the case, file a feature request; Moonfire NVR
currently doesn't support B frames. You may be able to configure your camera
to disable B frames in the meantime.

A more subtle problem occurs in cameras such as the Dahua Starlight series
when the following is true:

   * Audio is enabled (thus a single RTSP session has two streams).
   * The camera's clock changes abruptly. Note that many cameras use SNTP
     rather than NTP to adjust time, so they consistently step time rather
     than slew it.
   * They send RTCP Sender Reports (these include the NTP time).

Moonfire NVR currently uses the ffmpeg library to talk to the cameras. ffmpeg
doesn't properly support this situation. It uses the NTP time to adjust the
PTS and DTS, and thus experiences jumps forward and backward. The forward
jumps cause one frame to be artificially lengthened. The backward jumps create
an impossible situation which causes Moonfire NVR to abort the session and
retry.

In the long term, Moonfire NVR will likely implement its own RTSP support.

In the short term, you can use either of two workarounds:

   * Disable audio in the camera settings. Note that Moonfire NVR doesn't
     yet support recording audio anyway.
   * Disable time adjustment. You'll likely want to disable in-picture
     timestamps as well as they will become untrustworthy.

### `moonfire-nvr config` displays garbage

This happens if your machine is configured to a non-UTF-8 locale, due to
gyscos/Cursive#13. As a workaround, type `export LC_ALL=en_US.UTF-8` prior to
running `moonfire-nvr config`.