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      1. LEIGHTRONIX Knowledge Base
      2. UltraNEXUS-HD
      3. Video

      Avoiding Video File Playback Problems and Blocklisted and Red Highlighted Files

      Most playback problems stem from the video file's format elements falling outside of the recommended specifications of standard broadcast industry video files.

      Also, see the following tutorials:

      A file may be blocked from playing (Blocklisted), if it has format violations.

      Checking for Blocked Files:

      You can check whether a file is blocklisted on the Video Info page of the unit's web interface (WebNEXUS). You can see the details for the file in the window on the right. In that window, the offending format issues will be in red. If the file appears in red, it has been blocked from playing.

      To access the Video Info page:

      1. From WinLGX, go to the Tools menu and select Web Interface.
      2. This will open your default web browser and bring up the web interface login page.
      3. Type in your user and password (same as for WinLGX).
      4. Then click the Video Info button on the right side menu.

      Enabling Blocked Files:

      • Some blocklisted files may have an Enable button in the right side window.
      • You can click that button to unblock the file, but LEIGHTRONIX does not provide support for those instances, and be aware that playing those files may cause playback issues with other files, as stated below.
      • Also, the file will no longer appear in red once a file is enabled.
      • You can disable a video by right-clicking the file and selecting Disable, or you can choose Rescan, and the system will rescan the file for format violations.

      Be Cautious When Enabling Blocked Files:

      • Some file issues can affect the video player and cause other perfectly correct files to play poorly or not play at all.
      • Some file issues can cause the UltraNEXUS-HD to reboot.
      • Other issues can cause the unit's player hardware to lock up, causing some files to fail or play intermittently.
      • This can make troubleshooting difficult with misleading file failures.

      If you have a file that has previously played without issue and now fails to play, check the files that played before it to ensure they meet the proper specifications. You will also want to check the events log for problems with the files that played before the failed file.

      Common format violations

      Below is a list of format elements and their limits to be aware of and keep in check.

      Video Bitrate Issues

      Make sure the video bitrate is 10 MB/s or less.

      Avoid bitrate spikes:

      • If there are no errors in the log and nothing red on the Video Info page, the video file may have video bit rate spikes that cause the player to freeze or fail. The file may play fine at times but then stutter or not play at all other times.
      • A file can have an average bitrate below 10 MB/s but can contain points in the video where the bitrate far exceeds 10 MB/s. What may happen is that the file's overall specs show an average bitrate rating of 10 MB/s or less, so the file would not be flagged or blocklisted.
      • To avoid this, you can try re-rendering the file using a constant bitrate (CBR) setting or run the file through our UltraNEXUS-HD Encoder Software, which will fix the spikes.
      • You may be able to locate the spikes by downloading the file to your PC and playing it using the VLC player. The VLC player tool will look at the bitrate as it's playing. In VLC, go to the Tools menu and select Codec Information. In that window, select the Statistics tab. Observe the Input Bitrate. Click the arrow next to Input Bitrate to see a graph of the bitrate as it changes while the file is playing in VLC. Anything over 10 MB/s can be a problem.

      File Type

      Only use the following four formats:

      • MP4 (This is the recommended file type)
      • MOV
      • M2T
      • MPG (Not recommended for High Definition files)

      Video Resolution

      Use standard broadcast resolutions:

      • 720 x 480
      • 1280 x 720
      • 1920 x 1080

      Nothing larger than 1920 x 1080

      Nothing larger than 720 x 480 for MPG files

      Correct Video Codec

      H.264 (AVC) video codec for MP4, MOV, and M2T

      MPEG2 video codec for MPG.

      Correct Audio Codec

      AAC audio for MP4 and MOV files

      AAC or MPEG Layer II audio for M2T files

      MPEG Layer II audio for MPG files

      Avoid Missing Elements

      No Files without audio – it can be muted, but there must be an audio stream.

      No files without video – it can have black video, but it cannot be an audio-only file.

      Reference Frames

      The file cannot have more than four reference frames.

      If you aren't sure how to get your editing program to change the reference frames, you can run the file through our UltraNEXUS-HD file converter. This will correct the reference frames.

      Some editing software may keep reference frames at or below four if you render it as 1280 x 720.

      Avoid Corrupt Files

      Try playing them directly on your computer using VLC Player to see if they play all the way through. If they do not, you likely have a corrupt file.

      Convert the File

      If you aren't sure about a file's compatibility, you can run it through our free UltraNEXUS-HD file converter, which should fix most issues.

      The converter is available from our knowledge base by searching for "converter."

      Or here's a link to the converter page directly: File Converter