AV-Sync media file preparation

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1. General

Two steps are required to prepare your video for use with AV-Sync:

  1. Prepare the video file (replace the audio with the AV-Sync track). The video file will play on your mediaplayer.
  2. Prepare the audio file (split off the audio from the video to a MP3 file). The audio file will be uploaded in the TourEditor to be played on the Podcatcher.

Creating these files is an automatic process when using the video tool.

For more information on the usage of the tool, or for detailed instructions on how to do the media file preparation manually, please refer to the following sections.

2. AV-Sync video tool

The easiest way to prepare you media files is by using the AV-Sync video tool. You can download it here:

https://help.guideid.com/downloads/AV-Sync_Video_Tool_0.3.exe

Note: When opening the program, you may see the message “Windows protected your PC”. Please click the link “More info” and then the button “Run anyway” to continue.

You can drag and drop any video on the tool, and it will create two new files in the same directory as the input file:

  1. <inputfilename>_video.mp4
  2. <inputfilename>_audio.mp3

The video file is to be placed on your mediaplayer. The audio file is to be uploaded in the TourEditor, to play on the Podcatchers.

2.1. Advanced video settings

If the advanced checkbox has not been selected, the video tool will use settings that suit most cases. If it has been selected, the following video options are available:

  • Convert: This checkbox enables conversion of the video. When unchecked, the video content is ‘multiplexed’ into the output file unmodified. This means that video resolution and quality will remain unchanged. When checked, video is transcoded to the h264 codec. Note that conversion may be automatically enabled, if your video is encoded using a video codec that is not supported in MP4 files. If so, the progress will indicate “Converting video”.
  • Flexcode: This checkbox enables the IDentifier code input field to be used for flexible mode AV-Sync videos. Please refer to the AV-Sync manual for details.
  • Room audio: If unchecked, the output video will contain the AV-Sync track instead of the original audio. If checked, the original audio is converted to a single channel and added to the output video as well. The output video will contain a stereo audio track, with the AV-Sync track on the right, and the original audio on the left channel. This makes it possible to still play the original audio in the room with the video, in addition to hearing the audio on the Podcatchers.

2.2. Advanced audio settings

If the advanced checkbox has not been selected, the video tool will use settings that suit most cases. If it has been selected, the following audio options are available:

  • Bitrate: Choose the bitrate for the audio to be played on the Podcatchers. Note that a higher bitrate improves the quality, but also the time required to sync the Podcatchers. We advice a bitrate of 64k for mono, and 128k for stereo. If left to auto, the encoder uses the input file to choose the best bitrate for you.
  • Channels: Choose the amount of channels for the audio to be played on the Podcatchers. If the input file contains stereo audio, you may choose to reduce it to mono. This way the bitrate can be reduced, reducing the sync time per Podcatcher. Using stereo is advised when using headphones.
  • Extend: This input field allows extending the audio file with silence for the specified time. This could be used for loop correction, however preferably use the slider in the tour editor to configure this: see “Fine tuning” in the AV-Sync manual.

3. Manual method

To manually prepare you media files, the use of video editing software is required. Please refer to the software’s user manual to determine how to execute the following steps.

3.1. Basic

The following steps are required for normal usage of AV-Sync.

  1. Save the original video
    Save the original video that is to played to an easy to access location on your hard drive.
  2. De-mux (split) the audio track from the video, and save it in MP3 format (64 kbps, mono, 48 kHz, -1dB peak level)
    • Split the audio that is to be played by the Podcatcher from the original video
      • Download Avidemux (or any other software you would like to use).
      • Open the video file.
      • Choose “Save audio” from the “Audio” menu.
      • Browse to a location on your hard drive to save the audio file. Choose a file name like “MyAVSyncClip.m4a”.
    • Prepare the MP3 file for playback on the Podcatcher
      • Download Audacity (or any other software you would like to use).
      • Open the audio file you have saved in the previous step.
      • Make the sure that the “Project Rate” as visible in the lower left of the screen is set to 48000 Hz.
      • If required, amplify the track to an appropriate volume level. We recommend -1dB peak level.
        • Choose “All” from the “Select” menu.
        • Choose “Amplify” from the “Effect” menu.
        • Enter the new peak amplitude: -1
        • Click “OK”.
      • Optionally, extend the audio track for loop correction. However preferably use the slider in the tour editor to configure this: see “Fine tuning” in the AV-Sync manual.
        • Scroll right and click on the end of the track, where a yellow line will appear.
        • Choose “Silence..” from the “Generate” menu.
        • Adjust the duration of the silence to the measured loop time (the time the media player requires to restart the video) and choose “OK”.
      • Export the file in MP3 format, without ID3 tags.
        • Choose “Export” -> “Export as MP3” from the “File” menu.
        • Select “Constant” at the format options.
        • Adjust the quality to one of the recommended formats:
          • 64 kbps, Mono
          • 128 kbps, Stereo
        • Click “Save”.
        • Browse to a location on your hard drive to save the audio file. Choose a file name like “MyAVSyncClip.mp3”.
        • At the window “Edit Metadata Tags” choose “Clear” to remove all metadata.
        • Click “OK”.
    • The MP3 file is now ready to be uploaded in the TourEditor.
  3. Download the AV-Sync track
    • The regular AV-Sync track can be downloaded as a zipped WAV-file from this link to a known location on your computer.
    • Unzip the file: click right mouse button, choose “Extract all..”
    • When using the AV-sync in flexible mode, multiple, different AV-Sync tracks are required. You can ask our helpdesk for more information.
  4. Mux (add) the AV-Sync track to the original video
    • The AV-Sync track is provided in WAV format, which provides the best signal quality to the AV-Sync box. The audio content of the track must not be altered in any way for the system to function. We recommend not converting the AV-Sync track to a different format if not required. However for many video formats, the MP3 or AAC format is more standard to use as audio track. Conversion to these formats is no problem, as long as the bitrate is set high enough to prevent signal degradation. As a guideline, use 128 kbps or higher for AAC, or 192 kbps for MP3. Conversion can be done using editing software of your choice. This section provides an example using Audacity and Avidemux.
    • Optionally convert the AV-Sync track to MP3 format, for muxing with video in MP4 format.
      • Download Audacity (or any other software you would like to use).
      • Open the AV-Sync track.
      • Export the file in MP3 format.
        1. Choose “Export” -> “Export as MP3” from the “File” menu.
        2. Select “Constant” at the format options.
        3. Adjust the quality to 192 kbps or higher.
        4. Select “Mono” as channel mode.
        5. Click “Save”.
        6. Browse to a location on your hard drive to save the audio file. Choose a file name like “AVSyncTrack.mp3”.
        7. Click “OK”.
    • Add the AV-Sync track to the video. Make sure that both video and audio start at offset 0. Also make sure that the AV-Sync track is cut short when the video ends. The full original AV-Sync track has a fixed length of 2 hours.
      • Download Avidemux (or any other software you would like to use).
      • Open the video file.
      • Choose “Select track” from the “Audio” menu.
      • Select “Track 0 from.. “, choose option “Add audio track” when it appears.
      • Browse to the location of the AV-Sync track on your hard drive and open it.
      • Click “OK”.
      • Select “MP4 Muxer” as Output format.
        • Note: Using “MP4v2 Muxer” may cause problems when using Brightsign media players.
      • Click “Save” from the “File” menu.
      • Save the new video to an easy to access location on your computer using a new name. This video file is to be used for playback on the media player connected to the AV-Sync box.

3.2. Advanced

This section describes optional steps for more advanced AV-Sync setups.

  1. Play audio on speakers (room audio), in sync with audio played on Podcatchers.
    • This step is required if audio must be played not only on the Podcatchers, but also directly from the media player. This is the case if the use of audio guides is optional, for instance to allow listening in a different language.
    • You can skip this step if all audio is to be played through the Podcatcher.
    • Normally, for use of AV-Sync the audio track played by the media player is replaced by the AV-Sync track. The AV-Sync track requires only a single channel. You can use the other channel to play room audio. For this, the left channel of the original audio of the video must be added as the left channel to the AV-Sync track, making it stereo. This makes original audio available on the white RCA connector of the audio cable from the media player, which is normally unconnected. The AV-Sync track must remain on the right (as in, opposite of left) channel of the track, which should be output on the red RCA connector which is connected to the AV-Sync box.
    • Download Audacity (or any other software you would like to use).
    • Open the AV-Sync track.
    • Choose “Import” -> “Audio” from the “File” menu
    • Browse to the audio file that you have split from the original video (for example: “MyAVSyncClip.m4a”). Two audio files are now opened, both having two channels (stereo). These need to be merged to a single stereo audio file.
    • Click on the label “AV Sync Track” to open a menu. From it, choose, “Split Stereo Track”.
    • Click on the label of the audio file from the original video and do the same.
    • Remove the empty left channel of the AV Sync track by clicking the X mark.
    • Remove the right channel of the audio file from the video by clicking the X mark.
    • Click on the label “AV Sync Track” to open a menu. From it, choose, “Make Stereo Track”. The two remaining mono tracks now form a single stereo track.
    • Export the file in MP3 format.
      1. Choose “Export” -> “Export as MP3” from the “File” menu.
      2. Select “Constant” at the format options.
      3. Adjust the quality to 192 kbps or higher.
      4. Select “Stereo” as channel mode.
      5. Click “Save”.
      6. Browse to a location on your hard drive to save the audio file. Choose a file name like “AVSyncTrackWithRoomAudio.mp3”.
      7. Click “OK”.
    • Continue at the step “Add the AV-Sync track to the video” as described above.