Knowledge Base

Media Files

Formats, Containers and Codecs

The term "video format" can often be confusing, because it involves two distinct and very different technology concepts: containers (created by software called a multiplexer) and codecs (short for coder/decoder).

The container describes the structure of the file where the video and audio streams are stored, how they are interleaved, and which codecs are used by which stream. It is used to package the video and its components (audio/metadata) and is usually identified by a file extension such as .AVI or .MPG.

Codecs are used inside of a container. A codec is a way of encoding audio or video into a stream of bytes. It is the method used to encode the video and is the chief determiner of quality. The important thing to realize is that most good container formats can hold many codecs. Even .AVI files can hold a wide variety of codecs as their contents. The container does not decide the quality or features of the video itself; that is up to the codec.

The proper way to describe video is to indicate both: for example, an .AVI file containing DivX video and MP2 audio.

How Do I Know the Format of My Video File?

There are free tools available to see what format your video file has and which codec, container, and audio format is used. Examples are MediaInfo and GSpot. GSpot gives a lot of information on your video files, but has not been maintained since 2007.

• https://mediaarea.net/nl/MediaInfo
• http://www.headbands.com/gspot/

Play Media in The Observer XT

Decoders Installed with The Observer XT

Decoders are needed to play back media files. When you install The Observer XT, it installs the LeadTools Package 20.0 to play back video.

Important: Codecs from, for example, DVD burning software may conflict with the ones used by The Observer XT. See Codecs Installed by Other Programs.

The LeadTools Codec Package 20.0 contains the following:

• MP4 Demultiplexer
• MPEG Demultiplexer
• H.264/AVC Video Decoder
• MPEG-2 Video Decoder
• MPEG-4 Video Decoder
• AAC Audio Decoder

Supported Formats

Supported Video Formats

See "How Do I Know the Format of My Video File?" to determine video formats. The Observer XT supports playback of the following digital video formats:

• MPEG-1 (*.mpg, *.mpeg)
• MPEG-2 (*.mpg, *.mpeg, *.vob)
• MPEG-4 (*.avi) including DivX, Xvid, and H.264 *
• Uncompressed AVI (*.avi)
• DV-AVI (*.avi)
• MPEG-4 QuickTime (*.mov)

Note that not all playback speeds may be available in The Observer XT, even for supported formats.

* These video formats are not supported for creating an Episode Selection.

Important: We recommend not opening a video file directly from a mobile device (a smartphone, tablet, etc.). First copy the files to the PC with The Observer XT, then open that copy in the observation.

Supported Audio Formats

• MP3 (*.mp3)
• WAV (*.wav)
• WMA (*.wma)

AAC (*.aac) audio files are not supported, but video files with .aac audio are.

The maximum number of audio files that can be opened is determined by your license. With the Single Media Module you can import one audio file. With the Media Module, you can import up to twenty audio files in a single observation.

Supported Audio Formats for Visualization

You can visualize the following audio formats:

• MPEG Audio Stream, Layer 1 (*.mp1)
• MPEG Audio Stream, Layer 2 (*.mp2)
• MPEG Audio Stream, Layer 3 (*.mp3)
• MPEG-2 Advanced Audio Coding file (*.aac)
• AC3 Audio file format (*.ac3)
• PCM – Pulse-Code Modulation (*.wav)
• ADPCM – Adaptive Differential Pulse-Code Modulation (*.wav)
• Adaptive Multi-Rate ACELP Codec (*.amr)
• Windows Media Audio (*.wma)

When you play your video at a higher or lower speed, .wma audio files are still played at normal speed.

Other formats may be displayed depending on the audio decoders installed on your computer.

Troubleshooting

Invalid Video/Audio

When you try to open a video/audio file, you may get a message stating that the file is of invalid type. This can occur for different reasons, for example the appropriate codec is not installed, the codec cannot play that format, the file does not contain a video stream, or the appropriate demultiplexer is not installed.

The warning message shows details of the format The Observer XT tries to play. Check in the list above whether it corresponds to the supported formats and that the necessary codecs are installed. If necessary, contact the Noldus Help Desk to solve this issue.

When a media file is opened and the audio codec is not found, an error message appears; however, the video plays correctly in The Observer XT.

Record Video

Record Video with MediaRecorder

We recommend recording video with MediaRecorder and using these videos in The Observer XT for offline scoring. See the MediaRecorder documentation for an overview of the supported cameras.

Codecs Installed by Other Programs

Codecs Can Give Problems

Codecs for media players and DVD burning software already installed on your PC may conflict with the codecs that are installed with The Observer XT. It may happen that The Observer XT uses the wrong codec to play back the videos. This may lead to wrong time stamps in the event log, or videos that cannot be played back. Therefore we strongly recommend not installing such programs on the computer with The Observer XT.

Check Which Codecs The Observer XT Uses

1. Open the observation containing video.
2. Right-click the video window and select Properties. The video and audio codecs that are used by The Observer XT are shown next to Video Codec and Audio Codec. Additional information is shown under Filter Details.

The Observer XT provides some audio codecs (see Play Media in The Observer XT). To play back other audio files you must have the right codecs installed. If the required codecs are not available, The Observer XT cannot play it back properly. Please note that The Observer XT plays audio files with a maximum of two audio channels.

Source: The Observer XT 17 Help - Media Files, Noldus Information Technology