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Video Validator
Check Audio Loudness, Video Codecs, MOOV Atoms, Bit Rates and much more!
Video Validation Checks
Video CodecThe video codec is the algorithm used to encode the video. Common codecs are H.264 and VP9. In order to play, the browser or device must support the codec to decode the video. H.264 is supported by almost all browsers and devices. If you're serving the video with a different codec, make sure your targeted device supports it. |
Video Aspect RatioThe aspect ratio is the video width in proportion to the height. A common aspect ratio is 16:9. On the web page of app where the video will be played, the ad unit will likely expect a video that matches the placeholder's aspect ratio. You want to avoid playing portrait videos in a landscape container, as it may be considered a bad user-experience. |
Video DimensionsThe width and height of the video, in pixels. Common sizes are 1920x1080, 1280x720 and 640x360. Serving a video in a non-standard size may lead to letterboxing by the video player: black bars usually at the top and bottom of the video. While technically the video will play fine, it may not be a great user-experience. |
Video Frame RateThe frame rate determines the number of video frames per seconds (fps). Common rates are 23.98, 24 or 29.97 fps. A low frame rate results in a video appearing choppy or jerky. Higher frame rates are a pleasure to the eye, but comes with a higher file size. |
MOOV Atom LocationThe MP4 format consists of atoms (packets of data), that are arranged in a particular order. The MOOV atom acts like a table of contents for the video. In order for the video to start playing, the MOOV atom has to be read first. If that atom is located at the end of the file, the whole file has to be downloaded before playback can begin. On slow networks, users may have to wait a couple of seconds depending on the size of the video. For the video to start playing immediately, the MOOV atom has to be placed at the beginning of the file. |
Video Color SpaceThe color space is a mathematical representation of a range of colors. Common color spaces are RGB and YUV. YUV encodes a video taking human perception into account, allowing for reduced bandwidth and file size. It's doesn't make sense to show colors you can't see anyway, as compared to RGB. |
Video Chroma SubsamplingChroma subsampling is a method used to encode videos by implementing less resolution for color information than for black/white information. A common subsampling type used for videos is 4:2:0. Chroma subsampling takes advantage of the human's visual system's lower acuity for color differences than for black/white. Savely removing information that we can't notice saves bytes, resulting in lower file sizes. |
Audio CodecThe audio codec is the algorithm used to encode the audio stream. Today's standard is AAC. In order to play, the browser or device must support the codec to decode the video. AAC (Advanced Audio Coding) or AAC-LC (low complexity) are supported by almost all browsers and devices. If you're serving the video with a different codec, make sure your targeted device supports it. |
Audio LoudnessThe audio loudness refers to the perception of sound. It's measured in LUFS or LKFS, where -24 is a commonly accepted value. The audio loudness can be set high or low while creating the video. If the video ad is much louder than the original video content that was being played before the ad, this may not be appreciated by the user. YouTube, NetFlix and Apple Music all have maximum LUFS levels to maintain a good user-experience. |
Audio True PeakThe true peak refers to the maximum loudness peak throughout the video. A common threshold is < -1 dB. Imagine a video of nature: a river with some butterflies — just some soft meditation sounds. Then there's an explosion. LUFS levels are determined by averaging the video's loudness over time. It may have been in an acceptable range in this example. The true peak however detects the explosion, as it was the loudest part of the video. |
Audio Sample RateThe audio sample rate defines how many times per second a sound information is stored. Common samples rates at 44.1 and 48 kHz. A sample rate that is too low results in poor audio quality. Higher samples rates result in better quality, but also comes with a higher file size. |
Audio ChannelsThe number of channels on which audio information is stored. Usually 2 (stereo). Videos with more than 2 audio channels are commonly meant for (home) cinemas. For video ads, it may just be too much. |
Audio CompressionThe audio compression method refers to the amount of deleted audio information during encoding. It's either lossy or lossless. Lossless algorithms preserve the original audio data so the sound is exactly the same after compression. Lossy algorithms remove parts of the audio information, but encodes it in a way we barely hear a difference. Lossy compression is preferred as it results in less file size with a negligible loss in quality. |
Audio Bit RateDefines the amount of data stored for every second of audio. Common bit rates are 128, 256 or 320 kbps. Higher bit rates result in better sound quality, as more audio data can be stored per second. It's however a trade-off between file size and quality. |
File FormatThe container is a format used to bundle the video and audio data into one file. Common containers are MPEG-4, WebM and QuickTime. In order to play the video, the browser or device must understand the container format to find out where the video and audio parts are located. MPEG-4 is supported by almost all browsers and devices. If you're serving the video in a different format, make sure your targeted device supports it. For example, serve videos in QuickTime formats only to Apple users. |
Video Bit RateThe container bit rate defines the amount of data stored for every second of audio + video. Higher bit rates result in better video/audio quality, as more data can be stored per second. It's however a trade-off between file size and quality. |
Video Bit Rate ModeThe bit rate mode determines wether or not the amount of data stored per second remains constant over time. Contant bit rates means that the amount of data your device has to load every second remains the same. It's therefore more reliable on slow networks. Variable bit rates result in higher quality, but the data stream will not be contant. If bandwidth is not an issue, variable bit rates are generally preferred. |
File SizeThe total size (in bytes) of the video. Higher file sizes require users to have a higher bandwidth. To avoid buffering or stalling, the file size (bytes) divided by the video duration (seconds) should not exceed the user's bandwidth (in Mbps). |
File ExtensionThe file extension of the video file, for example: mp4. Publishers commonly have a restricted number of video file types they accept. |
Video DurationThe duration of the video in seconds. Common ad durations are 10, 15 or 30 seconds. Publishers commonly have restrictions regarding the duration of videos. Videos taking too long may abandon users. Too short and it may be difficult to transmit the message. |
Video Mime-TypeThe mime-type is a two-part identifier for file formats transmitted over the internet. For an MP4 file, it's video/mp4. The mime type should correspond with the actual file format. This test makes sure MP4 files have a video/mp4 mime-type, and similarly WebM a video/webm mime-type. |
