Due to the many distinct screen resolutions and file formats in DOOH, Vistar uses a few methods to ensure creatives match the required resolutions and formats across all media owner networks. These methods include transcoding, resizing, and letterboxing. Vistar factors in these adjustments when providing media buyers guidance on creative specifications to help them plan their campaigns and upload the correct size of creatives.
Transcoding
Transcoding is the process of converting a video file from one format to another format. Vistar uses a third-party service, Zencoder, to transcode all uploaded creative assets to the ad platform to match the required formats across its different media owner networks. You can view a list of available input and output formats that Zencoder can handle. For technical details on the transcoding outputs, see here.
Our system automatically convert all .png creatives to .jpg by default to reduce the chances of campaigns being blocked due to incompatible file type.
Any video creative you upload on the direct side or a buyer uploads in their DSP is transcoded, provided the creative resolution is no greater than 3840x2160 and vice versa.
Note: When a request is sent for both static and video MIME Types and a static file is transcoded, the ad server returns an ad response with the following logic:
- The system chooses a static image asset first.
- The system selects the asset with the highest bitrate if there is no image.
- If the bitrates are identical, the system alphabetically chooses based on asset URL.
Vistar-owned Resizing
Vistar uses resizing to adapt creative assets for screens with different resolutions and aspect ratios. When Vistar resizes a creative, it generates a new image or video file that better matches the target display while keeping the original aspect ratio when possible.
If an exact match isn’t possible, Vistar may apply letterboxing to adjust the creative to the screen. Vistar may also map creatives to standard (canonical) resolutions to simplify creative submission and improve compatibility across inventory.
This is the default behavior when your creatives must closely match the requested dimensions and you aren’t expected to modify them. In these cases, Vistar ensures that the delivered creative fits the screen.
Vistar-owned Resizing Logic
When an exact resolution match isn’t available, Vistar checks a set of standard (canonical) resolutions to find the best match for the display.
If the network supports resizing, Vistar can use a canonical resolution when either of the following is true:
- The display resolution closely matches the aspect ratio of a larger canonical resolution, within 6% variance.
- The display resolution closely matches the aspect ratio of a smaller canonical resolution, and the scaling difference stays within supported bounds.
- The display resolution closely matches the aspect ratio of a canonical resolution that can scale up in one dimension and down in the other, as long as both changes stay within supported bounds.
If Vistar finds a suitable match, it uses that canonical resolution to resize the creative. If it doesn’t find a suitable match, Vistar uses the display resolution.
Media Owner-owned Resizing
Media owner-owned resizing lets you deliver creatives even when they don’t exactly match your screen dimensions. This behavior is controlled by the Allow Resize setting.
When you enable this setting, Vistar may return a creative that’s close to the requested dimensions, within a small aspect ratio tolerance (within 6%). You’re responsible for resizing or adapting the creative to fit your display.
The Allow Resize setting doesn’t mean that Vistar resizes the creative. It means you accept flexibility in the delivered asset and handle the final adjustment.
Use this option if your screens can scale creatives or if exact dimension matching isn’t required. In these cases, you ensure that the creative fits the screen.
Media Owner-owned Resizing Logic
If the network supports media owner-owned resizing, Vistar can return a creative whose aspect ratio closely matches the display rather than requiring an exact resolution match.
In these cases, Vistar looks for a canonical resolution whose aspect ratio is within 6% variance of the display resolution. Vistar can then return that creative for you, the media owner, to adapt to the screen. If it doesn’t, Vistar requires a closer match or uses another supported method. This logic is configured internally. To change this, reach out to support@vistarmedia.com.
Letterboxing
Letterboxing is the process of adding black bars to the top and bottom or left and right of an image or video so that the image or video can be shown with a slightly different aspect ratio. When letterboxed the original image or video is not cropped, stretched, flattened, or modified in any way, as shown in the following example:
Original Asset:
Letterboxed Asset:
Vistar uses letterboxing to allow buyers to upload standard sized creatives and have them be eligible to deliver on non-standard screen sizes. This increases the reach of standard sized creatives, so media owners can more easily monetize screens with non-standard sizes and buyers are not responsible for uploading creatives for every single distinct size to deliver across all targeted inventory. Like with resizing, you can review letterboxed assets in the creatives approval view by clicking on the number in the Assets column. Letterboxed assets are indicated by a check-mark in the Letterbox column.
Note: Letterboxing is disabled for media owners by default. To opt into letterboxing, please reach out to support@vistarmedia.com
Vistar’s letterboxing process will enable standard sizes to be eligible to serve on screens with aspect ratios within 25% of that standard size. The upper and lower bounds of this process are outlined in the table below:
| Width | Height | Aspect Ratio | Lower Bounds | Upper Bounds |
|---|---|---|---|---|
| 1080 | 1920 | 0.56 | 0.42 | 0.70 |
| 1280 | 960 | 1.33 | 1.00 | 1.67 |
| 1920 | 1080 | 1.78 | 1.33 | 2.22 |
| 840 | 400 | 2.10 | 1.58 | 2.63 |
| 1400 | 400 | 3.50 | 2.63 | 4.38 |
Letterboxing Logic
If the network supports letterboxing, Vistar checks whether a canonical resolution can fit the display within supported aspect ratio limits.
Vistar can use letterboxing when both of the following are true:
- The canonical resolution is within 25% variance of the display aspect ratio.
- The display resolution is less than 1.5 times smaller than the canonical resolution.
If those conditions are met, Vistar can use that canonical resolution and apply letterboxing to fit the display.