1, pr export has a black edge because the aspect ratio of the material you imported at the beginning is the benchmark. If the aspect ratio is preset at the beginning, there will be no black edges when exporting.

2. First import a video. Put it in orbit.

3. Select File-Export-Media in the upper left corner to enter the export page.

4. It can be clearly seen that there is a black edge on the left when exporting.

5. According to the video you made, click the stretch in the upper left corner to fill or zoom to fill.

6. Finally, click Export in the lower right corner. Wait a minute, look at the exported video without black edges.