FFmpeg Scale and Stretch: A Comprehensive Guide

When it comes to adjusting the dimensions of an audio-visual file, FFmpeg provides several options for scaling and stretching. In this article, we'll explore the various methods available in FFmpeg and discuss their implications on the video stream.

One popular method for scaling and stretching is using the `ffmpeg` command with the `-i` option followed by the input file name. The next step is to specify the aspect ratio using the `-aspect` option. For instance, if you want to set the aspect ratio to 720x540, you would use the following command:

```

ffmpeg -i -aspect 720:540 -c copy

```

However, this method has its limitations. According to ĭelgado's answer, MP4Box can also achieve this goal using the `-par` option, but it doesn't work as described. If you only need to change the metadata flag and adjust the Display Aspect Ratio (DAR), you can stream copy the video without transcoding.

If you want to scale the image while changing the Sample Aspect Ratio (SAR) during transcoding, use the following command:

```

ffmpeg -i -vf scale=720:540 -c:v

```

Keep in mind that this method requires transcoding since you cannot stream copy the video stream while applying a video filter. If you want to change the video display aspect ratio to 4:3, you have two options: either scale the pixels and adjust the SAR or set a metadata flag at the container level that tells external media players to stretch the image to your desired DAR.

It's essential to understand the difference between Sample Aspect Ratio (SAR) and Display Aspect Ratio (DAR). While SAR is related to the actual pixel dimensions, DAR refers to how the image should be displayed. By choosing the right approach, you can ensure that your audio-visual file is optimized for playback on various devices.

In conclusion, FFmpeg provides a range of options for scaling and stretching video files. Whether you choose to use the `-aspect` option or apply a video filter during transcoding, it's crucial to understand the implications on the video stream and the difference between SAR and DAR. With these guidelines in mind, you can successfully adjust the dimensions of your audio-visual file using FFmpeg.

Ffmpeg scale and stretch