VideoFrame.reformat ignores source colorspace by default

Created by: animetosho

Overview

Unless otherwise told, it seems like VideoFrame.to_rgb (and conversely to_image) assumes the source colorspace to be 601, regardless of what it actually is.
If given a source that, for example, is using a 709 colorspace, the resulting RGB output is incorrect.

Expected behavior

to_rgb should use the colorspace specified by the source.

Actual behavior

If src_colorspace is not supplied, 601 is assumed.

Investigation

On a source using a 709 colorspace, specifying src_colorspace='ITU709' in to_rgb/to_image causes the correct output to be generated. Unfortunately, it seems like PyAV doesn't offer a way to determine what the source colorspace is, so this strategy isn't feasible unless the colorspace can be determined via other means.

Reproduction

Use the keyframe saving example with a source using a BT.709 colorspace.

Versions

• PyAV: 8.1.0
• libav*: 4.4