Is it possible to force a specific aspect ratio?

[Buzzard85 1]

When I set my Roku Express+ to 4:3 (I have an older TV) it can only play content that is either 4:3 or 16:9. Any content wider than 16:9 is tinted green so I was wondering if I can create a custom profile that forces all Emby content to either be 4:3 or 16:9. I tried:

<CodecProfiles>
	<CodecProfile type="Video" codec="">
		<Conditions>
			<ProfileCondition condition="LessThanEqual" property="Width" value="1280" isRequired="true" />
			<ProfileCondition condition="LessThanEqual" property="Height" value="720" isRequired="true" />
		</Conditions>
		<ApplyConditions />
	</CodecProfile>
</CodecProfiles>

Unfortunately those conditions only resize the video and don't affect the aspect ratio. Is it possible with a custom profile or is it only possible by manually re-encoding?