Keep original loudness range unchanged, EBU R 128 does not specify a default 7

[wyup]

According to command help and wiki examples, default loudness range for ffmpeg-normalize for EBU R 128 normalization is 7.
However, a default LRA is not specified by EBU R128, only that Program Loudness Level target is −23.0 LUFS, and -1 db True Peak, as specified:
https://tech.ebu.ch/files/live/sites/tech/files/shared/r/r128.pdf
Minimum requirements for authentic programmes range from values 5 for a narrow loudness range (commercial/promo) to wide loudness range of 15 (movie/drama), as specified here:
https://tech.ebu.ch/files/live/sites/tech/files/shared/tech/tech3342.pdf

A default LRA of 7 is arguably a compressed loudness range.
Given that ffmpeg-normalized is used for a unspecified content that can be movies which need a high dynamic range, in order to get a target EBU R 128 normalized volume, IMHO LRA should be left untouched by default.

[slhck]

While I understand your argumentation, ffmpeg itself uses a default of 7, and this is why the same default is set here.

Asking the user to specify a range explicitly for every command would also be very confusing.

If there were a set of recommended parameters, I could imagine adding certain presets (e.g. music, dialog, movie,...) that set these values automatically.

[wyup]

I see. And an option to keep the source range? After all, EBU R 128 is mainly volume normalization, not so much compression. The user should provide a custom range, if needed.
Otherwise, the user would find compression not wished for.

[slhck]

The issue is that ffmpeg's loudnorm filter should also work in a single pass, for which you won't have an input loudness range calculated. Perhaps it would have been a better choice to make the loudness range target a mandatory setting, but this would have kind of forced a two-pass approach onto users. I guess the original author just picked something that was meaningful for them.

An option to keep the loudness range target is already implemented in ffmpeg-normalize! It's --keep-loudness-range-target. This will set the LRA to the input's LRA and override the default of 7 LUFS:

ffmpeg-normalize/ffmpeg_normalize/_streams.py

Lines 460 to 473 in 7edfe8c

	if self.media_file.ffmpeg_normalize.keep_loudness_range_target:
	_logger.debug(
	"Keeping target loudness range in second pass loudnorm filter"
	)
	input_lra = self.loudness_statistics["ebu_pass1"]["input_lra"]
	if input_lra < 1 or input_lra > 50:
	_logger.warning(
	"Input file had measured loudness range outside of [1,50] "
	f"({input_lra}), capping to allowed range"
	)
	self.media_file.ffmpeg_normalize.loudness_range_target = self._constrain(
	self.loudness_statistics["ebu_pass1"]["input_lra"], 1, 50
	)

PS: So far, I have not received feedback about the loudnorm filter being too aggressive by default. There is no ticket in FFmpeg about it either. I assume that most users don't care, and those who do will already set their target value per their needs.

That being said, I am still thinking about whether presets would make sense as a more user-friendly set of options. But I have limited experience with what works and what is recommended in various industries.