Is your feature request related to a problem? Please describe.

Yes, I am currently using ffmpeg-normalize 1.26.4 in Python 3.10.9 with

from ffmpeg_normalize import FFmpegNormalize
normalizer = FFmpegNormalize(
        normalization_type="ebu",
        target_level=-23,
        print_stats=True,
        keep_loudness_range_target=True,  # needed for linear normalization
        true_peak=-2,
        dynamic=False,
        audio_codec=my_codec,
        audio_bitrate=my_bitrate,
        sample_rate=None,
        debug=True,
        progress=True,
    )
    normalizer.add_media_file(input_file, output_file)
    normalizer.run_normalization()

where 2nd runs with ffmpeg execute with lra={input_lra} which produces a linear normalized audio for any input_lra >= 1. If I try to convert a song with input_lra < 1 (e.g. 0.7 in audio from https://www.youtube.com/watch?v=HTYOa2_1aH4) I get the following error:

Value 0.700000 for parameter 'LRA' out of range [1 - 50]
Error setting option LRA to value 0.7.
Error initializing filter 'loudnorm' with args 'I=-23:TP=-2.0:LRA=0.7:measured_I=-12.7:measured_TP=-2.2:measured_LRA=0.7:measured_thresh=-22.7:offset=+0.1:linear=true:print_format=summary'
Error reinitializing filters!
Failed to inject frame into filter network: Result too large
Error while processing the decoded data for stream #0:0

I am able to resolve this issue by using loudness_range_target=7.0, instead of keep_loudness_range_target=True for any input_lra <= 7.0, but then get the following warning for input_lra > 7 (e.g. 16.10 in audio from https://www.youtube.com/watch?v=GibiNy4d4gc):

Input file had loudness range of 16.1. This is larger than the loudness range target (7.0). Normalization will revert to dynamic mode. Choose a higher target loudness range if you want linear normalization. Alternatively, use the --keep-loudness-range-target option to keep the target loudness range from the input.
In dynamic mode, the sample rate will automatically be set to 192 kHz by the loudnorm filter. Specify -ar/--sample-rate to override it.

which does perform dynamic normalization instead of linear normalization.

Describe the solution you'd like

In order to solve this and ensure backwards compatibility I'd suggest to a add a flag --keep-lra-above-loudness-range-target (constructor parameter: keep_lra_above_loudness_range_target=True). In combination with loudness_range_target=7.0. This should ensure LRA=7 for input_lra <= 7 and LRA=input_lra for input_lra > 7 and allows to convert any song with the same parameter-set independent of input_lra

Describe alternatives you've considered

An alternative solution would be to set input_lra < 1 to LRA=1 in order to fit into the range of [1 - 50] with something like --force-linear-normalization

Without any change in ffmpeg_normalize I would need to measure input_lra in order to know what parameters to set, but then I can basically use ffmpeg directly without using ffmpeg_normalize at all.

Additional context

I am new to the topic of audio normalization, followed some tutorials and weblinks, played around with ffmpeg in order to achieve linear normalization, as I did not like how dynamic normalization changed the audio. I read that target_LRA should be 7.0 (EBU R128) and therefore used 7.0 when possible (so if input_lra < 7) and used LRA=input_lra for LRA > 7. Using --keep-loudness-range-target in ffmpeg_normalize seems to override --loudness-range-target = 7.0 and therefore only use LRA=7.0, if the input_lra is already 7.0. So I hope --keep-lra-above-loudness-range-target might be an improvement by respecting --loudness-range-target = 7.0 as long as possible.