examples

Examples

Please add any useful examples here, with a short description of what they do.

Contents:

• File Input/Output
• Normalization
• Filters

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File Input/Output

Normalize multiple files

Normalize two WAV files and write them to the specified output files with uncompressed PCM WAV as audio codec:

ffmpeg-normalize file1.wav file2.wav -o file1-normalized.wav file2-normalized.wav

Overwrite the input file

You can (if you really need to!) also overwrite your input file. Warning, this will destroy data:

ffmpeg-normalize input.mp4 -o input.mp4 -f

Normalize videos, compress audio

Normalize a number of videos in the current folder and write them to a folder called normalized, converting all audio streams to AAC with 192 kBit/s.

ffmpeg-normalize *.mkv -c:a aac -b:a 192k

Use Windows loops for multiple files

For Windows CMD (Batch), the above would be written as a loop:

for %i in (*.mkv) do ffmpeg-normalize "%i" -c:a aac -b:a 192k

With PowerShell:

ls *.mkv | ForEach-Object { ffmpeg-normalize $_.FullName -c:a aac -b:a 192k }

Create an MP3 file as output

Normalize an MP3 file and write an MP3 file (you have to explicitly specify the encoder):

ffmpeg-normalize input.mp3 -c:a libmp3lame -b:a 320k -o output.mp3

Change the output container from the default (MKV)

Normalize many files, keeping PCM audio, but choosing a different container:

ffmpeg-normalize *.wav -c:a pcm_s16le -ext aif

Normalization Options

Perform peak normalization

Instead of EBU R128, one might just want to use simple peak normalization to 0 dB:

ffmpeg-normalize test.wav --normalization-type peak --target-level 0 --output normalized.wav
ffmpeg-normalize test.wav -nt peak -t 0 -o normalized.wav

Extra options

If you need some fancy extra options, such as setting vbr for the libfdk_aac encoder, pass them to the -e/--extra-options argument:

ffmpeg-normalize input.m4a -c:a libfdk_aac -e='-vbr 3' -o output.m4a

Check the loudness statistics

You can check the statistics of a file to verify the levels with -p. Pass -n to avoid running the normalization:

ffmpeg-normalize test/test.wav -p -n -f

This will return a valid JSON object:

[
{
    "input_file": "test/test.wav",
    "output_file": "normalized/test.mkv",
    "stream_id": 0,
    "ebu": {
        "input_i": -39.77,
        "input_tp": -27.49,
        "input_lra": 2.1,
        "input_thresh": -49.82,
        "output_i": -22.15,
        "output_tp": -9.46,
        "output_lra": 2.1,
        "output_thresh": -32.24,
        "normalization_type": "dynamic",
        "target_offset": -0.85
    },
    "mean": null,
    "max": null
}
]

Changing the loudness range

By specifying a different loudness range target (-lrt), you can change the dynamics of the EBU R128 normalization. For more info about loudness range, see this page.

The default is 7, but by setting a lower value, you can "squeeze" the signal more:

ffmpeg-normalize test/test.wav -lrt 1

Filters

Dynamic normalization

You can use pre-filters to modify the audio signal before or after it is normalized, e.g. by using dynamic compression. This smooths out any volume differences in the signal.

Examples for low, mid, and high dydnamic compression:

ffmpeg-normalize test.wav -prf "dynaudnorm=p=0.9:s=0"
ffmpeg-normalize test.wav -prf "dynaudnorm=p=0.5:s=5"
ffmpeg-normalize test.wav -prf "dynaudnorm=p=0.3:s=15"

Denoising

Apply a denoiser, e.g. anlmdn. This removes background white noise, for example.

Examples for low, mid, and high denoising:

ffmpeg-normalize test.wav -prf "anlmdn=s=0.0001:p=0.1:m=15"
ffmpeg-normalize test.wav -prf "anlmdn=s=0.0001:p=0.01:m=15"
ffmpeg-normalize test.wav -prf "anlmdn=s=0.001:p=0.01:m=15"

You can combine this with dynamic audio compression, of course:

ffmpeg-normalize test.wav -prf "anlmdn=s=0.001:p=0.01:m=15,dynaudnorm=p=0.3:s=15"

High-pass filtering

Remove low rumbling noise:

ffmpeg-normalize test.wav -prf "highpass=f=100"