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@ -829,46 +829,6 @@ out |
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Convert the audio sample format, sample rate and channel layout. This filter is |
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not meant to be used directly. |
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@section volumedetect |
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Detect the volume of the input video. |
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The filter has no parameters. The input is not modified. Statistics about |
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the volume will be printed in the log when the input stream end is reached. |
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In particular it will show the mean volume (root mean square), maximum |
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volume (on a per-sample basis), and the beginning of an histogram of the |
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registered volume values (from the maximum value to a cumulated 1/1000 of |
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the samples). |
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All volumes are in decibels relative to the maximum PCM value. |
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Here is an excerpt of the output: |
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@example |
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[Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB |
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[Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409 |
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@end example |
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It means that: |
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@itemize |
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@item |
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The mean square energy is approximately -27 dB, or 10^-2.7. |
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@item |
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The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB. |
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@item |
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There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc. |
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@end itemize |
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In other words, raising the volume by +4 dB does not cause any clipping, |
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raising it by +5 dB causes clipping for 6 samples, etc. |
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@section volume |
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Adjust the input audio volume. |
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@ -934,6 +894,46 @@ volume=volume=6dB:precision=fixed |
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@end example |
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@end itemize |
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@section volumedetect |
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Detect the volume of the input video. |
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The filter has no parameters. The input is not modified. Statistics about |
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the volume will be printed in the log when the input stream end is reached. |
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In particular it will show the mean volume (root mean square), maximum |
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volume (on a per-sample basis), and the beginning of an histogram of the |
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registered volume values (from the maximum value to a cumulated 1/1000 of |
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the samples). |
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All volumes are in decibels relative to the maximum PCM value. |
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Here is an excerpt of the output: |
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@example |
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[Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB |
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[Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609 |
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[Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409 |
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@end example |
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It means that: |
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@itemize |
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@item |
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The mean square energy is approximately -27 dB, or 10^-2.7. |
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@item |
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The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB. |
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@item |
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There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc. |
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@end itemize |
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In other words, raising the volume by +4 dB does not cause any clipping, |
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raising it by +5 dB causes clipping for 6 samples, etc. |
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@c man end AUDIO FILTERS |
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@chapter Audio Sources |
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