MSC3246: Audio waveform for extensible events #3246
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turt2live
added
proposal
erkinalp
reviewed
Jun 16, 2021
uhoreg
reviewed
Jun 29, 2021
turt2live
commented
Dec 7, 2021
turt2live
changed the title
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Note that this has now been rescoped to just waveforms, with @uhoreg's comment about range being unresolved at the moment. |
julioromano
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to element-hq/element-x-android
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Oct 27, 2023
[MSC3246](matrix-org/matrix-spec-proposals#3246) specifies the waveform as a list of ints because: > Because floating point numbers are not allowed in Matrix events Though DSP on audio data is almost always done using their floating point representation. This PR brings the float<->int rescaling in the `matrix` module so that the application code can always work with float waveform samples.
zecakeh
reviewed
Sep 27, 2025
Comment on lines
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| Under the `m.audio_details` content block, a new optional field named `waveform` is added. It is | ||
| an array of (non-floating) numbers to represent the amplitude of the audio over time. Because | ||
| floating point numbers are not allowed in Matrix events, integers should be between 0 and 256, | ||
| inclusive. Though there is no limit to the number of entries in the array, senders should aim to | ||
| have at least 30 and not more than 120. |
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I believe that the way that the waveform is computed should be specced, otherwise different clients might generate different waveforms for the same audio file, which defeats the purpose of this field.
This is already the case with Element Web and Element X Android that generate waveforms with very different values.
poljar
reviewed
Oct 1, 2025
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| Under the `m.audio_details` content block, a new optional field named `waveform` is added. It is | ||
| an array of (non-floating) numbers to represent the amplitude of the audio over time. Because | ||
| floating point numbers are not allowed in Matrix events, integers should be between 0 and 256, |
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Is this the unsigned 8-bit integer PCM sample format?
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See #3245 for implementations (Element Web/Desktop, currently).