question

Amazon Customer avatar image
Amazon Customer asked

Audio File Volume

Hi, I am building a skill that plays audio clips.

A problem that I'm running into is that the volume of any given clip may not match the volume of Alexa's speaking voice.

Does anyone have any suggestions for this issue?

Thanks.

alexa skills kitalexa
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luandrecast avatar image
luandrecast answered

What is the format of the audio clip?

For AVS, the acceptable audio recorded format is :

  • audio/L16; rate=16000; channels=1
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I am using rate=16000 ... I don't know whether the clips I'm using are audio/L16, and how many channels. How can I determine that?

BTW they are .mp3 format.

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Sindy@Amazon avatar image
Sindy@Amazon answered

Thanks for your question. I'll research to verify if there's a standard "default" volume level for audio files (to match the Alexa voice volume). In the mean time, this information may assist:

https://developer.amazon.com/appsandservices/solutions/alexa/alexa-voice-service/reference/speaker

Update from our Alexa dev team:

"There are several tools to adjust the base volume of MP3 files. ReplayGain(https://en.wikipedia.org/wiki/ReplayGain ) is a common standard for normalizing volume through MP3 tags, which most playback systems support. In case our playback doesn't support the ReplayGain standard (I can't find documentation on it one way or another), MP3Gain(https://en.wikipedia.org/wiki/MP3Gain ) is a tool which uses the ReplayGain algorithm, but directly modifies the MP3 file's audio data to adjust the volume scale factor on each frame."

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