nth frame to time

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Kayacan CITAK 2022-7-25

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https://ww2.mathworks.cn/matlabcentral/answers/1767200-nth-frame-to-time

编辑： Akshat 2023-8-31

I wanna find in the audio recording, how many seconds does it correspond to the frame. How can i do that?

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dpb 2022-7-25

Do you know the sampling rate? If so, it's trivial; if not, you're stuck. 44.1kHz is a fairly common rate, but not the only one.

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Answer 1

Akshat 2023-8-31

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https://ww2.mathworks.cn/matlabcentral/answers/1767200-nth-frame-to-time#answer_1298131

编辑：Akshat 2023-8-31

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Hi Kayacan,

I understand that you would like to find out the timestamp of a frame number you have. You can do this with the help of sampling rate of audio clip.

The sample rate can be found out using the “audioread” function (https://in.mathworks.com/help/matlab/ref/audioread.html#btiabil-1-Fs , the variable "Fs" gives us the sampling rate).

Once you have the sampling rate in the variable “Fs”, you can simply multiply the inverse of this with “n” which is your frame number. The math behind this is that every second has “Fs” number of frames. Thus, every frame is lasting 1/Fs seconds. Multiply this by “n” and you get the frame timestamp.

I have done the same with a sample audio file (change the 'test.wav' inside audioread to the name of your audio file), and here is the code I used for the same:

[y, Fs] = audioread('test.wav'); 
n = 1024;  % frame number 
sampleDuration = 1 / Fs;  % Duration of each sample in seconds 
timeStamp = n* sampleDuration;  % Time stamp