Help - Audio Bitrate / size calculation

7 replies
Found 6th Feb 2011
Hello

I am trying to work out how much data will be used in the following scenario:

5 KHz
8 bit
for 7 seconds

How many KB would the file be?

any one know how to work it out, have been racking my brains but cannot seem to work it out.

7 Comments

This is my laymans guess which is almost certainly wrong

5000 hertz = 5000 cycles per second
8 bit encoding = 8 bits to represent every cycle
5000 * 8 = 40000 bits per second of auido
40000 * 7 = 280000 bits for seven seconds
280000 / 1024 = 273.4375 kb

Original Poster

tvfan

This is my laymans guess which is almost certainly wrong5000 hertz = 5000 … This is my laymans guess which is almost certainly wrong5000 hertz = 5000 cycles per second8 bit encoding = 8 bits to represent every cycle5000 * 8 = 40000 bits per second of auido40000 * 7 = 280000 bits for seven seconds280000 / 1024 = 273.4375 kb



thanks but the end number is still in k bits.

When I tried to work it out i get 35KB for the file size. not sure if it is correct
Edited by: "mds1256" 6th Feb 2011

Original Poster

whatsThePoint

why not make the file and then see what size it is?



bacause there is usually header data etc (audio tags) added to the file so wouldnt be a good test.

I did do it and it came to 37kb, which isnt an available answer lol


Edited by: "mds1256" 6th Feb 2011

Sorry the above value 273.4375 is Kilo Byte, not Kilo Bit to make it clearer.

I'd assume from the information you have given that the encoding method is lossless, and the sample rate is 5KHz. Important !!! - not using MP3,etc!!!!

Since you have piqued my interest (which is not easy as I am avoiding doing some boring work) - I found this on the Red Book (CD) standard of lossless audio encoding:

2 channels x 44,100 samples per second per channel × 16 bits per sample = … 2 channels x 44,100 samples per second per channel × 16 bits per sample = 1,411,200 bit/s = 1,411.2 kbit/s.






Edited by: "tvfan" 6th Feb 2011

Original Poster

thanks, this is mono so only single channel.

the question is asking about how much data would be transmitted over a network when calling some one (so i assume its raw audio data) with using the following specs:

5 KHz
8 bit
for 7 seconds
Edited by: "mds1256" 6th Feb 2011

Well using my extensive knowledge (ha) of bitrate calculations and the most reliable source that is wikipedia and the answer they have come up with in their scenario, I'd say my answer was right. But what do I know?

Just a point - if its telephony then compression is definitely used (look up PCM)

Original Poster

tvfan

Well using my extensive knowledge (ha) of bitrate calculations and the … Well using my extensive knowledge (ha) of bitrate calculations and the most reliable source that is wikipedia and the answer they have come up with in their scenario, I'd say my answer was right. But what do I know? :pJust a point - if its telephony then compression is definitely used (look up PCM)



lol many thanks for your help, i will look that up
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