Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
I want to read pcm samples from a file using fread and want to determine the signal strength of the samples.How do I go about it?
For reading, how many bytes constitute 1 pcm sample? Can I read more than 1 pcm sample at a time?
This is for WAV and AAC files.
You have to understand that WAV-files (and even more so AAC-files) are not all the same. I will only explain about WAV-files, you’ll hopefully understand how it is with AAC-files then. As you pointed out, a WAV-file has PCM-encoded data. However that can be: 8-bit, 16-bit, 32-bit, …Mono, Stereo, 5.1, …,8kHz, 16kHz, 44.1kHz, etc. Depending on these values you have to interpret the data (e.g. when reading it with the fread()-function) differently. Therefore WAV-files have a header. You have to read that header first, in the standard way (I do not know the details). Then you know how to read the actual data. Since it is not that easy, I suggest you use on of the libraries out there, that read WAV-files for you, e.g. http://www.mega-nerd.com/libsndfile/ . Of course you can also google or use SO to find others. Or you do it the hard way and find out how WAV-file headers look like and decode that data first, then move on to the actual PCM-encoded data.