It also sounds as though you perhaps used a variable bit rate (VBR) because 129 kbps (the files can’t possibly be 129 bps – that would be a ridiculously low bit rate) is not quite standard for CBR (continuous bit rate) mp3 files – although 128 kbps IS a standard bit rate, so this could simply be a reporting error. The basic formula is: File Size (bits) = Duration (seconds) * Bit Rate (bits per second). It’s important to realise that mp3 file codecs (CODEC is short for encode/decode) are usually expressed in kbps, which stands for kilobits PER SECOND, in other words, this is the amount of data which is streamed per-second when you play the file, which is why it’s called the bit rate – it DOES NOT refer to the total number of bits in the file itself the file size is determined by the duration of the encoded audio multiplied by the bit rate. It sounds as though you have recorded your audio book as mp3 files, yes? In terms of mp3 file encoding, describing a file as 128 or 129 “bits” makes no sense.

If you find this useful and/or have any comments or suggestions then do let me know via the comment section below (please read our website rules before posting). Note that the file size reported by your device may vary slightly from that shown due to file allocation methods, possible differences in the amount of header information and/or the fact that some operating systems calculate hard disk space differently from others (e.g., some calculate it in binary and call 1kB 1024 bytes whilst others – and most hard drive manufacturers – calculate it in decimal and call 1kB 1000 bytes) – this calculator handles both methods. For compressed files encoded with VBR (Variable Bit Rate), the displayed file size can be slightly less accurate because in this case the bit rate can vary depending on the programme material. For compressed files encoded with CBR (Constant Bit Rate), the displayed file size should be as accurate as possible (notwithstanding variables such as header information etc- see below). requires only the Bit Rate information (in this case the Sample Rate, Bit Depth and Channel information is ignored). In addition to the duration, calculating the size of compressed files such as MP3 etc. Calculating the size of uncompressed files also requires the Sample Rate, Bit Depth and Channel information (but not the Bit Rate, which is automatically calculated).

Duration Hours: Minutes: Seconds: Milliseconds: Settings - Uncompressed (WAV, AIFF etc.) Sample Rate: Bit Depth: Channels: Settings - Compressed (MP3, AAC etc.) Bit Rate (kbps): (kilobits per-second) Reset Uncompressed (WAV, AIFF etc.) Bit Rate: 1411.2 kbpsĠ Compressed (MP3, AAC etc.) Bit Rate: 0 kbpsĮnter the duration of your file in hours, minutes, seconds and milliseconds.

Pcmark 10 file size