[Flac] Some queries regarding FLAC

Andrew Snare ajs at pigpond.com
Wed May 12 02:46:41 PDT 2010


On May 12, 2010, at 9:24 AM, Nawal Kishor Mishra wrote:
> 
> Dear FLAC team,
>     I have some fundamental doubts regarding FLAC encoder:
>  
> 1) In FLAC encoder there is no option of specifying the bitrate. There is something called compression-level. I believe that based on the nature of input WAV file and compression-level chosen bitrate is coming into picture. As such there is no user control on the bitrate. Is that correct?
> 2) In FLAC encoder I am also not seeing any option of specifying CBR or VBR. I assume that by default FLAC encoder is VBR. Is that correct?

Hi Nawal,

1) There is no direct user control on the bitrate.
2) FLAC is VBR in the literal sense.

FLAC is a lossless encoder; it tries to use as few bits as possible while preserving all audio information. This means that the bit-rate can't easily be fixed: lossy encoders (eg. MP3, Vorbis, AAC) typically throw out additional information until the target bit-rate is reached.

The compression-level for FLAC relates to flexibility in how the encoder can represent the original audio without losing any information. There are normally a lot of different ways to do this, and the compression-level essentially indicates how much work the encoder should do while searching for the best amongst them. (The more work, the more likely the encoder will find a better representation of the audio, but with diminishing returns as more work is done.)

Cheers,

 - Andrew


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