24bit PCM compress Options

[yg2003618]

anyone knows about how to compress 24bit PCM 48Khz audio, I know that most codecs process 16bit pcm. i want compress 24bit PCM at real time, 3:1 or 4:1 compress rate. who can help me? i know that subband adpcm maybe a choice. anyone knows more about that?

thanks alot.

[googlebot]

It depends, if high dynamic range is a top priority (at the cost of others), then yes.

And especially regarding ultra low delay codecs: 144 samples per frame is such a tight limit for the set of possible filtering operations, maybe a higher "vertical" input resolution can help the encoder make better choices under these extreme circumstances. But that's only a guess.

This post has been edited by googlebot: Nov 26 2010, 21:28

[saratoga]

It depends, if high dynamic range is a top priority (at the cost of others), then yes.

And especially regarding ultra low delay codecs: 144 samples per frame is such a tight limit for the set of possible filtering operations,

No thats the absolute limit assuming an infinitely fast processor, not the ancient arm7 core the OP is using. Realistically he probably has a fraction of that to work with.

maybe a higher "vertical" input resolution can help the encoder make better choices under these extreme circumstances. But that's only a guess.

I think thats unlikely. Hes using ARM7, which means 32 bit fixed point inputs to the encoder, no matter what the actual PCM is (since arm7 lacks dsp extensions for things like 16 bit multiplies). In practice, since he is using lossy anyway, the choice the input PCM format is likely to be of no consequence.

[googlebot]

I think thats unlikely. Hes using ARM7, which means 32 bit fixed point inputs to the encoder, no matter what the actual PCM is (since arm7 lacks dsp extensions for things like 16 bit multiplies).

A 4 bit signal stays a 4 bit signal. A mandatory conversion to 32 bit int doesn't change that, neither for 16 bit or 24 bit. The samples are just padded with zeroes.

In practice, since he is using lossy anyway, the choice the input PCM format is likely to be of no consequence.

Could you please explain the inference? I don't understand it. Especially how it is supposed to refute to the paragraph you have cited.

This post has been edited by googlebot: Nov 26 2010, 22:22