Marcus & Dan,
Thank you very, very much for the detailed information!
Dan: That's exactly what I thought when going into this at first. But, I
decided to give gzip a shot just to see how well it did. Turns out that
(at least for bursty environments) it almost halves the size of the
original file. It should be noted that the file was in fc32 format so
there were likely a lot of unused bits there (or so I guess).
Marcus: I have been giving thought to truncating some of the bits. Going
as far as thinking about dropping from sc16 to sc8. I have worked with 8
bit sample files before and had plenty of success demodulating, so I'm
thinking that it might be an okay path to go down. Dynamic range goes to
hell, but it it's worked in the past... I think that re-packing as 12 bit
would give considerable space savings without a lot of CPU overhead. I'll
have to give that one a go :) I really like your idea of using FLAC. Just
a quick Google search netted
http://www.rtl-sdr.com/compressing-filtering-iq-data/. What concerns me is
that when I tried to use the command line flac in Ubuntu it said that the
sample rate must be between 1 and 655349 Hz. I'll have to poke around at
it to see what happens when I set an incorrect bit rate (maybe a multiple
of will be fine?).
Thank you both!
-Dave
On Sat, Jul 16, 2016 at 5:14 AM, Marcus Müller <marcus.muel...@ettus.com>
wrote:
> Ah!
>
> On 16.07.2016 11:04, Marcus Müller wrote:
> > and maybe, but this is really speculation, you can just modify the
> > error calculation to just ignore the 4 lower bits of the actual sample
> > data, and safe another few percents of data volume.
> Yeah, there's a FLAC__stream_encoder_set_bits_per_sample[0] function--
> guess that you don't need to modify anything. Also, there's a whole
> listing of things .._set_compression_level[1] sets internally. This
> approach (using FLAC as lossless waveform encoder) might be really
> interesting.
>
>
>
> [0]
>
> https://xiph.org/flac/api/group__flac__stream__encoder.html#gabfa3c989377785cda7c496b69dcb98cb
> [1]
>
> https://xiph.org/flac/api/group__flac__stream__encoder.html#ga07fc8c7806381a055a1eef26387e509f
>
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