Hi ben,

awesome! So, yeah, Felix wrote it as a GSoC project "back in the day",
and thus, it contained the most important (or what he and his mentors
considered most important) features first: and that was the AAC / LC
encoder (which technically is MPEG4 HE AAC v1, as far as I understand).
I don't know about the availability of free software encoders for
xHE-AAC, but full HE AAC v1 and  v2 (which brings better music quality)
should be available through Fraunhofer's FDK-AAC implementation – in
fact, Luca's gr-dab DAB+ works use exactly that library (or rather, a
fork of that library) for the audio encoding. If I remember correctly,
Fraunhofer brought out FDK-AAC around the time Felix handed in his
second milestone :)


So, if you'd want to wrap that, you'd be very much more than welcome! In
fact, I'd head over to [1], and look at mp4_encode_sb , rip out the DAB+
specific parametrizations and put in the DRM specific ones (but I'm,
alas, not aware which those are).


I think the frame lengths and stuff should be the same for AAC LC
(only), HE AAC v1 (which is LC + the Spectral Band Replication SBR)  and
v2 (v1+ Parametric Stereo), so, again, I //think// this is all a matter
of swapping out the encoder and modifying a few metadata bits :)


Cheers,

Marcus


[1] https://github.com/kit-cel


On 19.08.2017 08:32, Benny Alexandar wrote:
>
> Hi All,
>
>
> Nice to see some discussion on DRM. Well, I also used gr-drm and is
> not fully supported like multiple audio and data services. DRm also
> uses tow audio codecs namely AAC and xHE-AAC. gr-drm supports only
> AAC. I don't know about any xHE-AAC encoder/decoder open source
> available. If anybody knows please let me know. I'm there to enhance
> the gr-drm to make it a fully blown DRM transmitter.
>
>
> -ben
>
> ------------------------------------------------------------------------
> *From:* Benny Alexandar <[email protected]>
> *Sent:* Saturday, August 19, 2017 10:30:23 AM
> *To:* [email protected]
> *Subject:* Re: [Discuss-gnuradio] [GSoC 17] DAB: Updates
>  
>
> Hi All,
>
>
> Nice to see some discussion on DRM. Well, I also used gr-drm and is
> not fully supported like multiple audio and data services. DRm also
> uses tow audio codecs namely AAC and xHE-AAC. gr-drm supports only
> AAC. I don't know about any xHE-AAC encoder/decoder open source
> available. If anybody knows please let me know. I'm there to enhance
> the gr-drm to make it a fully blown DRM transmitter.
>
>
> -ben
>

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