[maemo-users] Recording calls

From: Thomas Waelti twaelti at gmail.com
Date: Tue Jan 19 00:14:24 EET 2010
I have now uploaded my "recaller" widget to the autobuilder, it built OK and should show up in extras-devel during the next hours (IF the servers work again - I have 0.2.0 of sleeper still not showing up in the package interface after 2 hours in the queue).
The widget is encoding in AAC stereo right now at 128 kBit - this takes about 1 MB per minute in very good quality. Probably overkill, but the 27 GB in MyDcos give you 460h of recording time, so everything has become a bit relative on a monster like the N900 :-)

And yes, the widget can also be used as a simple recorder/dictaphone.

Best regards

> Just one thought on this:
> Most people are going to do playback on the device.  I would focus on the best codec available for recording and playback on the N900.  If people want to use it some other place, maybe making an export function (for Wav or MP3 or whatever) would suffice.  Worst case, make a selectable setting for which codec to use and let the user decide?
> One idea:  Most phone conversations are mono.  Maybe a good strategy would be to record in stereo, with inbound on one channel and out-bound on the other?  It would make listening to it later interesting, since you could balance out one side or the other to catch pieces obscured by overlap?  Would also help clarify who said what on a 2-party call at least.
> What's the app/widget garage name?  Would love to load it up and take it for a test drive.  I miss this from my 6230, though I honestly don't use it often.  (Had a hot key for it to turn it on while driving in case there was something I needed to take note of for later.  Hard to take notes while driving. :)
> ---- "Thomas Wälti" <twaelti at gmail.com> wrote:
> =============
> The problem is to find a compromise between:
> a) CPU/power usage
> b) Encoding efficiency
> c) Playback capability
> d) API availability
> Due to a) and d), I'm only looking at the gstreamer encoders available
> on the N900. Du to c) I have dropped the ANB and AWB codecs from
> evaluation - I was unable to quickly find a standard software for
> playback on Windows (e.g. WMP or VLC bot failed)
> Tonight, I'll try low bitrate AAC as it is probably a good compromise
> between these factors. I will also try speex, as it's on the N900 by
> default and technically ideally for encoding this kind of audio.
> However, I'm not so sure about playback capability on Windows :-) Is
> Speex on the N900 using the DSP? Because I guess that all NokiXXXenc
> are, e.g. the AAC one.
> Thanks
> -Tom
> On Mon, Jan 18, 2010 at 09:37, Harri Haataja <realblades at gmail.com> wrote:
>> 2010/1/14 Kahlil Johnson <jzarecta at gmail.com>:
>>> On Thu, Jan 14, 2010 at 9:01 AM, Dave Neary <dneary at maemo.org> wrote:
>>>> Thomas Wälti wrote:
>>>>> The documented method looks really hacky, IMHO the gstreamer based
>>>>> method of Zaheer Abbas Merali (gst guru par excellence :-) posted in
>>>>> http://talk.maemo.org/showpost.php?p=464494&postcount=50 should be the
>>>>> way to go. Using nokiaaacenc, you could probably directly save as AAC
>>> What about a real free format like OGG vorbis?
>> Um.. speex?

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