[Freeswitch-users] New features needed when playing files - playback application

Steven Ayre steveayre at gmail.com
Thu Mar 21 16:09:11 MSK 2013


+1, I'd forgotten that module. :o)

http://wiki.freeswitch.org/wiki/Mod_soundtouch

Looks like at least some of the functionality is there:

   - 7 temp down 0.05
   - 9 tempo up 0.05



On 21 March 2013 13:02, Michael Jerris <mike at jerris.com> wrote:

> We have a mod_soundtouch, I don't remember what features are in there,
> check it out.
>
> On Mar 21, 2013, at 8:50 AM, Steven Ayre <steveayre at gmail.com> wrote:
>
> What you're after is 'audio timescale pitch modification', aka
> 'time-stretching'.
>
> It's a bit more specialised than a normal playback, so I suspect would
> better implemented in a new application/module.
>
> There's a few OSS libraries that might be of use. From a quick Google:
> http://www.surina.net/soundtouch/ (LGPL)
> http://breakfastquay.com/rubberband/ (GPL)
>
> -Steve
>
>
>
> On 21 March 2013 09:38, Clive Lansink <clive at lansink.co.nz> wrote:
>
>>
>> There are two features I need in the playback application for playing
>> sound files for an IVR application I am developing. Maybe one feature is
>> there but I don't think the other is but perhaps people could advise me
>> about that.
>>
>> 1. I need to be able to start at a specified time offset in the file.
>> When playing is interrupted, there is a variable that can tell the number
>> of milliseconds of audio that was played. If I want to resume playing, I
>> need to be able to start from that point, or in fact any arbitrary point,
>> in the file. I think I can achieve this with the uuid_fileman API command
>> so maybe that will work. When I last looked at this I was confused as to
>> whether the seek parameter was samples or milliseconds.
>>
>> 2. I want to be able to vary the speed of playback but in such a way as
>> to keep the overall pitch of the recorded voice unchanged. There are
>> algorithms that do this and I presume they work by removing samples from or
>> adding samples into the audio stream. I think uuid_fileman also has a speed
>> subcommand which kind of worked when I played with it, but it was not
>> constant pitch.
>>
>> The application I am working on is a replacement of a system that
>> delivers human narrated information to blind people over the phone. The
>> existing system uses old analogue Dialogic cards and has these features,
>> and the replacement system should also have these capabilities. Recorded
>> bulletins of information can be quite lengthy, maybe an hour or more to
>> read right through. So this is perhaps not typical of IVR systems. People
>> need to be able to skip around and possibly speed up or slow down the
>> reading, but without altering the pitch of the narrator's voice. I know I
>> can create the necessary functionality if I have the above features in the
>> playback application.
>>
>> Note that the application will also use TTS to turn textual information
>> into speech but that is a separate issue and not relevant here. The
>> application still needs to handle human narrated information.
>>
>> Can anyone comment on these features and, if something needs to be added,
>> how easy it would be to do this and how it might be done?
>>
>>
>
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