[vlc-devel] Need help developing text-to-speech-module in VLC - offering £5.000

Rémi Denis-Courmont remi at remlab.net
Thu Apr 7 12:34:22 CEST 2011

   Hej igen,

On Thu, 7 Apr 2011 11:59:14 +0200, Sandra Derbring
<sandra.derbring at gmail.com> wrote:
>> Then you need a speech synthesis engine. There are quite a few
>> open-source ones. But I don't know which ones, if any,
>> supports Swedish phonetics and have a GPL-compatible copyright
>> license. Did you already sort out that part of the equation?

> Since we work with users who probably will having a license for a
> speech synthesis engine already, we were hoping that the module
> could have support for a few of the most usual engines, both
> licensed and free, and a function for checking which is on the
> user's system (or alternatively, letting the user state this).

> In terms of free vs licensing, will this be a problem?

Cost is not an issue. However GNU GPL compatibility could be an issue. To
"talk" to a closed-source or other "GPL-incompatible" speech engine, some
extra care must be taken to cleanly delineate the VLC open-source software
parts from the proprietary parts.

> On top of my head, I can think of espeak (not very good) and Festival,
> supporting Swedish phonetics, but I am sure there are more. The basic
> is that the engine wouldn't come with the module, but work with the one
> already in place on the user's system (if applicable).

I am not aware of a standard programming interface for speech synthesis.
If there is none, then a separate "glue" plug-in needs to be written for
each and every engine that is to be supported. So the more engines, the
more work.

>> And last, you need to filter out the original voice from the original
>> audio track. Or do you not mind loosing the original audio sound
>> effects? I
>> don't suppose you will always have a clear/speech-less audio channel
>> available in the original media.

> We were hoping to be able to preserve the original sound, but to
> the finished module, we are interested in letting the users set their
> preferences in terms of volume for the different channels. Do you think
> this would be possible? If not, we'd liked it filtered out but not mute.

Balancing or remixing channels is feasible, except that VLC has no user
interface concept for this at the moment.

However, sound effects and voices are on the same channels in the original
medium. So I meant it's difficult to remove the original voices while
keeping the original sound effects.

>> It depends a lot on the requirements, and what existing components
>> be sourced or would be provided by you.

> I'll be happy for more questions, or pointers, that would help us
> understand what resources we need, and who could provide them. Given
> these premises, do you have a more clear picture of what effort we
> could be talking about?

As long as OCR is not involved, it seems reasonable.

Rémi Denis-Courmont

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