There are many text to speech software, but the one I'm looking for would allow to synthesise the user's own voice. And possibly imitate the voice of someone else without consent (just for joking, kind of what is done with photoshop today on images).
VocaliD creates custom crafted synthetic voices by combining the recipient’s residual vocal abilities with an anatomically similar voice donor’s speech database. The result is a voice that sounds like the recipient in age, personality and vocal identity but is as clear and understandable as the donor’s speech.
TEDWomen Talk: "Synthetic voices, as unique as fingerprints" (Dec 2013). Abstract:
Many of those with severe speech disorders use a computerized device to communicate. Yet they choose between only a few voice options. That's why Stephen Hawking has an American accent, and why many people end up with the same voice, often to incongruous effect. Speech scientist Rupal Patel wanted to do something about this, and in this wonderful talk she shares her work to engineer unique voices for the voiceless.
Although recording own voices is done since ~2004, it is still a hard task. The Nemours Speech Research Laboratory is looking for volunteers to record voices for voiceless children. They record 1600 sentences to build a voice. This is needs a significant amount of time, some practice and good equipment, otherwise your breath and background noise will be recorded as well.
The Edinburgh University is using HTS (BSD like license) which is based on HTK (proprietary license) and Festival. The Festvox project of Carnegie Mellon University is closely related. They have built voices for that system.
In the following you'll find a few voice recording services. I never tried them myself, because I considered them as too expensive for the use I had in mind.
Acapella offers custom voice creation. It will be very expensive though and you'll need about 3 months to get take all the recordings (for high quality). Still, the custom voices are not as good as their regular ones.
CereVoiceMe is the only service I know of that gives a price in advance: For about 775 USD you can record "a couple of hours" of your voice and it'll be converted to a TTS voice. I'm not sure if they offer French voice recording.