  Recently, end-to-end ASR based either on sequence-to-sequence networks or on
the CTC objective function gained a lot of interest from the community,
achieving competitive results over traditional systems using robust but complex
pipelines. One of the main features of end-to-end systems, in addition to the
ability to free themselves from extra linguistic resources such as dictionaries
or language models, is the capacity to model acoustic units such as characters,
subwords or directly words; opening up the capacity to directly translate
speech with different representations or levels of knowledge depending on the
target language. In this paper we propose a review of the existing end-to-end
ASR approaches for the French language. We compare results to conventional
state-of-the-art ASR systems and discuss which units are more suited to model
the French language.
