Hello!
As an author of tvstreamrecord I would glad help you with your problems. Here is a small guide for using RTSP or other stream types (may vary depending on your hardware!). If you have other or further problems, feel free to contact me. As I can't unfortunately speak French, please in English.
First append your stream type (e.g. RTSP) in Configuration -> FFMPEG -> Stream types.... As example: rtmp rtp rtsp
You can now try to record your streams. If no file was generated, please check your log for more details regarding ffmpeg. If you see any errors, which cause your stream to be infinitely retried, you may need to try one of the other ffmpeg versions, which are provided with Synology. This can be altered in Configuration -> FFMPEG -> Full path to ffmpeg... in:
/volume1/@appstore/VideoStation/bin/ffmpeg /volume1/@appstore/AudioStation/bin/ffmpeg /volume1/@appstore/MediaServer/bin/ffmpeg
You can also find more information in my manual.
With best regards
Pavion