Improve the README with details about the processing workflow of the script.

README.md

@@ -15,12 +15,37 @@ to a reference frame (so called I-frames). These frames are only present roughly
 which corresponds to quite long duration (in the order of a second).
 
 I really want to cut the movie with a better precision. So I have written a Python script
-that leverages _ffmpeg_, _ffprobe_ and _mkvmerge_ to do the job with the required precision.
+that leverages _ffmpeg_, _ffprobe_ and _mkvmerge_, _subvodocr_ to do the job with the required precision.
 
 # Parameters
 
 # How does it work ?
 
+The processing follows a quite long pipeline:
+
+1. The original .ts file is first transformed into an .mp4 file using _ffmpeg_ to correct timestamps:
+
+2. The .mp4 is then transformed into a Matroska container (which is the default container) still using _ffmpeg_:
+
+3. Then the movie is then cut using the indications passed as parameters. It is possible to give as many parts as needed.
+
+Each part is treated with the same algorithm.
+Trouver l'estampille de la trame 'I' la plus proche (mais postérieure) au début de la portion.
+Trouver l'estampille de la trame 'I' la plus proche (mais antérieure) à la fin de la portion.
+On a alors
+debut  -----    trame  --------- trame  ---------  fin.
+'B/P'  'B/P'*   'I'               'I'   'B/P'*   'B/P'
+Si la trame de début est déjà 'I', il n'y a rien à faire (idem pour la fin).
+Sinon on extrait les trames 'B' ou 'P' depuis le début jusqu'à la trame 'I' non incluse
+
+4. Then each part that have been previously obtained are merged using _mkvmerge_:
+
+5. The subtitles (image based) are then extracted using _mkvextract_:
+
+6. These images are then processed using _vobsubocr_ to create SRT files:
+
+7. The SRT files are then remuxed inside the Matroska container using _mkvmerge_:
+
 # How to determine where to cuts
 
 Use `mpv --osd-fractions --osd-level=3 ./movie.ts`