Differences

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--- doc:appunti:linux:video:subtitleripper [2024/02/01 11:13] – [OCR the images from the .sub file] niccolo
+++ doc:appunti:linux:video:subtitleripper [2024/02/01 11:56] (current) – [How to rip DVD subtitles with vobsub2srt] niccolo
@@ Line 9: / Line 9: @@
   * **lsdvd** - From the official Debian repository.
   * **vobcopy** - From the official Debian repository.
+  * **mediainfo** - From the official Debian repository.
   * **mkvtoolnix** - From the official Debian repository.
   * **vobsub2srt** - From the Deb Multimedia repository.
 ===== Ripping the .vob from the DVD =====
+A DVD can contain several **titles** and you should identify which one you want to rip; generally it is the longer one or the one with most chapters. We check the DVD content using the **lsdvd** tool:
+<code>
+lsdvd /dev/sr0
+Disc Title: DVD_TITLE
+Title: 01, Length: 01:02:36.480 Chapters: 03, Cells: 03, Audio streams: 02, Subpictures: 04
+Title: 02, Length: 00:00:12.800 Chapters: 01, Cells: 01, Audio streams: 02, Subpictures: 04
+Title: 03, Length: 00:21:01.760 Chapters: 01, Cells: 01, Audio streams: 02, Subpictures: 04
+Title: 04, Length: 00:00:00.480 Chapters: 01, Cells: 01, Audio streams: 02, Subpictures: 04
+Title: 05, Length: 00:21:10.000 Chapters: 01, Cells: 01, Audio streams: 02, Subpictures: 04
+Title: 06, Length: 00:20:24.720 Chapters: 01, Cells: 01, Audio streams: 02, Subpictures: 04
+Longest track: 01
+</code>
+The longest title is the **#1**, so we will extract it using **vobcopy**:
 <code bash>
 vobcopy -n '1' -i /dev/sr0 --large-file -o .
 </code>
+The resulting file will be saved into the working directory (as specified by the **%%-o%%** option) and it will be named by the DVD title, something like **DVD_TITLE.vob**.
+You can inspect the content of the file using the **mediainfo** tool, in our case the file contains one video stream, two audio streams and three subtitle streams. The subtitles are in the standard DVD format: VobSub, which is a images (bitmap) format, not text.
 ===== Converting the .vob into .mkv format =====
@@ Line 22: / Line 44: @@
 As far I know, there is not a tool capable of extracting the VobSub subtitles directly from the vob file; we might hope that **ffmpeg** was capable of doing this, but it seems not.
-Fortunately the **mkvextract** can extract the VobSub stream from a //mkv// file, so we firstly use ffmpeg to convert the //vob// into //mkv//. In the following example all the stream are copied, without re-encoding. At this step you may want to re-encode the video  to squeeze the MPEG2 stream into the more efficient H264 format.
+Fortunately the **mkvextract** (from the mkvtoolnix Debian package) can extract the VobSub stream from a //mkv// file, so we firstly use ffmpeg to convert the //vob// into //mkv//. In the following example all the stream are copied, without re-encoding. At this step you may want to re-encode the video  to squeeze the MPEG2 stream into the more efficient H264 format.
 <code bash>
@@ Line 37: / Line 59: @@
 ===== Extracting .sub and .idx files from the .vob =====
+From the //mkv// file it is now possibile to create **two files** (.sub and .idx) for each subtitles stream. The stream numbering expected by ''mkvextract'' in our example is as follow: **#0** is the video stream, **#1** and **#2** are the two audio streams, so the first subtitle stream is the **#3**:
 <code bash>
 mkvextract 'DVD_TITLE.mkv' tracks -c 'S_VOBSUB' '3:subtitles-3'
 </code>
+The result will be two files: **subtitles-3.sub** and **subtitles-3.idx**. It is possible to repeat the command to extract the other subtitles (**#4** and **#5** in our example).
 ===== OCR the images from the .sub file =====
 <code bash>
-vobsub2srt --ifo './VTS_01_0.IFO' --dump-images --tesseract-lang ita subtitles-3
+vobsub2srt --ifo './VTS_01_0.IFO' --dump-images --tesseract-lang ita 'subtitles-3'
 </code>
 The .IFO file is required to get the correct palette, width and hight, but it is not mandatory.