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• How the ffmpeg is fixing Handle page termination with same page number ...? [closed]

  11 avril 2024, par adarsh

  Im working on the teletext subtitle feature and faced with subs not clearing issue.
the subtitle lines remain displayed until being replaced by a new version of the specific line. So the subtitles never disappear and often an old line is still displayed, after another, more recent line is displayed/updated.
take a look at the issue in this sample video file : https://code.videolan.org/videolan/vlc/uploads/58c2e1660e94e2df5e8cdb75edf531d9/GODFATHER__03_.ts
Issue reported : https://sourceforge.net/p/zapping/bugs/203/

  


  The player is using ffmpeg and libzvbi library.

  


  At first I suspected that the Erase Page Flag (C4) in the Page Header was not set, but the flag was indeed set (at least once between two LOPs with subtitles). After further debugging it turned out that the Teletext service in the two issues consists of just a single Teletext page - which is the reason here :

  


  The Teletext spec defines the Magazine Serial Flag (C11) in Table 2 (ETSI EN 300 706 v1.2.1) as (bold font by me) :

  


  When set to '1' the service is designated to be in Serial mode and the transmission of a page is terminated by the next page header with a different page number.
When set to '0' the service is designated to be in Parallel mode and the transmission of a page is terminated by the next page header with a different page number but the same magazine number.
The same setting shall be used for all page headers in the service.
(BTW it doesn't really matter, but in these two cases this flag is always 0)

  


  In vbi_decode_teletext in /src/packet.c, storing the page is aborted, if the condition "page terminated" in the C11 definition is not met. But as the service here consists of only one page, this condition is never met !

  


  Luckily, this issue was fixed in ffmpeg- https://github.com/FFmpeg/FFmpeg/commit/b1e0e216462a989a39e7b413aef6d32f8cedc154

  


  and also in zvbi :
https://github.com/zapping-vbi/zvbi/commit/40a6ab0200c46b67b059b5b1fb15793ce780892a

  


  I understand the root cause and fix in zvbi library, and how it is ignoring c4 flag in case the same page no.

  


  But i want to understand how the ffmpeg fix is working ?
ffmpeg fix : https://github.com/FFmpeg/FFmpeg/commit/b1e0e216462a989a39e7b413aef6d32f8cedc154

  


  what is the rule for repeated page headers ?

  


• How to use ffmepg create video from some bitmaps(the format is ARGB32) [closed]

  16 février 2013, par xiangyun

  I have some bitmaps(the format is ARGB32), I want use ffmepg to create video from this bitmaps, the video format is mp4, encoder video stream use H263.
  This is my frist time use ffmpeg ,I had read sample code in ffmpeg doc, but I still don't know how to create mp4 file from serial bitmaps. And I want use this native code in android app. Anybody who had experience on ffmepg can help or teach me ?

• M3U8. Convert all parts to mp4 [closed]

  5 juin 2020, par Zikrulloh Tolibjonov

  My name is Zikrullah. I have the m3u8 file of the serial. 1 m3u8 file contains all parts of the series and all audio languages for the player. The parts in it were saved in ts format for 10 seconds (as far as I understand). When I opened the m3u8 file, it contained a link to other m3u8 files. If I'm not mistaken, these are separate m3u8s for audio languages. but all m3u8 and ts files related to the video are on a other server. I need to upload all the files to my server while keeping them all in order. Of course using php. I'm sorry if I made a mistake. I don't know English well, but I tried :)