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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 ?

  


• Can no longer get ffmpeg to run in Terminal on macOS

  31 décembre 2023, par Chewie The Chorkie

  Here's a command I tried to run which always worked :

  


  Mac-mini:images Admin$ ffmpeg -r 30  -f image2 -s 1080x1080 -i %d.png -vcodec h264 -crf 25  -pix_fmt yuv420p zVideo.mp4


  


  The output I get is :

  


  dyld[94095]: Library not loaded: /usr/local/opt/theora/lib/libtheoraenc.1.dylib
  Referenced from: <20EBE016-0DD0-3F29-96CD-D22BC2E40B38> /usr/local/Cellar/ffmpeg/6.1.1/bin/ffmpeg
  Reason: tried: '/usr/local/opt/theora/lib/libtheoraenc.1.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/usr/local/opt/theora/lib/libtheoraenc.1.dylib' (no such file), '/usr/local/opt/theora/lib/libtheoraenc.1.dylib' (no such file)
Abort trap: 6


  


  I've tried reinstalling ffmpeg, installing the command line tools from Xcode, and Xcode itself.

  


• Integrate necessary ffmpeg libraries in own project for MCU (microcontrolers) [closed]

  16 septembre 2023, par Borel Kamnang

  I use two ffmpeg commands here :

  


  ffmpeg -i BigBuckBunny_320x180.mp4 -vf scale=192:96,setsar=1:1 outputBBB.mp4
ffmpeg -i outputBBB.mp4 -vf "fps=12,scale=-1:96:flags=lanczos,crop=192:in_h:(in_w-192)/2:0" -c:v rawvideo -pix_fmt rgb565be BigBuckBunny_192x96_12fps.rgb


  


  The first is to downscale an original video and the second is to convert the scaled video to a .rgb format.

  


  As anew user of ffmpeg, I would like to know what are libraries used for that two command to just integrate them in my Arduino IDE C++ project an just call the necessary functions to do the downscale and the conversion.

  


  And another of my concerns is knowing how I can run any ffmpeg in an Raspberry Pi Pico W (RP2040) or ESP32 microcontroller ?

  


  I tried to include the ffmpeg libraries folder in a created Arduino IDE project for Raspberry pico w and the link for files doesn't work. In addition to having the config.h and config components.h files missing in the folder downloaded from the ffmpeg site, there are too many dependencies between .h and .c files.

  


  extern "C" {
  #include "src/ffmpeg/libavcodec/avcodec.h"       
  #include "src/ffmpeg/libavutil/mathematics.h"
}
void setup() {
   Serial.begin(115200);
   delay(10000);
 }
 loop(){
 }


  


  It's been three days today that I've been trying to compile from Arduino IDE, and correct the links in the files.
The problem is also that I don't even have the certainty of what it will work in the Raspberry Pi PicoW or ESP32 afterwards.