Recherche avancée

Sur d’autres sites (6657)

• Using FFMPEG/RaspiVid streams in C++ program

  24 octobre 2020, par Naveen

  I need to capture the video coming from CSI/Webcam on my Rpi either using FFMPEG or Raspivid. I can do this in commandline using this command.

  


  ffmpeg -i /dev/video0 -f avi - | ./videocapture


  


  I have written a C++ program which uses read() and write() systemcalls. read() to read the STDIN(O/P from ffmpeg). This is copied to a series of buffers(each 65K). . Then another threads reads the buffer and writes the buffer content to a file. So basically I want to create a video file at the end. But when I play the video file it does not work because of file formatting. This is my thread code which writes to the file. Does this look good ? Could you please suggest what I might be doing wrong ? I am sure that the output of ffmpeg is correct.

  


  void WriteToFile(buff_t *buff, char *filename){
// std::cout<<"Starting the thread!!"</     std::cout<<"Couldn't open file, Exiting !!!!!"</  std::cout<<"Buffer Empty!!"</ std::cout<<"Writing To File!!!"<code>

  


• HEVC with Alpha Encoding on Windows

  14 juillet 2023, par CodeVortex

  I know, this question has been asked before, but most of the answers to them are very old.

  


  Actually, I am developing a website which uses transparent videos. So, I am using .webm format for them. However, as you know it is not possible to run .webm with transparency on Apple products. So, after researching on internet(stackoverflow etc), I found a solution that I should convert my video into a series of PNGs and then convert them into HEVC with alpha channel. However, according to the research I done, only the Apple hardware can properly encode HEVC with alpha channel.

  


  I am a newbie to these codecs and formats stuff. So, I think that I read somewhere that latest versions of FFMPEG can also encode HEVC with alpha. However, being a noob I can't figure out any way to write a command for this purpose. Being a beginner with almost non-existent skills in this field of expertise, it is nearly impossible for me to understand the documentations correctly. I also tried using shutterencoder and some other tools but failed.

  


  Although, there is a quicktime .mov solution but with that the file size becomes too large for my 10 sec video, almost 334 mb and as you know this size is too large for a animation video on a landing-page style basic website.

  


  So, now my question is there any way to properly encode HEVC with alpha on Windows or Linux to maintain transparency ?

  


  If this is not possible, then is there any other way to create such transparent videos on Windows or Linux which can be played on browsers of Apple devices ?

  


  I am stuck on this for 3 days, So, any type of help is greatly regarded. I am also providing the link to my videos, if someone wants to take a closer look on codes and formats of these videos : Videos Link

  


  P.S : if anyone with a mac device can encode these transparent videos for me, then that would be best and I shall be very grateful to you

  


• lavc/vvc : Ensure subpictures don't overlap

  22 février, par Frank Plowman

  lavc/vvc : Ensure subpictures don't overlap
  This is essentially a re-implementation of
  
  https://patchwork.ffmpeg.org/project/ffmpeg/patch/20241005223955.54158-1-post@frankplowman.com/
  That patch was not applied last time.  Instead we opted to identify
  
  issues which could be caused by invalid subpicture layouts and remedy
  
  those issues where they manifest, either through error detection or code
  
  hardening.  This was primarily implemented in the set
  
  https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=13381.
  This has worked to some degree, however issues with subpicture layouts
  
  continue to crop up from the fuzzer and I've fixed a number of bugs
  
  related to subpicture layouts since then.  I think it's best to return
  
  to the initial plan and simply check if the subpicture layout is valid
  
  initially.
  This implementation is also lighter than the first time — by doing a
  
  bit more logic in pps_subpic_less_than_one_tile_slice, we are able to
  
  store a tile_in_subpic map rather than a ctu_in_subpic map.  This
  
  reduces the size of the map to the point it becomes possible to allocate
  
  it on the stack.  Similar to 8bd66a8c9587af61c7b46558be3c4ee317c1af5a,
  
  the layout is also validated in the slice map construction code, rather
  
  than in the CBS, which avoids duplicating some logic.
  Signed-off-by : Frank Plowman <post@frankplowman.com>
  

  • [DH] libavcodec/vvc/ps.c