Recherche avancée

Sur d’autres sites (3361)

• Custom real-time input for ffmpeg in C

  10 août 2016, par Victor.dMdB

  I’m implementing a custom io with avformat_alloc_context and avio_alloc_context to be able to read the output of another function in real-time. A buffer is populated by this function in a boost asio thread, while ffmpeg is reading this buffer from another thread.

  I initialise an io buffer where this function writes into, and which ffmpeg reads :

  BufferData input_buffer = {0};
  
  input_buffer.size = 65536;
  
  input_buffer.ptr = (uint8_t *) av_malloc(buf_size);
  
  memset(input_buffer.ptr,'0',100); 
  
  
  
  fprintf(stdout, "initialisation: buffer pointer %p buffer data pointer: %p\n", &input_buffer, input_buffer.ptr);

  Why i do the memset is explained here.
  Then to test out the pointer address I did :

  BufferData * decode_buffer;
  
  decode_buffer->size = 65536;
  
  decode_buffer->ptr = (uint8_t *) av_malloc(decode_buffer->size);
  
  
  
  AVIOContext * av_io_ctx = avio_alloc_context(decode_buffer->ptr, decode_buffer->size, 0, &input_buffer, &read_function, NULL, NULL);
  
  
  
  AVFormatContext *av_fmt_ctx = avformat_alloc_context();
  
  av_fmt_ctx->pb = av_io_ctx;
  
  
  
  
  
  BufferData * tmpPtr = (BufferData * ) video_input_file->av_io_ctx->opaque;
  
  
  
  fprintf(stdout, "video decoder before: buffer pointer %p, buffer data pointer: %p\n", tmpPtr, tmpPtr->ptr);
  
  
  
  open_res = avformat_open_input(&av_fmt_ctx, "anyname", in_fmt, options ? &options : NULL);
  
  
  
  fprintf(stdout, "video decoder after: buffer pointer %p, buffer data pointer: %p\n", tmpPtr, tmpPtr->ptr);

  For reference

  typedef struct {
  
      uint8_t *ptr;
  
      size_t size;
  
  } BufferData;

  The read function

  static int read_function(void* opaque, uint8_t* buf, int buf_size) {
  
      BufferData *bd = (BufferData *) opaque;
  
      buf_size = FFMIN(buf_size, bd->size);
  
      memcpy(buf, bd->ptr, buf_size);
  
      bd->ptr  += buf_size; //This seemed to cause the problem
  
      bd->size -= buf_size;
  
      return buf_size;
  
  }

  And the result will be :

  initialisation: buffer pointer 0x7f2c4a613620, buffer data pointer: 0x7f2c48c56040
  
  
  
  video decoder before: buffer pointer 0x7f2c4a613620, buffer data pointer: 0x7f2c48c56040
  
  
  
  video decoder after: buffer pointer 0x7f2c4a613620, buffer data pointer: 0x7f2c49e24b50

  Is it a normal behaviour that the buffer data ptr is changed by avformat_open_input ? since I would like to keep the initial pointer address given I am using it in another function, and have malloced it the required memory.

• How to plot animated time series in R ?

  28 août 2016, par pOrlando

  I am trying use the ’animation’ package in R to plot an animated time series.

  My dataset consists of a time vector and a value vector, each with 1800 rows.

  I keep getting an error message after running the loop which reads :

  Error in jpeg(gname[i]) : unable to start jpeg() device
  
  In addition: Warning messages:
  
  1: In jpeg(gname[i]) : unable to open file 'g11:30:00.jpg' for writing
  
  2: In jpeg(gname[i]) : opening device failed

  Here’s the source code

  timemax<-1800
  
  setwd("~/Documents/Animation/")
  
  graphdata<-read.csv("filling_line_data_construction_v2.csv")
  
  attach(graphdata)
  
  gname<-paste("g",time, ".jpg", sep="")
  
  for (i in 1:timemax){
  
      jpeg(gname[i])
  
      plot(time[1],value[1],type="l",ylim=c(0,35), xlim=c(0,100),
  
        ylim = c(0, 35),ylab = "", xlab="time")
  
      lines(time[1:i],value[1:i])
  
      dev.off(dev.cur())
  
  }

  The end goal is to string together these 1800 plots as a stop animation video by calling the ffmpeg shell :

  shell("C:/ffmpeg/bin/ffmpeg.exe -report -i g%d.jpg -b:v 2048k fillin_lineR.mpg",mustWork=FALSE)

  This is code that I’ve been trying to adapt from http://www.animatedgraphs.co.uk/LondonR.html#slide-30, but this example uses a .tif file instead of .jpg, and my computer gives me 1800 error messages when trying to make a video from .tif files...

  Thanks in advance !

• Add watermark to all videos in a folder and enable it only during certain time intervals

  20 octobre 2016, par Neo Herakles

  I’m making a batch file to watermark all my videos in a folder using FFMPEG, I have to place the watermark at 1/3 of the duration of the video, I currently have this, it worked individually but I can’t seem to make it work for the whole folder, what am I doing wrong ? Also, is there a way to enable the watermark multiple times ? once at 1/3 of the duration, another at 2/3 of the duration.

  @echo off
  
  setlocal
  
  for %%I in ("%~dp0\water\*.mp4") do (
  
     for /F "delims=" %%I in ('ffprobe.exe -v error -show_entries format^=duration -of default^=noprint_wrappers^=1:nokey^=1 %%I.mp4 2^>^&1') do set "duration=%%I"
  
     'ffmpeg.exe -i "%%I" -i Watermark.png -filter_complex "[0:v]scale=iw:ih[v0];[1:v][v0]scale2ref=iw/6:ih/10[logo][0v];[0v][logo]overlay=W-w-3:H-h-3:enable='between(t,%duration%/3,(%duration%/3)+2)'[v]" -map "[v]" -map 0:a -codec:v libx264 -preset ultrafast -crf 23 -codec:a copy "%~dp0\out\%%~nI.mp4"'
  
  )
  
  endlocal
  
  pause

  Thanks a lot for all the help I’ve received during these days, it really helped me to improve, although I still have a long way to go.