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• Can't scrub frame by frame through .mp4 files in VLC created using FFmpeg command line, but changing container to .avi can scrub frame by frame in VLC

  16 juin 2022, par ICBanMI

  I wrote a really simple demonstration of the issue. I create a 4k video that is 150 frames, and output it to mp4. When I open that in VLC(Vent 3.0.17.4), I can scrub forward a few frames at the beginning(e key) before it stops entirely. If I move it towards the end of the file( 4 secs), it can't scrub forward at all.

  


  What I found out through testing. I can scrub forward/backward 3 seconds normal in vlc. I can scrub forward frame by frame using quicktime's latest version(2016). If I mux it to .avi file format, scrubbing using the e key works as expected in VLC. Copying the meta data from an mp4 that can scrub forward frame by frame doesn't change anything. Renaming the .mp4 file to .avi doesn't fix the issue... only muxing out to an avi does. Using a build of version 5.0.1 of ffmpeg.

  


  I included both VLC commands in code. I'd be more than happy to walk way from this with just muxing everything to avi... but .mp4 is a requirement along with being able to scrub forward frame by frame in VLC. Not sure if code or command line is where the issue is... as sample mp4s from the net used in VLC don't appear to have this issue.

  


  #include <iostream>&#xA;#include &#xA;&#xA;int main()&#xA;{&#xA;   FILE *m_pFFmpeg;&#xA;&#xA;   // Working - Can scrub forward frame by frame in latest version of vlc&#xA;   //const char *cmdOutput = "ffmpeg -hide_banner -y -r 30 -s 3840x2160 -f rawvideo -pix_fmt rgb24 -i - -framerate 30 -an -vcodec libx264 -pix_fmt yuv420p -video_track_timescale 30 -vf vflip -preset veryslow -qp 0 output.avi";&#xA;   &#xA;   // Not working - Can&#x27;t scrub forward frame by frame in latest version of vlc. Only difference is the .mp4 at the end&#xA;   const char *cmdOutput = "ffmpeg -hide_banner -y -r 30 -s 3840x2160 -f rawvideo -pix_fmt rgb24 -i - -framerate 30 -an -vcodec libx264 -pix_fmt yuv420p -video_track_timescale 30 -vf vflip -preset veryslow -qp 0 output.mp4";&#xA;  &#xA;   int g_x_dis_res = 3840;&#xA;   int g_y_dis_res = 2160;&#xA;&#xA;   m_pFFmpeg = _popen(cmdOutput, "wb");&#xA;&#xA;   uint8_t *export_buffer = new uint8_t[g_x_dis_res * g_y_dis_res * 3];&#xA;&#xA;   for (int i = 0; i &lt; (g_x_dis_res * g_y_dis_res * 3); i&#x2B;&#x2B;) {&#xA;      export_buffer[i] = 127;&#xA;   }&#xA;&#xA;   for (int j = 0; j &lt; 150; j&#x2B;&#x2B;) {&#xA;      fwrite(export_buffer, 3 * g_x_dis_res * g_y_dis_res, 1, m_pFFmpeg);&#xA;&#xA;      printf("Export Frame %d\n", j &#x2B; 1);&#xA;   }&#xA;&#xA;   delete[] export_buffer;&#xA;&#xA;   fflush(m_pFFmpeg);&#xA;   _pclose(m_pFFmpeg);&#xA;&#xA;   return 0;&#xA;}&#xA;</iostream>

  


• vulkan : add support for regular descriptor pools

  22 septembre 2024, par Lynne

  vulkan : add support for regular descriptor pools
  This permits :
  
   - The use of Vulkan filtering on many more devices
  
   - Better debugging due to lack of descriptor buffer support in layers
  Much of the changes here are due to a requirement that updates to
  
  descriptors must happen between the command buffer being waited on,
  
  and the pipeline not being bound.
  We routinely did it the other way around, by updating only after
  
  we bind the pipeline.
  

  • [DH] libavfilter/vf_gblur_vulkan.c
  • [DH] libavfilter/vf_nlmeans_vulkan.c
  • [DH] libavfilter/vulkan_filter.c
  • [DH] libavutil/hwcontext_vulkan.c
  • [DH] libavutil/vulkan.c
  • [DH] libavutil/vulkan.h
  • [DH] libavutil/vulkan_functions.h

• Play Raspberry Pi h264 stream in C# app

  5 septembre 2019, par CoreMeltdown

  I have a Raspberry Pi board with dedicated camera that records video only in h264. I am looking for the best method to stream and play recorded video in real-time (as in, less than 1 sec delay) in c# windows forms app. The additional requirement is that such stream can be easily processed before displaying, for example for searching for objects on the image.

  Stuff I tried :

  - VLC server on raspi and VLC control in c# forms app <- simple solution, with RTSP, but has a serious flaw, which is a 3sec delay in image displayed. I couldn’t fix it with buffor size/options etc.

  - creating a socket on raspi with nc, receiving raw h264 data in c# and passing it to mplayer frontend <- If I simply start raspivid | nc and on the laptop nc | mplayer, i get exactly the results i want, the video i get is pretty much realtime, but the problem arises when i try to create mplayer frontend in c# and simulate the nc.exe. Maybe I’m passing the h264 data wrong (simply write them to stdin) or maybe something else.

  - using https://github.com/cisco/openh264 <- I compiled everything, but i can’t even get to decode sample vid.h264 i recorded on raspi with h264dec.exe, not to mention using it in c#.

  h264dec.exe vid.h264 out.yuv

  This produces 0bytes out.yuv file, while :

  h264dec.exe  vid.h264

  Gives me error message : "No input file specified in configuration file."

  - ffmpeg <- I implemented ffplay.exe playback in c# app but the lack of easy method to take screencaps etc. discouraged me to further investigate and develop.

  I’m not even sure whether I’m properly approaching the subject, so I’d be really thankful for every piece of advice I can get.

  EDIT
  Here is my ’working’ solution I am trying to implement in c#

  raspivid --width 400 --height 300 -t 9999999 --framerate 25 --output - | nc -l 5884
  
  
  
  nc ip_addr 5884 | mplayer -nosound -fps 100 -demuxer +h264es -cache 1024 -

  The key here is FPS 100, becuase then mplayer skips lag and plays the video it immediately receives with normal speed.
  The issue here is that I don’t know how to pass video data from socket into mplayer via c#, because I guess it is not done via stdin (already tried that).