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• FFmpeg Centos Compile Error - caused by libwebp (error : implicit declaration of function ‘libwebp_error_to_averror’)

  2 septembre 2022, par fvid1

  I'm trying to compile FFmpeg on Centos 7.9. I followed the official instructions : https://trac.ffmpeg.org/wiki/CompilationGuide/Centos

  


  I need support for WebP images, so I installed libwebp and libwebp-devel via YUM, and used the option --enable-libwebp.

  


  But at the ffmepg "make" stage, the following error is returned :

  


  CC      libavcodec/libwebpenc_common.o
libavcodec/libwebpenc_common.c: In function ‘ff_libwebp_get_frame’:
libavcodec/libwebpenc_common.c:283:17: error: implicit declaration of function ‘libwebp_error_to_averror’ [-Werror=implicit-function-declaration]
                 ret = libwebp_error_to_averror(pic->error_code);
                 ^
cc1: some warnings being treated as errors
make: *** [libavcodec/libwebpenc_common.o] Error 1


  


  Does anyone know why this error is occuring and how it can be corrected ?

  


  I've tried compiling without using --enable-libwebp and it works fine.

  


• Continuous RTMP Streaming with FFmpeg Without Restarting the Process for New Videos

  3 avril 2024, par 刘小佳

  I'm facing a challenge with my workflow and would appreciate any guidance or solutions you might have. My business scenario involves a service that periodically generates new video files locally (e.g., 1.mp4, 2.mp4, ...). These files are then streamed to an RTMP server using FFmpeg, and clients pull the stream via HTTP-FLV for playback.

  


  My goal is to ensure continuous streaming between video files without restarting the FFmpeg process each time a new video is ready to be streamed. Restarting FFmpeg for each new file introduces a disconnect in the client playback, which I'm trying to avoid to maintain stream continuity.

  


  I've explored several approaches based on the FFmpeg Concatenate wiki (https://trac.ffmpeg.org/wiki/Concatenate), but haven't achieved the desired outcome :
  
Approach 1 :
  
Using a list.txt file with ffconcat version 1.0 and dynamically updating the file (next.mp4) being played :

  


  ffconcat version 1.0
file next.mp4
file next.mp4


  


  And then streaming with :
ffmpeg -re -stream_loop -1 -f concat -i list.txt -flush_packets 0 -f flv rtmp://xxx
  
However, when attempting to replace next.mp4 (e.g., moving 2.mp4 to next.mp4 during the streaming of 1.mp4), I encountered a "device busy" error.
  
Approach 2 :
  
Using a nested list approach where list1.txt includes 1.mp4 and list2.txt, and vice versa :

  


  // list1.txt
ffconcat version 1.0
file '1.mp4'
file 'list2.txt'
// list2.txt
ffconcat version 1.0
file '2.mp4'
file 'list1.txt'


  


  Streaming with : ffmpeg -re -stream_loop -1 -f concat -i list1.txt -flush_packets 0 -f flv rtmp://xxx
  
In this setup, I tried modifying list1.txt to replace 1.mp4 with 3.mp4 during the streaming of 2.mp4, but FFmpeg would loop back to 1.mp4 and 2.mp4 before streaming 3.mp4 in the next cycle.

  


  Am I missing something in my methods ? Does anyone have a better approach to fulfill this requirement ? Any help would be greatly appreciated !

  


• Input seeking for frame at specified timestamp with Py-AV

  9 décembre 2019, par neonScarecrow

  I have a project already using Py-AV and am trying to replicate a specific ffmpeg command. The goal is to get a frame roughly around the specified timestamp.

  Here’s the ffmpeg commmand :
  https://trac.ffmpeg.org/wiki/Seeking

  ffmpeg -ss 14 -i https://some_url.mp4 -frames:v 1 frame_at_14_seconds.jpg

  Here’s my code :

      #return one frame around 14 seconds into the movie
  
      target_sec = 14 
  
      container = av.open('https://some_url.mp4', 'r')
  
      container.streams.video[0].thread_type = 'AUTO'
  
      video_stream = next(s for s in container.streams if s.type == 'video')
  
      time_base = float(video_stream.time_base)
  
      target_timestamp = int(target_sec / time_base) + video_stream.start_time
  
      video_stream.seek(target_timestamp)
  
      for frame in container.decode(video_stream):
  
          frame.to_image().save('frame_at_14_seconds.jpg')
  
          break

  Additionally, I have found any documentation about this, but does anyone know if either command (ffmpeg/av.open) is downloading the entire file to a tmp file behind the scenes. I’m looking for a less memory-intensive way to read a frame for every second in an up to 60 second video.