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• How to decode stream data via ffmpeg library [closed]

  23 juillet 2024, par Steffen Roeber

  I found this example on GitHub : avio_read_callback.c. Unfortunately, it is a very simplified example because it reads the whole input file into memory and processes it at once.

  


  Does anyone have a better example of how to use avio_alloc_context with the read callback and how to handle incoming data block by block ? Specifically, I'm looking for details on :

  


  

  • The appropriate size for avio_ctx_buffer_size

  


  • The correct return value in the read callback if there isn't enough data

  


  • Handling situations where more memory is needed after some data has already
been copied, such as when avformat_open_input fails initially

  


  


  I have an H.264 stream that works sometimes, depending on the buffer sizes, but I occasionally experience data drops.

  


• ffmpeg amix : process pcm data stream realtime

  29 décembre 2020, par YouCL

  I am building an exe with ffmpeg libs. In this exe, I got 2 3 pcm data streams from lower level sdk, I need to mix/merge these data to an audio file on the fly. Now I am trying amix filter, my questions are :

  


  

  1. How to send raw pcm data to ffmpeg filter graph by hand instead of frames from decoder as usual ?

  


  2. One of the pcm data streams starts and ends randomly. If I set 3 source filters, is it going to work ?

  


  


• How to do reprocessing H264 data to image/video

  3 octobre 2017, par somethingunexpected

  I have been working on a project which blows my mind.

  First of all, I have an IP camera that streams H264 data. I am able to stream it with its RTSP url via VLC/ffmpeg/python (rtsp ://ip:port/PSIA/Streaming/channels/2 ?videoCodecType=H.264). So, there is nothing to worry about streaming.

  However, on the project, camera is connected to the another system. This system gives the H264 data via ethernet to my PC, so camera is not connected directly to the PC.
  The system gives the data in every 10 ms at 1000 bytes. For example, if incoming data is 800 bytes, it adds 200 null bytes.

  What I can do is to extract these null bytes and take the raw data via a socket. For latency, I use thread module so there is no data leakage.

  What I gotta do is to turn these raw H264 data to an image sequence or a video that can be displayed via VLC, ffmpeg, Classic Media Player etc.

  I preferrebly want to write my code in Python and every operation has to be in real-time. So, any help would be appreciated.