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• Fragmented MP4 file playback in web browser

  5 octobre 2013, par Steven Chang

  I want to build a MP4 streaming server.
  I generated MP4 file with ffmpeg as follow.

  $ffmpeg -i input.avi -movflags frag_keyframe output.mp4  
  

  It works normally in Google Chrome but IE9 and Safari just play a short period.
  (One keyframe duration)
  What is the proglem?

  Thanks

  The HTML code is here:
  

• "error C2400 : inline assembler syntax error in ‘opcode’" pxor compiling ffmpeg with mmx flag enabled

  4 octobre 2013, par Kristofer

  I'm trying to compile (visual studio 2005) ffmpeg with mmx flag enabled (HAVE_MMX) but get the following error: "error C2400: inline assembler syntax error in ‘opcode’" And it's complaining about xpor_r2r

  Ideas?

  [Update] Jester pointed out that it's probably a problem with the macro: #define mmx_r2r(op,regs,regd) \ __asm__ volatile (#op " %" #regs ", %" #regd)

  Directly using: __asm__ pxor mm7 mm7 works Adding volatile (as in the macro mentioned) gives the same error, syntax error as before in 'opcode' found 'data_type'.

  Just removing volatile from the macro does not work, instead gives error in 'opcode' found '('

  Removing the paranthesis instead gives error in 'opcode' found 'bad_token'

• FFMPEG libavformat internal buffering

  4 octobre 2013, par Theodor

  I'm using FFMPEG for a C++ audio streaming and playback application.

  I use the avformat_open_input function to open an URL to an external compressed audio file and then I step through to stream using av_read_frame. Then for each packet i directly decode the data and queue it in the audio buffer using OpenAL.

  My question is if FFMPEG internally prebuffers compressed data from the external URL?

  Does FFMPEG keep downloading data in the background even if I don't call av_read_frame?

  Or is it my responsibility to maintain a intermediate buffer where I download as many packets as possible ahead of time to avoid starving the audio-playback?

  If so, how much does it buffer/download internally? Can I configure this?

  I have been looking through the documentation but have not found any information on this.

  Thanks.

  Update: According to this thread http://ffmpeg.zeranoe.com/forum/viewtopic.php?f=15&t=376 libav should by default prebuffer about 5MB depending on AVFormatContext::max_analyze_duration. However I haven't noticed this behavior and it doesn't seem to change if I alter max_analyze_duration.

  If I monitor the memory consumption of my process it doesn't increase after I call avformat_open_input and if I simulate slow-network, av_read_frame directly stops working like if it didn't have any packets buffered.

• FFmpeg on Xcode

  4 octobre 2013, par user2741735

  I'm developing an app for ios which uses IP Camera to stream live videos to the user. I installed macports and ffmpeg using terminal on my mac. I have taken the IP Camera output and converted into .ts file using ffmpeg on terminal. Now I want the procedure to do the same using Xcode i.e. writing code in xcode to convert IP Camera output to .ts files. Thanks in advance.

• How to copy frame data from FFmpegSource2 (FFMS2) FFMS_Frame struct to OpenCV Mat ?

  4 octobre 2013, par Yashil

  I'm trying to read video file using FFmpegSource2 (FFMS2) and then process frames using OpenCV. What is the proper and efficient way to copy frame data from a FFMS_Frame struct returned by FFMS_GetFrame function to an OpenCV Mat?

  Thank you very much in advance.