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• Why MP4 generated through FFmpeg API can't be played in the Windows Media Player ?

  2 septembre 2021, par James

  I encoded some frames into a MP4 using FFmpeg API, but the MP4 could't be played in the Windows Media Player.

  


  By comparison with the normal MP4 using ffprobe, I found that the FOURCC of the problematic MP4 is 'H264' while the normal MP4 is 'AVC1'.
According to H.264 Video Types, 'AVC1' has start codes but 'H264' hasn't.I also learned that we shoud manually add sps and pps before H.264 stream when demuxing a MP4.

  


  Now I don't know how to add start code or sps/pps to my MP4, please give me a hand.
How I should do to generate a MP4 which can be played in the Windows Media Player ?

  


  I have tried to add h264 bitstream filter but it didn't work. The code below :

  


   AVBitStreamFilterContext *bsfc = NULL;
bsfc = av_bitstream_filter_init("h264_mp4toannexb");
if (bsfc == NULL) {
            printf("bsfc is NULL\n");
}
        
av_bitstream_filter_filter(bsfc, codec_ctx, NULL, &(pkt->data), &(pkt->size), pkt->data, pkt->size, 0);

av_bitstream_filter_close(bsfc);


  


  After a lot of trying, I found that manually adding sps and pps to codec_ctx->extradata effective :

  


  unsigned char sps_pps[23] = { 0x00, 0x00, 0x00, 0x01, 0x67, 0x64, 0x00, 0x29, 0xac, 0x1b, 0x1a, 0x12, 0xe0, 0x51, 0x90,
                              0x00, 0x00, 0x00, 0x01, 0x68, 0xea, 0x43, 0xcb };
codec_ctx->extradata_size = 23;
codec_ctx->extradata = (uint8_t*)av_malloc(23 + AV_INPUT_BUFFER_PADDING_SIZE);
if (codec_ctx->extradata == NULL) {
    printf("could not av_malloc the video params extradata!\n");
    ERR_NULL_EXIT
    }
memcpy(codec_ctx->extradata, sps_pps, 23);


  


  The code above refered to an answer of @szatmary

  


  Now generated MP4 can be played in Windows Media Player. But a new question emerges because I don't konw what correct value of sps/pps is. It cause that the width and height of frame presented in the Windows Explorer is incorrect. So I need to set the correct sps/pps. I also read the document of sps/pps but get confused because some parameters have variable bits. So can anybody tell me how to set the sps/pps correctly ?

  


• av_register_all generates an exception in Release mode on Windows [closed]

  7 août 2012, par ranyakir

  I have a program that uses libav. It works well when compiled in Debug mode (Windows, VisualStudio 2010). However, when the program is compiled in Release mode, it crashes in av_register_all. The exception I get is Privileged Instruction.

  Anyone has an idea if there is anything special that needs to be done in Release mode to get libav to work ?

  Best regards
  Ran

• configure : Don’t add -fPIC on windows targets

  5 juin 2013, par Martin Storsjö

  configure : Don’t add -fPIC on windows targets
  This avoids warnings about this option not having any effect on
  
  this platform.
  We still want to enable the pic configure item for these platforms
  
  (if detected via the compiler builtin define __PIC__) to get proper
  
  inline assembly workarounds.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] configure