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• ffmpeg avformat_open_input() failed to open a dshow device url containing Chinese Characters

  16 octobre 2024, par Sang

  The USB Webcam is OK, but the device I want to use is a "virtual camera" named "无他伴侣(竖屏)", whose video is from the smart phone like Android or iOS. Connect the phone to PC, run an app on the phone, then run a PC client application, which can preview the video. The phone app is called "无他相机", and the PC app is called "无他伴侣", its website is https://www.wuta-cam.com/.

  


  I run FFmpeg at the Windows Commandline with the command ffmpeg -list_devices true -f dshow -i dummy, it's OK to list the devices.(in order to display Chinese correctly, run chcp 65001 in advance.)

  


  Run the command ffplay -f dshow -i video="无他伴侣(竖屏)", it's OK to play the video.(of course you need to comfirm its PC client previewing fine in advance.)

  


  Now I want to get the decoded frames from that virtual camera in my program, I call avformat_open_input() with video=无他伴侣(竖屏), it failed, the return value is -5, I/O error.

  


  Anyone knows the reason ?

  


  Below is my code snippet.

  


  avdevice_register_all();
avcodec_register_all();
//const char * url= "video=Logitech Webcam C930e";// This is fine.
char url[] = "video=无他伴侣(竖屏)";// This is bad.

AVFormatContext *pFmtCtx = avformat_alloc_context();
AVInputFormat *iformat = av_find_input_format("dshow");
int nRet = 0;
nRet = avformat_open_input(&pFmtCtx, url, iformat, NULL);
if (nRet)
{
    const size_t buffer_size = 256;
    char err_description[buffer_size];
    av_strerror(nRet, err_description, buffer_size);
    printf("%s.\n", err_description);// --> I/O error.
    printf("FAILED to open input.(Line:%d,%d)\n",  __LINE__, nRet);
    return -1;
}


  


• libavdevice/avfoundation.m : fix protential unreleased lock issue

  26 août 2021, par Chengfeng Ye

  libavdevice/avfoundation.m : fix protential unreleased lock issue
  The problem here is that the lock ctx->frame_lock will
  
  become an unreleased lock if the program returns at
  
  line 697, line 735 and line744.
  Bug tracker link : https://trac.ffmpeg.org/ticket/9385\#ticket
  Signed-off-by : Chengfeng Ye <cyeaa@connect.ust.hk>
  

  • [DH] libavdevice/avfoundation.m

• How can I watch my video from a sdp file ?

  7 avril 2019, par Marco Peca

  I’m using ffmpeg to create a streaming. It works fine. I have a server and with ffplay I can watch my stream.
  My only (big) constraint is real time.

  I have to embed it into an HTML page accessible from mobile devices.
  I tried with HTML5 video tag but I can’t include sdp files into it.

  With ffmpeg I create a stream from my webcam. I have also created the sdp file but in HTML5 doesn’t work.

  The code is here :

  ffmpeg server :

  sudo ffmpeg -re -f video4linux2 -i /dev/video0 -fflags no buffer rtp://224.10.20.30:20000

  file.sdp

  v=0
  
  o=- 0 0 IN IP4 127.0.0.1
  
  s=No Name
  
  c=IN IP4 224.10.20.30
  
  t=0 0
  
  a=tool:libavformat 55.7.100
  
  m=video 20000 RTP/AVP 96
  
  b=AS:200
  
  a=rtpmap:96 MP4V-ES/90000
  
  a=fmtp:96 profile-level-id=1

  ffplay : (It works)

  ffplay file.sdp

  How can I view the stream in a browser ?