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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;
}


  


• Converting Raw video data to a good quality compressed video using ffmpeg [closed]

  12 janvier 2013, par Deepak Bhatia

  I have a raw video data of size 10 MBytes but when I convert the same to MPEG4 Video, its size becomes 20 MBytes. I am using ffmpeg 1.1.

  Why the size is increasing on using MPEG4 Encoder for compressing the raw video ?

  Thanks in advance.

  Deepak Bhatia

• Compress Videos in Android using FFMPEG

  3 mai 2017, par Gaurav Kumar

  I have already put the gradle of writing minds to compress videos.

  compile 'com.writingminds:FFmpegAndroid:0.3.2'

  Now after syncing project, I have list of videos fetched from external or internal storage. videos of size upto 100 or 500 mb. Now when user clicks on that, video must compress and returned the compressed url so that i will be able to upload the compressed video to the server.

  Please suggest or do some lines of code or any guidance.
  Thanks in advance !!.