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• FFmpeg function avformat_open_input for USB video device throws exception : No such file or directory

  8 juin, par ffvideoner

  Windows & C# & FFmpeg.AutoGen

  


  I used the ffmpeg-function (from library FFmpeg.AutoGen) to show video from rtsp-stream :

  


  ffmpeg.avformat_open_input(&pFormatContext, "rtsp://127.0.0.1:8554/abc", iformat, null);


  


  It works right.

  


  Now I want to use this function for USB video device.

  


  FFmpeg outputs this device name :

  


  ffmpeg -list_devices true -f dshow -i dummy

[dshow @ 0000000000163000] "GENERAL WEBCAM" (video)


  


  This is how I'm trying to get the video :

  


  string deviceName = "GENERAL WEBCAM";


  


  or

  


  string deviceName = "video=GENERAL WEBCAM";

ffmpeg.avformat_open_input(&pFormatContext, deviceName, ffmpeg.av_find_input_format("dshow"), null);


  


  For both variants of device names, I get an error :

  


  No such file or directory.


  


  But here it works :

  


  ffmpeg -video_size 1280x720 -framerate 30 -f dshow -i video="GENERAL WEBCAM":audio="Microphone (3- GENERAL WEBCAM)" -c:v libx264 -crf 30 -preset ultrafast ffmpegvideo.mp4


  


  Why doesn't avformat_open_input work with video device name ?

  


• FFMPEG with VP9 + RTSP

  4 janvier 2021, par Jim Jin

  When we use HEVC + RTSP, ffmpeg works fine. The stream is captured by webcam.

  


  ffmpeg -f dshow -rtbufsize 100M  -f vfwcap -i "0" -strict experimental -c:v hevc_qsv -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test


  


  The output is like :

  


  frame=  355 fps= 37 q=-0.0 size=N/A time=00:00:11.27 bitrate=N/A dup=159 drop=0 speed=1.18x


  


  Then we switch to VP9 + RTSP.

  


  ffmpeg -f dshow -rtbufsize 100M  -f vfwcap -i "0" -strict experimental -c:v libvpx-vp9 -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test


  


  The fps and speed looks too slow :

  


  frame=  263 fps=9.5 q=0.0 size=N/A time=00:00:07.94 bitrate=N/A dup=119 drop=0 speed=0.288x


  


  Then we use ffplay to play the stream. There are a lot of error messages and the video seems frozen.

  


  [vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available0B f=0/0
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available


  


  Finally, we try hardware VP9 encoder.

  


  ffmpeg -f dshow -rtbufsize 100M  -f vfwcap -i "0" -strict experimental -c:v vp9_qsv -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test


  


  It can't work.

  


  [swscaler @ 0000021e88df9fc0] deprecated pixel format used, make sure you did set range correctly
[vp9_qsv @ 0000021e8687df80] Selected ratecontrol mode is unsupported
[vp9_qsv @ 0000021e8687df80] Low power mode is unsupported
[vp9_qsv @ 0000021e8687df80] Current frame rate is unsupported
[vp9_qsv @ 0000021e8687df80] Current picture structure is unsupported
[vp9_qsv @ 0000021e8687df80] Current resolution is unsupported
[vp9_qsv @ 0000021e8687df80] Current pixel format is unsupported
[vp9_qsv @ 0000021e8687df80] some encoding parameters are not supported by the QSV runtime. Please double check the input parameters.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!


  


  So, how can we deal with VP9 + RTSP successfully ?

  


• UVC webcam with ffplay outputs only noise ?

  1er mars 2024, par Abdulla Masud

  (My end goal is to use a UVC webcam with esp32 or raspberry pi. I was hoping to learn while doing some fun projects.)

  


  I have an old UVC webcam (Creative model ct6840) but I can't seem to get it to work with ffplay. I have tried looking through the documentation and other questions here but nothing is working for me. So far I have only been able to achieve a noisy-jittery output.

  


  Running ffplay -f rawvideo -video_size 670x480 /dev/video1, I get :

  


  

  


  Can someone help me understand how to make the camera work with ffplay ?

  


  The following is the information of my webcam :

  


  $ ffmpeg -f v4l2 -list_formats all -i /dev/video2

  


  [video4linux2,v4l2 @ 0x17eb3c0] Compressed: Unsupported :          GSPCA OV511 : 320x240 640x480


  


  $ v4l-info /dev/video2

  


  ### v4l2 device info [/dev/video2] ###
general info
    VIDIOC_QUERYCAP
    driver                  : "ov519"
    card                    : "USB Camera (05a9:0511)"
    bus_info                : "usb-0000:00:14.0-8.2"
    version                 : 6.1.79
    capabilities            : 0x85200001 [VIDEO_CAPTURE,?,READWRITE,STREAMING,(null)]

standards

inputs
    VIDIOC_ENUMINPUT(0)
    index                   : 0
    name                    : "ov519"
    type                    : CAMERA
    audioset                : 0
    tuner                   : 0
    std                     : 0x0 []
    status                  : 0x0 []

video capture
    VIDIOC_ENUM_FMT(0,VIDEO_CAPTURE)
    index                   : 0
    type                    : VIDEO_CAPTURE
    flags                   : 1
    description             : "GSPCA OV511"
    pixelformat             : 0x3131354f [O511]
    VIDIOC_G_FMT(VIDEO_CAPTURE)
    type                    : VIDEO_CAPTURE
    fmt.pix.width           : 640
    fmt.pix.height          : 480
    fmt.pix.pixelformat     : 0x3131354f [O511]
    fmt.pix.field           : NONE
    fmt.pix.bytesperline    : 640
    fmt.pix.sizeimage       : 614400
    fmt.pix.colorspace      : JPEG
    fmt.pix.priv            : 4276996862

controls
    VIDIOC_QUERYCTRL(BASE+0)
    id                      : 9963776
    type                    : INTEGER
    name                    : "Brightness"
    minimum                 : 0
    maximum                 : 255
    step                    : 1
    default_value           : 127
    flags                   : 48
    VIDIOC_QUERYCTRL(BASE+1)
    id                      : 9963777
    type                    : INTEGER
    name                    : "Contrast"
    minimum                 : 0
    maximum                 : 255
    step                    : 1
    default_value           : 127
    flags                   : 32
    VIDIOC_QUERYCTRL(BASE+2)
    id                      : 9963778
    type                    : INTEGER
    name                    : "Saturation"
    minimum                 : 0
    maximum                 : 255
    step                    : 1
    default_value           : 127
    flags                   : 32
    VIDIOC_QUERYCTRL(BASE+24)
    id                      : 9963800
    type                    : MENU
    name                    : "Power Line Frequency"
    minimum                 : 0
    maximum                 : 2
    step                    : 1
    default_value           : 0
    flags                   : 0
    VIDIOC_QUERYCTRL(BASE+32)
    id                      : 9963808
    type                    : BOOLEAN
    name                    : "Brightness, Automatic"
    minimum                 : 0
    maximum                 : 1
    step                    : 1
    default_value           : 1
    flags                   : 8


  


  Can someone guide me here please ? Any advice will be greatly appreciated 

  


  (P.S. the camera works perfectly with "guvcview" gtk application but since I want to use the camera with raspberry pi, I want it to work with ffplay...)