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• what codec to specify to accessing my HDMI-to-USB adaptor, under Linux ? [closed]

  14 mai 2022, par David

  A week or so ago,I bought a HDMI-to-USB adapter, to use to capture video
TV content from my TV's set-top box. (Xfinity, if it matters. Box generically is :
"XiD X1"...I have both the Pace and the Cisco models available here in this house.)

  


  Specifically, here's the adapter I bought,from Amazon :
https://www.amazon.com/gp/product/B09FLN63B3

  


  So, I'm fluent in both Windows (Win-11) and Linux (Debian 'Bullseye', on my chromebook).

  


  The adapter does not come with any recommendations for what software/drivers to (try to) use, but I was prepared for that.
After some google searches, I decided to first try using the cmd-line
'ffmpeg' program, because I'm
quite familiar with that (excellent !) piece of open-source software !

  


  So, after a day or two of (mostly) success recordings under Win-11, using
ffmpeg's Microsoft-based 'dshow' (aka 'DirectShow'), I decided to attempt to get
up to the same level of accomplishment on my Chromebook, under Linux, also
using 'ffmpeg'.

  


  [Ok...a very brief explanation of 'mostly' successful. I'll
post another separate question here, about the specifics of my glitches,
using 'dshow' on Windows. But, essentially, when I try to record to a MP4
file, I get 2 scenarios of glitch : #1 : Suddenly, dropped packets surges up,
and I get "1000 dropped' yellow msg #2 : On other trials, I get '...contains
no image...'.) So, I figured I should first give a Linux a chance,
before spending more effort trying to resolve the glitches on Windows.]

  


  My first snag, was learning that 'dshow' seems to be specific to 'Windows',
and thus ffmpeg is getting 'unknown' for my reference to 'dshow'. After more hours of 'guessing', I've finally learned/concluded that there are other things
(something call "DeckLink" is one such alternative ?) for Linux, but I'm unclear
what extra Linux packages might exist for ffmpeg support, or whether I will need to built a more complete 'ffmpeg' (e.g. from source code), to get things going under Linux ?

  


  Is my device able to be accessed from some tools other than 'ffmpeg' ?
(e.g. VLC or Handbrake or whatever ?) more easily, on the Linux platform ?

  


  [If I had to, I'd probably invest another $20-$50 in some other hardware
device that goes from HDMI-to-USB (USB-A/B), if it were ]

  


  All ideas are welcome...(TIA)

  


  — Dave

  


• configure : Define feature test macros for —std=gnu99

  31 janvier 2016, par Henrik Gramner

  configure : Define feature test macros for —std=gnu99
  Makes the printf() family functions on MinGW use the correct C99 POSIX
  
  versions instead of the broken pre-VS2015 Microsoft ones.
  Also allows us to get rid of some _GNU_SOURCE and _ISOC99_SOURCE defines.
  

  • [DH] common/cpu.c
  • [DH] common/set.c
  • [DH] configure
  • [DH] encoder/analyse.c
  • [DH] encoder/ratecontrol.c
  • [DH] x264.c

• FFmpeg function avdevice_list_devices causes C++ Runtime error

  29 mai 2023, par ffvideoner

  I use Windows, C#, FFmpeg.AutoGen.
I want to get list of devices.

  


  public static class Helpers
{

    private static unsafe AVDeviceInfoList** _devicesList;

    public static unsafe void GetMediaSourceNames()
    {

        ffmpeg.avdevice_register_all();

        AVFormatContext* context = ffmpeg.avformat_alloc_context();

        ffmpeg.avdevice_list_devices(context, _devicesList);

    }

}


  


  Function avdevice_list_devices() causes error :

  


  


  Microsoft Visual C++ Runtime Library.
This application has requested the Runtime to terminate it in an unusual way.

  


  


  What am I doing wrong ?

  


  UPDATE

  


  Another reason for the error :

  


  Assertion s->oformat || s->iformat failed at src/libavdevice/avdevice.c:192


  


  If we look at the context in debugging, we will see that context.oformat and context.iformat are equal to zero.

  


  UPDATE 2

  


  If set some non-zero value, then the error will disappear.
Like this :

  


  AVInputFormat avformat = new AVInputFormat();

(*context).iformat = &avformat;


  


  But can't get list of devices.
Now the code looks like this. The last line throws an exception "Object reference not set to an instance of an object". But in debugging can see the value of nb_devices is ten (in fact, there are no devices at all).

  


  public static class Helpers
{

    private static unsafe AVDeviceInfoList* _devicesList;


    public static unsafe void GetMediaSourcesNames()
    {

        ffmpeg.avdevice_register_all();

        AVFormatContext* context = ffmpeg.avformat_alloc_context();


        AVInputFormat avformat = new AVInputFormat();

        (*context).iformat = &avformat;


        fixed (AVDeviceInfoList** devicesListPointer = &_devicesList)
        {
            ffmpeg.avdevice_list_devices(context, devicesListPointer);
        }


        int devicesQuantity = (*_devicesList).nb_devices;

    }

}