WebCam Driver Question

[Dave Yeo]

I think what needs to be done is the audio and video streams being muxed into a container such as AVI, WEBM or Matroska so that the video and audio are in sync. The program to do that is FFmpeg where you should be able to pipe or feed the files into it and get a stream out.
There's likely directions of the internet for doing it.
Even better would be to use FFmpeg's libavcodec in a program to do the muxing, beyond my abilities.

[Remy]

I think what needs to be done is the audio and video streams being muxed into a container such as AVI, WEBM or Matroska so that the video and audio are in sync. The program to do that is FFmpeg where you should be able to pipe or feed the files into it and get a stream out.
There's likely directions of the internet for doing it.
Even better would be to use FFmpeg's libavcodec in a program to do the muxing, beyond my abilities.

I'm already working on ....  under Avxcat v2

Review some information from older post:
https://www.os2world.com/forum/index.php/topic,2453.msg27476.html#msg27476

Syntax I use has changed a lot due to syncro issue and other issue using latest ffmpeg (release 4.2.2-3)
I could get better result inverting audio and video input file order.
Sharing with you, here is a working example :
Of course, You have to start Wim's exes first.
ffmpeg -y -use_wallclock_as_timestamps 1 -thread_queue_size 64 -i \PIPE\Webcam\Audio -itsoffset 1.05 -use_wallclock_as_timestamps 1 -thread_queue_size 64 -f mjpeg -i \PIPE\Webcam\Video -c:v copy -c:a copy -map 1:v:0 -map 0:a:0 mywebcam.avi

(adjust -itsoffset 1.05 value if you have video/audio not syncro)

Of course, you can make the choice to change avi to mp4 etc.... but this will introduce ffmpeg process which could impact result at this step.
I've got some better results piping ffmpeg result into an other ffmpeg process.
ffmpeg -y -use_wallclock_as_timestamps 1 -thread_queue_size 64 -i \PIPE\Webcam\Audio -itsoffset 1.05 -use_wallclock_as_timestamps 1 -thread_queue_size 64 -f mjpeg -i \PIPE\Webcam\Video -c:v copy -c:a copy -map 1:v:0 -map 0:a:0 -f avi - |ffmpeg -i - mywebcam.mp4

Output of the second ffmpeg (or directly from first process) could be of other type (e.g. flv for rtmp...). You'll have visible latency due to ffmpeg process time (some special parameters exist to reduce streaming latency but already exist)

Warning: Piping from firs FFMPEG into second FFMPEG may consume a high amount of storage
From what I could see, about 174Mb shared low storage while runing only one ffmpeg step with avi output file requires about 42Mb shared low storage.
ffmpeg -y -use_wallclock_as_timestamps 1 -thread_queue_size 64 -i \PIPE\Webcam\Audio -itsoffset 1.05 -use_wallclock_as_timestamps 1 -thread_queue_size 64 -f mjpeg -i \PIPE\Webcam\Video -c:v copy -c:a copy -map 1:v:0 -map 0:a:0 mywebcam.avi    (or -f avi mywebcam.avi or any other format)

Note: If you start webcam through WCC, you can display/control current recording using:
 ffplay -i http://127.0.0.1:14225 -x 190 -y 144

[Remy]

Hi Wim,

It works nice since.

Regards
Rémy

Hi Rémy,

Fine. In the meantime I have updated webcam.exe and wmaudio.exe and added  wmvideo.exe and I think my package is now complete.
I think I tested it with your wcc.exe but I don't remember. My memory is getting worse. I have attached it here so Martin could try these too.

@Martin - Use "webcam /n" to start the Webcam Server and use "wmvideo /n" to start the Webcam Monitor Video and see what you get.

Regards,
Wim

Hi Wim,

This latest build has always 48000Hz audio output !
I went back to the previous build which allow me to set 44100Hz

Regards
Rémy

[Wim Brul]

Hi Wim,

It works nice since.

Regards
Rémy

Hi Rémy,

Fine. In the meantime I have updated webcam.exe and wmaudio.exe and added  wmvideo.exe and I think my package is now complete.
I think I tested it with your wcc.exe but I don't remember. My memory is getting worse. I have attached it here so Martin could try these too.

@Martin - Use "webcam /n" to start the Webcam Server and use "wmvideo /n" to start the Webcam Monitor Video and see what you get.

Regards,
Wim

Hi Wim,

This latest build has always 48000Hz audio output !
I went back to the previous build which allow me to set 44100Hz

Regards
Rémy

My latter build takes the audio sample frequency specified by the user and validates it against the usb audio descriptors of the webcam. Logitech c250/c270/pro9000 webcams do not support 44100 Hz. according to their audio descriptors and since the last scanned audio descriptor specifies 48000 Hz. this frequency is used. Similarly 16000 Hz. will be used by the Logitech Quickcam Pro for Notebooks because this is the only audio frequency that this webcam reports supported. This latter build is supposed to work with audio from all kinds of uvc compliant webcams.

On the contrary my former build takes the audio sample frequency specified by the user and validates it using a list of hardcoded values that work with the Logitech c250/c270/pro9000 webcams and this list includes 22050 Hz. and 44100 Hz. that happen to work on these webcams despite of the fact that their usb audio decriptors omit these. Scanning of usb audio descriptors was not yet implemented but that is really the way to go.

[Martin Iturbide]

Hi Martin,

I wanted to test any kind of sound from my USB Webcam - Logitech C920 HD Pro Webcam
I'm using "Webcam00-20210120.zip" and Lar's USBAUDIO.

Please attach lsusb report of this camera for me to inspect.

Hi

I have a strange behavior with lsusb (lsusb-20130526.zip) with this device. If I don't plug the camera, I get the normal report. If I plugged the camera, I get no report at all from any device. Even that  "webcam /n" is working fine to see video from the webcam.

Any other tip to get the USB hardware report?

Regards

[Martin Iturbide]

Hi Martin,

I wanted to test any kind of sound from my USB Webcam - Logitech C920 HD Pro Webcam
I'm using "Webcam00-20210120.zip" and Lar's USBAUDIO.

Please attach lsusb report of this camera for me to inspect.

Hi

I took this log with testlog, but I'm not sure if that is what you need Wim.

Code: [Select]

Device 1:
  ctrlID=1 DevAdr=2 ConfigVal=0 IfNo=0 Speed=2 Port=1 HubIx=3
  USB Release number=0x200 DevReleaseNumber=0x11
  Class=239 SubClass=2 Protocol=1 MaxPacketSize=64
  Vendor:Product=046d:082d NumConfigurations=1 Logitech, Inc. HD Pro Webcam C920
  Configuration: NumInterfaces=4 ConfigValue=1 StringIx=0 Attr=0x80 MaxPower=250
  Interface 0: Alt=0 nEP=1 Class=14(Video) SubClass=1 Protocol=0 StringIx=0
  Endpoint: Adr=0x83 Attr=0x3 MaxPktSize=64 Interval=8
  Interface 1: Alt=0 nEP=0 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Interface 1: Alt=1 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=192 Interval=1
  Interface 1: Alt=2 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=384 Interval=1
  Interface 1: Alt=3 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=512 Interval=1
  Interface 1: Alt=4 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=640 Interval=1
  Interface 1: Alt=5 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=800 Interval=1
  Interface 1: Alt=6 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=944 Interval=1
  Interface 1: Alt=7 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=2688 Interval=1
  Interface 1: Alt=8 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=2848 Interval=1
  Interface 1: Alt=9 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=3040 Interval=1
  Interface 1: Alt=10 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=4992 Interval=1
  Interface 1: Alt=11 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=5116 Interval=1
  Interface 2: Alt=0 nEP=0 Class=1(Audio) SubClass=1 Protocol=0 StringIx=0
  Interface 3: Alt=0 nEP=0 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0
  Interface 3: Alt=1 nEP=1 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0
  Interface 3: Alt=2 nEP=1 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0
  Interface 3: Alt=3 nEP=1 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0

Regards

[Remy]

Hi Wim,

It works nice since.

Regards
Rémy

Hi Rémy,

Fine. In the meantime I have updated webcam.exe and wmaudio.exe and added  wmvideo.exe and I think my package is now complete.
I think I tested it with your wcc.exe but I don't remember. My memory is getting worse. I have attached it here so Martin could try these too.

@Martin - Use "webcam /n" to start the Webcam Server and use "wmvideo /n" to start the Webcam Monitor Video and see what you get.

Regards,
Wim

Hi Wim,

This latest build has always 48000Hz audio output !
I went back to the previous build which allow me to set 44100Hz

Regards
Rémy

My latter build takes the audio sample frequency specified by the user and validates it against the usb audio descriptors of the webcam. Logitech c250/c270/pro9000 webcams do not support 44100 Hz. according to their audio descriptors and since the last scanned audio descriptor specifies 48000 Hz. this frequency is used. Similarly 16000 Hz. will be used by the Logitech Quickcam Pro for Notebooks because this is the only audio frequency that this webcam reports supported. This latter build is supposed to work with audio from all kinds of uvc compliant webcams.

On the contrary my former build takes the audio sample frequency specified by the user and validates it using a list of hardcoded values that work with the Logitech c250/c270/pro9000 webcams and this list includes 22050 Hz. and 44100 Hz. that happen to work on these webcams despite of the fact that their usb audio decriptors omit these. Scanning of usb audio descriptors was not yet implemented but that is really the way to go.

I checked my c270 under windows.
It supports 16bits 16000Hz, 16bits 32000Hz and 16bits 48000Hz
right, 44100 isn't listed (despite it works well) - 16000, 32000 and 48000 are real selectable frequencies.
Are they available ? (I always get 48000 as output)

Regards
Rémy     

[Wim Brul]

Hi Martin,

I wanted to test any kind of sound from my USB Webcam - Logitech C920 HD Pro Webcam
I'm using "Webcam00-20210120.zip" and Lar's USBAUDIO.

Please attach lsusb report of this camera for me to inspect.

Hi

I have a strange behavior with lsusb (lsusb-20130526.zip) with this device. If I don't plug the camera, I get the normal report. If I plugged the camera, I get no report at all from any device. Even that  "webcam /n" is working fine to see video from the webcam.

Any other tip to get the USB hardware report?

Regards

Perhaps you encountered 0000680: lsusb not working again?

[Wim Brul]

Hi Wim,

It works nice since.

Regards
Rémy

Hi Rémy,

Fine. In the meantime I have updated webcam.exe and wmaudio.exe and added  wmvideo.exe and I think my package is now complete.
I think I tested it with your wcc.exe but I don't remember. My memory is getting worse. I have attached it here so Martin could try these too.

@Martin - Use "webcam /n" to start the Webcam Server and use "wmvideo /n" to start the Webcam Monitor Video and see what you get.

Regards,
Wim

Hi Wim,

This latest build has always 48000Hz audio output !
I went back to the previous build which allow me to set 44100Hz

Regards
Rémy

My latter build takes the audio sample frequency specified by the user and validates it against the usb audio descriptors of the webcam. Logitech c250/c270/pro9000 webcams do not support 44100 Hz. according to their audio descriptors and since the last scanned audio descriptor specifies 48000 Hz. this frequency is used. Similarly 16000 Hz. will be used by the Logitech Quickcam Pro for Notebooks because this is the only audio frequency that this webcam reports supported. This latter build is supposed to work with audio from all kinds of uvc compliant webcams.

On the contrary my former build takes the audio sample frequency specified by the user and validates it using a list of hardcoded values that work with the Logitech c250/c270/pro9000 webcams and this list includes 22050 Hz. and 44100 Hz. that happen to work on these webcams despite of the fact that their usb audio decriptors omit these. Scanning of usb audio descriptors was not yet implemented but that is really the way to go.

I checked my c270 under windows.
It supports 16bits 16000Hz, 16bits 32000Hz and 16bits 48000Hz
right, 44100 isn't listed (despite it works well) - 16000, 32000 and 48000 are real selectable frequencies.
Are they available ? (I always get 48000 as output)

Regards
Rémy   

Content of xhprobe.cmd:

Code: [Select]

ffprobe -show_streams -v quiet -i \PIPE\Webcam\Audio > xhprobe.txt

When I use "webcam /a16000' and I check the audio stream with "xhprobe" then xhprobe.txt shows that the audio stream is indeed 16000 Hz. (sample_rate=16000). This way I checked 16000, 24000, 32000, 48000 Hz. and these all work alright with my logitech c250 camera.  I also checked 22050, 44100 Hz. and  these default to 48000 Hz. so everything works as designed.  When you are always getting 48000Hz. then I suspect you are not passing the proper /aN value.

[Remy]

Hi Wim,

I have a few questions about parameter /f and fps :   

webcam allows to set
/fN - Select Nth discrete frame interval setting for video.
 Proper values for N are 0 up to the highest setting available on your webcam.

Do you know how to get available setting for a webcam ?
I expect getting a discrete frame interval value for each supported fps
Is there a link between the value 0 to n and the supported fps from highest to lowest ?

Test show me that the bitrate is reduced when increasing the n value for /f parameter
I didn't notice any real quality degradation when using /f2 which provides a very smaller output file.   

For all resolution, I always have 25fps for my webcam into ffprobe output.
Are any parameters on webcam to set a different supported fps for a given frame size ?

Thanks
Rémy 
 

[Wim Brul]

Hi Rémy,

Hi Wim,

I have a few questions about parameter /f and fps :   

webcam allows to set
/fN - Select Nth discrete frame interval setting for video.
 Proper values for N are 0 up to the highest setting available on your webcam.

Do you know how to get available setting for a webcam ?
I expect getting a discrete frame interval value for each supported fps
Is there a link between the value 0 to n and the supported fps from highest to lowest ?

Let me try and explain how it works using your logitech c270 webcam. Suppose that you want to obtain 640x480 mjpg video with the default frame rate. You would then use the /f0 parameter (or you would just omit that parameter altogether) and webcam.exe obtains the dwDefaultFrameInterval value for that video format from the usb descriptors. Since dwDefaultFrameInterval=333333, which means 33.3333 milliseconds, this results into 30 frames per second aka 30 fps. When you would use /f2 then webcam.exe obtains dwFrameInterval(2)=500000 which results into 20 fps. The mapping is given by the usb descriptors and lsusb is your friend.

Note that the actual frame rate as experienced by the client could be lower than the frame rate at which webcam.exe obtains video frames from your webcam. When the client is not fast enough in obtaining frames from webcam.exe then webcam.exe will drop frames. When the client is much faster than webcam.exe then it will be waiting in webcam.exe for the next frame to become available.

Test show me that the bitrate is reduced when increasing the n value for /f parameter
I didn't notice any real quality degradation when using /f2 which provides a very smaller output file.   

For all resolution, I always have 25fps for my webcam into ffprobe output.
Are any parameters on webcam to set a different supported fps for a given frame size ?

Thanks
Rémy

Yes, higher values of N for the /fN parameter result into lower frame rates.

It seems to me that ffprobe does not measure the actual frame rate.

Wim

[Remy]

Thanks Wim for this clear explanation.
Because I was monopolized trying to use ffprobe only, I missed to check its results.
I'll check result out of lsusb to adjust my ffmpeg parameters (I found very nice tips to have a very good syncronized video, some changed parameters on the string cmd I recently posted and "no" latency when using a control video during recording in copy mode)
With the correct info from lsusb, I'll be able to set correctly ffmpeg -time_base values of the recorded video which is always incorrect (preventing video/audio process) except if set using some parameters (e.g. -r but not alone or -time_base to set all timebase values)

Thanks
Regards

Have already made big progress under new AVxCAT V2 code (big amount of changes and additions)
(webcam audio recording finalized, now finalizing video + audio recording includong optional small ffplay video (only) to control what's recorded)

[Remy]

I forgot that lsusb worked only a few times and since, it never worked again.

[Wim Brul]

Hi Martin,

I wanted to test any kind of sound from my USB Webcam - Logitech C920 HD Pro Webcam
I'm using "Webcam00-20210120.zip" and Lar's USBAUDIO.

Please attach lsusb report of this camera for me to inspect.

Hi

I took this log with testlog, but I'm not sure if that is what you need Wim.

Code: [Select]

Device 1:
  ctrlID=1 DevAdr=2 ConfigVal=0 IfNo=0 Speed=2 Port=1 HubIx=3
  USB Release number=0x200 DevReleaseNumber=0x11
  Class=239 SubClass=2 Protocol=1 MaxPacketSize=64
  Vendor:Product=046d:082d NumConfigurations=1 Logitech, Inc. HD Pro Webcam C920
  Configuration: NumInterfaces=4 ConfigValue=1 StringIx=0 Attr=0x80 MaxPower=250
  Interface 0: Alt=0 nEP=1 Class=14(Video) SubClass=1 Protocol=0 StringIx=0
  Endpoint: Adr=0x83 Attr=0x3 MaxPktSize=64 Interval=8
  Interface 1: Alt=0 nEP=0 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Interface 1: Alt=1 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=192 Interval=1
  Interface 1: Alt=2 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=384 Interval=1
  Interface 1: Alt=3 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=512 Interval=1
  Interface 1: Alt=4 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=640 Interval=1
  Interface 1: Alt=5 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=800 Interval=1
  Interface 1: Alt=6 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=944 Interval=1
  Interface 1: Alt=7 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=2688 Interval=1
  Interface 1: Alt=8 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=2848 Interval=1
  Interface 1: Alt=9 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=3040 Interval=1
  Interface 1: Alt=10 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=4992 Interval=1
  Interface 1: Alt=11 nEP=1 Class=14(Video) SubClass=2 Protocol=0 StringIx=0
  Endpoint: Adr=0x81 Attr=0x5 MaxPktSize=5116 Interval=1
  Interface 2: Alt=0 nEP=0 Class=1(Audio) SubClass=1 Protocol=0 StringIx=0
  Interface 3: Alt=0 nEP=0 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0
  Interface 3: Alt=1 nEP=1 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0
  Interface 3: Alt=2 nEP=1 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0
  Interface 3: Alt=3 nEP=1 Class=1(Audio) SubClass=2 Protocol=0 StringIx=0

Regards

Hi Martin,

The information in the testlog is not sufficient. So I googled once more and I found an lsusb report of the Logitech HD Pro Webcam C920. This shows that the builtin microphones  of that webcam deliver 16000/24000/32000 Hz. 16-bit stereo. When you start "webcam.exe /a24000" and also start "wmaudio /a1 /v30" then the audio of your webcam will be reproduced by the 1st audio adapter in your system when that adapter is capable of reproducing 24000 Hz 16-bit stereo.

Regards,
Wim

[Martin Iturbide]

Hi Wim

This is what I get:

webcam.exe /a24000:

Code: [Select]

[X:\HOME\DOWNLOADS\WEBCAM00-20210120]webcam.exe /a24000
started.
format:mjpg
 acquire webcam
 set configuration
 negotiate video format
/a server (audio) On-Line.
 obtain video format
 commit video format
 set video alt interface
 set audio frequency
 starting iso video
 set audio mike volume
 set audio alt interface
 starting iso audio
[00000057]
obtain audio error.
wmaudio /a1 /v30

[X:\HOME\DOWNLOADS\WEBCAM00-20210120]wmaudio /a1 /v30
started.
 opening audio input pipe
 opening ampmixer device
 informing dart being used
 allocating dart buffers
 creating event semaphore
 setting ampmixer volume

Is it supposed to be enabled there?

If I try record.exe

Code: [Select]

[X:\HOME\DOWNLOADS\AUDREC02]record /a1
started.
 opening ampmixer device
 informing dart being used
 allocating dart buffers
 creating event semaphore
 opening audio output file
 writing audio output file
[00000280]
 writing audio output file
 closing audio output file
 closing event semaphore
 deallocating dart buffers
 informing dart use ended
 closing ampmixer device
stopped.

No way to record audio yet.

I don't know what "strange mood"  does this webcam produce that I can not produce the USB report, not with lsusb and not with "USB Device Monitor". 

Regards