How broken is the em28xx driver?

How broken is the em28xx driver?

[Alexandre-Xavier L-L]

Hi everyone,

Is it just me or every device that I try doesn't work. Here's a list,
they all use the em28xx driver.

Ion video 2 pc
Plextor ConvertX PX-AV100U
Startech SVID2USB23

Video of the results: https://www.youtube.com/watch?v=wgQKziHupkI

I have even tried a August VGB100 which doesn't use the em28xx driver
and it doesn't work too.

I have already posted on the mailing list about these issues relating
to the interlaced signal, but it's the first time that I try with a
progressive signal. Although the results are better, I cannot qualify
it as something that is working.

Is the development of the em28xx driver still going on? I would like
to know which alternative driver that I could use or which would be
the step that I could do to fix the driver (I don't have a lot of
knowledge about it). I can even mail one of my devices to somebody who
is willing to fix the em28xx driver.

Sorry if I insulted anyone by saying that the em28xx is broken, but I
have the impression that it doesn't work and that it won't ever work
with any device because they may be too much defects that prevent it
from working correctly. It could have worked before (I have seen a
video from 2013 where it did), but maybe there were regressions and no
one noticed it broke. I can't install old git releases because they
are not compatible with newer kernels.

Regards,
Alexandre-Xavier

Re: How broken is the em28xx driver?

[Mauro Carvalho Chehab]

Hi Alexandre,

Em Fri, 24 Feb 2017 04:09:42 -0500
Alexandre-Xavier L-L <axdoomer@gmail.com> escreveu:

> Hi everyone,
> 
> Is it just me or every device that I try doesn't work. Here's a list,
> they all use the em28xx driver.
> 
> Ion video 2 pc
> Plextor ConvertX PX-AV100U
> Startech SVID2USB23
> 
> Video of the results: https://www.youtube.com/watch?v=wgQKziHupkI
> 
> I have even tried a August VGB100 which doesn't use the em28xx driver
> and it doesn't work too.
> 
> I have already posted on the mailing list about these issues relating
> to the interlaced signal, but it's the first time that I try with a
> progressive signal. Although the results are better, I cannot qualify
> it as something that is working.
> 
> Is the development of the em28xx driver still going on? I would like
> to know which alternative driver that I could use or which would be
> the step that I could do to fix the driver (I don't have a lot of
> knowledge about it). I can even mail one of my devices to somebody who
> is willing to fix the em28xx driver.
> 
> Sorry if I insulted anyone by saying that the em28xx is broken, but I
> have the impression that it doesn't work and that it won't ever work
> with any device because they may be too much defects that prevent it
> from working correctly. It could have worked before (I have seen a
> video from 2013 where it did), but maybe there were regressions and no
> one noticed it broke. I can't install old git releases because they
> are not compatible with newer kernels.

The em28xx driver works fine. It is actually one of the drivers I
use most when testing something, as I have a lot of those devices
(although I don't have the specific models you have).

That said, the green bar on your video usually happens on two
situations:

1) If you have a PAL input, but you're capturing video at NTSC;
2) When there's not enough bandwidth at the USB bus for the video.

Analog TV capture, at 640x480, usually consumes 60% of the available
bandwidth for ISOC frames on a USB 2.0 bus. Maybe you don't have
enough bandwidth, or your USB controller is broken.

Ah, one last thing that occurs to me: some domestic RF generators
found on video games and on other CEC electronics sometimes produce 
outputs that don't quite follow the TV standard defined by ITU-R, 
causing troubles for analog TV decoders to identify it. Maybe
that's the case. If so, try to capture from some other video
source.

Thanks,
Mauro

Re: How broken is the em28xx driver?

[Alexandre-Xavier L-L]

Hi Mauro,

You're right, I forgot to set the region.

I discovered that the Ion Video 2 PC does work with my portable DVD
player and my ATSC TV broadcast to analog NTSC box for antenna
television. I see interlacing in the video, but I don't know if the
signal sent to the Ion Video 2 PC is interlaced, because it may just
be an interlaced video converted to progressive without any filters.

It still doesn't work with old video game consoles, but it's a bug
with the em28xx driver because it works on Windows. The way to "fix"
it is to comment the line that you've told me about a while ago in
"em28xx-video.c":

//if (dev->board.is_webcam)
    v4l2->progressive = true;

This would make the video work, but only in the upper half of the
screen (with a green bar at the bottom half). From what I understand,
one of the two interlaced fields is not displayed.

Do you know how to fix this issue?

Thank you,
Alexandre-Xavier


On Fri, Feb 24, 2017 at 4:43 AM, Mauro Carvalho Chehab
<mchehab@s-opensource.com> wrote:
> Hi Alexandre,
>
> Em Fri, 24 Feb 2017 04:09:42 -0500
> Alexandre-Xavier L-L <axdoomer@gmail.com> escreveu:
>
>> Hi everyone,
>>
>> Is it just me or every device that I try doesn't work. Here's a list,
>> they all use the em28xx driver.
>>
>> Ion video 2 pc
>> Plextor ConvertX PX-AV100U
>> Startech SVID2USB23
>>
>> Video of the results: https://www.youtube.com/watch?v=wgQKziHupkI
>>
>> I have even tried a August VGB100 which doesn't use the em28xx driver
>> and it doesn't work too.
>>
>> I have already posted on the mailing list about these issues relating
>> to the interlaced signal, but it's the first time that I try with a
>> progressive signal. Although the results are better, I cannot qualify
>> it as something that is working.
>>
>> Is the development of the em28xx driver still going on? I would like
>> to know which alternative driver that I could use or which would be
>> the step that I could do to fix the driver (I don't have a lot of
>> knowledge about it). I can even mail one of my devices to somebody who
>> is willing to fix the em28xx driver.
>>
>> Sorry if I insulted anyone by saying that the em28xx is broken, but I
>> have the impression that it doesn't work and that it won't ever work
>> with any device because they may be too much defects that prevent it
>> from working correctly. It could have worked before (I have seen a
>> video from 2013 where it did), but maybe there were regressions and no
>> one noticed it broke. I can't install old git releases because they
>> are not compatible with newer kernels.
>
> The em28xx driver works fine. It is actually one of the drivers I
> use most when testing something, as I have a lot of those devices
> (although I don't have the specific models you have).
>
> That said, the green bar on your video usually happens on two
> situations:
>
> 1) If you have a PAL input, but you're capturing video at NTSC;
> 2) When there's not enough bandwidth at the USB bus for the video.
>
> Analog TV capture, at 640x480, usually consumes 60% of the available
> bandwidth for ISOC frames on a USB 2.0 bus. Maybe you don't have
> enough bandwidth, or your USB controller is broken.
>
> Ah, one last thing that occurs to me: some domestic RF generators
> found on video games and on other CEC electronics sometimes produce
> outputs that don't quite follow the TV standard defined by ITU-R,
> causing troubles for analog TV decoders to identify it. Maybe
> that's the case. If so, try to capture from some other video
> source.
>
> Thanks,
> Mauro