Re: [Bino-list] Possible to use two v4l2 inputs?

[Goetz Dapp]

Hi Martin!

On 05/01/2012 01:47 AM, Martin Lambers wrote:
> Hi Goetz!
>
> On Mon, 30 Apr 2012 10:29:17 -0600, Goetz Dapp wrote:
>> Hi Martin and others,
>>
>> On 04/08/2012 01:53 PM, Martin Lambers wrote:
>>> Hi Götz!
>>>
>>> On Sun, 08 Apr 2012 13:30:49 -0600, Götz Dapp wrote:
>>>>> The latest version now has an option --device-format to request
>>>>> MJPEG format, and the GUI "Open device" dialog was improved to
>>>>> allow opening two devices and requesting MJPEG format.
>>>>>
>>>>> Can you test this?
>>>> just tested it, it works just fine! Thanks so much!
>>> Thanks for testing!
>>>> Just out of curiosity: is there any way to record the bino output
>>>> stream?
>>> No, currently everything in Bino assumes that media is read-only.
>>> Adding encoding support would require serious work and would add
>>> *lots* of complexity. I'd rather keep things simple and keep Bino a
>>> video player only. Encoding/transcoding of stereoscopic video is
>>> probably best left to a dedicated tool.
>>>
>>> Best regards,
>>> Martin
>> I have a question regarding ffmpeg - realize this is not an ffmpeg
>> mailing list, and apologize in advance. But given your expertise you
>> might be able to give me a quick hint how to resolve it, particularly
>> since you managed to convince ffmpeg in Bino to capture in MJPEG
>> somehow (which the camera natively supports). Since Bino does not do
>> "capture," I have been trying to directly capture a stream, but
>> failed miserably - and I have not been able to figure out where I am
>> going wrong.
>>
>> Essentially I am trying to record a stream from a webcam in the size
>> 1280x720 at 30fps directly in MJPEG without any conversion.
>>
>> Could you give me a hint how to write me a quick command line command
>> that does that? Maybe with an visual output, too? I.e. it writes it to
>> the file but also displays what it is recording? If that does not
>> work, just writing the file would suffice, too.
>>
>> I have tried the following command, but only get garbled stuff...
>>
>> ffmpeg -an -f video4linux2 -s 1280x720 -b 2000k -r 30 -i /dev/video0
>> -vcodec mjpeg /test.avi
>>
>> I apologize for my lack of understanding and thank you all in advance,
> The way I did this in Bino is to use a 'private option' for the v4l2
> device. You can see the supported private options with 'ffmpeg --help';
> look for "V4L2 indev AVOptions". It seems you should try '-input_format
> mjpeg' instead of '-vcodec mjpeg'. You can also request framerate and
> frame size using these private options.
>
> So the following might work:
>
> ffmpeg -f video4linux2 -framerate 25 -video_size 640x480
> -input_format mjpeg -i /dev/video0 /tmp/test.avi
>
> Martin

Thanks, this is a great start and helped me a lot! Congrats on the new
release by the way, this is awesome!

Goetz