[Ffmpeg-devel] Re: [PATCH] Configure selectable video grab format

Ramiro Polla angustia
Wed Jan 31 18:17:31 CET 2007

Michel Bardiaux wrote:
> Ramiro Polla wrote:
>> Ramiro Polla wrote:
>>> Michel Bardiaux wrote:
>>>> M?ns Rullg?rd wrote:
>>>> [snip]
>>>>> That said, I don't like the design of the grabbing code at all.  
>>>>> IMHO it would
>>>>> be much cleaner to simply run ffmpeg -f v4l2 -i /dev/video0 or 
>>>>> whatever,
>>>>> dropping the whole concept of a default grabbing device used if no 
>>>>> input is
>>>>> specified.
>>>> FWIW I agree.
>>> Me too =).
>>> The code for using a default grabbing device is really buggy (the 
>>> grabbing interfaces depend on what has been set for output).
>> It seems this would be just removing a bunch of redundant code (like 
>> Michael said), and making few adaptations to the existing -i code.
>> One problem with -i <grab device> is when you want to use the default 
>> grab device. This could be accomplished by (some suggestions):
>> a) using the '-' character
> Please dont, '-' generally means stdin. AAMOF ffmpeg -i - < 
> /dev/video0 *should* work as expected.
Generally as in POSIX programs, or FFmpeg? (Sorry to ask. I searched a 
little, but it's quite hard to google for "-")
>> b) making -grab mean -i <default device>.
> Why do you insist on having a default grab device?
First I wanted to set the default grab *format* (as is what currently 
happens in FFmpeg). Now I'm talking about default grab *device*.
It would be nice to have default devices since most grab interfaces have 
a widely used device (like /dev/bktr0, /dev/tuner0, /dev/video0...)
And for the VFW grab interface I'm writing, the devices are set by a 
number (0-9), 0 meaning default.

Ramiro Polla

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