[FFmpeg-devel] [PATCH] handle EAGAIN case in ffmpeg.c

[Benoit Fouet]

Luca Abeni wrote:
> Hi Benoit,
>
> Benoit Fouet wrote:
>   
>> here is a patch to $subj
>>
>> what i'm trying to do is having v4l2 working
>>     
>
> Unless something broke in the last two or three weeks, v4l2 should be 
> already working... What's the problem you are seeing?
>   

shouldn't the DQBUF return EAGAIN when it has no frame available ?

> (I remember v4l2.c had problems with some v4l2 drivers returning 
> timestamps always equal to 0... But that's a bug in the driver, not in 
> ffmpeg)
>
>   

i'll check that

> I'll test it this night with latest svn, just to check if something 
> strange happened in the last weeks...
>
>   
>> this raises a question to me: how can we wait for the driver to give us
>> a frame. I think we should wait somewhere, depending on the framerate we
>> want.
>>     
> The way is currently works is that the v4l2 input format blocks until 
> there is an available frame (unless you specify the 
> AVFMT_FLAG_NONBLOCK... In that case you have to modify ffmpeg.c)
>
>   

i thought the DQBUF was always a non blocking ioctl, isn't it the case ?

> Regarding your patch: as far as I understand, with the current code you 
> should never receive EAGAIN as a result (because AVFMT_FLAG_NONBLOCK is 
> not used). So, I think this patch is not needed.
>
>   

ok

-- 
Ben
Purple Labs S.A.
www.purplelabs.com