Re: dvgrab wait for device

On Mon, Jun 29, 2009 at 9:59 PM, Carl Karsten<[email protected]> wrote:
> On Mon, Jun 29, 2009 at 7:52 PM, Dan Dennedy<[email protected]> wrote:
>> On Mon, Jun 29, 2009 at 11:16 AM, Carl Karsten<[email protected]> wrote:
>>> On Mon, Jun 29, 2009 at 12:41 PM, Dan Dennedy<[email protected]> wrote:
>>>> On Mon, Jun 29, 2009 at 7:35 AM, Carl Karsten<[email protected]> wrote:
>>>>> if there is no device when dvgrab is first run, it aborts.  Yet if it
>>>>> is streaming I can unplug the device and plug it back in, and the
>>>>> stream continues.  If there were some way to get dvgrab to just wait
>>>>> for a device, that would be great.  Or if someone can replace the
>>>>> execvp(dvgrab with the C code from dvgrab... then I can take that off
>>>>> my list of things to look into :)
>>>>
>>>> Hmm, well, there can be multiple Firewire buses on your system, and
>>>> dvgrab looks for a device across all the buses to see which bus to
>>>> use, which is required to acquire a  libraw1394 handle. You would have
>>>> to add some loop around that with a limited retry.
>>>
>>> Would it help if this was limited to being told what -card was in use?
>>>  or guid, or something to avoid the scan?
>>
>> It should work today using -card and -noavc, but it will time out
>> waiting for DV after 10 seconds. Thiis timeout is a feature. Do you
>> need AV/C
>
> Nope.  one of the args is:
>    *argp++ = "-noavc";
>
>>  and what do you want to do about this timeout?
>
> how about
> --timeout 0
>
> Looks ilke this is the place...  tomorrow I will take a shot at tweaking it.
>
>
>        // Wait up to N seconds to see if we got any data
>        // this is a little unclean, checking global g_done from
> main.cc to allow interruption
>        while ( !g_done && m_frame == NULL && tryCounter-- > 0 )
>        {
>                timespec t = {0, 25000000L};
>                nanosleep( &t, NULL );
>        }
>
>        // OK, we have data, commence capture
>        if ( !g_done && m_frame )
>        {
>                sendEvent( "Capture Started" );
>                m_captureActive = true;
>                m_total_frames = 0;
>
>                // parse the SMIL time value duration
>                if ( m_timeDuration == NULL && ! m_duration.empty() )
>                        m_timeDuration = new SMIL::MediaClippingTime(
> m_duration, m_frame->GetFrameRate() );
>
>                if ( m_dst_file_name )
>                        pthread_mutex_unlock( &capture_mutex );
>        }
>
>        // No data received in N seconds, throw an error
>        else if ( !g_done )
>        {
>                if ( m_dst_file_name )
>                        pthread_mutex_unlock( &capture_mutex );
>                const char *err = m_hdv ? "no HDV. Try again before
> giving up." : "no DV";
>                if ( m_hdv )
>                        reset_bus( m_port );
>                throw std::string( err );
>        }
>        else
>        {
>                if ( m_dst_file_name )
>                        pthread_mutex_unlock( &capture_mutex );
>        }

skipped trying to figure out how to add parameters (and given the 10
second time out isn't documented, does it really have to be kept?)

This may to do what I need:

-while ( !g_done && m_frame == NULL && tryCounter-- > 0 )
+while ( !g_done && m_frame == NULL )

Now to see how dvswitch works with this.

-- 
Carl K

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