Hi All,
I am trying to implement a video device that gets data externally. The
external data comes via a library with a callback at 25 fps.
Copying the colorbar example, I see that there is the option of Active or
Passive mode for the video device. As I understand it: Passive mode has
pjsip provide the clock for the device, whereas Active mode has the device
create its own clock, and it calls stream->vid_cb.capture_cb when it has
data available. This is switched on/off via the "has_callback" option.
This seemed to be pretty straight forward until I noticed that the encoder
seems to be getting frames seemingly from nowhere, e.g. when I explicitly
do not call the callback function from the video device.
It seems that there is some logic in vid_port.c around this - e.g. in the
function enc_clock_cb there is the following statement:
/* We are here because user wants us to be active but the stream is
* passive. So get a frame from the stream and push it to user.
*/
This seems to suggest that the active role is overridden for some reason. I
am having a hard time following the logic through, or at least the
reasoning behind it.
Can anyone explain why I still get frames sent to the encoder when I am not
pushing them from the video device callback? Is this a bug, intended
functionality or a misunderstanding on my part?
Thanks,
Brian.
Hi All,
I am trying to implement a video device that gets data externally. The
external data comes via a library with a callback at 25 fps.
Copying the colorbar example, I see that there is the option of Active or
Passive mode for the video device. As I understand it: Passive mode has
pjsip provide the clock for the device, whereas Active mode has the device
create its own clock, and it calls stream->vid_cb.capture_cb when it has
data available. This is switched on/off via the "has_callback" option.
This seemed to be pretty straight forward until I noticed that the encoder
seems to be getting frames seemingly from nowhere, e.g. when I explicitly
do not call the callback function from the video device.
It seems that there is some logic in vid_port.c around this - e.g. in the
function enc_clock_cb there is the following statement:
/* We are here because user wants us to be active but the stream is
* passive. So get a frame from the stream and push it to user.
*/
This seems to suggest that the active role is overridden for some reason. I
am having a hard time following the logic through, or at least the
reasoning behind it.
Can anyone explain why I still get frames sent to the encoder when I am not
pushing them from the video device callback? Is this a bug, intended
functionality or a misunderstanding on my part?
Thanks,
Brian.
